*my* Tubelab SE build...

[rknize]

I don't seem to have the P/N in my part list, but you want something for the TO-220 package type.

http://www.mouser.com/Search/Product...ap%2f4nOvM8%3d

[oldmanStrat]

4724K-ND

its the kit with screws and shoulder washers.

[PaulyT]

Thanks! Ok, another stupid question: is there some reason not to use this to insulate the CCS ICs? Seems like the less high-voltage metal around, the better, for safety... but George didn't do this, why?

[oldmanStrat]

Originally posted by PaulyT
Thanks! Ok, another stupid question: is there some reason not to use this to insulate the CCS ICs? Seems like the less high-voltage metal around, the better, for safety... but George didn't do this, why?

Not so stupid a question - I wondered the same thing. Looks like the tab is the anode which is connected to B+ - so that heat sink has some serious voltage on it.

I would think you could insulate it. you'll need shoulder washers too.

Lets see if Russ beat me to the punch again

[rknize]

Most 3-terminal devices that have conductive cases for heat sinking tie the case to the center pin. This is just how the guts of the internal package are arranged. If you look at the spec of the CCS, the center pin is the input. If you look at the schematic, the inputs of both CCSs are tied to B+. So in this case, it's OK for the CCSs to "short-out" together on the heatsink. Georges PCB does not tie the heatsink supports to ground.

I think he is just taking the simplest road here. He does have you put insulators on the heater supply rectifier/regulator because it's not OK for those two packages to be shorted. You can insulate the CCSs if you want to make the heat sink safe. If that is your goal, you should also ground it for safety. I would also ground the FET heatsinks too, even though those packages are non-conductive.

[rknize]

You win!

[oldmanStrat]

its not if you win or lose, it's how you play the game :P

so now I'm in waiting mode for the power transformer to show up before I can do a checkout.

This time I'm going the simple hammond case route. it won't be pretty, but it should be a lot easier to mount connectors, switches, pots etc

[rknize]

I was in the same boat for a while while waiting for iron for the SSE. I found an old, umarked transformer that seemed to have 700VCT HT winding. PSUD told me that if I left off C4 I'd get a hair over 300V B+. Worked like a charm, except for the buzz coming from the Hammond choke. Ran like that for a month or two at least until the custom Edcor arrived for it.

[oldmanStrat]

Ok, Russ asked me in another thread where I was with the build... so I was guilted into spending some time this eve on the SE amp instead of practicing my guitar

Yeah, it was torture.

So here is the planned inside of the chassis. I'm using a very standard aluminium chassis, with an optional grey ugly cage if I put it where normal people can touch it.

The idea is that I will put the PCB on standoffs on the bottom of the enclosure and cut holes for the tubes on the top plate. Since I didn't do anything special for PCB mounting under the chassis, the gain tubes probably won't poke out much. That's fine, because I planned this build to be more easy access to the board than an under chassis would allow.

Sort of taking George's Lexan amp to heart but using the standard hammond enclosure. I am considering hinges on the top plate... perhaps some gas shocks to open the hood. Ok, kidding on the last I can only imagine the amp toppling over with the weight of the xfmrs.

[oldmanStrat]

and here is the top on with power xfmr and opt placement.

I'd considered putting the big AC cap on top, but it wouldn't fit under the cage.

Oh and this is a 300B only build ... of course it's possible I'll tear it down and do a 45. But I'm thinking I'd rather do a new amp for a 45 once I find the right tubes.