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  #1  
Old 10-21-2010, 10:12 AM
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Phase switch after volume pots?

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I'm working on a wiring harness right now, and so far, I have a VVVT setup. (2 J, 1 P).
I want to set it so I can run the j pickups out of phase.
But both pickups are custom wound to 11k w/ the same number of windings. I think this would cause a nearly complete volume cancel.
Would putting the switch after the volume allow me to adjust the level of phase difference?
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Old 10-21-2010, 10:17 AM
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Nope, it would require a phase shifter circuit to adjust the actual phase difference. Simply flipping the leads around gives you 180 degrees, and that's all you can do with a switch.

I don't see what the issue would be?
It doesn't matter if both pickups have the same output, you are only canceling out the signal that both pickups have in common.
Phase inversion by nature gives you a very thin tone with most of the frequency content canceled out.
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Old 10-21-2010, 10:24 AM
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I was under the impression that the closer the output of each pickup, the more cancellation.
So there'll be no difference in tone if I switch the phase after the volume pots?
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Old 10-21-2010, 10:57 AM
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Quote:
Originally Posted by Luckie View Post
I was under the impression that the closer the output of each pickup, the more cancellation.
So there'll be no difference in tone if I switch the phase after the volume pots?
Yes, the closer the amplitudes match, the more complete their destructive interference will be. Why is this an issue, however? Most pickups should have a well-balanced output anyways.

FWIW, there is no difference between inverting the phase before and after the volume pot. The signal itself will be exactly the same, and the volume control will function exactly the same.

If you do put the phase switch after the volume pot, though, be sure not to ground the third terminal of the volume pot.
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Old 10-21-2010, 01:16 PM
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Quote:
Originally Posted by Luckie View Post
I was under the impression that the closer the output of each pickup, the more cancellation.
So there'll be no difference in tone if I switch the phase after the volume pots?
That's only the case if the pickups are literally right on top of each other. Because the string vibrates differently in different areas along its length, your pickups will be generating different signals, with some overlap of course.

This is also the reason you usually want your bridge pickup to be wound a bit hotter than the neck pickup - there's less string vibration and it will be inherently quieter.
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Old 10-21-2010, 06:08 PM
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i'm having a hard time imagining when the thin, weak sound of out-of-polarity pickups would ever be useful on a bass.

also, three volume pots all in parallel makes for a bit of tone loss. a simpler circuit (maybe one that switches between pickups and uses fewer volumes?) would make for a stronger signal.
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Old 10-21-2010, 08:18 PM
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Quote:
Originally Posted by walterw View Post
i'm having a hard time imagining when the thin, weak sound of out-of-polarity pickups would ever be useful on a bass.

also, three volume pots all in parallel makes for a bit of tone loss. a simpler circuit (maybe one that switches between pickups and uses fewer volumes?) would make for a stronger signal.
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