phase - reverse polarity

[olfunk]

hey
im always hearing people on hear talking about phase reversal and stuff like that (also on the drums forum) and i just wondering how do you reverse the polarity on a mic?
thanks

 

[drummerdude666]

You can do it if you have a phase switch on your mixer or mic preamp. Or you can change it in your DAW.

 

[Mark7]

If you have a neutron flow you can reverse the polarity of that as well

Sorry

 

[wesley tanner]

actually, you don't need a device at all to flip the phase, all you gotta do is open up an XLR and flip ye old L and R wires. poof. great for use mikin' up a snare top 'n' bottom with pres that don't flip

 

[Cave Dweller]

Just so everyone's aware, the terms "Phase" and "Polarity" technically refer to different things. This post is talking about reversing the POLARITY of a mic. this is often (mistakenly) refered to as reversing the PHASE

PHASE has more to do with time, and the distance of multiple microphones from a single source.

For example, a transformer will shift the phase of a signal about 90 degrees. as do some passive crossover networks. EQ can also cause phase shifts. this mainly has to do with the time... certain frequencies will be slightly behind others... thus coloring the sound. this is sometimes good, sometimes bad.

or say you were micing up a drum kit... if you're using more than one mic, then you may encounter phase problems caused by different drums arriving at different mics at different times, and cancelling certain frequencies, causing COMB FILTERING.

there are many more detailed explanations on this forum, by people with much more technical knowledge than I.

 

[Cave Dweller]

https://homerecording.com/bbs/showthread.php?t=157988

seems i've been beaten to the topic. that'll show me for not visiting for a few days

 

[hueseph]

To add to the confusion, a phase problem can be corrected by reversing to polarity of a mic. Not always but sometimes. If you have two signals from one source which are 180degrees out of phase with each other, a reversal of polarity may fix the problem. A phase inversion should fix the problem.

 

[Cave Dweller]

A phase inversion should fix the problem.

but youre not really talking about phase, you're talking about polarity

 

[Bob's Mods]

For example, a transformer will shift the phase of a signal about 90 degrees. as do some passive crossover networks. EQ can also cause phase shifts. this mainly has to do with the time... certain frequencies will be slightly behind others... thus coloring the sound. this is sometimes good, sometimes bad.

Just a side note:
I have often wondered if plugins compensate for these minor side effects of using the real hardware. I suspect that many do not. They instead create the theoretical perfect EQ or what ever. As a result, the plugin does not truly simulate the hardware and our brains detect this difference without knowing why. These minor side effects contribute to the character of these devices and could potenitally improve plugin quality. Plugins make life cheaper and easier for home studio types, but they fall short of the real deal from my experience and this is one small reason why.

Bob

 

[xstatic]

People also need to realize that reversing the polarity gives a single shift of 180 degrees. Phase is not such a simple beast. Phase can be out by both negative and positive numbers. It can also be out by ANY amount. It could be postive 1462 degrees out, or negative 1048293 degrees out. This is part of the reason that phase should be refferred to as phase and polarity as polarity. In the end, even a matched pair of microphones will not give you something that is absolutely in phase. We hear phasing on a constant basis. There is a kind of acceptable amount of phasing that does not seem to bother us when we listen. There are certain frequencies that we don't mind hearing as much as others when more or less phasing is introduced. The Polarity button on your mixers and preamps is there to be used as a tool. Sometimes it helps, sometimes it makes it worse. The trick is to find that balance between mic selection and positions that works. When I say works, what I mean is "sounds good". The polarity button can be used as a tool to help achieve this. When I am lining two mics up, I flip the polarity on the farthest mic from the source until the sound is as bad as possible, then I flip it back. It seems to be a lot easier to distinguish when two mics are really interacting negatively than when they are playing nice.