audiofools...maybe not so much - Page 1
Forum section: electronics / general

author: ampdoctor
author_rank: Frequent Contributor
timestamp: February 04, 2014, 06:26:46 am
content: Ok, now that I've got your attention, the past few days I've been doing some investigations into psychoacousics and stumbled across something interesting. What I found was something called ASMR and it seems to be some serious lizard brain stuff. To quote wikipedia...Autonomous sensory meridian response (ASMR) is a neologism for a perceptual phenomenon characterized as a distinct, pleasurable tingling sensation in the head, scalp, back, or peripheral regions of the body in response to visual, auditory, olfactory, and/or cognitive stimuli. The nature and classification of the ASMR phenomenon is controversial. Tom Stafford, a professor at the University of Sheffield, says, "It might well be a real thing, but it's inherently difficult to research."A large part of this phenomenon seems to involve people experiencing a sense of relaxation as a result of hearing different "trigger sounds". Usually these include soft whispering, clicking noises, crinkling paper, hands rubbing across cloth, etc. The commonality among these things are that they're all sounds with very high frequency harmonic components.What I'm going to posit is that many audiophiles may be hyper-sensitive to sounds at the limits of human hearing in the higher frequency ranges. If there's even the slightest amount of ringing on the supply rails or very high order harmonic or IMD products, is it possible that they may be picking up on this and creating a sense of relaxation or agitation depending on the specifics of the content? So when these paleolithic emotions get triggered it's possible that they could be making a subconscious qualitative instead of quantitative decision about the goodness (relaxation), or badness (tension) of the sounds they're hearing.What I would like to hear are some thoughts, observations or comments on this subject with as little audiophile bashing as possible because there may be something going on here that we may be missing. In particular, I'm hoping for an interesting discussion of psycoacousics, and the percieved limits of human sensory experience.

author: hamster_nz
author_rank: Super Contributor
timestamp: February 04, 2014, 07:16:18 am
content: I am convinced that 99% of it is psychological due to expectations.My test subject is me. I've been debugging a project - Stereo Line In -> 24bit ADC -> FPGA -> Stereo 24bit DAC.I had four settings1) Out <= In2) Out <= Low_Pass_FIR_Filter(In);3) Out <= High_Pass_FIR_Filter(In)4) Out <= Low_Pass_FIR_Filter(In) + High_Pass_FIR_Filter(In)I was convinced that there was a bug in my code - I could hear a subtle difference between setting 1 & setting 4.I've spent along time tracking down the bug, but eventually had to admit that I was only hearing the difference because I expected it to have a bug. The math and simulation left no doubt - the two sample streams were identical.As soon as I convinced myself that the output was bit-for-bit identical, they then started to sound the same!So, much like differences in the tastes of wines. People expect a wine to taste a certain way, so they do. However I am sure that when given a glass of wine without knowing the accepted description for it even an experienced taster will fail badly to identify it. They haven't "tuned in" to the taste of wine, but have been given the expectation of the experience.However given the THD figures for the last device in the chain I can't see why people worry about 0.02% vs 0.01% in an Amp - but if anybody wants two pay for an FIR based all digital crossover, with zero phase shift, with S/PDIF in to 2xS/PDIF out, allowing you to bi-amp your speakers, control the crossover frequency and slope and completely remove the crossover, then come see me.

author: AndyC_772
author_rank: Super Contributor
timestamp: February 04, 2014, 07:47:44 am
content: I went to a hi-fi show some years ago, and a couple of things stood out:- the range of styles of music being demonstrated was extremely limited, and- the vast majority of visitors were middle-aged and older men; the demographic which tends to have theworsthearing, especially at the top end of the frequency range.On that basis I can well believe that a certain group of people derive pleasure from hearing certain sounds, and that those sounds might indeed be quite specific. But that's OK, everyone is entitled to enjoy listening to their own choice of music. I certainly do.That said, most audiophoolery - by definition - has nothing to do with techniques which could actually influence the sound coming from the speakers, at any part of the frequency range. It's all about technical terms being misused (intentionally or otherwise) to mislead potential customers into believing that a certain product might make their equipment sound better.

author: ampdoctor
author_rank: Frequent Contributor
timestamp: February 04, 2014, 08:05:09 am
content: Oh, I'm absolutely certain there is no shortage of psychological expectations of a perceived change. I had a client one time who without question could hear a difference in the sound of an amplifier due to the position of a switch. Even when I told him it wasn't connected to anything and just there to fill the hole he STILL heard the difference. Crazy huh?!I'd say this observation is valid for 99% of the population. The ones that get me curious are the 1% who actually can hear the difference between capacitor types or in my personal experience the difference between brands of transducer coils. Out of curiosity i ran a blind test on this guy and EVERY SINGLE TIME he got it right. The guy was a freak of nature! People like that are the ones that tell me there may be something more going on than meets the eye.We have to remember that when we look at things like the Fletcher-Munson curves these are based on actuarial data. More recently Robinson and Dadson repeated the experiments and came up with somewhat different results. There's no question that there are some people that exist on the statistical tails of those results. There's also a fair amount of experimentation that's been done in the field of listener fatigue which suggest that there's a noticeable psychological effect in people when distortion products are introduced to otherwise "clean" program material.

author: AndyC_772
author_rank: Super Contributor
timestamp: February 04, 2014, 08:26:51 am
content: I don't find it at all difficult to believe that swapping one coil for another could actually change the response of the transducer, though. Not by much, perhaps, if they're both produced with close tolerances to the exact same design, but it's not implausible that the frequency response and distortion could be affected.Compare and contrast with green marker pen / rocks / gold plated mains plugs etc.

author: ampdoctor
author_rank: Frequent Contributor
timestamp: February 04, 2014, 08:51:09 am
content: There's clearly no shortage of audio"phools" floating around who truly believe that if you dance around the room at midnight and wave a chicken foot over you stereo and put a granite pebble 20 degrees off axis on the northwest side of your power amplifier you'll have amazing sounding audio. Those people are completely delusional. Like I said though, the one's that interest me are those that appear to have a testable and almost extra-senory perception of audio.As an interesting aside; people do not see the world in 3-D. We actually see in 2-D and our brains make the necessary adjustments accordingly. Something similar can be said for audio. We don't hear in stereo! We actually hear in mono. And again our brains compensate due to the loudness perceived in the left vs the right ear, phase shifts, etc, to give us a different sense of our surroundings.And yes, these were two brand spanking new reverb tanks for a Fender guitar amplifier. Same specs, same manufacturer. Identical in every conceivable way. What got me going with him was that he came in with a new tank that he didn't like the sound of. Said it was wrong somehow and wanted me to scrounge up a NOS tank. I was like come on you've got to be kidding me?! So I did an informal test with two accutronics tanks and every single time... BINGO, he knew it! By conventional wisdom it should have been insignificant, especially with a reverb tank that's used as nothing more than a mechanical delay line. Since then I've never dismissed anything off hand.Animals can detect earthquakes days before they happen, birds can follow magnetic field lines during migration, seals can select their pups out of the cries of hundreds at the same time. In the animal kingdom we've observed outrageously bizarre things, yet when somebody says they can hear the difference between capacitors, near identical pcb layouts, or some other thing, we blow it off and say mehh, it's just psychological. Maybe not!

author: con-f-use
author_rank: Unknown
timestamp: February 04, 2014, 09:27:56 am
content: So you are basing your wild theory on a yet unproven, controversial hypothesis in the credible field of psychoacousics. Interesting, tell me more!Quote from: ampdoctor on February 04, 2014, 06:26:46 amThat's normally code for "I think it's bullshit but its not worth my time to prove it to you". I've seen our dean of medicine saying essentially the same thing about homeopathy. I've said the same thing to people asking about astrology. It makes them go away.Even if he didn't mean it that way, even he was convinced there is a real effect, there's this: Recently the editor of Nature said, that in hindsight 50% of their articles turn out to be false. And that's probably the most renown journal in science. Science is a work in progress and has to be done carefully and tested repeatedly. Even if a professor says something and is convinced of it, it doesn't mean too much. Theories, even proven ones, have to be tested again and again in as many ways as possible. Laymen are convinced far too easily by a scientific publication.Quote from: ampdoctor on February 04, 2014, 06:26:46 amWhen I read words like "seems", "experiencing a sense" and "usually" in a paper, Iusuallystop paying attention. People should refrain from hypothesizing and look to conduct independent, statistically significant, double blinded studies every time such a question comes up. In fact there are such studies on audio encoding/compression and audio filtering. They could identify certain post-processing that makes audio sound "better" to the human ear. However even comparably cheap equipment and a high grade of compression didn't make any difference to the perceived quality.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 04, 2014, 09:30:42 am
content: Complex stimulus triggering a complex memory, highly subject and stimulus dependent. No academic merit.Special versus general case statistics. If you're building an amplifier to sell millions, you work to the average person, damned what any particular result happens to be. Average hearing response, average impressions, average everything. That maximizes the number of people to whom it gives value (generally not "value to the average person"), and therefore maximizes the quantity that can be sold. Good business.Special case. A given person might experience things differently: different frequency response, different musical genres, etc. Optimizing to this will NOT maximize value to the average person (let alone the averageconsumer), but will maximize the value to that particular person alone (and anyone who has similar stats, but that's likely to be a very small fraction out of the total market).Double blind tests. As long as 1. the change is visible to the subject and/or 2. the change is known by the person administering the test (particularly obvious if they are one in the same person!),the results ARE NOT VALID BY ANY SCIENTIFIC OR STATISTICAL MEASURE! For some reason. . . . . . double blind tests are especially frowned upon by the audiophile community. Strange, wouldn't you think? Surely those most especially interested in optimal sound (whether general or specific, as per the preceding paragraphs) would be the most excited about actually having provably ideal results! Alas, this is not the case! So one can only therefore conclude..... experience is not just audio alone, but visual, perceptive and more.There is a monstrously large market for consumer equipment -- millions of units is small potatoes -- but it demands low cost. There is a narrow market for special-purpose equipment, ranging from the professional (those who actually objectively desire and require high performance equipment) to the rich (who have money to spare and therefore simply buy the most expensive) to the 'believers' (those on the very margins of the bell curve, who desire perfection suited specifically to their taste, and who are generally willing to pay for it). On the upside, the population even on the fringes is so large (tens of thousands, easily?) that it's a market all its own (part of the "long tail"), which is statistically why audiophool/phile-ry is so visible, and significant, and insignificant, all at once.Really what it comes down to is: if a person wants to pay, say, $10,000 for an audio system that is not objectively better than a $100 system, it is their prerogative to do so. Evidently, the sheer act of 1. spending money and 2. knowing that they paid it (and can brag to others that they paid this*) can yield benefits which the pure "sound" alone cannot account for.*Which is actually an evolutionary thing. Many species have evolved physical aspects which directly contradict "survival of the fittest", in terms of sheer performance alone; features which are costly to produce, yet physically useless -- counterproductive even -- to possess. This is known as the "handicap principle". Does it make sense to spend $10,000 on an audio system that's (objectively) worth $100? Yes! It shows -- not that you can afford $10,000 worth of equipment, because it's NOT worth that -- but that you can activelywastethat money and still come out ahead! That's the mind***k that... brings the ladies, I guess?!Tim

