I came across a reference
recently to a master volume
circuit published by Craig
Anderton in Guitar Player,
December 1982. According to
the later writer, it worked by
using ganged pots across the
two signals from the phase
inverter to the output tubes. He
claimed it was the best master
volume circuit for tone that
he'd come across. Anybody
know about this one, or have a
copy of the old magazine? 

RL


J Fletcher
1/6/98
9:17 AM

I remember that one,I installed
it in an amp a few years ago
for a customer.As I recall,it
used a dual 1 meg audio
pot.The output from the phase
inverter was coupled to the
wiper through a cap,one end of
the pot to ground,the other end
to the power tube grid through
a cap.I've tried it coupling the
phase inverter to the high end
of the pot and feeding the
power tube from the wiper
with the pot grounded at the
other end.Both seem to work
about the same although I
would think the later would
load down the phase inverter
less at low settings,giving it
more gain and
distortion.Sounded about the
same though,as I recall.



>> Incidentally, does anyone
know why the
Torres/Anderton mv control
connects the wipers to the
output of the driver(s) rather
than to the input of the power
tubes? << 

They probably thought it
would be easier to set the
vol/mvol balance because the
voltage at which the driver
starts to clip can be adjusted
by the mv if the wiper goes to
the driver tube. (The mv
wiper-acw resistance is a
variable load on the driver
output). The disadvantage is
that you are effectively
paralleling the 100k plate load
with a 1M pot so all the action
will be in the first 100k or so
of the pot travel. 

>> With the .047uf caps on
either side of the pot, would
the bias voltage be effected as
you turn down the mv? << 

I am not sure of the exact
circuit but it looks like the
caps should isolate the mv pot
from the bias supply so I guess
the answer is no. 

Dave

I did use the Dan Torres/Craig Anderton one. 

I used a dual 1 M pot and two new couplig cap (0,15-0,22 uF).
(LH Musik in Stockholm helped my out). 


                    1M ohm 
            new Cap _____ 
From ECC83--||-----|_____|------- to erth 
                      | 
                      | old Cap 
                      |---||----- to Pow Tube 

Hope this will help. 

By the way witch of this mods sound best.