Stack O Cap Options

[RJ Guitars]

Amp Gurus,

I've always struggled with the Trainwreck "Stack O Caps" as a good way to build a power supply. I can't argue with the previous success as measured by the results but I believe there are other ways to accomplish this that will also yield a good result.

These ideas developed over time in my shop although some are not my original ideas. Most of these my son put together when he was building various Wreckish amps in my shop. Dana Hall did a can cap installation on an Express and declared the results as satisfactory. I also did can caps on a Rocket build which used all VOX transformers and it works out very tidy. My amp was overall too different to compare it directly with a Rocket.

I have had extremely good results in building Rocket and my octal iteration of that amp (The Rockster) using a power supply board although it has not been especially popular with those that revere the traditional build style of the wrecks.

In the end the single board seems to be the easiest to implement and doesn't change much on the power supply design. It only takes 12 turrets, 3 stand offs, and can be made up in 10 minutes. It fits right into the same space as the Stack O Caps. This particular build is not finished and the idea hasn't been polished yet, I'll report back as we make progress.

enjoy,

rj

edited in the correct number of turrets 12/14/10

[Ken Moon]

The JJ cap cans sure give a nice-looking layout.

Are there any grounding issues when using the cap cans, because of the shared ground pins?

[Gibsonman63]

I am going for the can caps myself on my next build. All of these would be attractive options, since you have the tools to make nice neat holes in the chassis you sell.

[Bob S]

I've got cans on my express & liverpool. Both use a 40/20/20/20 with common ground. I also worried about the noise this might induce. Neither is as quiet as I would like, but acceptable even at bedroom volume.
My rocket was one of RJ's kits I bought from LonelyRaven on here. It has a single power supply board with individual caps & it's silent.
I know it's not comparing apples to apples - totally different gain characteristics. Maybe I'll try to address the noise issue after new year.
I'm with RJ on the stack o caps. Cant bring myself to do it.
The rest of the layout / lead dress is critical - I know from experience...
My feeling is to go with a board and individual caps.
Bob

[Zippy]

I like that WPS Option 1i, RJ. The grommet is an especially nice touch.

[Jackie Treehorn]

I think it's important to look at what Ken did in the context of trying to sell these amps at a reasonable price, build them in a reasonable time (meaning prioritizing time spent on tuning, building, evaluating), fit everything in an off-the-shelf chassis, and having personal preferences and a distinct style of construction. I don't believe there's any benefit at all in the sound of the amp to glue all the filter caps together, nor is there any detriment aside from the added difficulty of servicing or swapping parts.

Yes, everything matters, but not to the same degree or perhaps not even in the manner assumed by deciding to clone something as exactly as possible. A lot of Ken's choices (in parts selection, too) I just chock up to "style" not anything mandatory. Until you do things differently, you can't really know what matters.

[RJ Guitars]

Yeah, I think Ken worked wonders with what he had available. I expect that he didn't have access to as nice of a selection of machine tools as most of us have now. In the early days he didn't have the option of doing a Google search for information or to find obscure parts on the internet. I would be curious if he would use a heavier chassis and 47uF capacitors if he was designing amps today. I tend to revere his circuit ideas and ability to work with what he had available and see these contributions as the coolest part of his legacy.

rj

[M Fowler]

I'm going to start putting my B+5 and B+4 caps right on the board in the circuit where they are used and the rest can go on the end of my board.

So that would be one long board and no cap stack.

I do like to use can caps and have had zero issues using them.

Some builds I put the three small caps at the end of my tone board and the three larger ones on a separate board. Or just use one 40-47uf and one 80uf. Cuts down on the caps. Or in a Rocket you don't need that much capitance with tube rectifier.

[RJ Guitars]

The JJ cap cans sure give a nice-looking layout.

Are there any grounding issues when using the cap cans, because of the shared ground pins?

Ken, This amp is really quiet so from that perspective I didn't experience any problems. I did use a modified star grounding system in this build. I've had good luck with that idea.

rj

[fishy]

RJ,

Do you remember this amp. It was supposed to be an octal rocket based amp akin to your ventures but with distributed capacitance in the preamp and a capcan taking up the main power duties.

FWIW, the amp is dead quite

[M Fowler]

Fishy that is what I had in mind the radial caps right up in the circuit where they belong

[Bob S]

Fishy - thanks for sharing. Now I've got to find a way to fit the same idea onto my rocket reverb board

[Cliff Schecht]

I like the silicone to chassis cap stacking method. It's clever and it's proven to work well. It makes for some long wire runs from the capacitor to the B+ line but they're not that long so everything stays happy (enough). Who knows, maybe the long runs have an intentional affect on the sound..

I like the idea of shoving the caps below the preamp board too. I could see this working out well if you planned for it (as opposed to retrofitting an existing amp) and you could place those caps where they should be, right on the resistors they decouple.

[Zippy]

There are some nice examples of this at Hoffman's forum - as I recall, it was demonstrated there in a BFDR rebuild.

[mlp-mx6]

What does not make sense to me is to put the one kind of component you KNOW will wear out (the PS filter caps) *underneath* the board to which they are supplying power. You then have to disconnect a LOT of things to replace them. I know it is years between replacements (in a normal scenario) but why make it that much harder? Makes no sense to me at all.