[Harp-L] Speakers, mics and phase

[gregnospam <gregnospam@xxxxxxxxxxx>]

Yes- even with a single speaker, there is a phase relationship  
between the mic and the speaker that can help to accentuate, cancel  
or alter feedback. Imaging holding your mic in front of the speaker,  
facing it. If the mic's diaphragm moving in (away from the speaker)  
results in a signal that pushes the speaker cone out, (think, waving  
both hands back and forth in the same direction) then the two are  
sort of "coupled" and feedback will be likely. If they move in  
opposite directions (think moving your hands toward and away from  
each other, like clapping) they have a natural phase cancellation  
that can reduce feedback..

Now - the fact is it matters where you are in terms of wavelengths of  
distance from the speaker, but for yucks I wired one of my  
Kalamazoo's up with a speaker-phase-reversing switch. I can get  
feedback in either direction but the feedback tone occurs at a  
different frequency if its in phase than if it is out of phase - and  
I can get the volume knob a little higher before feedback when the  
switch is in one position vs. another.