Amp for connecting ATH-R70X to PC

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Amp for connecting ATH-R70X to PC - Comments and advice appreciated

I've done a fair bit of reading already, but I'm finding myself overwhelmed and worried about choosing the wrong project, as DIY audio is entirely new to me. I am, however, moderately experienced with circuits. In regards to sourcing components, I'm based in Ontario, Canada. In regards to what I'm willing to spend: if $50 gets me a good amp, so be it. If it will cost me $80, that's fine too. My budget is flexible, as I don't know what I should expect to pay.

My needs for this project are as follows
  • Be able to safely turn the amp on/off while headphones are connected
  • Wall outlet power (DC transformer, I'm not crazy enough to think I should go with AC)
  • Minimal alteration to sound; primary use is PC gaming
  • Reasonable size; I hope to later build a headphone stand where the amp will reside in the base
  • If possible, be able to handle varying headphone impedances for longer-term viability


I was looking at making a CMoy-based circuit (based on this guide), but I've been having difficulty finding info on suitable op-amps for high-impedance headphones such as mine (ATH-R70X, 470 ohms).

Is the CMoy a good choice given my needs (and if it is, which op-amp)? Are there alternatives I should consider?

Any guidance would be greatly appreciated!
 
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NWAvGuy's O2 Heaphone Amp

Any guidance would be greatly appreciated!

OK, I'll bite.

Check out NWAvGuy's O2 headphone amp. It's a solid design, well documented, well tested, well regarded. The diyaudio forum seems to be full of helpful souls:

http://www.diyaudio.com/forums/headphone-systems/193977-objective2-o2-headphone-amp-diy-project.html

The original design (and test results) can be found here:

NwAvGuy: O2 Headphone Amp

Nobody knows what happened to him, he just up and disappeared, but that's another story entirely. IEEE asks if he was a genius or a troll:

NwAvGuy: The Audio Genius Who Vanished - IEEE Spectrum

Boards, chassis, kits, components, complete builds, however much or little you are up for is available somewhere on the next.

Shameless plug: JDS audio labs has boards, chassis, very nice etched front panels at reasonable prices. No, I am not an investor in JDS labs or any of it's subsidiaries, just a satisfied customer.

And if it seems like too many parts to solder, too overwhelming, give serious consideration to buying one prebuilt. Will cost more than a CMOY, but you'll easily get more than that back.

And now the usual disclaimer: only my opinion, worth exactly what you paid for it.
 
All that being said, the R70x is quite undemanding. Despite its somewhat higher impedance, it is rather more sensitive than the usual 300 ohm Sennheisers in this class. Most any half-decent headphone output should drive it fine. (Note that back-panel outputs may have to be set up as such first, as they may default to line-out operation.)
 
Sorry for the late responses! I was away for three weeks prior to creating this topic, so work has been hectic as I help catch up where we slipped behind, as well as get used to the work flow again.

OK, I'll bite.

Check out NWAvGuy's O2 headphone amp. It's a solid design, well documented, well tested, well regarded. The diyaudio forum seems to be full of helpful souls:

http://www.diyaudio.com/forums/headphone-systems/193977-objective2-o2-headphone-amp-diy-project.html

The original design (and test results) can be found here:

NwAvGuy: O2 Headphone Amp

Nobody knows what happened to him, he just up and disappeared, but that's another story entirely. IEEE asks if he was a genius or a troll:

NwAvGuy: The Audio Genius Who Vanished - IEEE Spectrum

Boards, chassis, kits, components, complete builds, however much or little you are up for is available somewhere on the next.

Shameless plug: JDS audio labs has boards, chassis, very nice etched front panels at reasonable prices. No, I am not an investor in JDS labs or any of it's subsidiaries, just a satisfied customer.

And if it seems like too many parts to solder, too overwhelming, give serious consideration to buying one prebuilt. Will cost more than a CMOY, but you'll easily get more than that back.

And now the usual disclaimer: only my opinion, worth exactly what you paid for it.

Thanks! I've asked the recording department (I work in a music instrument/equipment store) to see if they can get one in, since we may have a way into the Canadian supply chain. That amp looks extremely promising for my interests, so thank you for bringing it to my attention.



If you want to try something different, here is an option :) - http://www.diyaudio.com/forums/headphone-systems/270294-crocodile.html
I do not source any kits etc, but I'm happy to provide gerbers and a BOM with a schematic. Also in theory I have a few bare PCBs left...
Big plus for you - will work pretty much from any DC source from 4...5V up to 12..14V.
I've never come across your circuit before, and sadly don't have the time to read up on it in depth. I do appreciate the offer, and I hope this doesn't come across as a poor statement on your work, but I'll have to pass.


All that being said, the R70x is quite undemanding. Despite its somewhat higher impedance, it is rather more sensitive than the usual 300 ohm Sennheisers in this class. Most any half-decent headphone output should drive it fine. (Note that back-panel outputs may have to be set up as such first, as they may default to line-out operation.)

Both my discrete sound and soundcard have lackluster amplifiers, so I've been using a Yorkville HEADAMP4 the last few months. That is helpful information nevertheless, though, so thank you.
 
That's the ART HeadAmp 4, if I see that correctly? Would you mind opening it up and taking a few photos of the insides? I've never seen any, and from reviews I suspect it uses a MOSFET SE Class A buffer or something like that.

For the R70x you could get away with as little as a 2x 9V cMoy (*) even if you're not a quiet listener like me. Half-decent voltage swing, not an awful lot of current needed, output impedance under 100 ohms should be fine. The kind of stuff that works well with other 250-600 ohm cans.

*) Note that some changes in the virtual ground/power buffer setup are recommended in the 1x 9V version, as that has lousy PSRR stock.
 
That's the ART HeadAmp 4, if I see that correctly? Would you mind opening it up and taking a few photos of the insides? I've never seen any, and from reviews I suspect it uses a MOSFET SE Class A buffer or something like that.

For the R70x you could get away with as little as a 2x 9V cMoy (*) even if you're not a quiet listener like me. Half-decent voltage swing, not an awful lot of current needed, output impedance under 100 ohms should be fine. The kind of stuff that works well with other 250-600 ohm cans.

*) Note that some changes in the virtual ground/power buffer setup are recommended in the 1x 9V version, as that has lousy PSRR stock.

You are correct. We tend to call ART products Yorkville since that's the parent company, and ART product arrives with our nightly Yorkville shipment. Rambling aside, here are the pictures!

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Both PCB's "stuck" together

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Top of lower PCB

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Bottom of lower PCB

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Bottom (when considering installed orientation) of upper PCB

Didn't snap one of the top side of the upper PCB as it was just traces & solder.



A bit off-topic: if there's common interest in seeing internals for other ART/Yorkville product, just let me know. I work at Long & McQuade, which is the retail child company of Yorkville. I have access to a lot of used equipment that no one will mind if I pop open and snap some pics. The same can be done for some other brands, but the majority of our used product is Yorkville, since we offer equipment rentals (easy access to repair parts, since not all customers treat the gear with care). I work in receiving, not sales, so hopefully I'm free of bias.
 

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Cool, thanks. Looks like a bunch of 4580s for the output plus whatever that is on the input (the interesting stuff is blurry, of course). Reasonably standard single-supply circuit I'd say (much like I'd do it), similar to but less cost-cutting focused than the Behringer HA400. It will appear the output stage is inverting with the pot being the input resistor? Not entirely sure what would give it its "character" (apparently it does not become entirely unpleasant when approaching clipping like other cheap amps usually do). Even-order distortion due to power supply sag?
 
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