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Music servers and other computer based digital audio technologies.

No question - you do not just stick a choke in

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


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