From mgarvi–(at)–anix.com Wed Feb 5 11:04:46 CST 1997
Article: 37347 of alt.guitar.amps
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From: mgarvi–(at)–anix.com (Mark Garvin)
Newsgroups: alt.guitar.amps
Subject: Vibrato pot with switch (was GP’s “MODZILLA” mods?)
Date: 5 Feb 1997 02:20:55 -0500
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In <5cnsec$k7--(at)--nn.Princeton.EDU> philli–(at)–ucson.princeton.edu (Phillip C. Saunders) writes:
>Hoffman Electronics in Florida carries a pot that works for this mod,
>but when I spoke to him about it he said the taper isn’t quite right for
>the Vibrato Intensity switch. It worked, but many people who did the
>mod didn’t like the feel and reinstalled the original.
I didn’t follow the start of this thread, but I assume it’s talking
about the loading effect of the 50k reverse-log vibrato pot. I’ve
mentioned in the past that the pot can load the plate circuit of
the previous tube (Weber got this right!
Many people disconnect the intensity pot, or try to install switches
or whatever. Finding a reverse log pot with a built-in switch is
almost impossible. In fact, finding other values of reverse log pots
is pretty tough (using a 100k rev. log pot would be a an OK solution
if you could find one).
BUT…here’s an idea:
You can find 50k reverse log replacement pots pretty easily–from Mojo
or Smart Parts in Chicago. It should be possible to ‘score’ one end
of the carbon element (in a replacement part…not in your original
black-face pot
words, you’d have to open up the pot and use an Exacto knife to
carefully slit the carbon on the *counter-clockwise* (CCW) end of the
pot. As you turn the pot CCW, the wiper will go past the open-
circuited end of the carbon element. This will remove the pot from
the circuit. There you are.
Expect a few db volume boost when the pot is at full CCW. That’s
what this is about, right? A slight increase in volume is usually
perceived as ‘better’ tone, but don’t let this throw you. In fact,
I’m not saying this is better than just turning up the volume a tad.
I’m offering it as a better alternative for those who were recently
talking about drilling holes for switches or trying to find RA pots
with switches. This sorta does the same thing, but without the
click-detent.
This same trick works for taking the tone control out-of-circuit on a
guitar so it doesn’t load the pickups. I just realized that it should
be a relatively non-intrusive way of doing the same for the vibrato
control.
A couple things:
I’m talking about the 50k RA (reverse log) vibrato intensity control,
NOT the speed control.
Do this with a replacement part. You will have to take it apart,
and you may mess it up if you’re not careful.
Turn the pot CCW and watch the wiper to make sure you’ve got the
correct end.
Use an ohmmeter to make sure that you’ve opened the carbon.
Solder a resistor (around 200k to 500k) across the two ‘active’
terminals of the pot. This will keep the couping caps at ground
potential, and will avoid possible ‘popping’ sounds as the control
is turned ‘on’.
Don’t put that thing on the couch. It’s filthy.
If you didn’t understand the post, ask before trying it.
Now paste a poodle on my head and call me Gerald!
MGarvin
From kee–(at)–den.com Wed Feb 5 11:05:01 CST 1997
Article: 37368 of alt.guitar.amps
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From: kee–(at)–den.com (R.G. Keen)
Newsgroups: alt.guitar.amps
Subject: Re: Vibrato pot with switch (was GP’s “MODZILLA” mods?)
Date: 5 Feb 1997 13:31:04 GMT
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Mark Garvin (mgarvi–(at)–anix.com) wrote:
: BUT…here’s an idea:
: You can find 50k reverse log replacement pots pretty easily–from Mojo
: or Smart Parts in Chicago. It should be possible to ‘score’ one end
: of the carbon element (in a replacement part…not in your original
: black-face pot
: words, you’d have to open up the pot and use an Exacto knife to
: carefully slit the carbon on the *counter-clockwise* (CCW) end of the
: pot. As you turn the pot CCW, the wiper will go past the open-
: circuited end of the carbon element. This will remove the pot from
: the circuit. There you are.
I might try coating one end with a thin layer of epoxy, same result.
