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    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Film Cap Voltage Question

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#24
Diabolical Artificer said:
Most engineers would answer none. I higher voltage cap will have thicker/better insulation/dialectic material one would guess & maybe a tad more inductance, but we're talking about pico henries possibly. At audio frequencies the capacitance of the cap itself together with the grid leak resistor dominates frequency response, at RF the tiny extra amount of inductance might make a small difference.

There might be a small difference in THD but I'd wager non a human ear can detect. That said for some amp design and building is part engineering part voodoo part trick cycle-ary. A £30 big cap with groovy gold lettering sounds better to some. Being a poor peasant I buy caps rated for 630v which in most parts of the circuit of an amp with 450v ish HT/B+ are sufficient and made by reputable manufacturers at the lowest price I can find and have been happy, chaps with deeper pockets may find pleasure in buying more expensive types.... funny old world innit.

Andy.
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The other thing is that the larger the cap, physically, the more noise and hum it can pick up.
It probably needs longer leads/traces which increases that possibility.
This may in some cases cause differences in sound.
Of course, with the bigger/more expensive and gold-embossed cap the sound is better ;-)

Jan
 
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#26
Well it's a 2-wire device so the same current runs in both wires so both are in the 'sound path'.
What sometimes helps is to connect the wire from the outside winding to the lowest impedance point, which often is the source side, to get some measure of screening.
But as a coupling cap between an anode and a grid, both sides see relatively high impedance so then this tactic works much less.

This is all for coupling caps; for decoupling caps this isn't an issue o0f course.

Jan
 
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#28
ejp said:
Everything is in the sound path.
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Well in a stricter sense, not so much. The question is, does it affect the sound? Yes. The PS no matter the type has an influence on the ability to produce all the sound from a source. Transformers have limits. I use transformers. The quality of the transformer and the engineering on the PS is the heart of my systems. I've had several people tell me about rectifier designs. I offered them my take with examples.

I unplug a good rectifier valve and swap to a super rectifier from STL or a couple of home brews I have. I like a design that uses an OA3 with a 5U3C or something like that. It's not in the path but it sure changes the dynamics of the piece using it.

I've seen stick fuses that were modified to NOT heat up on startup and were dampened in the material that doubled as a thermal transfer material. They change the warm up recovery time from 60 minutes to resistor warm ups. 3 minutes?

I'm one of those people that pay attention to the direction of everything. It might be a left handed thing or the 900 times I bumped my head. It goes in my left ear and out my right (direction). Sometimes it stops, I learn something, the trick now is to remember it tomorrow. 🙂

Regards
 
#29
greg7 said:
For a tube preamp DC blocking output cap position, what sonic difference does a higher voltage rating in a capacitor provide? In other words, is there any advantage sonically to using higher voltage rated caps over a lower voltage one of the same brand and model / part number, where all else is equal except voltage rating?
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Go for the cheaper capacitor and forget about it. There won't be any perceivable difference if you don't compare. ; )
 
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