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In Reply to: RE: No report on the experiment ... 8{(# posted by GStew on August 01, 2010 at 09:16:32
And then I saw many of those posts, too.
I think what made me reconsider is the problem with the switchers infecting the AC lines.
So, I am back to resigning myself to the noble task of AC powered linear supplies.
I have the stuff on had to make most of them and I intend to use chokes before (or maybe after?) the regulators to control some of the digital noises. There again I am not sure if the choke's filtering may result in ringing if used after. I like the idea of having some element that isolates the circuit in both directions. Wish I had an oscilloscope.
I am thinking of using a large choke in the ground line for this purpose.
Have you considered using a current regulator before the voltage regulator instead of cascaded voltage regulators? Not sure if you were using one or two. I am assuming one can use the LT regulators in this way. They say you can on the data sheet but unlike the LM317 data sheet they show no implementation.
Broke down and ordered one of the BURSON 5 volts shunt regulators yesterday for JULI@. Maybe these circuits have to be regulated electronically?
I will use the LT3080 for the the other rails since it has vastly superior ripple rejection to much higher frequencies. To use on the 5 volts rail would require paralleling and I am not sure I should attempt that.
Now to DO something.
Rick McInnis
Follow Ups:
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
Everything matters!
I have done endless modeling with the DUNCAN PS simulator and, of course, one then has to hear what it sounds like.
I am familiar with Swenson's circuit. It follows very closely what is considered best practice.
I use Hyne's large 12 volts regulator for my DAC. Maybe he would change his mind now that the technology has allowed a 2 ampere 5 volts line but a couple of years ago when I asked him to consider the possibility he said it would require something VERY large. I do wonder if such a thing is necessary. It could be better but, I suspect, only a little bit better, not worth the trouble. In other words, there are other areas that would yield more improvement for far less money, or I hope so.
If the other lines are not as critical, then it seems foolish to go with shunt reg's. The soundcard is a different story to my way of thinking.
I am sure Hyne's design is better, but, I bet, not that much better. The Burson's strike me as being very good engineers.
With the onboard 3.3 volts regulator on JULI@ which is an LDO type, needing less than 1 volt for the current requirements of JULI@ so I cannot imagine any damage being done. I really don't see what you are getting at - maybe with voltage too high for the regulator but when it has been in the circuit it was around 4.5 volts under load.
There is no question that too many of these narrow bandwidth regulators in cascade is the equivalent of a high order low pass filter in a loudspeaker crossover, bad. Which is why I am settling on an LC filter after the rectifier, a current regulator and then the voltage regulator for the 5 volts line. For the others I will just use a single voltage regulator, LT3080's). A capacitor after the rectifier will be used to tune the output voltage, just as Swenson, since I think a "choke input" is not needed here since a current regulator will be used.
My thinking is the choke will still be "working" after the LT1083 is beyond its range. By the Nature of the currents involved the choke will be 100mH which is quite large but with low resistance.
Easy enough to take it out if it seems to be causing a problem, which I think is highly unlikely. This will not be my first LC filtered power supply.
The LT3080 may have enough bandwidth to make this unnecessary. Who knows? I am nervous about paralleling, it always seems to have its own set of drawbacks. Of course, none of us gets to win in audio it is always the compromise one finds least obnoxious.
Oy,ve.
Rick McInnis
I got confused by the menu at PARTS CONNEXION where they listed it as such. With thought it occurred to me there is no way shunt reg could be substituted for an LM317 and sure enough it is a series regulator.
In the meantime I came across this: http://www.belleson.com/index.php
This seems like the "latest" in series regulators and though I would still prefer a shunt regulator I am going to give this a try for JULI@.
The fellow making these is a very nice guy and his shop is about one hundred miles up the road. I have to give it a try!
Didn't know you were such an electronics expert.
But I am an obsessed cheap hobbyist who has no choice but to learn to do things for himself.
When I see something I cannot even DREAM of doing myself I readily defer to the likes of Nelson Pass, John Broskie, Paul Hynes and Dave Davenport, who, along with cics, are my audio gurus. And those magic fingered moving coil cartridge artisans ...
What excited me most of cics's work is that he was making it possible for folks without unlimited budgets to have something good for CD playback.
I have been playing with this since I was fifteen when I got a Dynaco PAT 5 kit. (Why did I not get a PAS 3?) You would think I should know more than I do when time spent is considered. (That was forty years ago. YIKES!)
Hoping I have a working C squared set-up this evening. Can't wait to hear what has happened with the software in the last couple of years and very excited about hearing what the balance control can do.
Bye,
Rick McInnis
You are only in your 50's? You are just a young-in! I remember when my parents let me hook up their old Philco tv speakers to my mono record player. It wasn't stero but it was 2 channel mono---just awesome!
Good luck on your new mobo/cpu set up.
It is funny how in your fifties you can still feel young yet you know you are getting old, for better and for worse ...
Not surprising you were a tinkerer from the beginning. That same desire to make it better obviously started at a young age.
I hope I can actually get music out of it! Just have to solder five wires from the DAC board to the line stage. Just could not make myself finish up last night.
Whether anything resembling music results ... At least, I can always play records while sorting this out.
After two years (or so) LP immersion I hope I can listen to it. At worst, it will be something to play while I work on house projects. You can tell I have a little trepidation.
Are you considering the I3 upgrade?
Bye,
Rick McInnis
Yes I am considering the upgrade probably in Q4 (still talk like I'm working). But I have been busy with other non-audio matters for 2 months. When I get started I'm just wondering if I should buy all new (iow keep the old system intact) or mod my old sys. What approach did you take?
nothing wrong with my HDD, or keyboard, or that kind of thing.
Of course, you have no choice but to replace your memory. so that's it - new CPU, memory "card", and MB an d you're off!
Still trying to get some kind of real reason to go with the SDD for WINDOWS and programs, but nothing definitive and I have no interest in experimenting there since I think it is kind of silly though I would love to be proved (or even persuaded) wrong!
I would think there is no need to rush since there are still a few questions about the new system. And the prices may come down.
I was anxious for a new project and that is why I got the new stuff.
I am concerned by Julien's problems and wonder if there are a bad batch of MB's out there. Might as well hear what happens with his project.
What is most important is that you keep your ears in top shape! You possess a very perceptive pair of those.
Bye,
Rick McInnis
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