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 04, 2014, 09:34:28 am
content: Quote from: con-f-use on February 04, 2014, 09:27:56 amPertinent;http://xkcd.com/882/Tim

author: con-f-use
author_rank: Unknown
timestamp: February 04, 2014, 10:41:00 am
content: That is all fine and good as long as people know it's just a status symbol and there's nothing to it. I have a problem with companies claiming unproven and sometimes even outrageous things to fool people into giving them money. Joe averages hears terms like psychoacustics and high frequency components stimulating the brain stem, and makes money decisions based on untested claims engineered sound sciency. That's just fraud. It gets even worse when someone calls companies on their false advertisement, and they answer with lawsuits (see Monster cables).Even freaks of nature cannot get around physics. The ear has its limits, imposed by things like scattering and dampening of sound waves at the scull, the inertia of the ossicles, the speed, fuzziness and delay in neural transmission and sheer size of the cochlea. On top of that comes electrical noise, bodily noise (blood, heartbeat, breathing, muscle tremor, joint friction) and inhomogenities in your medium of transfer. Even if one clearly underestimates these hard limits, I sometimes see claims in defiance of these hard limits.By the way I liked the point of audiophiles being mostly middle aged men who are not sensitive to higher frequencies anymore. One could argue they're not consciously sensitive anymore and there might be an other mechanism of perceiving or residual neural activity. But that would be measurable and is very unlikely.

author: Polossatik
author_rank: Frequent Contributor
timestamp: February 04, 2014, 11:33:40 am
content: Quote from: con-f-use on February 04, 2014, 10:41:00 amhum yeah, the sad thing is of course that people who realize this in general don't spend ridiculous $$$ on silly things.Had a nice chap in my "friend of friends" circle, really good bloke, then he got "serious" about audio (got somehow a big paying job, so after the BMW5 and his GF's boobjob, he needed big woofers for his new house with a big living space...).I'm a bit "the tech" in the circle so when he asked I made some suggestions / what shop to go for "better" equipment etc.All fine, he bought some nice kit.Until suddenly he started to go bananas on "correctly ionised polarised" mains cables and other stupid stuff (he discovered a "hifi forum") .He was very disappointed that i never mentioned all this wonderfull stuff to him.And if i rejected what "he clearly could hear for himself" (he ordered a ton of expensive crap to play with) as "totally without any scientific/measurement basis" then i could really not be any good at "tech stuff".

author: amyk
author_rank: Super Contributor
timestamp: February 04, 2014, 01:07:12 pm
content: I was tested a few years ago and could hear a little beyond 30KHz (it's less of a discernable tone but I can still tell whether it's present or not), but don't care for the audiophile stuff - what matters far more than the quality, is whether I enjoy the music.

author: Sigmoid
author_rank: Frequent Contributor
timestamp: February 04, 2014, 04:14:44 pm
content: Quote from: ampdoctor on February 04, 2014, 08:51:09 amWell we have two ears, so by definition we DO hear in stereo.At least the lucky majority of us.We definitely do not hear in 5.1 surround though...Quote from: ampdoctor on February 04, 2014, 08:51:09 amYou brought up musician equipment. That's an entire different beast. An effect pedal does something to the sound that's usually not straightforward to model. It adds a distortion - shifts the phase and modifies the power of harmonics. So yes, hearing the difference between two almost identical effect pedals or distortion amps is a real thing - like tasting the difference between two batches of French cheese.There's a complex taste (or distortion) there to taste (or hear).And we know the brain is really good at capturing patterns in chaotic / nonlinear input.Audiophoolery is very, very different from this. The admitted goal of high-end reproduction equipment is to reproduce the original sound, to make it as if you were there. That's a lot simpler than adding that specific, iconic flavor to the output of an electric guitar.An effect or effect amp is beautifully nonlinear - its value is in its nonlinearity. A hi-fi device is marketed for linearity. There's no human factor in linearity, it can be measured. And usually audiophool stuff does NOT stand up to measurement.Also, for the human factor, blind listening tests usually tend to debunk audiophool stuff, which shows how large an effect one's preconceptions have. More about this:http://nwavguy.blogspot.com/2011/05/subjective-vs-objective-debate.html

author: Rufus
author_rank: Super Contributor
timestamp: February 04, 2014, 04:33:32 pm
content: Quote from: ampdoctor on February 04, 2014, 06:26:46 amIf they were 'hyper-sensitve' they would have no problem detecting the presence or absence of such sounds in ABX tests.When you have some proof that audiophiles can actually rather than just claim to detect a difference then you can start positing on what the difference is and how they detect it.

author: con-f-use
author_rank: Unknown
timestamp: February 04, 2014, 04:43:14 pm
content: Quote from: ampdoctor on February 04, 2014, 08:51:09 amWe don't blow it off just like that. First of all,when was the last time, you heard your cat bragging about how well it can detect earthquakes?(I've heard stupid shit from audiophiles about how special their hearing is and how bad everyone else's is. If it's so special, why don't they make awesome music, calibrate equipment or predict earthquakes? They'd be making money instead of spending it.)The way it goes is that people observe their animals being uneasy right before an earthquake. At this point that could just be coincidence or bias. So the next step is to record statistical data.What percentage of the time is the animal uneasy with no earthquake immanent? How does it's uneasiness correlate to earthquakes? Would I have a similar prediction rate if I guessed randomly at a rate of uneasiness similar to that of the animal?Then you investigate the physical reason, in case of cats a higher sensitivity in the sensory organ responsible for balance, that is susceptible to earthquake vibrations combined with highly sensitive vibrissae in their paws. Then you test that explanation by subjecting the animal to small vibrations that precede earthquakes. And the theory is right. Who would have guessed in a predator evolved to land on its feed and move in poor lighting?- For birds its magnetide inclusions in some of their neurons that act like a crude compass combined with a good memory for landscapes, routes and star constellations.- For seals its a large variance in the scream pattern combined with good triangulation and audio processing.-For audiophiles it's magic!It's not that people blow it off. There have been studies. It's just not reproducible, not significant and has no solid underlying theory. That makes it pseudo-science which is worse than esotericism.

author: edavid
author_rank: Super Contributor
timestamp: February 04, 2014, 05:29:09 pm
content: Quote from: ampdoctor on February 04, 2014, 08:51:09 amFalse.http://en.wikipedia.org/wiki/Earthquake_prediction#Animal_behaviorQuote

author: Sigmoid
author_rank: Frequent Contributor
timestamp: February 04, 2014, 05:46:30 pm
content: Quote from: con-f-use on February 04, 2014, 04:43:14 pmLol, yes.Indeed, if you ask a musician off the street, they'll likely say reproduction equipment and quality has little or nothing to do with music itself. A beautiful piece of music will still be itself if reproduced on a bad AM radio with batteries half dead and the antenna up a llama's ass.I'd say implying that reproduction quality has something to do with the enjoyment of music is like saying that calligraphy has something to do with the quality of literature.If you can read, you'll be able to recognize a letter 'a', regardless of how it's written or printed. In music, the same thing can be said about chords and intervals.So if audiophools really have some kind of sixth sense to hear minute distortions, it's actually something deleterious to "music".("You don't want to buy Penguin Books' print of Ulysses, the serif on their lowercase l's is a far too large, and the curvature of their 's'es is all wrong. Also they use digital bitmap printing, if you want proof, check under a microscope! It just gives off a far too aggressive, dry, digital feel! No real literature enthusiast would stoop so low as to read that crap!")

author: linux-works
author_rank: Super Contributor
timestamp: February 04, 2014, 07:12:49 pm
content: most people don't have golden ears, but some actually do.I was demo'ing some audio gear (including spkrs) at a show and the spkrs were from someone else. he told me that the red/black posts may not be right. I connected it and used the spkrs anyway.one guy came by and said he thought the absolute polarity was wrong. I don't believe he was there when the spkr owner explained that to me.could it have been just a coincidence? maybe. maybe not!very few people are good 'test gear'. I know I'm not. but a select few really are!

author: con-f-use
author_rank: Unknown
timestamp: February 04, 2014, 07:26:14 pm
content: No doubt there is variation in hearing. After an ear infection I got the frequency response of my inner ear measured to make sure there was no lasting damage. Turns out I'm six sigma better than the average for lower frequencies and two sigma worse for high frequencies. In retrospect it made sense. I tend to get headaches when around large transformers and can hear when a light bulb is about to burn out. But there's no magic to that.

author: AG6QR
author_rank: Frequent Contributor
timestamp: February 04, 2014, 07:34:02 pm
content: I'm sure there are individuals with unusually acute hearing in the high frequency range. They might be able to genuinely and reliably hear certain differences that are missed by people with more average hearing.But I don't believe even the best hearing individuals have ears that outperform our best oscilloscopes and spectrum analyzers. If a difference is audible, even if only to the elite top percent of listeners, then it should be visible on properly used reasonably high quality test gear. I think a really basic old 20MHz analog oscilloscope easily outperforms even an extraordinary listener.So if a bit of gear makes an observable change to the system's frequency response, even if it's not quite audible to me, I'll grant that some people might appreciate the difference. But if it merely provides more "openness", or "presence", or "richness", or some other effect that needs to be described by words that are more appropriate for a wine tasting room, excuse me if I remain skeptical.

author: linux-works
author_rank: Super Contributor
timestamp: February 04, 2014, 07:45:50 pm
content: I don't trust myself to be test-equipment. I have emotions and agendas that scopes and meters do notI agree that things that are audible have to be measurable, too. maybe we don't have the techniques down entirely, but it does not contradict the concept at all.and so, I will continue to use consistent test gear to evaluate designs and implementations, but I won't rule out that the odd person (lol) can sometimes hear things that most of us can't. its very rare, but it does happen.

author: ElektroQuark
author_rank: Unknown
timestamp: February 04, 2014, 07:46:59 pm
content: Quote from: Sigmoid on February 04, 2014, 04:14:44 pmYou are mixing source and target here.

author: Sigmoid
author_rank: Frequent Contributor
timestamp: February 04, 2014, 08:15:52 pm
content: Quote from: EdoNork on February 04, 2014, 07:46:59 pmMy point is, "stereo" is two recordings whose minute phase differences create a perception of spatiality. We do hear in "stereo", as the very technology has evolved as an effort to fool human ears. Stereo is a rendered "image" of 3d soundspace, similar to what a perspective projection is of 3d visual space.

author: jwm
author_rank: Regular Contributor
timestamp: February 05, 2014, 05:54:02 am
content: I was reading one forum recently where someone was seriously and profusely advocating taking everything you own apart and desoldering every 74ACxx chip you find (independent of whether it is in the audio path or not) and replacing it with a 74HCxx for a more analog sound. He claims it worked for him so must be the right thing to do and 74AC chips were clearly some sort of scam of the electronics industry. I have not taken audiofool sites seriously since then, I occasionally find myself reading an electronics thread and not realize it is from one of those sites until the advice starts getting odd several replies in and no one is calling the poster on it but is instead proposing a different nebulous idea and then them all wondering about things like jitter and noise without any real numbers. I just want to grab them and say... look! it's in the datasheet! you don't need to guess about things like jitter and distortion and use cargo cult science! it is fully specified! just look! right there!

author: BravoV
author_rank: Super Contributor
timestamp: February 05, 2014, 05:58:29 am
content: Quote from: jwm on February 05, 2014, 05:54:02 amAudiophoolery actually sort of social disorder or disease, you will never see a loner, must be a pack of them to start the magic, and its never about audio or electronics related since its just a medium.

author: alho
author_rank: Contributor
timestamp: February 05, 2014, 11:10:01 am
content: For ASMR I'm using 20€ Scullcandy headphones and crappy laptop, so crappy that it's spewing noise from CUP power electronics and USB bus to audio output. Nothing near audiophile quality is needed for ASMR. If I find my sub 5€ headphones I'll test if theres any difference. Probably not.Quote from: ampdoctor on February 04, 2014, 06:26:46 amIt not just a matter of sound. From looking posts athttp://www.reddit.com/r/asmr/it seems that for many visual and social triggers are important. Also music seems to be very unpopular for ASMR. r/asmr/ has 62k subscribers while r/ASMRmusic has 900. And what does most post at /r/asmr/ and r/ASMRmusic have common? Almost all are links to youtube. Might not be best source if you are looking for audio with very high frequency components.ASMR has nothing to do with audiophilery because it isn't repeatable instant on/off thing. It wouldn't be very good if your 10k$ gold plated unicorn hair cable would work well only sometimes and with delay of several minutes.QuoteI don't think that I've ever experienced anything unpleasant in similar way to ASMR, you could post question to reddit and see if you find someone who has. Perhaps sensory processing disorderhttp://en.wikipedia.org/wiki/Sensory_processing_disorder#Hyposensitivities_and_hypersensitivitieswould explain agitation caused by hypersensitivity to sound better than ASMR. But if someone is hypersensitive to high frequency sounds why would it only happen with audio equipment. Shouldn't audiophiles walk around with sound mufflers on their ears so they don't get agitated. After all there is lots of high frequency sounds out there.

author: Sigmoid
author_rank: Frequent Contributor
timestamp: February 05, 2014, 03:24:11 pm
content: Quote from: alho on February 05, 2014, 11:10:01 amNever??? Have you ever had a teacher draw his nails across the blackboard at school?

author: scientist
author_rank: Frequent Contributor
timestamp: February 06, 2014, 05:51:23 am
content: They fantasize about headphones. I'd say that's foolery.

author: VK5RC
author_rank: Unknown
timestamp: February 06, 2014, 08:28:50 am
content: Earlier in this blog a comment of not hearing in 5.1 was made, the external ear gives to sounds arriving from different directions a different spectra, the ear does a simple fft, this is easily tested, block one ear, blindfold and have a friend click his fingers in different positions, typical accuracy is better than 5 degrees with ONE EAR, While a lot of audiophile stuff is rubbish, some of the really complex analysis has not been done. (All silicon PA at home here!)

author: alho
author_rank: Contributor
timestamp: February 06, 2014, 12:24:58 pm
content: Quote from: Sigmoid on February 05, 2014, 03:24:11 pmNails on blackboard sounds unpleasant instantly and I don't feel nauseated for 10 minutes afterwards witch makes it different from ASMR.Quote from: con-f-use on February 04, 2014, 09:27:56 amHere is the full quote:QuoteI used to think that it happened randomly and was normal for everyone. Until few years ago I found out that its called ASMR and that it can be actively triggered and isn't common. Not the sort of thing that comes up at coffee table conversations.Also from wikipedia:QuoteI would be very surprised if ASMR wouldn't show up on MIR. Its way too pleasurable to not have measurable effects on brain.Anyways, good luck getting research funds to study some obscure phenomenon with very little scientific evidence.It seem to me that fairly constant stimulus causes increasing effect, so maybe its some flukey feedback loop in nervous system.It might have something to do with social grooming behavior. From wikipedia: "Grooming stimulates the release of beta-endorphin, which is one physiological reason for why grooming appears to be relaxing". An example of common AMSR video title would be something like "Roleplaying girlfriend gives hair cut while whispering softly". But I skip anything that even hints at roleplay and go for random noises or something instructional so... who knows?Quote from: con-f-use on February 04, 2014, 09:27:56 amIf my head tingles and I feel like I'm floating for 20 minutes or so, I don't really care if its caused by real effect or not. And it's free. Well I did buy a t-shirt to support ASMR related youtube channel, but it's still way cheaper than becoming an audiophool.

author: Sigmoid
author_rank: Frequent Contributor
timestamp: February 06, 2014, 04:18:41 pm
content: Quote from: VK5RC on February 06, 2014, 08:28:50 amI didn't say that isn't true. What I said is that good stereo can replicate everything 5.1 can. I've heard some pretty damn amazing stereo...The reason 5.1 was invented was cinema. Stereo only works if you control the position of the speakers relative to the listener. It's essentially a one-person affair, and doesn't hold up in a cinema, with people sitting all over the place.

author: linux-works
author_rank: Super Contributor
timestamp: February 06, 2014, 06:56:09 pm
content: just wait until 'object oriented audio' hits mainstream. (dolby labs is working on it; I interviewed there and got a glimpse of what they are heading toward).the idea is that you design audio for movies without tying it to the # of spkrs at playback time. you can create x,y,z points in space where the should 'should 'come from, then describe that in the meta audio file for each sound. there could be a virtual audio track for every single discrete sound along with the xyz mapping function of where it should 'slide to' over time.at playback time, you translate this set of spacial stuff down to the number of real spkrs you have (like 'rendering' in graphics). this is the harder realtime part and I've seen some impressive rackmount audio processing that does this.I love the idea: you create sound with spkr-independance and then map to them based on YOUR playback system. this would mean that all individual data is kept unmixed until the very final stage.this isn't about high end audio, but talking about 5.1 (etc) reminded me of this new 'OO' based audio approach. it will also mean a whole new ecosystem of tools to create the sound files, edit them and render them at the final stage.

author: NiHaoMike
author_rank: Super Contributor
timestamp: February 06, 2014, 07:11:15 pm
content: Quote from: linux-works on February 06, 2014, 06:56:09 pmGames already do that, in real time nonetheless.

author: linux-works
author_rank: Super Contributor
timestamp: February 06, 2014, 07:59:26 pm
content: how many spkrs can 'games' render to?at dolby, they were talking about having this scale to hundreds of spkr drivers.games that have audio that 'does not matter' is one thing. high quality audio from a respected audio company that does real science and r/d is QUITE another.

author: AndyC_772
author_rank: Super Contributor
timestamp: February 06, 2014, 08:43:27 pm
content: Sounds like a solution looking for a problem to me. Don't forget that it's very much in the commercial interests of companies like Dolby to come up with new products, whether there's a genuine market need for them or not.I can't remember the last time I went to see a movie at the cinema and thought "what this film really needs to bring it alive is a hundred speakers". In many cases, a properly focused picture and a sound system that's at least as good as the one in my living room would be a good start, and might go some small way towards justifying the ticket price.

author: linux-works
author_rank: Super Contributor
timestamp: February 06, 2014, 09:00:12 pm
content: personally, I hate multichannel movie sound. at home, I down-map the 5.1 nonsense to linear spdif stereo audio (so that I can send pure digital spdif into my crossover and keep the signal all 24/96 up until the final set of DACs).I can see the value in what they are doing, though; I'm in the minority and many younger folks love multichannel sound. they bought into it.and mastering for a fixed # of spkrs seems like the wrong approach when you can develop the sound stage independant of discrete playback devices and then map on a site-specific way, as needed.I do like the inventiveness of this even though I will likely not ever run multichannel stuff at home.

author: JuiceKing
author_rank: Regular Contributor
timestamp: February 06, 2014, 09:13:50 pm
content: I've been to a bunch of high-end stereo shows, and the sound of the different stereos is DRAMATICALLY DIFFERENT!You'd think that if the goal of audio equipment is to reproduce sound faithfully, that their performance would converge as price goes up. But it's quite the opposite. You can't charge more for something that sounds the same. These systems are different by design.I think most are very poor value for money, and the marketing is cooked up by fools and charlatans. But some systems sound just amazing and that's fun.

author: Sigmoid
author_rank: Frequent Contributor
timestamp: February 06, 2014, 09:36:46 pm
content: Quote from: linux-works on February 06, 2014, 09:00:12 pmMultichannel isn't a personal preference thing.Its goal is to eliminate the need for all the magical speaker placement measurements and the "listening chair" bolted to the floor in the dead center of the room.That said, I do not use multichannel, and downmap it myself to stereo.Nor do I have a listening chair. But I do own a good pair of flat response studio headphones for when it really counts.

author: linux-works
author_rank: Super Contributor
timestamp: February 06, 2014, 11:08:26 pm
content: I've mostly given up -caring- about soundstage, to that level. you move a little and the 'calibration' is off. it just does not seem to make sense to me to sit motionless in the sweet spot. so, I gave up trying for perfect imaging (with speakers). recorded sound is always going to sound recorded and sourced from discrete non-real sources. I'm ok with that, given that's just how it is.

author: vk6zgo
author_rank: Super Contributor
timestamp: February 07, 2014, 03:20:52 am
content: Quote from: linux-works on February 04, 2014, 07:12:49 pmI've run into a couple of cases of "people with golden ears" detecting a fault that the rest of us couldn't hear.Some years back,I worked at a manned TV/FM Broadcasting Station in the middle of the Western Australian Wheatbelt.The FM Station's was fed from two discrete Audio outputs of a UHF link,which in turn was fed by a long landline back to Perth.The Stereo pair of lines were normally equal length.One of the Techs told us there was something "funny"with the Stereo signal as heard through his home Receiver.He said it sounded like one channel was out of phase.We all listened,& couldn't hear anything wrong.It turned out that the Long Line Techs had found a fault on one leg of the Stereo pair,& not realising it wasn't a Mono line,diverted it to an alternate feed which was around 100km longer,booked the faulty line for repair,& went on their way.100km is a free space wavelength at 3kHz (probably a bit lower in that particular cable),& various fractions & multiples at other parts of the audio spectrum----definitely enough to stuff things up!Why we didn't hear it?---Probably noisy environment,less than ideal speaker placement,etc.The next episode was in a major city TV Station,where one Staff member reported he could hear a "hissing" sound on the TV stereo sound-----again on a home Receiver.The Transmitters were used "day about",so it was easy to determine which one was responsible,but very difficult to reproduce his results.We all listened at the Studio,at the Transmitter,& as far as possible,at home.No sign of a problem!We looked at the Sound Mod output with a Spectrum Analyser,all looked OK.The SA was "battling" a bit to see anything that close to the Sound Carriers,but we tried!No viewers complained,so we told him he had "golden ears" & had much innocent merriment "hissing" at him!Abruptly,while I was on leave, the "suspect"Sound Modulator failed,with spurii all over the place!Much egg on many faces!

author: ampdoctor
author_rank: Frequent Contributor
timestamp: February 07, 2014, 08:48:41 am
content: Hmm, this did seem to spur on some interesting discussion. For a bit of clarification on my end...ASMR; Personally I could care less about the phenomenon. The reason I brought it up was that it was the impetus or a jumping off point for more serious thought regarding the psychology of how sound is interpreted. Are these psychological triggers part of a more universal way our brain interprets and processes audio? Why is there a near complete absence of low frequency content? It opens the door just a crack for some interesting hypotheses in other areas of study that might be loosely connected.Audiophiles; It might have been better to say something along the lines of a few people in that "community", for lack of a better term, MIGHT be uniquely sensitive to things that the majority of the population miss. Clearly in the aggregate they are playing the "mine is better than yours because it costs more" game, or any number of other psychological deficiencies, but isn't it possible that a select few just maybe.....As vk6zgo noted there's no shortage of examples of people that you can point to and say "how the hell did he hear that?!" Obviously it's going to be difficult if not impossible to perform any empirical testing that would provide meaningful results, at least not at this point. And this is the area that keeps me curious and not willing to completely dismiss some of these observations as a purely psychological effect.Now, let's say somebody sits down and designs a good class AB power amplifier. I think it's safe to assume that pretty much everybody will agree that crossover distortion sounds "bad", but the question is how bad do the distortion products have to be before they become unacceptable? Moreover, do people hear some of the much higher harmonics and are just not consciously aware that they're hearing them? Or is it perhaps the combination of even and odd order harmonic content that some people are sensitive to? This could be part and parcel of why two people listen to the same system and one person says it sounds fine and another says it doesn't sound quite right.I'm not talking about anything unmeasurable here, I'm saying that it could be possible that human perception of the the world around them are more finely grained than what we give ourselves credit for. We know that when somebody loses one of their senses the others become far more acute as a way to compensate for the loss. In the case of somebody who loses their sight, their sense of hearing becomes markedly improved. If the ability to hear to that degree wasn't there to begin with there would be no possibility for improvement. Most likely our brains just prioritize the incoming data and discards what it doesn't need for whatever reason. But the information is there just the same.Obviously there are economies of scale that come into play when designing and manufacturing products far out on the tails of what we would consider normal. What's the point in producing a product who's differences can only be discerned by 1/10th of 1 percent of the population?! There's a strong argument for that, but if we think back on products from 50-75 years ago. Today we would consider the quality unacceptably poor, but when they were introduced we thought they were pretty amazing. So do we just sit idly by and say meh what's the point, or do we peer over the next mountain and see what there is to see?And no we don't hear in stereo. At least not in the way it's marketed to us. We hear not only through out ear canals but also the bones in our skull and jaw as well. Our sinuses also play a role as well. Factor in the distance to the source as well as sound pressure levels. Now add in that lower frequencies are more omnidirectional and higher frequencies are more unidirectional. It becomes clear that there's a lot more going on than just left side of the room goes in the left channel and right side of the room goes in the right. The composite sound stage we experience is far closer to mono than it is to stereo. But that's a completely different discussion with respect to how music is/should be mixed and mastered from source recordings.

author: JuKu
author_rank: Frequent Contributor
timestamp: February 07, 2014, 09:10:48 am
content: Quote from: Sigmoid on February 04, 2014, 04:14:44 pmActually, we do. In a study comparing the quality (in terms of envolvement, sense of being there, realism etc, specifically excluding artifacts, noise etc) versus number of channels, the quality went up almost linearily (!) up to 5.1 and logarithmically after that. In another study, the limit of audibility was found to be somewhere between 0.5 and 1 million channels(!). So, in theory and optimal conditions, you could hear a difference between 50000.1 and 500000.1 systems. Btw, the .1 is not enough either, we do sense dynamic bass direction: Did I kick you in the stomach, back or side? which side?

author: JuKu
author_rank: Frequent Contributor
timestamp: February 07, 2014, 09:51:47 am
content: Too much trouble to search for each writer and put the quote tags... Sorry. But a few points:- Double blind: There are two problems with that. #1, a double blind test only gives a positive result: If there is a difference, it means that what was tested is indeed audible. But a negative test only says that with this material, this equipment, this room, these subjects did not hear a difference today. but that's it. With some other people/material/equipment/room there might be an audible difference. You can't prove "no audible difference". #2: Real life situations very seldom are blind. And the hearing sensation is real, even if it might only partly come from movement of air molecules. We know (as a proven, scientific facts) that color TVs don't sound as loud as B&W TVs but they have a better sound; black speakers sound better than red ones; big speakers have better bass etc.- Measurements: I'm an engineer, so I believe in measurements. I also believe that we don't have enough knowledge about how humans hear to know what to measure. Besides,I haven't yet seen any audio equipment with different designs that measure equally(!). I can measure a zillion things and fine differences, but on many measurements, I don't know if those have any audible meaning. (A very, very simple example: This device has better channel separation than that one, but the leakage is asymmetrical. Which one has better stereo imaging?)- Sometimes high end hifi can approach the illusion threshold, where you start to believe that you are hearing the real thing, not just a glorious reproduction. When there, I believe that different rule set applies; very minor thing can keep the illusion up or break it to a mere glorious reproduction.- Some humans have indeed a different hearing than others. I am also much more sensitive in low frequencies than an average person. I don't have hyper-sensitivity, in the 500-2k area where normal people sensitivity is the greatest I'm average. But normally, the hearing sensitivity goes up when frequency goes down (Fletcher-Munson). I don't have that; at 200Hz I'm at least 20dB more sensitive than average people (the equipment range run out and I could hear the tram line rumble four blocks away leaking in the sound isolated test room).[- Racial comment: The hearing capability differences might be genetic: There has been quite a few well done scientific studies showing the meaning of 30k-50k range in faithful reproduction from Japan, that have not been reproducible in US.)- The listener might not be able to name the difference, even though s/he hears it. We once built two products to two brands. The products were otherwise identical, but to compensate a slight frequency response error in the other customer's power amp, the low-pass filter was tuned a bit lower in one of the products. The difference was 0.1dB at 20kHz, which I still believe should be inaudible by a wide margin. Still, the press (sometimes in comparison tests) gave comments about the other products high-end, like "Nothing is missing, but it is a bit smoother than X", far too many for me to believe those were random guesses.

author: Sigmoid
author_rank: Frequent Contributor
timestamp: February 07, 2014, 06:40:05 pm
content: Quote from: ampdoctor on February 07, 2014, 08:48:41 amA scope will "hear" everything. There are companies that use solid science to make good-sounding devices (such as Dolby), and there are industries where quality is paramount and professionals who can hear a channel out of phase (sound technicians are generally an object of my admiration).But all this has nothing to do with audiophilia, which has absolutely no relation to reality, or anything measurable.Quote from: ampdoctor on February 07, 2014, 08:48:41 amHuh? I don't get what you're saying. First you say there's a lot of directional info we perceive, and then say our hearing is more like mono? Could you elaborate?Anyway, good stereo is a LOT MORE than "left side of the room goes in the left channel and right side of the room goes in the right".This is equivalent to "left side of the room goes in the left channel and right side of the room goes in the right":http://en.wikipedia.org/wiki/File:Duccio_maesta1021.jpg...and this is good stereo:http://en.wikipedia.org/wiki/File:Entrega_de_las_llaves_a_San_Pedro_(Perugino).jpgQuote from: JuKu on February 07, 2014, 09:51:47 amTypical audiophool excuse. Double blind tests are good enough for medicines. You know, the stuff you trust your LIFE with.If, using a large enough sample, there is no difference, or the $10000 amp actually sounds worse than the $100 one, then I doubt there's reason to be quoting "what ifs".Quote from: JuKu on February 07, 2014, 09:51:47 amLol. When I pay for audio equipment, I am interested in sound quality, not in how its looks (and price) will affect my subjective perception of the sound. If hi-fi stuff was marketed honestly, like saying "this black mahogany supertextured finish and the impressive size of the unit will be a highlight of your living room", I'd say it's okay. But instead they spout shit like "our scientifically engineered mahogany finish absorbs subspace particle resonations and evens out the warp field for an optimal listening experience."Are you by any chance involved in selling this snake oil stuff? You sound awfully apologetic.Quote from: JuKu on February 07, 2014, 09:51:47 amThere are lots of honest companies who have put in years of research into finding out exactly what to measure. Dolby, once again... And we have practical and really cool stuff to thank that research, for example mp3 compression.I doubt the ones selling the magical $10000 amps do the science.Plus, for an engineer, you're making far too many excuses not to trust measurements. I'm sensing an ulterior (financial?) motive here.Quote from: JuKu on February 07, 2014, 09:51:47 amOf course it's not random. The press is trying to "impress" its sponsors.I'd like to see the same result in double blind tests. (That said, it's not impossible that such a minute difference is actually audible. That said, we're talking about a pretty specific, measurable difference.)

author: edavid
author_rank: Super Contributor
timestamp: February 07, 2014, 08:21:00 pm
content: Quote from: ampdoctor on February 07, 2014, 08:48:41 amThis is completely wrong. Just another myth.

author: scientist
author_rank: Frequent Contributor
timestamp: February 07, 2014, 08:34:50 pm
content: Quote from: ampdoctor on February 07, 2014, 08:48:41 amSeems to be markedly improved, because they have nothing to compare it against and their memory is extremely fallible.

author: Sigmoid
author_rank: Frequent Contributor
timestamp: February 07, 2014, 08:49:32 pm
content: Quote from: scientist on February 07, 2014, 08:34:50 pmThere's a bit more to it than that. For one, the brain contains a mechanism for blocking out and filtering input based on attention. (I mean, actually closing the neural pathways.)With a sense dropped out, more attention is directed to all other senses. Also, there's the thing about neuroplasticity, with areas of the brain repurposing themselves. For example research shows that many blind people use their visual cortex to process Braille writing.That said, it's true that there's no evidence of the hearing itself (in terms of frequency sensitivity, sensory limits, etc.) improving. It's just that if someone only has their hearing to rely on, there's a lot more processing happening on it in the brain.

author: Marco
author_rank: Super Contributor
timestamp: February 07, 2014, 09:17:05 pm
content: Quote from: linux-works on February 04, 2014, 07:12:49 pmYou're destroying the base by connecting them in anti-phase, I'm sure a lot of people won't notice but it's not something you need golden ears to recognize.

author: Bassman59
author_rank: Super Contributor
timestamp: February 07, 2014, 09:42:01 pm
content: Quote from: Marco on February 07, 2014, 09:17:05 pmThe effects of one speaker reverse polarity from the other is obvious if you know what you're listening for.Here's a good one. I am a live sound mixer, and I had a gig in a new venue where they did up a decent install with some older but perfectly functional gear. The mains top boxes were EAW KF650s, two a side, and they were flown with the two boxes in a pair butted up against each other. If you know anything about these boxes, you know that's a recipe for serious comb filtering, because the horns are too close together at that angle.I had no way to fix this (basically you spread the boxes so there's a 6" or so gap between them) but after soundcheck I grabbed the house engineer (young girl, actually interested in learning) and the promoter, and played some tunes through the rig and just had them walk slowly in front of the boxes from side to side. I didn't tell them to do anything other than listen.Both immediately heard the problem and asked how to solve it.These sorts of things, the time-domain interference issues (coupling between boxes, interference between a box and a nearby wall, etc), as well as the simple polarity flips, are easily recognized once you're exposed to them and the problem is explained.

author: ampdoctor
author_rank: Frequent Contributor
timestamp: February 07, 2014, 10:49:50 pm
content: QuoteIt's exactly what I said. High frequency content tends to be rather beamy and directional. Lows tend to spread out all over the place so you know they're there but it's hard to pinpoint the exact source. And when sounds get really loud, you can turn your head any direction and it has very little effect on whether you perceive it as coming more from the left or the right. This is also true for distant sounds. While the distribution of sound may be somewhat more dominant to the left or right, the information is still received on both sides.For example, at this very moment, I can hear the TV playing in the other room. If I cover one ear I can still hear everything with the same clarity, though at a slightly diminished volume. So maybe it comes down to what your personal idea of mono vs stereo happens to be. My definition of stereo would generally be something along the lines of "two point sources of audio that are phased and amplified as necessary to allow the brain to construct a sense of 3 dimensional space."With recorded sound, off the top of my head you've got natural stereo, panoramic stereo, dolby stereo, surround sound, dual channel high fidelity, pan pot stereo, pseudo stereo monophonic. I know there a a ton of other techniques studios use that I just don't know the names of. Often times when music is recorded and mastered different instruments are given dedicated channels and usually vocals and percussion are recorded mono or equally left and right. In the recording studio there are no hard and fast rules for doing anything. Depending on the skills of the recording and mastering engineers mono or stereo recordings can be quite unnatural sounding. To get a good idea of how good mono CAN sound, dig up a copy of some of the original Beatles albums. Those were all done in what I believe was pan pot mono and remastered later into stereo. The difference is mind blowing! That's also why I said that's a completely different conversation.

