From mike–(at)–ol.hp.com Thu Feb 9 11:10:14 CST 1995
Article: 34800 of alt.guitar
Path: geraldo.cc.utexas.edu!cs.utexas.edu!sdd.hp.com!hplabs!hplextra!news.dtc.hp.com!col.hp.com!mikem
From: mike–(at)–ol.hp.com (Mike McTigue)
Newsgroups: alt.guitar
Subject: Re: Volume / Tone problems with Fender ultra-Strat
Date: 9 Feb 1995 16:14:18 GMT
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The reason you lose the high end when you turn
down your guitar volume is that the impedence driving
your guitar cable and amp input goes up. When you
have the pot set at full, the pickups impedence is
what drives the cable (~7kohm for single coils, and
2x that for humbuckers). But when you turn the volume
down, the resistance of the pot inceases the output
imepedence. e.g.
250kohm
pickup ———-//////——–GND
^
|
|
To guitar cable
(wiper of pot)
The worst position is when the pot is in the middle.
For the example shown, the output impedence will be
about 125k in parrallel with 125k or 62.5k.
Some ways of fixing this problem are:
o Put a preamp in the guitar. Not for everyone
especially if you don’t want to do a mods.
Really the best solution. The active circuit
provides a constant output impedence to drive
cables and inputs.
o Use a short, high quility, low capacitance
guitar cable. Use a amp with low capacitance
input (or use a buffer with low capacitance
in front of the amp).
o Add a capacitor or a series combination of a
capacitor and resistor across the pickup side of
your volume control and the wiper. This has no
effect when the volume is on 10, but as the
volume is lowered, it allows the higher frequencies
to be less attenuated, therefore compensating for
the loss caused by the cable/input.
You’ll have to just experiment with different
values of C. To do this, bring out two wires
from the guitar and try different value while
you play. This method is not perfect as the
tone will change with volume, but not horribly
so. It is easy and doesn’t require hacking up
the guitar.
Good luck!
