Polarity invert toms ?

[Tim Weaver]

Re: Polarity invert toms ?

I will not take the bait to veer into polarity wrt feedback concerns, other than to say that isn't very simple either.

JR

I realise it's not that simple as well. Not all of the mics are equidistant from the sound source which means they cannot fully cancel with a simple polarity flip.

Part of my workflow is a healthy high pass filter applied to all floor mics. If the mics first feedback freq is at 315 and I flip polarity and that point moves down to 100 then I choose to leave the polarity flipped and then roll the high pass filter up to kill 100 hz, thereby killing the feedback as well. At that point I'll increase gain to find the 2nd and 3rd feedback points and kill those with the parametric. Then I'll group all my PCC's together and bring them up as a group then kill one or 2 more rings with parametric applied to the group. At this point you should have more than enough gain for your floor mics. If at this point I play with the polarity switch on those mics that I flipped, I will get feedback. They stay out of polarity from this point on.

The point is, all of this starts with polarity. I am not naive enough to think that a group of mics will perfectly cancel each other if one is out of polarity with the rest. What I am is lazy enough to not post the explanation as to why.

 

[John Roberts]

Re: Polarity invert toms ?

I realise it's not that simple as well. Not all of the mics are equidistant from the sound source which means they cannot fully cancel with a simple polarity flip.

Part of my workflow is a healthy high pass filter applied to all floor mics. If the mics first feedback freq is at 315 and I flip polarity and that point moves down to 100 then I choose to leave the polarity flipped and then roll the high pass filter up to kill 100 hz, thereby killing the feedback as well. At that point I'll increase gain to find the 2nd and 3rd feedback points and kill those with the parametric. Then I'll group all my PCC's together and bring them up as a group then kill one or 2 more rings with parametric applied to the group. At this point you should have more than enough gain for your floor mics. If at this point I play with the polarity switch on those mics that I flipped, I will get feedback. They stay out of polarity from this point on.

The point is, all of this starts with polarity. I am not naive enough to think that a group of mics will perfectly cancel each other if one is out of polarity with the rest. What I am is lazy enough to not post the explanation as to why.

Here we go.

Polarity in the context of feedback (according to the Johnny model of feedback) shifts where the narrow potential feedback nodes express, related to the path length of the acoustic path and speed of sound in air. So feedback can occur for either polarity, just at different spot frequencies related to wavelength and path.

This seems consistent with your reported experience so I will stop while we are in agreement.

JR