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[strat alot]

Sometimes I run across old Silvertone organs that have tube amplifiers
in them. They usually work fine and they go for cheap. Is it possible to
reconfigure the amps and use them for guitar? Is it even worth doing?

[kseely]

strat alot wrote:

[Wbittle]

HI,
I design, build and service guitar amplifiers and can tell you that
I started out by reconfiguring both old organ amps and hi-fi amps as a
kid. If the organ amp is just a power amp, you will have to add a gain
stage and normally a tone control section. Most organ amplifier sections
can easily be converted to use as a guitar amp or hifi amp. It is fairly
easy to add a 12AX7 preamp stage with tone controls to an organ power
amp and end up with a reasonably nice sounding guitar amp. A very basic
12AX7 gain stage would use a 100K plate resistor connected to a B+ of
between 200 and 300 volts with a cathode resistor of 1.2 - 1.8K ohms and
a grid leak resistor of 1 meg ohm. This stage can offer enough gain by
it's self to bring the signal from a guitar to a level that will drive
the average power amplifier. Most organ amplifiers have more then enough
reserve power supply capacity to handle several such stages. Most organ
amp chassis have more then enough room to mount the components.
Bill B.

strat alot wrote: