How sensitive vinyl player actually is ? - Page 1
Forum section: electronics / general

author: jimon
author_rank: Regular Contributor
timestamp: January 27, 2015, 09:08:12 pm
content: Was bored and curious on a same time, so did long awaited fix - replaced stylus in vinyl player head, previous one had too many hours on itSo in setup meantime I've connected oscilloscope to it, and see what's happens next :http://youtu.be/jz_E8bNpgp8Even small finger tap on a table disturbs signal significantlyPS. I've directly connected signal from phono preamp, without termination, so probably it's not perfect connection for any measurements, but well, it's good enough for 1 KHz sinusoidal mono signal.PS2. I'm not vinyl weeaboo who buys 5k$ digital or analog cables, but I spent a bit more money on RCA cables just to get proper connectors, because they tend to fail too often

author: SL4P
author_rank: Super Contributor
timestamp: January 27, 2015, 10:04:11 pm
content: I've gotta say that as an ex-vinly person from the 70's - this is pretty disappointing from a product that costs $400+ on eBay and Amazon.Perhaps some shipping screws still fitted in the mechanical undercarriage?

author: jimon
author_rank: Regular Contributor
timestamp: January 27, 2015, 10:46:41 pm
content: Quote from: SL4P on January 27, 2015, 10:04:11 pmNo shipping screws that I aware of (it comes with two shipping screws anyway).I don't really expected too much from this turntable (it's standing on default stands) + it's standing on cheap ikea (or jysk) tableWould be nice to try such experiment with proper setup. It's a pity that modern vinyl users don't plug scopes to see what's actually happening.

author: SL4P
author_rank: Super Contributor
timestamp: January 27, 2015, 11:04:47 pm
content: If you're looking - the places to explore for ingress of 'vibration' are:The plinth mounting (on the table).The turntable mounting on the plinth.The tone-arm suspension & tracking tension/bias.Of course once you get past those, look at rumble, wow and flutter specs!Cheers(and that's why we all shifted across to digital audio!)

author: saturation
author_rank: Super Contributor
timestamp: January 29, 2015, 05:04:00 pm
content: Such players are electromechanical transducers: any vibration or noise, including music played from the record, vibrations from the player drive mechanism, to people talking in the room, etc., is fed back into the system. Much technology, from audiophile voodoo to legitimate, was spent controlling or eliminating that feedback and noise sources when record players were at the prime: vibration dampers, sound proof boxes etc.,. While digital has it drawbacks, contamination from ambient changes wasn't one of them.

author: IanB
author_rank: Super Contributor
timestamp: January 29, 2015, 05:19:31 pm
content: Quote from: saturation on January 29, 2015, 05:04:00 pmNot to the same extent, but mechanical parts of a system are still vulnerable. For instance the laser tracking on the disk. I think excess vibrations here could lead to misreads and increase the error rate.

author: wraper
author_rank: Unknown
timestamp: January 29, 2015, 05:36:22 pm
content: Quote from: IanB on January 29, 2015, 05:19:31 pmFor audio it is important because of the crappiness of the audio CD standard which cannot guarantee data integrity. Therefore such CD ripping programs as EAC make multiple reads of the same disc at low speed. Depends on CD drive quality too. For normal data discs it does not matter so far as data can be read correctly after multiple attempts. Of course laser tracking issues will cause slow reads.

author: cosmicray
author_rank: Frequent Contributor
timestamp: January 29, 2015, 05:39:05 pm
content: The issues involved here are mass (of the cartridge/arm) and how isolated the turntable assemble is from vibration. B&O used to make very low mass cartridge assemblies, plus their turntables had good isolation. When unpacking the turntable, there were three large screws (used a US nickel coin to turn them) that released the assembly from it's shipping locked position. Then it gently floated. The dealer that sold me the turntable did a demo by raking the arm back and forth across a spinning album. This inflicted no scratches on the vinyl. The explanation was that the low-mass of the cartridge/arm allowed it to ride over the grooves, instead of digging in. I'm not sure if that explanation was accurate, but the vinyl showed no visible scratches, and no audible tics when played across that area.

