Correct. It's an inherent problem, USB power + unbalanced audio from the same source just do not mix. You get audio ground + USB power ground which are connected on both sides, there's your problem. Needs galvanic isolation somewhere, usually easiest provided by an extra USB charger (preferably the non-lethal variety, the cheapest one found on AliExpress may not qualify).
If the linear regs do not work, consider hacking in some discrete capacitance multipliers instead. If you weren't shooting for something so small, I'd even give an RC filter of maybe 10 ohms and several hundred µF (as much as you can fit) a shot.
Have you considered using two separate usb cables... one for power and one for data/audio?
In my build I separated the data(audio) and power lines and it has been deadly silent... absolutely no ground loop noise issues to speak of. I used a basic DIY two wire USB 2.0 power charge cable to supply power to the RECOM DC-DC Converter and a second separate 3.5mm trs line out audio cable from my motherboard to my amp's input jack.
An externally hosted image should be here but it was not working when we last tested it.
Here is another idea from agdr Audio that you might mull over to give you some ideas:
Switching Split Power Supply ± 12V 500mA Split Supply
Non-Conductive Panel Mount 2.1mm DC Barrel Jack
An externally hosted image should be here but it was not working when we last tested it.
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Also interested, but seems like this is dead so I'll route a single pcb with PSU V2 + SE-SE on it
I'm came to the party late but wow!
I've been using the power supplies for a number of years but I didn't finish the two SE-SE boards until this week. I built two of them and they work great, I housed one of them with the wire power supply board.
I've been listening to it for the last two days and I'm very happy. Truly non-fatiguing and a delight to listen to. I really don't want to put down my headphones, I have a bunch of headphone amps and wasn't in any hurry. However, I'm happy I pulled these boards out and finished putting them together.
Those tiny resistors were challenging for my old eyes.
I used a 25K dale stepped attenuator that I built, I didn't look at which value you suggested but this one seems a nice fit and I had it laying around.
Thank you for your effort, Owen, too bad they stopped production of some of the chips, I think a lot more people would have really enjoyed these. I still have a BAL-BAL board and the chips, someday I will get around to building it.
I've been using the power supplies for a number of years but I didn't finish the two SE-SE boards until this week. I built two of them and they work great, I housed one of them with the wire power supply board.
I've been listening to it for the last two days and I'm very happy. Truly non-fatiguing and a delight to listen to. I really don't want to put down my headphones, I have a bunch of headphone amps and wasn't in any hurry. However, I'm happy I pulled these boards out and finished putting them together.
Those tiny resistors were challenging for my old eyes.
I used a 25K dale stepped attenuator that I built, I didn't look at which value you suggested but this one seems a nice fit and I had it laying around.Thank you for your effort, Owen, too bad they stopped production of some of the chips, I think a lot more people would have really enjoyed these. I still have a BAL-BAL board and the chips, someday I will get around to building it.
Ive been using my Wire for years without any issues until today. The amp hasn’t been used in a few months and I plugged it in today to listen to my HD600s and I got very distorted sound. I quickly unplugged my HD600s and shut the amp off, I checked the power supply voltage and sure enough I lost the negative rail. I remember reading a while back that someone had some power supply capacitors go bad on their amp. Does anyone recall or has anyone had a similar power supply failure? I’m going to pull the psu board this weekend to investigate further I was just wondering if anyone else had a similar problem?
Just have to say mine is still going strong and sounds as good as ever. I too run +/- 15V and also suspect I will have to swap those caps with something higher rated at some point. I've recently attached a relay based lineout/headphone switch + muting combo which turned out great in that it eliminated excess cabling.
DIY Soekris dam1021 dual-mono fully-balanced DAC with headphone amplifier (final) - Album on Imgur
DIY Soekris dam1021 dual-mono fully-balanced DAC with headphone amplifier (final) - Album on Imgur
I have been sitting on my bal-bal board for a couple of years now. Unfortunately I didn't buy the components and the LME49610 is long gone. Is the current recommendation to build with LME49600 and OPA1632?
Looks like there are LME49610 on ebay, but I assume these will all be fake relabelled LME49600.
Looks like there are LME49610 on ebay, but I assume these will all be fake relabelled LME49600.