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Hi, It may be a bit late, but I have some suggestions on the PS. Essentially what you want is clean 250 volts and 12 volts. The 250 is really fairly easy, especially if you stick to solid state. I have no beef with PUSD, but it doesn't always give you the answer you seek. I have an Aikido PCB on the way for my next project and here is what I will use for the PS. The power transformer will be 180-0-180 similar to the one in your drawing. However I will be using a 100uf (350 volt rating for all caps) right after the rectifiers then the choke followed by a second 100uf. After that there will be a resistor (value depends on how much current you will be drawing) which in my case will be in the 470-1000 ohm range followed by another 100uf. In parallel with each 100uf there will be a .1uf audio grade cap. These will pass high frequencies that the electrolytics will have problems with. The Aikido operates at a steady current, so a "monster reserve" is not needed. the three stage filter will provide much cleaner B+ than the one stage you drew. The 1N4007 rectifiers are OK, but I find that "faster" ones work better. I have had good results with 1N4948 rectifiers (MCM and Parts Express plus others carry them at cheap prices). If you already have the others then try them. the multiple filter sections will usually clean up the noise they generate. I would also put a .01uf capacitor across the transformer (180 to 180) windings to clean up a bit of noise from the rectifiers.
For 12 volts for the heaters, I would use a 12.6 volt winding that can handle at least twice the needed current. I would use a full wave bridge rectifier in the 20 amp or greater current rating with a minimum of 50 volt rating. This would feed a large filter capacitor (I like at least 10,000uf at 25 volts or more) and then go to your regulator. After the regulator I would put a second cap in the 1000uf range. The voltage on the first cap will be approximately 1.4 times the 12.6 (minus about 0.7 volts for the rectifier). Approximately 16.5-17 volts. The minimum drop in the regulator is about 4 volts so it will bring it down to 12 for the tubes. The regulator will need to be on a pretty good sized heat sink. The use of the 12.6 transformer winding (or separate transformer) is on the close side to make this deliver 12 VDC, but all should be fine. An ideal transformer would be about 13.5 volts, but that is an unusual value and would have to be custom wound.
Now that all this is said. A simple and possibly equally good solution is to use a SMPS (switching mode power supply) such as the one from Lighthouse Electronics on the web. They have one for preamps that delivers about 40 ma at 250 volts and 12 DC. I would check the dc heater current rating though as it might not be enough for the tubes you chose.
_________________ Some of my DIY Tube Amplifier Projects:
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