Experimenting with Polarity.

[LOTYBOY]

Hey guys I was interested in your feedback on an idea I had.

First off let me say I am fairly new to recording but I love mixing audio in my home studio. One of my favorite things to do when I have free time and just playing around is to experiment with different settings, filters and techniques to create interesting results. Many of the results I have come up with aren't usable in a practical sense but are informative and I tend to learn a lot by just playing around.

One of the things I noticed when playing around is that if I create a duplicate of a track (Copying and Pasting in Sound Forge) and then flip the polarity of the duplicate, it "disappears" in the mix. It doesn't seem to matter how significantly I change the duplicate track by applying effects or filters or whatever. Flipping the polarity always causes the duplicate and its changes (which I can hear when polarities are the same) to "disappear."

This by itself is not at all eye opening or confusing. But I was thinking the other day about how I might use this to my advantage. Unfortunately I am away from home and won't be back for another week or so and cannot try this myself, so I was wonder what you guys think of my idea below.

Basically want to take two mics, recording into two tracks on my PC.

Mic #1 will be carefully placed and adjusted near a guitar amp, pointing right into the grills "sweet spot" so as to record a perfect guitar track.

Mic #2 will be across the room at the same height and angle also pointing at the amp grill.

For simplicities sake we'll say these mics are identical and that the volume of the amp is set so that its perfect for Mic #1.

Once record is pressed the guitar player plays, while a vocalist speaks into Mic #2 across the room. This should produce a recording mix of someone speaking over music.

But when listening to just the track recorded by Mic #2 (solo) you would hear only the vocalists words, with a hint of guitar amp in the background faintly bleeding into the mic, particularly whenever the speaker pauses. And lets say this bleeding guitar sound is undesirable for our purposes. Instead of a fullness enriched by the rooms acoustics we'll say it sounds tinny noisy.

So my question is what happens if you flip the polarity on Mic #2's track? And playback the mix? Would that faint guitar amp signal "disappear" from the mix just as a true duplicate does, leaving only the carefully miked signal and our vocalists words? Would the entire #2 mic track (vocals and all) "disappear" in the mix? Or will absolutely nothing happen, requiring a noise gate on Mic #2's track to eliminate that undesirable guitar bleed?

I will be home in a week and will try this when I get there but in the mean time the question keeps rattling around in my head and I would love to hear what you guys think.

 

[Whale Bone]

It wouldn't work because mic 2 is out of phase from mic 1 because of the distance, and even if you time aligned the mic 2 track to mic 1's, they are not the same sound (different place in the room) and would not cancel so cleanly like a copy and paste of a track in your example.

With limited effort I couldn't even make that idea work in a radio station for broadcasting phone calls where the annoucer's voice in the console was inverted and used to cancel the same voice in the phone to avoid feedback. It's hard to get perfect cancelation from different sources.

 

[SouthSIDE Glen]

It wouldn't work because mic 2 is out of phase from mic 1 because of the distance, and even if you time aligned the mic 2 track to mic 1's, they are not the same sound (different place in the room) and would not cancel so cleanly like a copy and paste of a track in your example.

All absolutely correct.

If you don't want the bleed, the best way to deal with it is to actually try and minimize the bleed itself, either though isolation in-studio or by recording the guitar and vocals separately.

G.

 

[LeeRosario]

Hey guys I was interested in your feedback on an idea I had.

First off let me say I am fairly new to recording but I love mixing audio in my home studio. One of my favorite things to do when I have free time and just playing around is to experiment with different settings, filters and techniques to create interesting results. Many of the results I have come up with aren't usable in a practical sense but are informative and I tend to learn a lot by just playing around.

One of the things I noticed when playing around is that if I create a duplicate of a track (Copying and Pasting in Sound Forge) and then flip the polarity of the duplicate, it "disappears" in the mix. It doesn't seem to matter how significantly I change the duplicate track by applying effects or filters or whatever. Flipping the polarity always causes the duplicate and its changes (which I can hear when polarities are the same) to "disappear."

This by itself is not at all eye opening or confusing. But I was thinking the other day about how I might use this to my advantage. Unfortunately I am away from home and won't be back for another week or so and cannot try this myself, so I was wonder what you guys think of my idea below.

Basically want to take two mics, recording into two tracks on my PC.

Mic #1 will be carefully placed and adjusted near a guitar amp, pointing right into the grills "sweet spot" so as to record a perfect guitar track.

Mic #2 will be across the room at the same height and angle also pointing at the amp grill.

For simplicities sake we'll say these mics are identical and that the volume of the amp is set so that its perfect for Mic #1.

Once record is pressed the guitar player plays, while a vocalist speaks into Mic #2 across the room. This should produce a recording mix of someone speaking over music.

But when listening to just the track recorded by Mic #2 (solo) you would hear only the vocalists words, with a hint of guitar amp in the background faintly bleeding into the mic, particularly whenever the speaker pauses. And lets say this bleeding guitar sound is undesirable for our purposes. Instead of a fullness enriched by the rooms acoustics we'll say it sounds tinny noisy.

So my question is what happens if you flip the polarity on Mic #2's track? And playback the mix? Would that faint guitar amp signal "disappear" from the mix just as a true duplicate does, leaving only the carefully miked signal and our vocalists words? Would the entire #2 mic track (vocals and all) "disappear" in the mix? Or will absolutely nothing happen, requiring a noise gate on Mic #2's track to eliminate that undesirable guitar bleed?

I will be home in a week and will try this when I get there but in the mean time the question keeps rattling around in my head and I would love to hear what you guys think.

Whale Bone said it like it is.

Fun fact:



It's not unheard of for someone to flip the polarity on one of the studio monitors in the control room while the singer sings over the loud speaker. It's "supposed" to minimize any bleed into the mic because of cancellation between both speakers, but I tried this and it's alot easier said than done.

It involves alot of circus balancing BS between the speaker level, mic placement and room acoustics.

It ends up working better as a last resort thing, or when you got Wyclef preferring to sing in the control room over the monitors. More about the performance than the actual sound quality at that point.

 

[LOTYBOY]

Thanks

You guys probably just saved me a ton of time experimenting with it. And you definitely saved me a ton of time thinking about it over the next week. It was more of just an exercise in theory without any real world application in mind.

Thanks again for humoring me and answering my question!