Phase this

  • Thread starter Thread starter VesuviusJay
  • Start date Start date
VesuviusJay

VesuviusJay

Poser Roaster
How do you tell if you have phase problems when miking drums or guitar. I read in one thread to listen with headphones while positioning the mic. But what exactly does phase cancellation "sound" like. Anyone have a wav file or something I could A==>B so I know when I am creating phase issues.
 
Try this...
Record a little bit of guitar. Then take a plugin(Waves) or probably any others...I use one of the waves compressors. If you look at the plugin there should be a 0 with a line thru it. THATS your phase reversal button.
NOW duplicate the track.
Then pan each track to the extreme opposite sides of each other.
THEN...pull up one of the plugins(it doesnt matter which) and hit that phase reversal button.
THAT should be the sound of phase.
IF you move your head around while listening it might actually make you dizzy.
 
VesuviusJay said:
How do you tell if you have phase problems when miking drums or guitar. . <snip>
Click to expand...

Very simply, if it sounds bad.
Record two mics on your guitar amp, one at the grill, one back about three feet. When you play them back at equal volume, you should hear some wild eq effects. Relative volume of the two will vary the intensity of the effect, moveing either mic will change the various 'pitches' of the effects. Or sliding the two tracks in time a few ms does the same.
On electric guitar, wild eq might be ok. Or not.:D
Wayne
 
MartyMcFly said:
Try this...
Record a little bit of guitar. Then take a plugin(Waves) or probably any others...I use one of the waves compressors. If you look at the plugin there should be a 0 with a line thru it. THATS your phase reversal button.
NOW duplicate the track.
Then pan each track to the extreme opposite sides of each other.
THEN...pull up one of the plugins(it doesnt matter which) and hit that phase reversal button.
THAT should be the sound of phase.
IF you move your head around while listening it might actually make you dizzy.
Click to expand...

This is NOT phase, but polarity, and is a different issue entirely. See the thread Phase. I can't understand!? for more on the difference.

The sound of phase cancellation is referred to as comb filtering, because what it does is cancel out a variety of frequencies. The cancellations are related to the difference in time between the two signals. The easiest way to hear it, for me, is to listen to the mics individually, and then together. If you seem to be losing a frequency or two, you have issues. Some times (sometimes) the polarity switch will make things sound better. It will NOT eliminate the phase cancellations, it will only change them. It may be an improvement, or it may not.

The real trick, for me, is to always check the polarity on each track, both ways. I can then choose the best sounding version. This way, if I miss a phase issue, it doesn’t matter.

Light

"Cowards can never be moral."
M.K. Gandhi
 
Holy schmoly I heard it its kind of like a flange effect no? As I moved one mic away from the other I heard a flange effect accross a band of frequency. Is this the wreched phase. :|
 
VesuviusJay said:
Holy schmoly I heard it its kind of like a flange effect no? As I moved one mic away from the other I heard a flange effect accross a band of frequency. Is this the wreched phase. :|
Click to expand...

Kind of. Flangers, phasers, and chorus, all belong to a class which would best be discribed as time based effects. What they do is delay the signal by a small amount, and then they modulate the delay time. The difference between the three effects is the length of the delay time, and the speed and width of the modulation. When you moved the mic, you were (in effect) modulating the delay time between the two mics, which gave you that "flanger" type of sound.

Light

"Cowards can never be moral."
M.K. Gandhi
 
Another source for the comb filtering is reflections from nearby hard surfaces. To use the guitar cab example again, as you pull a single mic back, the floor becomes part of the sound path.
 
so what then would be the ideal distance to spread the mic's? I assume put on the phones, and separate the mics until no audible phase is heard? Am I on the right track or...
 
And also is there a thread on runaway bass frequencies?
 
You must log in or register to reply here.
Back
Top