author: linux-works
author_rank: Super Contributor
timestamp: February 08, 2014, 04:40:15 am
content: Quote from: Marco on February 07, 2014, 09:17:05 pmI don't think that's correct.absolute polarity will not have the initial 'push' at you, but one half cycle later, it will!what you are probably thinking about is one spkr being correct and the other being out of phase. in THAT case, bass will cancel but if they are both using the same polarity, the difference is really only on attack and only on the first cycle. its something very few people can truly detect with reliability.

author: PetrosA
author_rank: Frequent Contributor
timestamp: February 08, 2014, 05:33:32 am
content: Some thoughts I had reading through this thread:I read some time back that testing was done on musicians to see if they have "better ears" than non-musicians. One of the things the research uncovered is that musicians have a much stronger ability to "fill in" missing sounds when listening to music on bad/cheap speakers. As a result, many musicians don't buy super high-end stereo equipment for their homes.Someone wrote, and others suggested that "A scope will "hear" everything." Yes and no. Human beings experience sound with their entire body. Each cavity resonates at a certain frequency and as we age and change, our perception of sound will change as well. We have stomachs, lungs, sinuses, skin etc. that all react to sound waves of different frequencies and they react differently depending on whether you've eaten or not, whether you have a cold or not, etc.. In my younger days I walked out of a number of concerts because the bass drums were so strong that I was getting queasy from the thumping in my torso. A scope can only show you what its inputs record, so unless you can figure out a way to deliver a feed directly from a human brain of all the sensory information into a scope, you're only getting part of the picture, usually limited to what a microphone can detect.

author: JuKu
author_rank: Frequent Contributor
timestamp: February 08, 2014, 08:41:13 am
content: Quote from: Sigmoid on February 06, 2014, 04:18:41 pmI've heard amazing stereo and amazing multichannel, too. A stereo can only replicate the front field, like in the entrance of a concert hall with doors open to the actual hall vs being inside the hall (multichannel). For some music, like club jazz, the front field can be enough. And in rock, no one cares about trying to reproduce the concert hall reverberation. But stereo can't hold a candle to an equal quality multichannel sound, especially on classical music.

author: JuKu
author_rank: Frequent Contributor
timestamp: February 08, 2014, 09:57:46 am
content: Quote from: Sigmoid on February 07, 2014, 06:40:05 pmJust to clarify: A scope is utterly useless in audio engineering, other than troubleshooting. A healthy human hearing is at least 1000x better than any scope I know of. But we do have microphones that are more sensitive or can handle more sound pressure than a human, and we have audio analyzers that can give a number and to a variable and in many aspects, can measure smaller details that we might be able to hear. So, "measurements" is a better word.QuoteA channel out of phase is blatantly obvious error, btw.QuoteA very insulting generalization. Sure, there are con mans in the industry and fools to be fooled. There always is everywhere where money moves. However, by my experience most of the companies really do solid engineering and research and many consumers do know what they are talking about.Quote from: JuKu on February 07, 2014, 09:51:47 amLol. When I pay for audio equipment, I am interested in sound quality, not in how its looks (and price) will affect my subjective perception of the sound. If hi-fi stuff was marketed honestly, like saying "this black mahogany supertextured finish and the impressive size of the unit will be a highlight of your living room", I'd say it's okay. But instead they spout shit like "our scientifically engineered mahogany finish absorbs subspace particle resonations and evens out the warp field for an optimal listening experience."Lol yourself: Which is the fool, the one who understands what is going on and can be wary (or appreciate) of non-technical issues or the one that thinks he's immune to stuff no human is not? And for your marketing language examples, the former sounds much more familiar than the latter. There are con mans, but not that many. Sounds like you believe a spec sheet tells you everything there is to know about a car?QuoteNot apologetic; I'd try to be realistic. But yes, I have experience in designing high quality audio stuff; no snakes harmed! Are you by any change running a store selling run-of-the-mill "hifi"?QuoteSure, we know a lot. I tried to point out that we don't know it all. At the moment, Dolby (an others) are hiring more researches to find out more, they are not closing the research department because all has been found out.To take a very, very simple example: It is known and approved that channel separation in stereo equipment has an effect on sound field reproduction (and that is why in most reviews, that is measured.) However, we don't know precisely how: I can measure the symmetry of the leakage (is L to R the same as R to L) and the distortion and frequency response of the leaked signal very accurately. But we don't know what effect those details might have to the perceived sound. (And that is why you seldom see channel separation detail specs.)One time, in an informal A-B test (we knew what we were listening to, but the point was to find out if there was a difference or not) we had otherwise identical (or changes that we thought should be inaudible) devices; same basic design and parts, slightly different circuit topology: One had better but uneven channel separation, the other was worse in numbers, but even in frequency. I thought I might have heard a minor difference, a college was sure there was one. But which one was better? We couldn't say, and the industry does not have much research nor a consensus on the subject either. And did I say channel separation is about as simple as it can be?Most of the issues are much more complex.QuoteYou'd be surprised. You'd be very surprised.QuoteOh, I do trust measurements, I'm an engineer. But I'm experienced enough to know that I don't know it all. As said, no two devices measure equally, so I'm not surprised that there is an entire (if small) industry around minute differences. What is slightly surprising is that we don't have a clear correlation between the measured differences and perceived sound quality. Therefore we have endless debate about the merits of some equipment. Either we don't know what to measure or the human hearing is much more sensitive than we know of. Personally, I'd vote for both.QuoteIn this case, the reporters did not know that the products used the same circuit boards. At least one magazine had not opened the products, and I'm rather sure the others did not find out either, otherwise they would surely have written about it. I believe the reporters genuinely heard a difference. What I find perplexing in this anecdote is that the difference should be inaudible by a far margin. I think that on the "keeping up the illusion" level, minute details matter, even if you might not be able to pinpoint what it is. Certainly, 0.1dB at 20kHz is inaudible as a frequency response deviation, but in right conditions, it seems to be enough to trigger the brain between "this /[is not] really real". Or they wrote what they wrote to fill in the pages - but I don't think so.You can see all there is to see from most windows, just like you can hear all there is to be heard with most hifi. But it takes an incredibly good and clean window to make you believe there is no glass.

author: hamster_nz
author_rank: Super Contributor
timestamp: February 09, 2014, 05:52:07 pm
content: Quote from: JuKu on February 08, 2014, 09:57:46 amI agree that a 8-bit DSO is missing the subtleties of an audio signal, but given that the source media is usually a stream of 16-bit samples at 44,100 (i.e. CD) there is only limited set of information the source.I had half written a full reply, but then decided that leaving just a few links would be sufficienthttp://forums.audioreview.com/cables/best-optical-cable-you-have-found-25693.htmlQuoteContrast withhttp://archimago.blogspot.co.nz/2013/05/measurements-toslink-optical-audio.html- actual measurements of actual cables.

author: NiHaoMike
author_rank: Super Contributor
timestamp: February 10, 2014, 01:02:47 am
content: Those audiofools who think coax has better bandwidth than fiber really are audiofools. Why would networking companies spend a fortune on fragile fiber cables if they could just use RG6? I was recently a contractor at a networking company and as it turns out, it's no surprise that fiber will easily go much further than any kind of copper cable. All the high speed copper runs were restricted to a few feet, while fiber does hundreds and thousands of feet no problem, even at 10Gbps.

author: BravoV
author_rank: Super Contributor
timestamp: February 10, 2014, 01:08:54 am
content: Quote from: NiHaoMike on February 10, 2014, 01:02:47 amThere is your mistake, corrected, they just don't do that.

author: linux-works
author_rank: Super Contributor
timestamp: February 10, 2014, 02:46:41 am
content: Quote from: NiHaoMike on February 10, 2014, 01:02:47 ambecause, well, REALTIME AUDIO is not packet data!jitter does matter (to some degree) in digital audio over spdif and over i2s. otoh, a packet audio format (like UAC2 audio, asynch usb audio class 2 which is a 'pull' data model instead of the usual 'push') does not suffer due to line jitter. in UAC2, the clock source is not the pc, its the DAC and there is buffering and windowing and reliability due to the packet and buffer model (and that data is ack'd, unlike spdif).but with spdif, yes, you can have jitter over different wires and its now up to the spdif receiver chip to filter that out. many modern ones can, but you can still argue its better not to have jitter on the line to start with.tl;dr; bits is not bits when timing is embedded.

author: hamster_nz
author_rank: Super Contributor
timestamp: February 10, 2014, 03:56:51 am
content: Hi AmpDoctor:Would you agree with this statement fromhttp://members.chello.nl/~m.heijligers/DAChtml/PLL/PLL1.htm:QuoteAlthough it sounds plausable, it is untrue. If you are using a CD for a source, a full range 20KHz signal, will slew at most about 0.3 LSB in 100ps. Jitter would need to be three times this level, and also be periodic (unlike the truely random noise one would expect), and this could at best inject a -96db signal into the audio output.Have a look at page 8 ofhttp://peufeu.free.fr/audio/extremist_dac/files/jitter92.pdf,where the jitter used was was 200x what it is claimed some people can hear - a -20db 20kHz tone is 'corrupted' with a perfectly un-random 20ns of jitter, and resulted in a tone of about -84db being injected into the sound.And 20ns is very, very poor. Even I can engineer to < 10ns jitter without performing any PLL-based clock recovery. While implementing S/PDIF interfaces, and injected random errors just for fun, I can assure you that even if an bit error occurs once in one-in-a-million event it is still very obvious as clicks - and recovery of the data at 2.8MHz isn't that hard. Checksumming and acking data packets is also a crock - DVI-D works at 500x that speed with no feedback, no error correction, and I don't see any random pixels flashing on my screen. Heck, fibre channel pushes 16Gb/s down a fiber, checksums all the packets and I've seen port error count sit at zero for days on end.These statement about hearing <1 ns jitter are as silly (and common) as saying that a higher quality HDMI cable will give you richer colours and better sound.I better stop now and do something productive...

