UAMP - Soul Shaking Audio for Your Ears - Page 1
Forum section: electronics / general

author: snoopy
author_rank: Frequent Contributor
timestamp: March 14, 2015, 01:26:21 am
content: Some local aussie dudes with a portable headphone amp for your phone.https://www.kickstarter.com/projects/1746450443/uamp-soul-shaking-audio-for-your-ears?ref=category_locationQuote

author: ConKbot
author_rank: Super Contributor
timestamp: March 14, 2015, 03:59:40 pm
content: Nothing really standing out there. No details, no ludicrous claims. Low impedance headphone (8, 16, maybe 32 ohm) could benefit from a better buffer depending on your source device, and high impedance phones (600 ohm) can benefit from some gain, again depending on the source. Hooking up earbuds to it may not be achieving anything you cant do with EQ software though(at least in smartphones). Not sure what sort of EQ apps are available for smartphone though, never really looked into it.

author: Warhawk
author_rank: Frequent Contributor
timestamp: March 14, 2015, 07:27:55 pm
content: Heh Interesting, I named my last project "uAmp" as well and believe or not, it is a headphone amp(in altoids box though).

author: Lightages
author_rank: Unknown
timestamp: March 14, 2015, 09:10:10 pm
content: I find it a bit expensive actually. You can get a complete Android phone with reasonable capabilities for that price. Especially if the "equalizer" is just bass and treble adjust. If it is a nice 10 band equalizer then it might be worth the money. If it is only 5 band, well most phones will do that already and so it would be a redundant feature.

author: tszaboo
author_rank: Super Contributor
timestamp: March 14, 2015, 10:30:10 pm
content: Quote from: Lightages on March 14, 2015, 09:10:10 pmVery similar size and features to the Fiio E5, but not the price. 0.01% THD, nothing extraordinery.

author: tom66
author_rank: Super Contributor
timestamp: March 15, 2015, 11:12:45 am
content: Doesn't this depend on the headphone output THD?

author: BradC
author_rank: Super Contributor
timestamp: March 15, 2015, 11:21:01 am
content: Quote from: tom66 on March 15, 2015, 11:12:45 amOf course, however if you can wind the headphone output down a bit to get it into cleaner turf. The SnR will probably suffer, but it would give you a cleaner sound at higher volume.I can see the sort of people this would appeal to (and there are a _lot_ of them). I have some friends who's ears are so damaged that their "normal" listening level is bordering on painful for me, and my listening level is almost inaudible to them. They are the guys that all have expensive headphones and *big* headphone amps to drive them at home. I know they'd fall over themselves to get a pocket amp that would give them that output level when coupled with an iPod or phone.

author: bartek
author_rank: Contributor
timestamp: March 16, 2015, 08:37:25 am
content: Hey everyone, I'm Bart from the Uamp team, I've been lurking in this forum for many years, and a big fan of the EEVblog, so it's pretty awesome to see my project has been posted up here.We are a small start-up so any feedback would be very welcome!Also, I'm happy to answer any questions as long as I don't break any of the forum's rules for self-promotion etc.

author: linux-works
author_rank: Super Contributor
timestamp: March 16, 2015, 05:13:58 pm
content: would be nice to see some actual measurements (rmaa or something). that would include driving pure resistive loads (low, med, high) as well as real reactive HP loads (again, 3 ranges of Z).what's the noise like? what is the crosstalk? how resistant is it to hum? how well is the controller filtered so that you don't hear digital noise from the psu?what is the output voltage swing? what is the max input range?you guys need to add a lot more details.would also be interesting to know the topology inside and if we can repair this ourselves or if its a throw-away device.

author: bartek
author_rank: Contributor
timestamp: March 17, 2015, 01:25:21 am
content: Quote from: mojo-chan on March 16, 2015, 03:14:04 pmThanks Mojo-chan, we did a lot of the hard work finding manufacturers/suppliers with our previous failed Kickstarter, so we did manage to find some pretty competitive pricing this time around. That being said, if we only got $15K then we might not have broken even, but the experience would still be worth it for us.Quote from: linux-works on March 16, 2015, 05:13:58 pmI'll post up all the detailed test measurements once the next iteration of the design is back from China, as a lot of people have been rightfully asking for them.With regards to repairability, we have changed to a replaceable battery (mini-connector vs solder) as many people were asking for it. However, to fit all the electronics in such a small enclosure we are using some pretty small SMD parts, most people will not be able to repair it unfortunately.

