Electrolyt / Dielectric capasitors

[kaj]

Hi.
Is it ok to use a polyeter film cap. as catode bypass cap. ?? Or are the electrolytic ones the best obtion??

[xtian]

Yes, no problem, as long as it's rated ~35v or better.

[kaj]

Yes, no problem, as long as it's rated ~35v or better.

Hi xtian
Thank you, I will give it a try!

[M Fowler]

The Champ II I'm working on doesn't have e-caps for the preamp cathode bypass caps or at least these don't look like e-caps.

However; I'm going to replace them along with the 4uf/450v and two 70uf/100v bias caps.

[xtian]

Well, that is some wavy gravy board action there.

I like those Rivera designed Fenders.

[M Fowler]

Well, that is some wavy gravy board action there.

I like those Rivera designed Fenders.

I'm tracking down noise at idle even with new tubes in and that wavy board was my first thought but it is not conductive.

EDIT the board is conductive giving off crackling sounds but very low level.

[rp]

Tonewise they seem fine, the typical marshall .68 on V2 was always a film but I never carefully a/b'd cathode bypass film and electrolytics. The pf caps aren't electrolytics either.

My heads up: you will find size an issue, I don't think you can use one on the power tubes unless you are up for <5uf, a 50mf will be huge and will prolly have to be 150V, smallest. For the preamp bypasses a 6V or 10V cap would suffice but there aren't many options available unless you are up for ordering one here one there form Mouser, Digikey, Newark... The Mallory 150s exist as 100V caps. Good news is there's little audible difference after 5mf, ie a 5mf/100V sounds pretty much like a 25/25, which sounds pretty much like a 250/25. I'll use 5mf amps with 10" or 8" speakers figuring it'll be fine.
If you run it through a web tone stack calculator you see the curve hardly change after 5mf, though I never tested this with a proper cab like a 4x12 closed back, just a 1x12 open back.