author: JuKu
author_rank: Frequent Contributor
timestamp: February 10, 2014, 08:37:21 am
content: few notes about jitter:- First and foremost: as linux-works said, bits are not bits when timing is embedded: A "digital" audio signal is actually half analog. We are not talking about data retrieval, which is indeed trivial. Besides, any data errors would be an non-working system. We are talking about the purity of the timing of the samples going out. There, the unit is indeed picoseconds.Quote from: hamster_nz on February 10, 2014, 03:56:51 amYou are mixing apples and oranges: For a digital display, the jitter needs to be small enough that the pixel data in the signal hits the correct pixel in the display (huge simplification, but you get the point). For "digital" audio, the pixel should hit the exact center.- The audibility depends very much about the receiver circuitry and may be even more, about the DAC chip. I've measured chips that I have no doubt a few ten picoseconds would be audible, maybe even low digits. Ok, not lately: Now when jitter is a known issue, designers know what and how they are fighting for. I have also measured products that 10ns (which is huge, about the limit of losing sync) does not have a measurable change in the output. So, we would assume a wide range of opinions and experiences. (The link where somebody had measured different cables, did show very minor jitter differences, but apparently, the receiver/DAC was rather good.) Any anecdotes and measurements are valid for that particular system only.- Coax has indeed much more bandwidth in consumer stuff that optical. The limiting factor is not the cable, it is the receiver module. The comparison to telecom is irrelevant: The telecom companies use a bit more money in their systems than your typical CD manufacturer, like 9c vs. 900$ for the receiver component.- The differences in optical cables are mainly the mechanical tolerance of the connectors, i.e. how well does the light hit the sensor. The purity of the plastic might have an effect too, but I haven't done much experimenting here (see last point). And sadly, the tolerance of cheaper receiver components is meaningful. Again, a particular brand of cable with a particular brand of player and DAC can give different results, depending on the individual parts.- Last: Jitter is an issue, but in high quality equipment, not a very big one nowadays. About any manufacturer aiming for quality gets that part right. On the other hand, about any manufacturer aiming for low price cuts some corners, and there are issues. But somebody buying stuff by price, by definition, doesn't care that much. Besides, the other equipment likely isn't that great either and there are bigger issues on sound quality. Therefore, jitter isn't that big deal there either.

author: ConKbot
author_rank: Super Contributor
timestamp: February 10, 2014, 12:04:34 pm
content: Note to self. Start selling various dielectric coaxes and SPDIF fibers to audiophiles. I wonder what sounds better, pure teflon? Polyethlyene? foamed PE? maybe the people with real taste would buy into an air-core coax? Oooohh and after that I can start selling dry N2 generators to purge the heliax, and also prevent oxidation.And if someone prefers optical, guess I could sell a SPDIF to multimode ST converters so you can use real glass fiber. Maybe an coax SPDIF to single mode media converterguess who's retiring early boys

author: JuKu
author_rank: Frequent Contributor
timestamp: February 10, 2014, 12:07:34 pm
content: You are on to something...

author: linux-works
author_rank: Super Contributor
timestamp: February 10, 2014, 03:59:05 pm
content: I was over at a friend's house who was doing some research on various coax cables to test for jitter. he ran what is known as 'jtest' (see DIYaudio forum) and we really could see the results (on a spectrum analyser, pc software) between various coax types. I saw it with my own eyes and I know this was not a faked setup.now, whether those jitter peaks will affect modern spdif receiver chips, that I don't know. 10 or 20 yrs ago, yes, it would. now, with reclocking receivers (such as the wolfson) its not really an issue anymore. without a reclocker at the rx side, the cable would start to matter again.now, I refuse to believe that usb cables would matter at all, ever. from usb to the dac is always a packet exchange, its not a one-way pipe like spdif is. the timing is derived from the pc (and not the dac, if UAC1 style) but still, a whole packet of data has to be received by the dac before its burst out and so, it does have local buffering. timing is controlled by the pc but the per-bit timing, during the exchange, is not relevant.when I started in digital audio, maybe 25 yrs or so ago, I was into DAT audio recording and a bunch of us were working on a digital copy box that would let us transfer spdif from one DAT to another, without that stupid scms nonsense getting in the way. we defeated it and then there was talk about how much 'loss' there would be if you took a DAT tape and make 100 copies (bit for bit) from machine to machine. would jitter accumulate in this situation?no, it would not. the bit-time is not relevant until its turned into analog. if you are going digital to digital, it really is 'bits == bits'. as long as you can recover all the bits (ie, no harsh bit losses) then only the final stage of dat PLAYBACK would matter. the 100 or so back-to-back copies would not change the quality of the audio.

author: AndyC_772
author_rank: Super Contributor
timestamp: February 10, 2014, 04:32:05 pm
content: I think the argument goes that there is some relationship between jitter at the SPDIF receiver, and jitter at the pin of the DAC which actually causes audio data to be updated.You're quite right that only that very last SPDIF link could ever possibly have an impact on the audio quality, assuming that previous steps didn't actually malfunction (ie. introduce bit errors). Up until that point, there simply is no timing information to use or maintain. If, for example, I play a WAV file, it'll sound exactly the same as if I email you a copy of it and you play it on identical equipment.It may well be an issue in some DAC designs, if (and only if) they attempt to directly recover a 'master' 44.1kHz clock (or some multiple thereof) from the SPDIF data stream, and actually connect that clock to the DAC chip itself - thereby providing a route whereby timing issues at the SPDIF input can have an influence.It's not a very good design technique, though, and its implications (both real and fictitious) have been argued to death on audiophool forums.

author: Sigmoid
author_rank: Frequent Contributor
timestamp: February 10, 2014, 05:41:08 pm
content: Quote from: JuKu on February 10, 2014, 08:37:21 amCorrect me if I'm wrong, but a digital signal is discrete in time and value domain. I'd expect each component of the signal chain to have its own clock, in order to correct any timing issues that each channel introduces.So the only clockrate that really matters should be that of the DAC - unless of course a bit "skips a beat", which would naturally result in some kind of corruption.For the stuff you're saying to make any sense, the time signal should be coming from the signal source (say, the rotation of the CD itself), and be propagated throughout the system up to the DAC.Some audiophool designs do seem to imply this - like the precision drive CD players with just the mechanical parts costing several grand... So while I'm not saying this is impossible, it sounds like an extremely stupid design, and I cannot imagine anyone seriously designing an electronic disaster like this.If someone actually did build it, then it's a vastly inferior design for a vastly superior price.Quote from: JuKu on February 10, 2014, 08:37:21 amThese things start becoming an issue when the signal starts to break down. The whole idea of digital is that it's channel-agnostic. The only time you notice the channel is when the channel's all fscked up. Unlike in analog, in digital, there's no difference (NO difference) between a perfect and a good enough channel.So unless that slightly misaligned sensor results in bit errors, it shouldn't matter at all. And if we have bit errors, we aren't talking about quality anymore, we're talking about bit error squeaks and blips in the audio.Unless, of course, see above. In which case, the designer is clearly an idiot.Quote from: PetrosA on February 08, 2014, 05:33:32 amYep. Well, it's basically a question of musical literacy. Whether you're interested in the music (the pattern of code comprised of tempo, volume, chords and intervals), or in the holistic experience of the record, with background noise, reverb, etc.Being a purist, I prefer the former, but do understand the latter too. That said, I think the vast majority of the high-end, $1000+ pricetag industry isn't really approaching that goal head on, and is instead lost in chasing ghosts and squeezing money out of select schlimazels.

author: AndyC_772
author_rank: Super Contributor
timestamp: February 10, 2014, 06:08:53 pm
content: You're absolutely correct, except that in some designs, the timing of the transitions in the SPDIF signal is used to derive the clock which actually controls the timing of the updates to the DAC.In such designs, the SPDIF signal is being used in two ways. The first is as a carrier of digital information, in which case bits == bits, and as long as the interface is error-free, it's doing its job perfectly well. A USB, Ethernet or wireless connection could do exactly the same.The issue comes when that same signal is used as a source of timing information. Then, depending on how the circuit works, there may be a route by which timing jitter in the SPDIF stream - which wouldn't in any way affect the correct recovery of the data bits - does nevertheless affect the stability of the recovered clock.The distinction between the two is what confuses some audiophools.

author: hamster_nz
author_rank: Super Contributor
timestamp: February 10, 2014, 08:52:49 pm
content: Quote from: AndyC_772 on February 10, 2014, 06:08:53 pmCan you expand a bit more because I must be missing something?Here's what I know for sure - The S/PDIF packet for stereo is 64 bits long, and has headers every 32 bits. The header for channel A data word is 00010111 (and will always be followed with a 0) or it's inverse 11101000 ((and will always be followed with a 1 ). The timing of the final transition can be used to recover the clock very accurately, and used to present the previously received samples to the DAC.The thing that amazes me is that audio travels 330 micrometer per microsecond, so even if the system was perfect except for jitter that is wider than an entire S/PDIF bit (300ns, so bad that the system couldn't acutally work) the difference would only be equivilent to moving your ears 100 micrometers at 20Hz - about half the width of a human hair. When my S/PDIF project rebuffers and sends it off to a DAC with < 10ns of jitter it is equivilent to 3.3 micrometers of head movemement!Unless highly periodic, jitter will result in unwanted high frequency noise, the majority of which will be higher than 20kHz and also at very low db. Exactly how such high freqency components get out the anti-aliasing filter, through the speaker's tweeter and into your ears, which themselves are designed to receive wavelengths from about 16m (20Hz) to 10mm (20,000Hz) is also a mystery to me (i.e. I can not see any valid physical mechinsim).

author: AndyC_772
author_rank: Super Contributor
timestamp: February 10, 2014, 09:24:20 pm
content: I don't think you're missing anything, and I completely agree that the amount of jitter which could possibly exist in a working system equates to tiny errors in terms of physical movement.For the sake of completeness, though, it's worth also considering the amplitude error that 10ns of jitter could be equivalent to. The greatest possible slew rate between one sample and the next is a change of 65536 counts in 1/44100 sec, which is 2.89Gsa/s, so that 10ns timing error equates to 28.9 counts. That's actually not quite so insignificant IMHO, and I can certainly believe it might be audible.As to what it sounds like, the only specific symptom I've ever heard mentioned is a negative effect on stereo imaging - which seems plausible enough, I guess.

author: Rufus
author_rank: Super Contributor
timestamp: February 10, 2014, 09:27:41 pm
content: Quote from: hamster_nz on February 10, 2014, 08:52:49 pmConsider the signal is a square wave at half the sample rate. Then alternately jitter the clock +/- half a bit time. The output is 1.5 clocks high and 0.5 clocks low. That jitter introduced 1/2 maximum amplitude dc level on the output and a lot of high frequency harmonics. Jitter isn't a time or phasing problem it aliases with the content to modify it.

author: DrGeoff
author_rank: Frequent Contributor
timestamp: February 10, 2014, 09:33:51 pm
content: Now compare all that with what is actually used to record and encode the source material...

author: hamster_nz
author_rank: Super Contributor
timestamp: February 10, 2014, 10:04:29 pm
content: Quote from: Rufus on February 10, 2014, 09:27:41 pmThat is completely true - but such a signal would never be fed into the DAC or ADC in the first place. Apart from it being bang-on on the Niquest limit of the system, it has a lots of harmonics well over the Niquest limit of the system. If you were to put a signal realistic rise-times into the signal then the effect of jitter is far less than you analysis hints at.As jitter can be introduced at any stage it was more an experiment of "if the jitter was introduced at the listener's head, by introducing random vibrations, what would it actually be like" - trying to get a physical appreciation for what is going on.

author: edavid
author_rank: Super Contributor
timestamp: February 10, 2014, 10:16:17 pm
content: Quote from: AndyC_772 on February 10, 2014, 09:24:20 pmThink about what you are saying... that would be an 0.05% amplitude error in a signal which you can't hear anyway.

