how to check phase issues in your mix?

Dirty Gear Pimp · 9th May 2008

hi all

ok so i have 2 parts to this question:

i was listening to this mix earlier someone was doing. while i was listening, i hit the mono button to hear the mix in mono in the control room and pressed the phase invert button on the console. which inverts the phase of the left channel to check your mix for phase issues. now when i hit the invert phase button, the vocals completely disappeared and the bass guitar disappeared. otherwise when the mix was in regular stereo and no phase switch hit, the mix sounded fine. so to me, sounds like something was cancelling out the vocals and bass guitar when the phase was flipped. what should be done to fix that? how do you people check your mix for phase issues when you are mixing?

2nd part of my question about phase:

so when you are micing up a guitar amp and using more than one microphone, what is the best way to check for phase issues and alignment? i know follow the 3 to 1 rule. but is there anything else you can do to make sure you dont have phase issues with your multiple mics on a single source?

thethrillfactor · 9th May 2008

Quote:

Originally Posted by Dirty Gear Pimp

hi all

ok so i have 2 parts to this question:

i was listening to this mix earlier someone was doing. while i was listening, i hit the mono button to hear the mix in mono in the control room and pressed the phase invert button on the console. which inverts the phase of the left channel to check your mix for phase issues. now when i hit the invert phase button, the vocals completely disappeared and the bass guitar disappeared. otherwise when the mix was in regular stereo and no phase switch hit, the mix sounded fine. so to me, sounds like something was cancelling out the vocals and bass guitar when the phase was flipped. what should be done to fix that? how do you people check your mix for phase issues when you are mixing?

When you inverted the left channel and summed to mono you are basically listening to the side information.

All you really need to do is sum to mono and listen to one speaker to check the mix in mono.

Quote:

Originally Posted by Dirty Gear Pimp

2nd part of my question about phase:

so when you are micing up a guitar amp and using more than one microphone, what is the best way to check for phase issues and alignment? i know follow the 3 to 1 rule. but is there anything else you can do to make sure you dont have phase issues with your multiple mics on a single source?

Pump some white noise into the amp and move the mics around the amp until you hear the noise getting louder. Where its the loudest is where you want to place the mics.

Richard Salino · 9th May 2008

To part 1:

Wouldn't doing that cause all mono elements panned center to null entirely? Am I missing something? Sorry, I mix ITB.

To part 2:

If you're close micing an amp and just want two mics for different flavors, getting the diaphragms to be as close to the same distance from the source will minimize phase issues. You can reverse polarity on one mic and move them around until you find the lowest signal. Then flip the polarity back to normal. Also, if you're working on a DAW, you can zoom in on the waveform to see if either mic needs to be moved closer or further from the source. Eventually, you'll be able to get really close visually.

If you're doing the one mic close, one mic distant thing, you'll always have a certain amount of phase cancellation. You can minimize it by moving the distant mic back, and by trying to reduce the amount of direct sound reaching the distant mic. For instnace, you could set up a figure 8 with the null facing the amp, so that it picks up mainly ambiance. That way the close mic and distant mic will be receiving different info and shouldn't mess with one another as much.

vanrobr · 9th May 2008

The bass and vocals disappearing means that they are in phase. Anything left over after summing to mono and phase flopping one side is out of phase.

When miking a guitar cab, get your first mic in a good spot on the amp. Now, on the second mic's channel, flop this out of phase, sweep the second mic around on the amp until the sound is as bad as possible. When you release the phase flop switch on the second mic, they will now be in phase.

9th May 2008	#1
Dirty Gear Pimp Gear maniac Joined: Jan 2006 Location: Otown Posts: 260 Thread Starter	how to check phase issues in your mix? hi all ok so i have 2 parts to this question: i was listening to this mix earlier someone was doing. while i was listening, i hit the mono button to hear the mix in mono in the control room and pressed the phase invert button on the console. which inverts the phase of the left channel to check your mix for phase issues. now when i hit the invert phase button, the vocals completely disappeared and the bass guitar disappeared. otherwise when the mix was in regular stereo and no phase switch hit, the mix sounded fine. so to me, sounds like something was cancelling out the vocals and bass guitar when the phase was flipped. what should be done to fix that? how do you people check your mix for phase issues when you are mixing? 2nd part of my question about phase: so when you are micing up a guitar amp and using more than one microphone, what is the best way to check for phase issues and alignment? i know follow the 3 to 1 rule. but is there anything else you can do to make sure you dont have phase issues with your multiple mics on a single source? __________________ I'm not a crack head... Just a gear junky.

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9th May 2008	#3
Richard Salino Gear nut Joined: Aug 2005 Location: Athens, GA Posts: 91	To part 1: Wouldn't doing that cause all mono elements panned center to null entirely? Am I missing something? Sorry, I mix ITB. To part 2: If you're close micing an amp and just want two mics for different flavors, getting the diaphragms to be as close to the same distance from the source will minimize phase issues. You can reverse polarity on one mic and move them around until you find the lowest signal. Then flip the polarity back to normal. Also, if you're working on a DAW, you can zoom in on the waveform to see if either mic needs to be moved closer or further from the source. Eventually, you'll be able to get really close visually. If you're doing the one mic close, one mic distant thing, you'll always have a certain amount of phase cancellation. You can minimize it by moving the distant mic back, and by trying to reduce the amount of direct sound reaching the distant mic. For instnace, you could set up a figure 8 with the null facing the amp, so that it picks up mainly ambiance. That way the close mic and distant mic will be receiving different info and shouldn't mess with one another as much.

9th May 2008	#4
vanrobr Gear Head Joined: Jan 2008 Location: London, Ontario Posts: 51	The bass and vocals disappearing means that they are in phase. Anything left over after summing to mono and phase flopping one side is out of phase. When miking a guitar cab, get your first mic in a good spot on the amp. Now, on the second mic's channel, flop this out of phase, sweep the second mic around on the amp until the sound is as bad as possible. When you release the phase flop switch on the second mic, they will now be in phase.