Yes or no? (design question)

[daz]

I'm considering redo'ing my turretboard because it's been tweaked to the point of being sloppy. But i cleaned it up and it IS solid now. But a new board and components would be nice. However, the MAIN reason i am considering it is a radical change in the way the PSU is laid out. At this point i have a 20/20/20/40 JJ multi cap can handling the pre/pi node duties. I am thinking of going to a board mounted setup with F&T 22uf caps for each node right at the node points themselves. Right now there is a ton of rail wire because the rail has to go to a node, back to the can, to the next node, back to the can etc. I have the rail wires run outside of the chassis for noise issues. (in tubing) But still, all that length of wire can't be good and board mounted caps would be far neater and literally a few feet less wire.

The question is, is this even worth doing? It was like this when i originally built this amp but endless tweaking had me replacing the board several times to start fresh and at one point i went the cap can route. Do you think theres any real advantage either noise wise or tone wise. I see a lot of amps with the PSU caps on the board but i also see many using multi cans. What do you all think? Any worthwhile reason to do this? Note that if not for the PSU change theres no need. It would be NICE to have a clean new board with all fresh new solder and all, but it's not necassary. Whether the board mounted caps would be better is the deciding factor.

[soundguruman]

Well F&T does have a really nice sound.
But board mounted caps are inferior as far as ripple current capacity.
Big Hunk Can Caps are much more robust and longer lasting.

I would use can caps, but keep the wires very short.

There's nothing wrong with rebuilding to perfect a design layout.
Neatness does count. It means you've done the best you can do.

[Enzo]

Individual caps today are well made and reliable. Big can caps are small batch creations made specifically for this niche market, and are not in general nearly as high in quality as discrete caps.


I have no idea what he is yammering about with better ripple current capacity. The caps we use have no trouble with ripple, the only ripple current concerns we have are typically in the grounding, and we have that concern no matter what type of cap we use.

I see a lot of amps with the PSU caps on the board but i also see many using multi cans.

You see modern amps made with discrete caps, you see old vintage amps made with multisection cans. Can you name a current production amp that uses cans?

Caps used to be much larger and wouldn;t have conveniently fit on the boards, or they would have been there. Much electronics used the sectional can cap to put the caps out of the way but for a few wires. One disadvantage of that was you couldn;t separate the ground returns for the sections. Now caps that used to be the size of an EL84 are much smaller and fit in places they didn;t before.

If you are replacing the can cap because the caps within are worn out, then I vote for new ones on the board.

[soundguruman]

Yeah, and if you notice, big can caps outlast those little wimp board mount caps...
by decades.

But on the other hand, those long wires are making the amp excessively noisy and cluttered.

So you're damned if you do or don't...

The real classics have can caps. They are hardly "specialty..."
Rather, most all tube amps used them since before I was born.
So there was hoards of them used in so many designs.
And they did last wayyyyyy longer.

[Jazz P Bass]

As Enzo stated, there is no way to separate the grounds on a can cap.

Plus, and this is a biggy, what happens to the can cap if one section goes bad?

I have purchased new can caps where a section inside was bad.
And that truly sucks.

[daz]

Ok, so this far it seems we are at separates on the board as having all advantages and no disadvantages. Anyone else?

[big_teee]

It sounds like a good time to build a new amp.
Then you can have two to beat on and tweak.
I do that when I build a new pickup design.
I make two, one in the guitar and the other I'm busy changing and tweaking.
Then I rotate them and change the other one.
There is always something I want to try or change.
When I get the two of them where I can make no improvements, I stop, and Say Done!
T

[daz]

It sounds like a good time to build a new amp.

I'd REALLY REALLY love to! But to build a new one sans tubes speaker and cabinet would still cost me $600 ! If i were to build new i would have to get trannys too since one is dented and the wires have been spliced. I wouldn't want to skimp or it would cost too much and just be another, albeit more extensive, refurb.

[Tom Phillips]

Comparing old can cap technology to modern caps may be interesting and nostalgic but it’s a whole different issue when you try to compare currently available new stock can caps to the current production mainstream electrolytic caps.

The currently offered can caps are definitely made for a niche market. They are nice to have when restoring a vintage piece of equipment when the owner insists that the unit retain its vintage look. However, they are made in small quantities by just a few companies and I doubt that the quality control is anywhere near that of a mainstream company. In addition the mainstream companies are still investing in R&D for their product lines. A supplier who bought some old production equipment after the original manufacturer discontinued the product is probably struggling to obtain the original quality materials and keep the equipment in good operating order.

As to modern caps, the quality and performance of the available parts range from crap to outstanding. If you want good parts you just need to carefully select from a good product line. It can be a crapshoot to purchase from suppliers that sell no-name parts without specification documentation traceable back to the actual manufacturer. It's also a problem to buy house branded parts because there is no guarantee that the seller won't switch suppliers or let their current supplier make uncontrolled changes. People build equipment that is intended to be launched into space or deployed on the bottom of the ocean and, in some cases, operated for 20+ years with no service. In these instances you can be sure that they select parts carefully. Parts such as “big can caps” would not be a candidate and no one on the design team would try to convince the others that they last way longer than good quality modern parts.

The design requirements for a guitar amp are, of course, different than spacecraft and other high reliability equipment but we, as custom builders, can still take reasonable advantage of modern technology. A small quantity builder or a one off custom build can utilize higher quality parts that would blow the budget for a big time manufacturer run by bean counters.

Regards,
Tom

[Mick Bailey]

My favourite caps in recent years for new-build are snap-ins. I've had a couple of commercial amps recently for repair where they'd made clearance holes in the chassis, peeled off the shrink-wrap and mounted them on the PCB so they poked through the chassis and looked like vintage cans. The low profile versions will sit inside an amp chassis, or sometimes can be mounted on the tag board. There's a large choice to be had and some pretty impressive ratings - way beyond what's offered for regular guitar amp use.