Phase Flip

[xaidmcx]

Ok... so ive been attempting to practice getting good and or different sounds from micing my amp... i have some pretty decent prosumer gear and nothing to put your nose down at... so when i record with 2 mics giving me 2 tracks recorded in the left and 2 in the right speaker i get a boomy sound... but as soon as i phase flip one mic in each speaker it loses the boomy sound. Is it common to use a phase flip when recording with multiple mics? Because even though i lose the boomy sound i don't feel i'm getting the supposedly bigger sound that multiple micing will do for a recording. If that makes sense... seems kind of like why did i set up 2 mics, because it sounds like just 1 mic.

Can anyone explain a little about what this is or why and any possible suggestions i could use to improve my micing techniques?

 

[tmix]

Hey X,
If I read you right you are placing both mics of a particular take on the same side and it is boomy, when you flip polarity of one of the mics from a particular take it thins out, but does not sound particularly big.
It that right?

I think what is happening is: The mics are probably in phase to a large degree, when you flip polarity in one mic (Panned to the same side) the low freqs cancel out mainly due to the fact they are more omnidirectional and fill both mics more equally, then in decreasing amounts the shorter, mid to high freq waveforms.

You can simply cut some of EQ in those wooley freqs, or pan the second mic more or less from enter than the first mic. You can thicken thing up by delaying one of the mic about 15 milliseconds as well.
You can experiment with panning the second mic to the other side and possibly flip polarity, add some delay etc which will really throw some sound around, but a warning... when anyone listens in mono the guitar part may totally disappear, so check all your work in mono.

Got to run.

Tom

 

[mixsit]

There are a couple of reasons for dual miking -bringing in a second tone view, picking up ambiance, stereo spread etc. In either case though it's safe to say the source tone, mic choice and placement should try to be optimum for what you want to begin with. Is your second mic a different distance than the first? If not, it may mean they're in phase but picking up too much lows.
If you're going for different distances by definition they will be out of phase at some frequences (frequencies vary by time difference). But this can be used (like eq) as part of the tone.
As a second mic is pulled back far enough to begin to see more room tone, these reflections will fill in the tone changes made by the direct line time differences.

 

[Robert D]

Ok... so ive been attempting to practice getting good and or different sounds from micing my amp... ... so when i record with 2mics giving me 2 tracks recorded in the left and 2 in the right speaker... ...seems kind of like why did i set up 2 mics, because it sounds like just 1 mic.

I'm assuming this is a mono guitar amp where the two speaker are wired in parallel and each producing the same sound? And you're close micing each speaker? There's really nothing in that scenario to give you a bigger sound, only possible phase issues. At best you have two mics picking up the exact same thing. The purpose for using multiple mics is to either capture stereo information, or to capture depth. There's no stereo information to capture here, so go for depth. Try using one mic for close micing the cab, and the other for micing the room. Experiment with placement, even with placing a mic behind the cab, or down the hall.

 

[MessianicDreams]

here's a couple of tips to not have phase issues when using 2 mics on 1 source:

1. try and have the capsules the same distance away from the source.
2. observe the 3-to-1 rule
3. time aline the tracks

follow any 1 of the those 3 rules and you should be fine





and, as a side not, it should really be refered to as the "polarity inverse" button - phase is a time-based relationship between two waveforms

 

[Robert D]

....or not.

 

[mixsit]

here's a couple of tips to not have phase issues when using 2 mics on 1 source:

1. try and have the capsules the same distance away from the source.
2. observe the 3-to-1 rule
3. time aline the tracks

follow any 1 of the those 3 rules and you should be fine

Please, if you can, explain how #2 is applied in this use. I can only think of one possible way, and even that one is dubious.

Wayne