author: JuKu
author_rank: Frequent Contributor
timestamp: February 11, 2014, 09:01:56 am
content: Guys, do your research!Point 1: Consider a simple SPDIF signal to DAC. The DAC timing has to runin syncwith the input. Not just at the same nominal rate, butin sync. If you think about it, there is no other way. (There are schemes where the DAC provides timing to the source, but those are rare and if you have that, you know it.) Re-clocking etc are just fancy names for advanced PLL, multistage PLL, whatever. But the timing comes from the incoming SPDIF signal. You can attenuate timing errors, but you have to live with the timing of the input signal.Point 2: SPDIF is one wire. The timing rides on the bit edges(!). It uses Biphase mark coding. To get the timing right with that requires infinite bandwidth(!!).Point 3: Jitter (noise in the DAC timing) isnotlike moving your head or the speaker, that is a false analogy. Jitter (usually) manifests as enharmonic distortion, which the ear isverysensitive of.--Jitter is a very real issue. Ok, a known one, we can deal with it, and designers make the compromises with desired quality, price, complexity etc.

author: JuKu
author_rank: Frequent Contributor
timestamp: February 11, 2014, 09:47:29 am
content: For the sake of discussion, lets ignore the rare and fancy systems where the final DAC runs the timing, giving the sync signal to the source. Those are rare, expensive, and if you have it, you know it. Almost no home system has that (although asynchronous USB DACs are becoming more common.) This is for ordinary digital audio:Quote from: Sigmoid on February 10, 2014, 05:41:08 pmThat basic assumption is wrong, and therefore, most of your conclusions (and especially, your snorts about high-end products) are also without base. Consider: Each stagemustgive out samples at the exact rate they are coming in. Otherwise you have to start inventing samples (local clock is fast) which would be awful. Or if the local clock is slow you'll lose lip sync, music plays a while after you hit stop on the player and no matter how big your buffer, eventually you run out of room in the buffer and have to start throwing out data. That is not good either. You have to run each stagein syncwith the incoming signal.QuoteAnd that is indeed the case. There is no way around it.In reality, CD players have a small buffer and the timing comes from a local oscillator. (Which in mediocre products, is polluted by having a motor in the same box and not taking adequate protection for the purity of the oscillator.)QuoteThat is a very common misunderstanding.We are so used to data transmission, that not many realize that digital audio relies onanalogtiming information carried along it (on bit edges).I'm bored and not much to do before the courier brings in the new parts, so I have time: First, seehttp://en.wikipedia.org/wiki/Differential_Manchester_encoding, and look at the second picture. This is how signal in SPDIF is transmitted. There is no separate clock signal, it is derived from the bit edges by a PLL. There is very good reading about jitter athttp://nwavguy.blogspot.fi/2011/02/jitter-does-it-matter.html. Do look at least the second image that shows how the encoding and limited bandwidth on the cable generates jitter. In the bottom are very real life examples: A motherboard (truly awful), a couple of popular cheap external USB DACs (better, but still audible) and a $1600 DAC (something for the designer to be proud of). Btw: I'm not the NwAvGuy, and I have no affiliation to any of those products.

author: AndyC_772
author_rank: Super Contributor
timestamp: February 11, 2014, 02:58:22 pm
content: Quote from: JuKu on February 11, 2014, 09:01:56 amOne word: FIFO. Your argument would only make sense if there were no such thing as dual-port RAM.Provided that, on average, one sample is clocked out for each one which is clocked in, then a simple FIFO can be used to *completely* decouple the cycle-to-cycle timing of the samples coming from the SPDIF interface, from the cycle-to-cycle timing of those same samples going out to the DAC. All it does is introduce a very small pure delay, which may only need to be a few samples' worth.You still need a clock to drive the DAC which runs at the same nominal rate as the incoming data, but it only has to match the long-term average rate. It can be as simple as a VCXO governed by a control loop that looks at the amount of data in the FIFO at any given time.How do I know this technique works? Several years ago I designed a DAC, from scratch, which works in exactly this way. The DAC chip itself is connected directly to the output of a VCXO, and the VCXO is controlled by a chunk of logic in an FPGA which wakes up every few seconds, makes a tiny adjustment (if needed) to the VCXO control voltage to keep the FIFO about half full, then goes back to sleep again.If you can spot a path by which jitter in the SPDIF signal could possibly affect the DAC clock in this topology, I'd really love to know what you think it is.

author: NiHaoMike
author_rank: Super Contributor
timestamp: February 11, 2014, 03:20:27 pm
content: The newer digital receivers also have adjustable delay to compensate for lag on some TVs and a "game mode" that simply sets the buffering to minimum and turns off processing that adds significant lag.

author: Sigmoid
author_rank: Frequent Contributor
timestamp: February 11, 2014, 03:40:30 pm
content: Quote from: hamster_nz on February 10, 2014, 10:04:29 pmNyquist.

author: Sigmoid
author_rank: Frequent Contributor
timestamp: February 11, 2014, 03:54:11 pm
content: Quote from: JuKu on February 11, 2014, 09:47:29 amI see AndyC_772 has already said pretty much the same I wanted to. FIFO, transmission control, burst read/transit. You know, these things have been around for a while now.Quote from: JuKu on February 11, 2014, 09:47:29 amWelcome to the real world, Neo.Quote from: JuKu on February 11, 2014, 09:47:29 amI'll look into the timing aspects of SPDIF, I'm curious. Still, we weren't talking about timing. We were talking about "misaligned sensors" and light not hitting dead center. That, timing information or not, sounds absolutely ludicrous.

author: JuKu
author_rank: Frequent Contributor
timestamp: February 11, 2014, 08:17:54 pm
content: Quote from: AndyC_772 on February 11, 2014, 02:58:22 pmYes, I believe the scheme would work and you could make money with it. The only possible jitter is the inherent noise of the vcxo (insignificant with good execution) and the timing of the contol loop (fraction of a Hertz, again insignificant when done right). I believe the product would be rather expensive, though. Sounds very high-end from all sides.I'm not aware of any comercial product doing that (price, likely?). Are you?(Edit: typo correction, iPad keyboard...)

author: JuKu
author_rank: Frequent Contributor
timestamp: February 11, 2014, 08:40:44 pm
content: Quote from: Sigmoid on February 11, 2014, 03:54:11 pmThat could affect the signal strenght on the sensor which affects bandwidth. I couldn't think any other explanation to the measurable jitter differences in receiver parts of same type and same manufacturer. If you have another idea, I'd like to hear it.(Yeah, if you have a jitter sensitive system, input 1 might sound better (or worse) than input 2. )But we are beating a dead horse. This issue was understood and solutions found at least 15 years ago.

author: JuKu
author_rank: Frequent Contributor
timestamp: February 11, 2014, 09:10:39 pm
content: Jitter is boring, let's change the subject to the audibility of absolute phase:Quote from: linux-works on February 08, 2014, 04:40:15 amNote that most waveforms are asymmetrical. I've heard demo signals where the absolute phase was changed, and I heard a change in the color of the sound. Maybe I heard it because I was supposed to, but the demo was set up to show that for some type of signals absolute phase matters. I've heard that female voice and trumpet are the natural sounds where the difference could be audible.Maybe some people can learn sounds so well that they can hear absolute phase. Probably, a lot of experimenting is required as well to learn the difference. In real life there are so many other things affecting sound color (speakers and room the biggest) that I don't think I have any chance (outside an artifically set up demo).

author: hamster_nz
author_rank: Super Contributor
timestamp: February 11, 2014, 09:11:12 pm
content: Quote from: JuKu on February 11, 2014, 09:47:29 amInteresting graphs on the link - do I read it right that the jTest is a 'torture test' based around a 11.55kHz -3db test tone, and a spectrum analyser picks up noise with individual frequencies at around -100db or less depending on quality of the DAC?But you are right, that with a better DAC when you are belting out 500W of power (+57dbm) the most energy in a jitter induced 'false' frequency on the truely aweful DAC is 0.1 microwatt (?40 dBm)? to 0.01 microwatt (-50dbm).

author: JuKu
author_rank: Frequent Contributor
timestamp: February 11, 2014, 10:11:23 pm
content: Quote from: hamster_nz on February 11, 2014, 09:11:12 pmYou can't really read signal to noise ratio from a graph. NwAvGuy did not publish the number. I've seen my share of graphs with numbers attached. Just an educated guess, but I don't think -80dB is far as S/(N+D) for the motherboard graph. That is somewhere between a phone and well done CD.

author: lewis
author_rank: Frequent Contributor
timestamp: February 12, 2014, 12:05:11 am
content: Quote from: linux-works on February 10, 2014, 03:59:05 pmUSB audio tends to use the isochronous transfer mode - the packets get chucked out of the computer to the DAC with limited latency, but with NO retires on lost/corrupted packets. It is essentially a one-way pipe. There is a CRC but no way for the endpoint to request a replacement packet. The USB host also prioritises the Interrupt and control transfer modes, so if the bus is busy any isochronous transfers may be delayed. The reliability of the connection therefore becomes an issue, and any induced noise interfering with the data link could corrupt packets with no way for the endpoint to do anything about it.You don't get corrupted data when you copy a Word document to a flash drive because file transfers use the Bulk transfer mode. In this mode there is no guarantee of latency (it can be as slow as you like), but there is full packet checking and retires on error. This is NOT the case with isochronous where "small errors are not catastrophic and can be tolerated".I've never seen this explanation mentioned elsewhere, but this may explain the alleged audibility of some USB cables. Or it's just total bollocks.

author: NiHaoMike
author_rank: Super Contributor
timestamp: February 12, 2014, 12:11:50 am
content: Quote from: lewis on February 12, 2014, 12:05:11 amA good solution is to put an indicator on the front of the DAC or converter that lights up if it detects a CRC error.

author: John Coloccia
author_rank: Super Contributor
timestamp: February 12, 2014, 11:57:45 am
content: Quote from: ampdoctor on February 04, 2014, 08:51:09 amSo obviously, they weren't identical. Reverb tanks are electro mechanical contraptions. I would EXPECT there to be a good amount of variance in it.re: different capsDid you carefully measure the actual value of the cap? The tolerances on many caps are very wide. Also, different cap construction have different frequency responses. When all of the variables are controlled for and a real experiment is done, the differences always disappear.Part of what I do is build guitar effects pedals. None of them sound exactly the same. There's always a little variability here and there, and that's with high quality, close tolerance parts. Every now and then I build one that just doesn't sound right, and the board goes in the trash. If I built these things with Radio Shack parts, they'd be all over the place and 50% would end up in the trash.

author: Sigmoid
author_rank: Frequent Contributor
timestamp: February 12, 2014, 03:41:03 pm
content: Quote from: lewis on February 12, 2014, 12:05:11 amBit errors do not "degrade quality". They translate into blips and screeches.Digital does not "degrade" like analog. It's either 100%, or it's 100% broken.

author: JuKu
author_rank: Frequent Contributor
timestamp: February 12, 2014, 04:37:44 pm
content: Regular spdif audio can be affected by cables. As said many times, the precise timing rides on bit edges, and limited bandwidth inject noise to PLL. The cable could in some cases have an effect (most obviously through the quality of shielding in coax).Isochronous USB needs a PLL too. I can see how an uniformed audiophile can convince himself that the quality of USB cable matters as well. I have harder time figuring out how cable could affect the PLL in USB.

