Please check my work :)

[athos56]

I'm tinkering with PSUD II to make a supply for a 300b amp and I was wondering if you would check my work. Here is both the schematic and PSU. A few notes, I entered in as much of the transformer info as I could and PSUD bumped up the voltage from 400v to 420v, I'm not sure if I should leave it there or not. Second I tried to determine the load (in ma) as close as possible and came up with 176ma for 2 300b's, 2 12ax7's, and 2 12au7's. As it is the sim comes out close to the 450 and everything looks smooth.

Thanks!

[athos56]

Schematic

[athos56]

I'm going to use tentlabs heater supplies for the 12ax7/12au7's and filament supplies from www.diyhifisupply.com for the 300b's. I plan on going with the One-electron opt's. The rest of the PSU is a Hammond 178CX (400v/465ma) a 167M5 (5v/3a) and 2 167N6's (6.3v/4a). The caps are F&T caps, 1 30uf/500v and a 100uf+100uf/500v cap. The choke is a Hammond 193N. The resistor is a highwattage wirewound 10ohm/50w bolt on. 50w is overkill but it was the only 10ohm bolt on in stock at Digikey.
Thanks for any comments

[Bas Horneman]

All looks good. Let us know how it turns out.

The 10k grid stopper for the 300B looks a little high. But I have to admit I never did try such a high value so I can't say how it would affect the sound.

The tentlabs heater supply is a little over the top. But I'm sure Guido won't mind.

[athos56]

Yeah, they may go out the door as a cost savings measure . Hopefully it will be up and running soon, I'm going to start buying parts. I'm thinking about using some nice wood for the chassis, I'll mount the inputs/outputs/plug and such on copper plates in front and back. The tubes are going to be mounted through the top on those tag board/socket combos. Hopefully that won't be a fire hazard . Maybe I'll make the top out of wood that smells nice when heated, hehehe. I'm not going to get the Aikido boards, opting for point to point.

BTW, if I choose to go with the standard metal top, what thickness do I need if I went with copper?

BTW x2... If I use the filament supply for the 300b I plan on omiting the two 47ohm resistors in the schematic, that would be the only change.

[Bas Horneman]

You should have no heat problems with a wooden chassis.

Pics of one of my amps.
http://basenjes.de/tubes/se6c41cpics.htm

2mm copper should be enough for a typical 42cm*35cm chassis.

But who can afford copper these days!!!!

[athos56]

Very Nice!

www.onlinemetals.com has 12"X12" copper plates that are not too expensive, for a thin sheet good enough for the front and back plates i'd spend ~20 bucks + Shipping. It would likely be a bit more for a top plate thick enough to support my iron. But if Heat isn't going to be an issue I'll likely stick to my plan. Thanks for the feedback!

[wakibaki]

It depends on how you intend to use it, but raw doublesided FR4 PCB is quite a good constructional material. If you can't see the edges, you can't tell it's not solid copper, and neither can most electronics if you're not using it as heatsink. It's fairly light and strong.

w

I guess singlesided too...

[athos56]

Originally posted by wakibaki
It depends on how you intend to use it, but raw doublesided FR4 PCB is quite a good constructional material. If you can't see the edges, you can't tell it's not solid copper, and neither can most electronics if you're not using it as heatsink. It's fairly light and strong.

w

I guess singlesided too...

Hey thats a cheap option. I was thinking I would either route out a space in a wood front and mount the plate in the back or use the plate as the entire front. If I do the former the PCB would work great. Thanks for the suggestion its going on the spreadsheet.

[boywonder]

How about contact cementing thin copper sheet onto 1/8" aluminum sheet for the top panel? Sort of a copper veneer...

(it's cheaper than explosion welding)