Fender Tone Circuits
From mgarvi–(at)–anix.com Sat Dec 2 09:27:48 CST 1995
In <49df1h$87--(at)--nrp1.news.primenet.com> mike–(at)–rimenet.com (Mike Rejsa) writes:
>*Many* thanks to Mark for his in-depth treatment!
>Minor question: Is there any effective difference between the 250pf/0.1/.047
Hi Mike, If the ‘slope’ resistor (100k in the Fender circuit) and the
250pf/.047 circuit is around 295 hz with about a 19.7 db mid cut
250pf/.022 circuit is around 430 hz with about a 16.8 db mid cut
The numbers above are derived using simplified versions of the tone
The .022 circuit gives the bass control wider range, because like
The other (.1) cap (at the top of the bass pot) is primarily DC-blocking,
Nor does the value of the bass pot enter into the center frequency
Mark Garvin
Article: 6039 of alt.guitar.amps
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From: mgarvi–(at)–anix.com (Mark Garvin)
Newsgroups: alt.guitar.amps
Subject: Re: Tone circuits: part 3
Date: 2 Dec 1995 05:08:07 -0500
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>Fender setup and the 250pf/.022/022 Marshall version? (Pots are different
>too, of course…)
treble pot (250k) stay the same, then the center frequency of the:
circuit which I outlined in a follow-up post. No guarantee on
accuracy, since I’m rushing this.
all simple R/C nets, these are limited to 6db per octave. Placing
the notch frequency a bit higher affords about 2-1/2 octaves down
to the guitar’s low E string (82.4 hz). The standard Fender .047
circuit’s mid notch is less than two octaves up from the low E
string, so the low E cannot be ‘boosted’ be even 12 db.
since the reactance is still relatively low down to bass frequencies.
Changing to .022 doesn’t make that much difference, esp in the Marshall
circuit with a 1 meg bass pot.
calculation very much. It DOES work as a voltage divider against the
100k slope resistor, so values over 250k don’t do a whole lot of good.
In fact, if a 1 meg pot is used there, best make sure that it’s a
true log taper (1/10th of the value at half-rotation) rather than
a semi-log (usually around 1/3rd at half-rot.). Otherwise all the
bass boost will happen in the low range of the pot…no audible
effect with further rotation.
