Jensen Copper in Oil 0.22 uF, 630V Coupling Capacitor

[ptlud]

I am about to assemble a Stereomour amp and would like to know if I can use a couple of Jensen Copper Foil in Oil 0.22 uF 630V capacitors in place of the stock 0.1 uF coupling caps.  I have the Jensen's left over from another project.

Will there be an electrical or sonic issues?

By the way, I am building the amp to be used with 45 tubes.

Thanks,

Paul

[Paul Birkeland]

I am about to assemble a Stereomour amp and would like to know if I can use a couple of Jensen Cooper Foil in Oil 0.22 uF 630V capacitors in place of the stock 0.1 uF coupling caps.

This is something you can do, but really only after you've built the amplifier with the stock parts and know that it's working.

-PB

[Paul Joppa]

The main audible effect is probably to slow the recovery from transient overdrive (grid current) which will affect the pacing of the music more than the frequency response. Whether this difference is audible in your system, or which one is preferable, is an open question until you do the experiment. It won't hurt anything.

IIRC, some Jensen oil caps had electrical leakage problems. Since this one is "left over" it may be from that vintage - do some searching on the web forums! A leaking interstage cap will drive the 45 grid positive, leading to excess dissipation and cathode current - both will shorten lifetime, so it's important to check!

[ptlud]

Paul,

Thanks for the prompt response to my question.  The Jensen caps were bought by me maybe 10 years ago.

Paul

[ptlud]

Paul,

I'm curious whether the sonic effects are due to the increased capacitance (0.1 uF to 0.22 uF) or due to the composition of the capacitor (copper foil in oil).

Thanks,

Paul

[Paul Joppa]

It's the capacitance, if you're talking about the overload recovery time. Interstage cap drives grid-to-ground resistor, so the recovery time follows the time constant, R times C. I should probably have noted that a bigger capacitor recovers more slowly, but it takes a larger transient to disturb the equilibrium the same amount - there's a tradeoff, and it depends to some degree on how often you see peak transients.

There are many other audible sonic differences that seem to have to do with the capacitor construction and materials. Those are so difficult to predict that experimentation is the only practical answer.