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Electronics Gurus - Bass Volume Question

Lyle Caldwell

Lyle Caldwell

Sep 7, 2004
1,192
95
Memphis
www.psionicaudio.net
#1
I have a Jazz Bass wired to switch between series and parallel modes. It all works well and sounds very nice. I'd like to be able to put in a resistor when in series so the output level doesn't jump up over the parallel mode. I'm not using the volume pot for swells, just slight changes, so I'm not too concerned about changing the pot taper. I have separate leads for series and parallel modes, so the parallel wiring would not be affected by a volume limiting resistor.

But I don't know how to calculate what resistor to use, first of all. I suppose I could measure the volume pot on full when in parallel and then measure again in series with the volume turned down until the level is consistent, and then use a resistor having the value of the difference (say, 247K in parallel but only 222K in series would tell me to use a 25K resistor to control the series volume). Then I'd place the resistor in series between the (parallel) pickups and the volume pot - is this correct?

Thanks in advance
 
#2
it would actually depend on the output impedance of the pickups and potentially even on the input impedance of the amplifier.

My advice would be to suck it and see. Place a large value potentiometer in series instead of the pot and tweak it until it sounds right - then measure the value and replace with an appropriate resistor combination.
 
#3
I've decided I'll put a 300K trimpot in series with the series lead before the master volume pot and just turn it down until I get the output level I need. Same as using a fixed resistor, but I can change it or tweak it if it needs to be "between" fixed resistor values. I'll just hot glue it to the back of the tone pot and it should work fine.

I'll also probably put a 1M tie down resistor between the volume out and ground to minimize any switching noise (it can be very apparent right now if I switch while a note is ringing out, as the levels are so different, but maybe matching the levels using the trimpot will be enough - if not, I'll try the tie down resistor).

If anyone is wondering, this is the wiring layout I'm using:

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