author: linux-works
author_rank: Super Contributor
timestamp: March 17, 2015, 01:56:17 am
content: curious if you care to reveal which chips or topologies you are using?if not using something like a TPA6120 chip, maybe you can do some side by side tests against one of those. I'm thinking of building one that is based on that TI chip and lots of people have had success with it. if you are already using it, good for youalso wondering if you are going to be using digital attenuation or analog (that is digitally controlled)?

author: linux-works
author_rank: Super Contributor
timestamp: March 17, 2015, 04:09:05 am
content: I'm into audio, and you can't be into audio and not have some experience with the headphone scene..so this interests me, to some degree. fixability is high up on my list, though. if you are a sony, you can afford to have users throw your stuff away when it breaks, but the more specialty stuff should be more maker/builder/fixer friendly.if you are able to space parts (allow some gap, when possible) so that regular (but still skilled) humans can have a chance of fixing a bad or blown part, it would be a really good idea. add a few extra mm to the case to allow for itI would pay more for a system where I'm not locked into special batteries and I'm not prohibited from opening it up and fixing things if they go bad. jacks often are wear items. if you design this so that a jack swap is possible (at least a few times), THAT's a huge differentiator.be sure to consider wireless (qi, etc) charging systems, too.

author: snoopy
author_rank: Frequent Contributor
timestamp: March 17, 2015, 04:28:36 am
content: Quote from: bartek on March 16, 2015, 08:37:25 amAre you going to get it assembled locally or does the price limit where you can manufacture it ?cheers

author: bartek
author_rank: Contributor
timestamp: March 17, 2015, 11:02:12 am
content: Quote from: linux-works on March 17, 2015, 01:56:17 amThe TPA6120 is a great chip, I have one on my desk at the moment. Unfortunately it's not really ideal for a small battery powered devices (needs a minimum of 10V and relatively high supply current). I think it is more suited to a higher end design where its ultra-low distortion won't be wasted!We are using digital attenuation as it's smaller and our target market is more used to changing volume by pressing up/down buttons. It's noisier than a pot but has better channel matching.Also we are using an op-amp based design rather than headphone amp ICs, with dual supplies. But that's all I want to reveal for now..Quote from: linux-works on March 17, 2015, 04:09:05 amI definitely understand! On the plus side you will be able to get into our product with just 4 screws and no glue. The downside is that it will be all SMD as I only had 40 x 40mm to work with and a large part of that is taken up by the audio jacks and USB etc. I'll do my best to space components apart but there is not much room unfortunately.I like the suggestion for wireless charging, I'll look into it!Quote from: 3roomlab on March 17, 2015, 04:12:36 amNo probs, any feedback is good for us. To be honest, with the technical knowledge people have on this board I was expecting harsher feedback haha!

author: linux-works
author_rank: Super Contributor
timestamp: March 17, 2015, 01:52:02 pm
content: might be hard to do for small size, but a cool option would be to have BT audio (the good protocol, apt-x, at least) be present in some way. I can see 2 links, possible: a link from the player (phone, etc), and a link from the amp to the headphones.now, from the phone to the amp, it could be useful if you want to avoid wires between a phone (maybe in one pocket) and the amp module that might be elsewhere on you.the other link method is when you are using a dedicated mp3 player but it does not have BT and you want to use BT phones. in that case, you'd have this box take in line-based audio from a cord and transmit audio via BT to the wireless phones.I doubt that both links being BT would be at all usefulbut being able to enable the BT link on either end would be pretty 'trick' and I've not seen any box offer that, before.when you are transmitting BT to phones, your amp is mostly bypassed and you are just a transmitter, now. but if you look at the other case, where a BT sender sends to your device and you have nice expensive wired phones on the amp module, that could be a reasonable use-case.also, for the psu, not sure if you are going to allow usb (micro?) charging as well as wireless charging, but if you allow wired charging over usb, you could also (maybe) have a usb dac in the box and add yet another function (fiio has a few small boxes that act like usb dacs but are mostly phones amps.)maybe too much stuff to fit in a small box (lol) but just brainstorming some neat ideas, in case any sound interesting to you.

