2 volume pot issue, only sound with both on
I'm putting together a new bass and am trying to wire it up with 2 humbuckers, 2 volume and 2 tone knobs.
Issue I'm having is that when only one volume knob is turned up, I get nothing. I have to turn the other volume up just a bit to get any sound.
Volume pots: 250K Bourns
Tone pots: 250K Bournes
I'm using a .49uF 50WVDC Cap on the tone pots.
I've wired it up the same as this diagram except I don't have the pickup selector switch in there. I've soldered both the positive leads to the tip ring on the output jack.
It seems that with out the switch, there is nothing isolating the two output signals and either volume will provide a path to ground, killing the output of both pick ups. May be some one can suggest a fix such as rearranging the placement of the vol pots in the circuit so they don't act as one, or put in the switch.
The problem is that you wired the volume pots as if there would be a pickup selector switch, and then didn't use the switch.
When there is a pickup selector switch, it is most common to use the wiper terminals of the volume pots as outputs, because the volume pots behave better that way. The tradeoff is not being able to solo a pickup, because each pot controls the output impedance, but that is what the pickup selector switch is there for. What you need to do is use the wiper terminals as inputs, like in a standard Jazz bass.
This is normal for the wiring scheme you selected. It's how the volume knobs work on a Les Paul type guitar. A Les Paul doesn't allow you to adjust the blend level between the two pickups. When the switch is in the center position, both volume knobs affect both pickups.
In order to fix this so that you have independent volume control, simply swap the lugs of the pickup wires with the selector switch wires on the volume pots. Basically, you want your pickups connected to the pot center lugs, and the selector switch wires (output jack in your case) connected to the left lugs. The ground connections stay the same.
the overall point is valid, but this detail is incorrect:
it's the tones that end up affecting everything, rather than just their own pickup.
Thanks for the input! Lets me know it's doing what is expected for how it's wired.
I'll try swapping the wires on the volume and see how that goes.
This is the classic problem of having to connect the volume pots "backwards" (pickup to middle lug) to enable mixing down one of them to zero.
If you do that then you don't need the switch, but the problem is that there is more load on the pickups (when pots it not full open or close and the resonance peak is quickly killed. That is why guitarists connect them forward. For many basses this is actually a desired effect (Jazz bass players seem to like it) but other pickups can sound bland.
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