Cathode Bypass Caps: E'lytic vs. non-polar

[ViperDoc]

Couple of questions:

1) What's the difference between using electrolytic vs. non-polarized radial caps on a preamp tube cathode to ground?

2) As the voltages on preamp tube cathodes is usually low, a 50V-rated cap would be enough, yes?

Thanks.

[TriodeLuvr]

Couple of questions:

1) What's the difference between using electrolytic vs. non-polarized radial caps on a preamp tube cathode to ground?

2) As the voltages on preamp tube cathodes is usually low, a 50V-rated cap would be enough, yes?

Thanks.

Electrolytic caps are used to provide the necessary capacitance in a physically small package. If the value is small enough, say 1uF or less, a film cap can probably be used. Preamp cathodes typically only charge to a few volts. I've seen 10V and 15V caps in some circuits.

Jack

[ViperDoc]

I read that Electrolytics are claimed to be "slower" than film caps, but I'm not sure how that affects tone. Preamp sag?

[geoff 1965]

i've got a wima 3.3uf polyester on the cathode in one of my amps and the tone/detail is superb but quite different to the higher value electrolytics.if you notice the low value poly/films are used a lot where the triode cascades into another to cut bass and keep a clearer signal.read the notes on ZP's lite2 cascade mod in the downloads and experiment yourself,you will tell the difference.

[ViperDoc]

Thanks, I'll check that out.