(long message alert, sorry 'bout that)
I have been doing a lot of testing with a Duet Master system, which is a blender of
saddle pickup and microphone and determined that when the invert button is up
that the master's output on XLR is 180 degrees out of phase with the saddle pickup input.
As a side note the phase of the saddle pickup input and the mic pickup input are also 180 degrees
out of phase which I expected because electret condenser mics signals are 180 degrees out of
phase with the sound wave coming in from the front. (If they are wired common source)
If this makes sense to you then here's my question:
Do saddle pickups produce a signal that is opposite the motion of the guitar top (assuming that
when the top moves forward it produces a positive pressure and a microphone picking that up
would produce a positive voltage)
So that as the top is moving forward/positive the saddle pickup's signal is moving negative
and thus the Duet Master inverts the signal of the pickup.
I am thinking that compression of the saddle pickup causes a positive voltage, meanwhile
the string is compressing the saddle it is pushing the top backwards.
And the reason I'm doing all this testing is that I am trying to come up with a blender for my
mandolin and want the signal from the pickup in phase with the signal from the microphone.
Whew! Thanks for reading this far.