author: Lightages
author_rank: Unknown
timestamp: January 29, 2015, 06:49:41 pm
content: I remember an article in Radio Electronics in the 80s? that explored the performance of vinyl and some of the capabilities were rather surprising. Vinyl is still far inferior to modern digital reproduction, but it was interesting to see what vinyl could do.

author: oldway
author_rank: Super Contributor
timestamp: January 29, 2015, 08:21:30 pm
content: QuoteQuality turntables had an heavy platter (for example, Lenco L75 : 3.8Kgs) to minimize this problem.

author: AndyC_772
author_rank: Super Contributor
timestamp: January 29, 2015, 09:16:28 pm
content: This isn't really a very useful experiment unless the frequency spectrum of outside interference can be determined. It looks very dramatic to see the scope trace jump around, but that doesn't mean there's significant interference making it through to the signal in the audio band.Connect the scope to the output of the preamp via a reasonably sharp 20Hz high-pass filter, and you might be able to capture some worthwhile data. Until then, I think the experiment is misleading.

author: SL4P
author_rank: Super Contributor
timestamp: January 29, 2015, 10:04:31 pm
content: Speaking of all the other audio voodoo (nice word!)...In the right circumstances - let's bring that old word'microphonics'back into the conversation.Even the choice of the 'wrong cables with the wrong drivers & termination couldleave your cables open to vibration/pulse interference- tapping on the table, etc. Of course the mechanical microphonics were most often experienced when tapping on active components with specific physical weaknesses - e.g. valves & internal resonances.Digital signal transmission certainly gave relief from this - notwithstanding the cable, capacitance effects and other variables are still the same - they simply mask the 'analog' nature of the ingress vector. With the right environmental factors the problem is still there, you just can't hear it.

author: jancumps
author_rank: Unknown
timestamp: January 29, 2015, 10:10:56 pm
content: If you have speakers with removable front,you should at least once in your life take the front off and watch the woofer wile you plunge the arm on the record.

author: jancumps
author_rank: Unknown
timestamp: January 29, 2015, 10:17:08 pm
content: Quote from: oldway on January 29, 2015, 08:21:30 pmI have one at home from the 60's with a platter that weights 4.3 Kg.

author: jimon
author_rank: Regular Contributor
timestamp: January 30, 2015, 10:34:27 pm
content: Quote from: wraper on January 29, 2015, 05:36:22 pmIIRC audio CD's (CDDA) are using Reed–Solomon error correction, which is good enough, same goes for CD-ROM.Quote from: cosmicray on January 29, 2015, 05:39:05 pmEvery tonearm have at least two settings - tracking force and anti-skating weight, first one means how much weight tonearm apply on needle, for mmf2.2 they recommend 1.75g, which is ok, you can set less and it will be ok to some degree. So tonearm + cartridge can give you different mass, but in terms of weight it's always around 1-2.5g. Also it's not so easy to actually damage vinyl record.Quote from: oldway on January 29, 2015, 08:21:30 pmIn mmf2.2 they use 1.7kg.Quote from: AndyC_772 on January 29, 2015, 09:16:28 pmI haven't really thought through whole experiment (it's more playing around), sure I'll redo it more properly at some point.I think most valuable will be to have master. Then it's should be possible to compare them, probably with this ultimate test LP that I have it's actually very simple, I know that they recorded 1 KHz sin signal there, so oscillator + PLL jig and that's it

author: wraper
author_rank: Unknown
timestamp: January 30, 2015, 10:48:00 pm
content: Quote from: jimon on January 30, 2015, 10:34:27 pmIt's not good enough. What it cannot correct, get interpolated. Data CD is not the same.http://www.pcguide.com/ref/cd/mediaECC-c.html

author: JuiceKing
author_rank: Regular Contributor
timestamp: January 31, 2015, 12:45:20 am
content: Quote from: jimon on January 27, 2015, 09:08:12 pmThis is to be expected. Even very expensive turntables will transmit shocks like knocks on the table or stamping on a suspended floor. Looking at sine waves from your turntable will drive you crazy.