author: linux-works
author_rank: Super Contributor
timestamp: March 17, 2015, 04:06:50 pm
content: the headphone market has exploded the last 5 or so years. vendors are getting into it and often just for profit reasons.I tried a b&w set of phones (b&w used to be a very decent brand) but the phones were ALL about 'style' and the sound was worse than ear buds. still, a lot of customers buy it because it looks cool. the world is mostly NOT techies, as we all know.. ;(a good bang for the buck is a diy phones amp. those are all repairable, you can pick the level of parts you want and many have solid designs and real engineering behind it. so, there is no loss for product in this space, for those who really want good sound for their cans. my first DIY was the tangent pimeta and I still use that as a portable amp, today. that uses op-amps and buf634 buffers inside the feedback loop and does a quite nice job.integration with a dac, though, is a newer step up and I see more utility in a dac/amp combo than just an amp. but you get into a whole other set of issues if you start to be a usb dac (and being an spdif dac is not as useful today since most music sources either are usb-sourced or don't have an spdif-out anymore).fiio has some neat product ideas. I wonder how you can compete with someone like that?

author: Richard Crowley
author_rank: Super Contributor
timestamp: March 17, 2015, 04:15:23 pm
content: So we have portable devices that have been forced to include software controls and warnings to remind people to NOT crank up the headphone levels for health AND safety reasons.But then we have someone coming along with a gadget to completely circumvent that valid concern? Do I have that right?

author: linux-works
author_rank: Super Contributor
timestamp: March 17, 2015, 04:26:22 pm
content: I would imagine that its not about increasing volume, its about having good current drive, in the final stage (most portables cut corners on that). and for high-z phones like senn hd650 (600 and 580) you need voltage swing, which most portables do not have.you could always have a max-output limit on this box, too, of course. I think france still has laws about max volume out on a portable; not sure if other countries have laws like that or not (?)

author: linux-works
author_rank: Super Contributor
timestamp: March 19, 2015, 02:10:34 am
content: android audio, as I understand it, sucks. normal android audio does not support high res (not even sure if it has 24bit audio). even if you play high res, I think it downsamples it. some players can bypass the audio layer and do their own thing. not every kernel on android supports usb audio, fewer still support UAC2 (audio class 2). android is a farking mess. apple is not much better, either.maybe things will get better over time, but right now, its still not really good for much beyond simple redbook audio, if even that.I'd love to be able to use a phone to do usb-audio to an outboard dac. streaming over wifi can work, but many phones stopped having local sd-card storage and so phones for audio use seem a bit of a dead-end to me, for the most part.the fiio and ibasso players seem pretty nice, and oddly enough, they are android based but not dalvik (from what I hear). some of those players even support dsd audio, which I find pretty forward-thinking (DoP; not dsd-native, but still!)

author: ConnorGames
author_rank: Regular Contributor
timestamp: March 23, 2015, 03:16:29 am
content: And there areveryfew circumstances where a consumer would benefit from anything above 16bit/48k anyway. Especially if said consumer wants to keep his or her hearing!

author: ehughes
author_rank: Frequent Contributor
timestamp: March 23, 2015, 08:55:27 pm
content: http://www.aes.org/e-lib/browse.cfm?elib=14195High-res audio is dumb.There is virtually not reason for it. The people who say they can hear a difference can't when subject to a blind test.

author: Richard Crowley
author_rank: Super Contributor
timestamp: March 23, 2015, 09:00:05 pm
content: Quote from: ehughes on March 23, 2015, 08:55:27 pmYeah, we've been all through this in countless previous discussions, many of them on this forum.The "golden ears" audiophools claim they can "hear" the difference and nothing we can say or do will dissuade them of their fantasy.

author: N TYPE
author_rank: Regular Contributor
timestamp: March 24, 2015, 07:53:08 am
content: Solution looking for a problem? a lot of high end headphones take batteries and have amps built in anyway

author: linux-works
author_rank: Super Contributor
timestamp: March 24, 2015, 06:49:53 pm
content: and yet, the vinyl releases still have much less dynamic range due to having to 'fit' inside LP grooves.so, vinyl is nothing great to me. yes, the mastering is better but vinyl STILL SUCKS. none of the problems have ever been solved and can't be solved (such as: playing is destructive by nature; noise level is still very bad, distortion is bad compared to digital, freq response is bad compared to 24/96, stereo separation is worse than cd, etc etc).and 24bit audio will still just have 20 honest bits of data. the rest are dither or noise. but at least you get real 20 bits instead of 16.

author: Bassman59
author_rank: Super Contributor
timestamp: March 25, 2015, 04:54:53 pm
content: Quote from: mojo-chan on March 25, 2015, 09:46:33 amThat compression is a mastering decision and has absolutely nothing to do with the final format.