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RE: Did not get around to it ...

Regarding choke-filtered power supplies...

In reading some of the posts by John Swensen, especially his posts on low-DCR in the Tube DIY Asylum, I believe there is a science to designing good choke-filtered supplies and John knows that science... and better yet, listens to what he does. I strongly recommend his choke-filtered 9v & 12v supply as shown here:

http://www.audioasylum.com/cgi/t.mpl?f=pcaudio&m=42853

He takes into account not only filtering noise in both directions, but also sizing & selecting components to minimize noise creation in the supply AND having the supply exhibit a critically-damped response, which he suggests is important to good sound.

My only caution with that supply is that in the few situations I've used the Panasonic FM & FC series caps, I've not liked their 'inherent' sound. I'd check with him for alternatives... Elna Silmec or Cerafine, Nichicon FG or FX, etc.

He can also likely provide alternative components for 5v & 3.3v versions.

My gut feel is that just adding chokes without some amount of design may be a crap-shoot on whether it improves the situation or not... and John has done the hard work here, so this is a good and safe bet.

This is the configuration I'm planning to go to when I put my cMP into a home-built case (with more room for PS stuffs).

Then on regulators, first, I think you're making the right move to add regulators for the sound-card power. While you can often get away with non-regulated supplies for analog tube and solid state circuits (and done right, some say it's better-sounding), logic circuits have a pretty small range of input voltages for proper operation. Hopefully you haven't damaged your Juli@ (a possibility).

On regulator types, my next thing to try is the LT3080 and see if it makes an audible improvement over the LT1083. I'll be trying it first in my 'dirty' supplies and on the 3.3v & ATX 12v regulator positions... These are the easiest for me to change out and easiest to put back if there isn't an improvement... but experience has shown that it will be audible (whether for the good or the bad) in those positions. I hope to be doing that in the next couple of weeks.

If it does, then I'll setup the paralleled regs for the 5v where I'll use 4 regulators. If that works well (and if you want to go that direction), if you are cautious about following in my footsteps, I'd be happy to wire one up for you.

But ultimately I plan to go to current-sourced shunt regulators. I have heard from one of my 'tweak mentors' that cascading series regulators does not sound good (in his humble opinion), so except in one position, I haven't done that. But CCS-sourced shunt regulators, such as the Burson, the Tent, the OPA, the Borberly, and the DIYAudio Salas (and other) ones are ok. This link I posted in an earlier conversation:

http://www.diyaudio.com/forums/power-supplies/168631-5v-high-current-low-noise-regulator.html

Is for a varient on the Salas design for high currents and what I intend to try after the LT3080 for the ATX-20 5v & P4 12v regulators. I expect the only thing that will be better are Paul Hynes' regs, which may be next after that.

I hope this all helps... and let us know what you do.

Later!

Greg in Mississippi
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