author: SL4P
author_rank: Super Contributor
timestamp: January 31, 2015, 02:52:53 am
content: Quote from: JuiceKing on January 31, 2015, 12:45:20 amLOL !

author: wraper
author_rank: Unknown
timestamp: January 31, 2015, 09:32:32 pm
content: Get 50+ kg granite brick under your turntable O0. That will remove most of the vibrations.

author: dannyf
author_rank: Super Contributor
timestamp: January 31, 2015, 10:09:12 pm
content: QuoteUsing a spring to suspend a tank of water from the ceiling. In the tank, float your player with inflated floaties.No more vibrations.

author: jimon
author_rank: Regular Contributor
timestamp: January 31, 2015, 11:25:59 pm
content: I wonder if laser vinyl player (http://www.elpj.com/) is also so sensitive. They cost 16k$+, I looked on photos what's inside and patents how does they work, BOM should be <1k$So I plan to build one

author: SL4P
author_rank: Super Contributor
timestamp: January 31, 2015, 11:36:39 pm
content: Quote from: jimon on January 31, 2015, 11:25:59 pmThink physics.All you eliminate in the pickup domain is the mechanical stylus.All the other issues are separate problems.(Edit: And dust/crackle sounds better in laser mode, as it's not pushed out of the way)

author: wraper
author_rank: Unknown
timestamp: February 01, 2015, 12:15:28 am
content: Quote from: jimon on January 31, 2015, 11:25:59 pmMy guess you will end with nothing or very poorly working device. As for me it is completely not trivial to read analog (stereo!) track with laser on the black surface and get sensible result out of it. This is not reading zeroes and ones from the CD. You would need custom moving (tracking) optics for this as minimum.

author: jimon
author_rank: Regular Contributor
timestamp: February 01, 2015, 12:32:03 am
content: Quote from: SL4P on January 31, 2015, 11:36:39 pmhttp://www.vinylrecorder.com/stereo.htmlSorta, horizontal movement is basically L + R, while vertical is L - R. Sophisticated laser pickup head should be able (in theory) pick-up L - R precisely (width of groove is not influenced by noise). Horizontal movement is impossible to pickup precisely because there are no zero volt reference for groove.So let's say :L + R = AL - R = BThen :L = (A - B) / 2R = (A + B) / 2And external noise :A' = A + noiseIn result :L = (A - B) / 2 + noise / 2R = (A + B) / 2 + noise / 2I wonder if you can add an additional pickup for noise, and then just use subtract it.

author: SL4P
author_rank: Super Contributor
timestamp: February 01, 2015, 06:38:52 am
content: Hmm - interesting analysis. Fun to look at it that way.

author: Richard Crowley
author_rank: Super Contributor
timestamp: February 01, 2015, 07:14:10 am
content: Of course, back in the monaural era, there was little sensitivity to vertical motion of the stylus, so turntables weren't as vulnerable to ambient motion. But stereo makes the pickup cartridges just as sensitive to vertical motion as horizontal, and that raised the bar on vibration mitigation for stereo turntables.

author: calexanian
author_rank: Super Contributor
timestamp: February 01, 2015, 07:30:13 am
content: I heard it touched on but let me elaborate. Not specified by RIAA but always assumed to be present was a high pass rumble filter in the phono preamp circuit. The frequency response an contour of the circuit was something that varied from manufacturer to manufacturer and certain turntable/tonearm/cartridge/needle combinations worked better with certain rumble filters depending on setup. generally speaking that gets rid of that noise to a reasonable listening level anyways. As far as the capabilities of vinyl to hold data, i suggest you look at a demo/production video of the RCA Selectavision system. I believe the video/audio signal of those discs there a modulated 3 MHZ signal on a vinyl disk inside a plastic jacket. I have one of those stylus modules floating around somewhere. You could fit a movie on a double sided disc about the size of a laserdisc. They actually worked via a capacitance method like a condenser mic rather than a magnetic phono cartridge like a dynamic mic.Have a lookhttp://en.wikipedia.org/wiki/Capacitance_Electronic_DiscCheck out this guys voice. I feel like buying a 78 oldsmobile right now!http://youtu.be/pymAoh7KH64