Bass with 2 pups, 2 volumes, 1 tone. Strange volume phenomenon - help?

slyd

Hi guys

I've just rebuilt an old bass, put in 2 passive soapbars, and changed the 1 volume, 1 tone, 2 pup switches, to no switches, just 2 volumes, 1 tone (as per diagram).

Strange thing is, . . .. with both volumes full, when I back off either volume just a tiny bit, the volume boosts (louder than with both full). I came across this same issue with the bass that G-Man built, and it had me wondering. Now that I have it again, and I've wired exactly as per SD diagram for 2 soapbars, 2 volumes, 1 tone, I'm really curious ???

Any thoughts :-[

AlanRatcliffe

Recrimp the legs of the pots tightly onto the tracks - they are loose.

slyd

Alan Ratcliffe wrote: Recrimp the legs of the pots tightly onto the tracks - they are loose.

Hi Alan, i went and tried that, but still the same. ☹

AlanRatcliffe

Are you sure the pups are wired in the same polarity?

Otherwise it could be natural phase cancellation - there are always some common high frequencies cancelled with two pickups, but it rarely makes a huge difference to the volume (but will be more noticeable with some more abrupt pot tapers). Hard wire in a 3-way switch, bypassing the pots to check. If it behaves the same with the switch, it's not the pots.

Wildaker

Sounds like the pickups are out of phase with each other. Try swapping the black and white wires of one of the pickups (white to ground, black to the pot input).

slyd

Thanks guys

Alan, with your mention of pot tapers, I swapped out the Log pots for Linears, and there all was sweet.
Also has much more pup volume balance control.

Cooool
?

AlanRatcliffe

Great!

I can't help wondering if an unusual input impedance might be part of the issue too. What are you plugging into?

slyd

Alan Ratcliffe wrote: Great!

I can't help wondering if an unusual input impedance might be part of the issue too. What are you plugging into?

I'm just plugging into my workshop test amp, a little Behringer 15W guitar modelling amp. You think that may have an influence? . . . . . ???