[Speedskater]

Board schematic?

[undertow]

Board schematic?

This is all I have right now... Don't know all the other part #'s, but I do know the diode part #'s in above thread we are talking about directly. By the way I have another one of these working and identical right now in something else. So I can easily verify and cross reference the parts which is why I know the part #'s on that board, just putting a second one together with parts I had is all.

[*Scotty*]

It's probably more important to upsize the rectifier diodes to a much larger than stock value than to obsess over a low noise diode in this application. Your idea of using 15amp diodes is a good one and should net an audible improvement. It would also be a good idea to upsize the transformer as well to about 150watts
225watts seems to be the point of diminishing returns.
 I used 16amp Schotky diodes in my phono stage and a 225watt transformers with good results. It is very easy to cripple an otherwise good sounding circuit design with an undersized diode bridge and transformer, thank you bean counters.
Scotty
 

[undertow]

Understood... There was no obsession over the diodes...Simply I just had some I wanted use up vs. order more. No biggie they should work, and yes they should spec. out well above the average parts that would have been on this board so we should be good to go. Confusion came I guess from calling them Zener diodes, but I did not realize part # 1N4007 was not a zener, it's in the same style package, but I found that the datasheets do have to specify a "Zener voltage" now, which the 1N4007 does not have zener voltage and is a standard diode which is even better because I believe for sure now we are fine with the Fairchild Stealth replacements (arguably a waste due to quality, and cost for this application, but whatever).

I know the transformer is a pretty sizeable toroid with 16 v out taps on the primary and secondary, about 6 amp. But the application it is driving only requires a total of 300 mA max! So hopefully the 6 amp transformer and 15 amp Stealth diodes can handle it

[*Scotty*]

The "only 330ma current draw" is what sandbags many designers. They ask the question, how much could it possibly need, and arrive at the wrong answer much of the time, if the bean counters don't get them first. I doubt that my phono stage draws 300ma total, but it certainly appreciated the greater than 150 watt transformer it has. The 16 amp diodes were admittedly overkill and a 10amp would probably have worked just as well but the 16 amp ones were availble and cheap at the time.
 The math says 16vX 6amps equals 96 watts which a good sized transformer, but I would bet that you could hear the difference between it and a transformer rated at 12 amps if you could find one.
If your regulators can take another 2 volts higher from the secondaries Parts Express has a 160 watt transformer with 18+18 secondaries for $48.25 and a honking 250watt 18+18 for $54
http://www.parts-express.com/avel-y236502-160va-18v-18v-toroidal-transformer--122-610
http://www.parts-express.com/avel-y236651-250va-18v-18v-toroidal-transformer--122-620
Scotty
Scotty

[undertow]

Believe me I am not disregarding the fact you can never have to much power reserve... Yes I think it is a 100 watt transformer. Problem is even if I wanted to spend something (again these are just existing parts I am using) I don't believe I would be able to fit it in the chassis. Already this transformer is a sizeable doughnut which goes from wall to wall in the chassis already. It works just fine, figured might as well use up the parts more than I am trying to go further is all.

[Speedskater]

So it's just a simple dual output regulator. With the option of choosing an adjustable or fixed voltage chip. D5 to D8 are the work diodes, while D1 to D4 are the reverse voltage (transient) protection diodes.

[*Scotty*]

Yeah, I hate it when that happens. Big cheap chassis are always ugly, I know because I have 3 of them. You can put the transformer in an inexpensive box and run an umbilical with low voltage AC from the secondaries to rectifier in the circuit bearing chassis. Once again, this is the method I used on my phono stage.
 As it happens DC does not travel well and should always be generated as close as possible to it point of use.
Scotty

[undertow]

So I felt compelled to share the results after building and testing this thing last night.

Pure success! No smoke, no wild voltage swings, no nasty noise.

This power regulator works perfectly. Dead silent when inserted into the system, you would never even know it was turned on.

I noted that with the fairchild rectifiers in place the voltage was super stable, I was able to adjust the outputs to dead on 18.00 volt on both sides. At most after warm up it varied by less than a 1/10th of a volt between 17.94 v, and 18.12 v...

Once I let it stabilize for 10 or 15 minuets, and it warmed up I got it dialed into dead on 18, maybe with small pulses out to 18.02v , and down to 17.98 v, but never really moved.

So if nothing else it seems these higher spec. parts are just more "Stable" which can't be a bad thing!

Thanks guys