Cathode bypass voltage?

[revolver1]

I picked up some Riffa 330uf, 63A electrolytic's with the intention of putting one on the cathode bypass.

The trouble is the more I think about it I seem to remember reading that anything over 6A will sound really bad here.

I can't find the post to either confirm or denie this, does anyone know anything about this?

Cheers

[danman]

The cathode voltage of the preamp tube is extremely low. Any cap rated 10 volts or higher will be fine. You would normally use a low voltage cap here because of the limited board space. A higher voltage electrolytic cap would be much larger and cost more than a lower voltage. I'm not sure that a higher voltage cap would necessarily sound bad though. Gibson used 400v bumblebee caps in the 159 Les Paul where a 5v cap would have been more than enough. They seem to sound pretty good though.

[revolver1]

Ok, that has me feeling a little more at ease. The thing is those bumble bee's are paper in oil and what I can't seem to remember was it was something about electrolytic's not working properly if their rating was way higher than what was applied across them.

I had a feeling it was either a post from Nekeil or Novosibir...?

I sure hope I'm wrong 'cos those Riffa would look awfully sweet right in there.

[danman]

A 63 volt cap will be just fine. If it was 600 volt I might reconsider using it. Fender used 25 volt bypass caps on all of their amps for years when a 5 volt would have been sufficient.

[neikeel]

Ok, that has me feeling a little more at ease. The thing is those bumble bee's are paper in oil and what I can't seem to remember was it was something about electrolytic's not working properly if their rating was way higher than what was applied across them.

I had a feeling it was either a post from Nekeil or Novosibir...?

I sure hope I'm wrong 'cos those Riffa would look awfully sweet right in there.

I think you meant 6v.
But no, not me, guvnor! Voltage rating can be what you want. It is the microfarad value that I prefer to keep lower than stock. 330uF is full bandwidth and some more!
25uF is plenty on a shared V1 (or even split on a V1a NMV) cathode. Voltages on cathodes of the preamp tubes (except cathode follower are negligible - take a squint at at chart).

[revolver1]

Thanks guys.