author: linux-works
author_rank: Super Contributor
timestamp: February 12, 2014, 04:44:43 pm
content: Quote from: Sigmoid on February 12, 2014, 03:41:03 pmthis isn't a digital bit error, per se, but it is a digital audio error: ever hear a DAT machine mistrack? back when I was involved with DAT some of us would use non-standard tape lengths (60meters or 2 hours of standard play was most common and in-spec) but 3 hour 90meter or even 120meter tapes were also found and meant for data DDS drives (which can adjust tension to make up for thinner tapes). on audio systems, none that were made back then were able to auto tension and so every so often, you'd hear a mistrack and it would sound like a buzzsaw. very annoying and ruining of the audio ;(the cure was to keep the system aligned, cleaned and never use thin tapes. it was not cheap to keep the machines always CLA'd (to use a photo term) and so many of us had to deal with the odd buzzsaw here and there.I never saw errors over the spdif lines, no matter how badly I abused cables. I built many spdif switches and buffers and media converters (toslink and coax) and used the worst possible cabling - but never heard any bit errors. you have to really go out of your way to create data corruption in spdif, at the bit level.at the timing level, sure, things are easy to get wrong, but the format (with reclockers at the rx side) is very forgiving.

author: lewis
author_rank: Frequent Contributor
timestamp: February 12, 2014, 10:22:50 pm
content: Quote from: JuKu on February 12, 2014, 04:37:44 pmThe PLL is nothing to do with it. If the packets get dropped, and with no way to recover them, the audio is affected.

author: AndyC_772
author_rank: Super Contributor
timestamp: February 13, 2014, 07:53:25 am
content: Quote from: JuKu on February 11, 2014, 08:17:54 pmIt does. I've been listening to it every day for about the last five years.QuoteThe total cost is about £3 for the VCXO and maybe £10 for the FPGA, so the added cost of simply getting the topology right is negligible. Other than designers having a mental block about how a product "should work", I can't think of a single good reasonnotto design a DAC this way.USB has been mentioned too, and my DAC does also have a USB input. It uses an off-the-shelf TI USB DAC chip which is designed to go into cheap sound cards - but as well as analogue, the chip also has an SPDIF output. I don't doubt that the jitter performance of the SPDIF stream is pretty poor, but of course, that doesn't matter in the slightest in this case. It all goes into the FPGA, through a FIFO, and emerges under control of the VCXO.I did look quite seriously into making the design available commercially, but there's a huge amount of work involved in bringing a product to market over and above a clever schematic and a working prototype. Since I already have a job, and I can't see myself ever getting rich off yet another piece of niche hi-fi gear, I decided against it.Instead, I got an upgrade to the sound of my hi-fi, and the satisfaction of knowing that what I'm hearing is coming from a design which isrightin an academic sense. And, of course, that fact alone makes it sound better!

author: JuKu
author_rank: Frequent Contributor
timestamp: February 13, 2014, 08:29:34 am
content: Quote from: AndyC_772 on February 13, 2014, 07:53:25 amWelcome to real world: You just at least quadrupled a typical outboard DAC parts costs, and are on different planet for a receiver. For a typical $1000 street price receiver, the digital audio in section budget is <$1. Add some for the micro and bigger PCB, convert to $ and we might be at 24$. There are 23000 (yeah, every penny counts) reasons NOT to design run-of-the-mill consumer stuff that way. (This is why I don't want to do those; vast majority of my audio work has been high and even higher end.)QuoteDoes it do 96kHz/24bits?QuotePM me if you would want to talk about licensing it.

author: auxie22
author_rank: Contributor
timestamp: April 08, 2014, 11:38:23 am
content: Quite a number of years ago I use to have hypersensitivity disorder and struggled to be in a crowded room like a mall / shopping centre and most audio equipment to me sounded horribly "muddy" (what I know now is the "muddy" sound was actually Fcu roll off between 18-20k and so it seemed "muddy" to me at the time) or seemed strange or distorted because I could hear the nyquist frequency on CD's. I got my hearing tested and could hear between 20Hz-25kHz. I could hear the difference between most audio systems due to the difference in the extreme top end. Not long after that I became a Live Sound Engineer and started going deaf even though I used earplugs, the constant 90+ dB SPL's and not to mention age slowly brought the upper end of my hearing down to 16kHz and due to this I have had a much better time in large crowded areas and even with sleeping. Sometimes I think the "Golden Ears" aren't always a blessing. I know I struggled with it and am happier "without them". I can actually enjoy music on most audio systems now unless my analytical objective Sound Engineer side comes out.

author: powerhouse
author_rank: Contributor
timestamp: April 08, 2014, 05:09:32 pm
content: Your title and post got my attention (also found the above post very interesting). I must admit that I'm not familiar with psychoacoustics, but I did and do listen to music using what some would consider audiophile equipment, and have listened to a variety of mid to high-end stuff. Oh, I used to be able to hear 20kHz (or even higher?), now it's at 16kHz or so. I can still make out lots of noises, high pitched sounds, etc. that most people including youngsters don't hear or notice.To put it simple, for me the difference between enjoyable audio equipment to let's say less enjoyable hifi stuff is in the extent to which it engages me. If I get tired after listening to familiar music over some time it means something in the equipment chain is not up to the task. If the music keeps engaging me then the audio equipment is worth closer examination. Selecting the right auditioning music also helps. Tomshardware gave an excellent example on how NOT to do hifi auditioning - seehttp://www.tomshardware.com/reviews/high-end-pc-audio,3733.html. According to their editor spending more than $2 in a DAC is a waste of money. If you look at their method there is - in my opinion - no way they can tell apart the (near) true-to-life reproduction of music versus the average rendering of digitized music. (The reasons why I think so are: 1. TH uses mostly studio multi-track recordings that are impossible to relate to any real concert experience; 2. The auditioning periods are much too short, you can't make out much if any difference when listening to a 3 minute track on DAC1, then on DAC2, etc.; 3. They were trying to identify differences in what they hear, whereas I would be looking for what's missing; 4. It hasn't been mentioned, nor is there any reason to assume, that TH chose any music recorded in a concert hall that the auditioners were familiar with. When I audition audio equipment I bring with me at least one or two recordings where I am familiar with the recording venue and specific acoustic properties; 5. TH used stereo headphones which, as good as they are, can't really reproduce a natural sound stage.)One reason why not-so-good audio equipment reproduces music in a way that exhausts me is the effort I'm forced to make to locate instruments/players on stage.I can't tell if this has to do with the ASMR you mentioned, but I certainly can provide plenty of examples where even a "small" change in the audio setup (for example a different interconnect) can make a noticeable difference to me, even though it may be on the level of how I feel or how I enjoy the music, and not on any identifiable difference in the sound. In many cases I would need to listen to music for a prolonged time to become aware of it, and I doubt if the difference I hear (or better "feel") could be easily identified by test equipment. Let's put it this way, there are few if any specs that audio equipment producers publish that have any bearing on the quality of the music reproduction - even the price tag doesn't give an indication (though good stuff tends to cost more).All my audio equipment and cables have been selected by me on the basis of purely subjective criteria: the level of pleasure it gives me when listening to music. In short, yes, I think there is a lot more to music and music reproduction than what many want to make us believe. ASMR could perhaps help to explain this.

author: powerhouse
author_rank: Contributor
timestamp: April 08, 2014, 05:41:41 pm
content: Quote from: Sigmoid on February 06, 2014, 04:18:41 pm+1

author: powerhouse
author_rank: Contributor
timestamp: April 08, 2014, 07:05:05 pm
content: Quote from: JuKu on February 08, 2014, 09:57:46 amExactly !!!I've read through most of the posts now and it always amazes me on how many people think that they fully understand the world and the human being and on how we hear and perceive music. Because I don't.The only thing I know is what I like. And I like to hear a classic concert so that when I close my eyes I can hear the solo violin a little left centre, near the front of the stage, and it doesn't move or become fuzzy with the change of pitch or frequency or string played. And so on for each instrument in the orchestra, or singer. But this is only one of many qualities I expect to find in my audio gear. Measurebators will be hard pressed to put the qualities I'm looking for into numbers. And those companies who try to put audio quality into numbers can go look elsewhere for customers who are impressed by those - I'm definitely not!

author: edavid
author_rank: Super Contributor
timestamp: April 08, 2014, 07:52:38 pm
content: Quote from: powerhouse on April 08, 2014, 07:05:05 pmStraw man argument... you don't have to "fully understand the world etc." to know when an audiofool is spouting bullshit!

author: DrGeoff
author_rank: Frequent Contributor
timestamp: April 08, 2014, 11:31:28 pm
content: The recordings are not made using perfect microphones.They are not digitised using perfect ADC units.The consoles that they are mixed on are not perfect. If analogue bus summing is used on an external console than it goes through another DAC/ADC step.Then the mastering stage will require further passing of the signal through various analogue boxes (another DAC/ADC step). Finally you have your 16-bit dithered digital stereo file ready for CD impression.So why would anyone think that buying excessively over engineered equipment make any real noticable difference? You could just buy an Apogee or similar DAC (as is used in the studios) to get the same output.

author: linux-works
author_rank: Super Contributor
timestamp: April 09, 2014, 12:07:40 am
content: most recordings are crap. its so true!there are very few that truly deserve 'special handling'. its for those that the audiophiles really go to extremes.I have a collection of 24/96 and even 24/192 flac files but its not material I listen to, much. it ends up being 'demo material' more often than not.the regular stuff I listen to does not need high-end playback gear.but then again, if we build our own, its not expensive, it uses better parts than a sony (etc) would put in and we can change things if we want to. I built audio gear because its not expensive, I can do it and I can get much better specs than most mass producers are willing to spend on. but I'm not saying I hear the extra difference.

author: DrGeoff
author_rank: Frequent Contributor
timestamp: April 09, 2014, 12:38:58 am
content: Quote from: linux-works on April 09, 2014, 12:07:40 amI wouldn't say that most are crap. Many recordings are made with what is available at the time. The music is usually more important than the recording chain. Older recordings impart the sound of various 'eras' of recording technology and performance styles.Quote from: linux-works on April 09, 2014, 12:07:40 amI have loads of 24/96 and 24/44.1 recordings, mixes and masters. I could sit in the studio and listen to the music through high-end studio equipment, but it's not very convenientA lot of mixing and mastering these days is done for the purpose of the mass consumer crowd, ie iTunes and earbuds.Quote from: linux-works on April 09, 2014, 12:07:40 amWe owe a lot to the ubiquitous 5532 op ampBuilding your own audio gear is fun and can be quite satisfying. Adding the extra few dollars that the manufacturer decided to skimp on can make a significant difference to the sound. This is where DIY audio shines.

author: linux-works
author_rank: Super Contributor
timestamp: April 09, 2014, 12:44:25 am
content: listening to most of my cd's gives a bad experience since I hear the failures in the mix. noise, distortion and way too much compression (and even gross mistakes like letting singers swallow the damned mic instead of having a reasonable distance so it does not clip) make the music sound like crap.conversion from analog using 20 yr old a/d boxes also is a failure point. I got a copy of steely dan 'gaucho' in 24/96 format and it finally is something close to enjoyable. the cd copy is borderline acceptable and that band is one who actually cares about the resultant sound. it was only the redo for the 24/96 format that they finally got the end sound as good as modern state of the art playback gear.having too good of a playback system can work against you; you start to hear the failings and its not pleasant to hear full resolution when a lot of the wave is distorted or noisy.

author: linux-works
author_rank: Super Contributor
timestamp: April 09, 2014, 09:17:24 am
content: sacd is rippable with some kind of playstation hack, iirc.I've seen sacd 'rips' before, so I'm pretty sure it can be done. dvd-a is one that I'm not sure is rippable even by the PS.

author: BravoV
author_rank: Super Contributor
timestamp: April 09, 2014, 10:26:21 am
content: Quote from: linux-works on April 09, 2014, 09:17:24 amGoogle for "dvdcpxm"