guitar output. stereo output - but out of phase and cancelling..

[doezer]

hi y'all

quick question for the tech heads here.

my guitar has two pickups a contact K&K pickup and the stock undersaddle piezo pickup (its a Taylor)

so the jack plug is a stereo one and the cable tehn splits to two monos into the mixer. The trouble is i think the signal comes in out of phase or something because they tend to cancel each other out. well not fully but certainly in the higher frequencies if i turn the piezo one up using the volume knob on the guitar, the volume decreases or stays the same...

any ideas? much appreciated..

d

[pogo97]

That does sound like a phase issue. I guess, depending on how it's wired, you could detach and reverse the wires for one of the pickups and see if that does the trick.

[dboomer]

Whenever you mic (or in your case PUs) a source with 2 mics and combine them the laws of physics say that if the two signals (at any frequency) arrive at EXACTLY the same time (phase) they will double in intensity. And if they arrive exactly out of phase with each other they will cancel to infinity. Usually you get a little of both with almost nothing exactly in phase or exactly out of phase. But since you can only double on the good side and you can lose to complete silence on the other the losses usually outweigh the gains.

You could try plugging each output individually into a channel of a mixer and flipping the POLARITY switch and listening to what you get. If you like that better you can rewire the polarity of one (but not both) of your pickups

[doezer]

hi thanks to all very informative.

@dboomer
you say flip the POLARITY switch ... which POLARITY switch.?

cheers

[Shaster]

Originally Posted by doezer

hi thanks to all very informative.

@dboomer
you say flip the POLARITY switch ... which POLARITY switch.?

cheers

Some mixers have signal polarity switches on them, but not many in the lower price ranges AFAIK. This would be a non surgical way to see if switching your wiring would work. If it's a phase issue (and not polarity) it might not make much difference.

Although I'm unfamiliar with these units they might (Don can confirm or dispel) help in the same manner as a polarity switch http://www.midi-store.com/Hosa-GXX-1...e-p-16955.html

Or maybe do your soldering surgery after your guitar, and after any expensive cables FIRST, to see if it helps.

[dboomer]

Originally Posted by doezer

which POLARITY switch.?

Channel polarity switch (sometimes mislabeled "phase" switch)

[ATTACH=CONFIG]350972[/ATTACH]

[moogerfooger]

take a short XLR cable and reverse pins 2 and 3 on one end, and put it on one of the guitar leads. there is even a adapter you can buy that will do it for you. then plug in both into your mixer panned hard left and right. while playing bring both pan pots to the center and observe what happens, if the sound gets louder and better, they were out of phase, or reversed polarity. if they get thinner and cancel, they were OK to begin with. but my guess is one is wired backwards. look at each XLR connector and observe what color wire is going to which pin. if pin 2 (hot) is white on one lead and black on the other, you've just found the problem.