Posted by Wayne Parham [ 70.242.199.195 ] on December 11, 2007 at 15:24:10:
In Reply to: Re: Fisher SA-300b volume]balance Mod posted by Peter Swartz on December 11, 2007 at 00:55:03:
The suggestion of lifting the ground on the balance pot was just a possible solution, one that might work for you, depending on the output impedance of the previous stage and the input impedance of the following stage. It's not really the best way to do it, but since you had already purchased the pots, I thought it might be worth a try. It's easy enough to do.
Honestly, the balance pot should be at least twice the value of the volume pot and it should have linear taper. Using the wrong pots is probably what's causing your problem. If you want to replace a 500K volume pot with a pair of pots, one for balance and one for volume, you probably should have gotten a 150K volume pot and a 350K balance pot. The volume pot should have logarithmic taper, the balance pot, linear taper.
Wire them like this:
LEFT RIGHTin 1 ___ in 3 ___
| |
|2 |2
|----- 1 |----- 1
350k | | 150k 350k | | 150k
balance | | 2 volume balance | | 2 volume
| |---- out | |---- out
| | | |
gnd 3 ___|_____|____ 3 gnd gnd 1 ___|_____|____ 3 gnd
If you don't feel comfortable doing the job, maybe you should take it to a shop. They can do this for very little money.
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