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Re: Tone control OT
Title: Re: Tone control OT
Andy,
Certainly, a guitar produces a signal level
lower than what you'll find in a standard fender tone stack , which
can be tens (even hundreds) of volts... tubes are voltage amplifiers
and that's what they do... (transistors are current amplifiers
and tend to operate at lower voltages and higher currents) A
typical 12ax7 will draw only 1.5-3 ma of current but with a standard
250v plate supply the output can swing hundreds of volts, even
-before- clipping.
Charles Zwicky wrote:
Actually, capacitors of different types
can exhibit quite a range of sonic differences, even if the
capacitance is matched.
Walt Jung wrote a definitive study of capacitor differences in audio,
and many guitar and amp folks will assert that ceramic capacitors are
required to get the 'best' sound out of a classic Fender tone control
stack circuit. I may be of interest in this case that Walt Jung
found ceramic capacitors to have higher distortion than metal film and
much mich higher than polystyrene (favored by audiopiles)...
CZ
Interesting
Jung finds a max of 0.1%distortion using a 3V signal.
so there's *something* in it.
I'd figure that in a guitar the cap has somewhat less voltage across
it, and hence less distortion. (although that's a bit
of a guess)
I don't think that accounts for "essential for a vintage
tone",
as is sometimes claimed.
Especially as the guitar still sounds vintage with tone at 10,
in which case the cap is shorted out!
andy
ps.
and no doubt all capacitors are a tiny bit microphonic,
those ceramics have certain similarities to a piezo p/u.
--
...
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