Thanks again Abrax. For my Aya Ds dac I decided to dump the dc blocking caps which got in the way of SQ regardless of what caps I tried. Suddenly one day it dawn on me, what about using a line trafo, out of curiousity I found a 600-600 ohm trafo on ebay which could handle some dc & seller stated its measured well. It was a no brainer for me to try cause I bought them at $18 each. Well the rest is history, couldn’t believe how much better it sounded but I too had to re tweak the ps of my Aya. Killed 3 birds with 1 stone. Low cost as compared to audio caps, dc blocking & low pass filter to smooth out the Nos sound.
Cheers
Cheers
.
I only ever use single rails these days - two power supplies is just double trouble. Besides single rail suits balanced very well - no current needs to go to GND.
@sumo - I've only fairly recently been noticing the sound of caps. It was the output caps of that SE buffer which first drew my attention to cap sound, so I'm a relative noob here. I've not tried my own trafos without series caps to block DC but I might try a servo sometime....
@sumo - I've only fairly recently been noticing the sound of caps. It was the output caps of that SE buffer which first drew my attention to cap sound, so I'm a relative noob here. I've not tried my own trafos without series caps to block DC but I might try a servo sometime....
I do that too with a resistor load near my ac filters. Got the tip from a ham radio site, sometimes experience beats endless simulations.
Tried a (15w) bulb at first, and when it worked, I ordered some power resistors. It definitely helps to improve each stage as much as possible and not rely entirely on leverage schemes within the rest of the circuits.
I will search Jon Risch to learn more about what he’s done as well, thanks for the tip.
Edit;
I had seen some of the Jon Risch work, but had already built mine at that point..
Sumo, did you get an isolation transformer ever?
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So I currently have four marks against the need for an ultra low impedance supply on the analog portion of a dac.
1: They utilize balanced signal currents so there should not be much if any ripple current from the output section of the dac making its way into the supply.
2. Last time I did an experiment on the ESS9038 checking for the audible differences between using only 1 phase and leaving the other phase disconnected and grounding the other phase to V-ground I did not hear a difference in SQ.
By leaving one of the phase disconnected the current through the supply is no longer balanced and therefore the impedance of the supply actually matters.
3. Even with a varying supply current, the currents that are output are so small that even with a bad regulator the voltage variation of the supply will be practically nothing.
4. Ultra caps and batteries are consistently considered to sound better than regulators as dac supplies even though they have higher impedances than good regulators.
1: They utilize balanced signal currents so there should not be much if any ripple current from the output section of the dac making its way into the supply.
2. Last time I did an experiment on the ESS9038 checking for the audible differences between using only 1 phase and leaving the other phase disconnected and grounding the other phase to V-ground I did not hear a difference in SQ.
By leaving one of the phase disconnected the current through the supply is no longer balanced and therefore the impedance of the supply actually matters.
3. Even with a varying supply current, the currents that are output are so small that even with a bad regulator the voltage variation of the supply will be practically nothing.
4. Ultra caps and batteries are consistently considered to sound better than regulators as dac supplies even though they have higher impedances than good regulators.
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The reason that you need a series C before the trafo is because your trafo can’t handle DC Abrax. If you can null the dc offset at the dac so much the better. Having a bigger trafo has it advantages. For 1 you’ll have much lower dcr the other efficiency of transfer is far better.
Its like a bigger uf cap vs smaller cap. Not sure if I explain this correctly though. lo but I think you’ll understand.
Cheers
Its like a bigger uf cap vs smaller cap. Not sure if I explain this correctly though. lo but I think you’ll understand.
Cheers
Nulling the DC at the DAC won't cut it because I have MOSFETs between DAC and trafo. Their threshold voltage drifts with temperature - so I need a servo at the buffer stage.
@hellokitty - a scope isn't a good choice for looking at ripple which is going to be of the order of a mV or less. There will be a fair amount of HF noise (CM noise perhaps) so you'll not be able to pick out what's in the audio band. Suggest recording the ripple with an SDcard recorder and examining the .wav file in Audacity where you can FFT.
@hellokitty - a scope isn't a good choice for looking at ripple which is going to be of the order of a mV or less. There will be a fair amount of HF noise (CM noise perhaps) so you'll not be able to pick out what's in the audio band. Suggest recording the ripple with an SDcard recorder and examining the .wav file in Audacity where you can FFT.
Opamps can do better than transformers in CMRR and CM distortion in dacs is not audible IME.
CM things cancel out at the load if utilizing balanced amp anyway.
Also don't misunderstand when I say transformers are bad.
Euphony is the reason started I learned electronic design to begin with.
Euphonic distortion and high performance are on separate sides of the coin.
CM things cancel out at the load if utilizing balanced amp anyway.
Also don't misunderstand when I say transformers are bad.
Euphony is the reason started I learned electronic design to begin with.
Euphonic distortion and high performance are on separate sides of the coin.
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