skibum5545 Posted June 28, 2006 Report Share Posted June 28, 2006 (edited) I have seen volume pots drawn in diagrams with two different configurations, as drawn below: The only difference being, of course, that on the first one, one end of the resistor is left open, and on the second one, that end is wired to ground. In terms of how they function, then, the first one uses the pot simply as a variable resistor, where full volume is no resistance and no volume is just 500k ohms--or 250k, or whatever-- in the signal path. The second, however, operates as a voltage divider where max volume is still no resistance, and off connects the hot feed from the jack to ground, cutting out the pickup(s) entirely... right? Anyway, I'm wondering if my analysis of the circuits is correct, and also if there is any major difference between the two in terms of performance. Will it affect the tone? Does humbucking vs. single coil matter? Will I get hum with one but not the other? My hypothesis is that it won't matter a bit, unless the pot provides so little resistance that the "off" on the first one doesn't cut all the signal. Any response is helpful; no response is too in depth, and only the most absurdly inane could be too simple. Thanks much! PS I hope to wire up my bass this weekend, so a response by then would be helpful. Edited June 28, 2006 by skibum5545 Quote Link to comment Share on other sites More sharing options...
lovekraft Posted June 28, 2006 Report Share Posted June 28, 2006 The righthand diagram is correct - the other one doesn't really work, for obvious reasons, and probably just acts as an antenna for noise. Quote Link to comment Share on other sites More sharing options...
skibum5545 Posted June 29, 2006 Author Report Share Posted June 29, 2006 Thanks for the quick response, Lovekraft. I agree that the righthand one undoubtedly works better, and that the lefthand one probably will be noisy, but, uh...which particular obvious reason for not working were you referring to? Quote Link to comment Share on other sites More sharing options...
JoeAArthur Posted June 29, 2006 Report Share Posted June 29, 2006 The wiring on the left is only a variable resistance - it's voltage divider characteristics depend on the input impedance of the amp. You will never get a total volume cutoff. If the pot value is 1 meg and the input impedance of the amp is 1 meg (typical tube Fender) then the most volume reduction that can be achieved is 1/2 or 6db. If you do have a typical tube Fender, that is the same volume difference as switching the plug from the #1 jack to the #2 jack. Quote Link to comment Share on other sites More sharing options...
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