Phase/ two mics one guitar cab

  • Thread starter Thread starter nagol5178
  • Start date Start date
N

nagol5178

New member
I am new to all of this. I am using an ART MPA ii pre amp into my interface. I will be using the E906 and the sm57 at the same time to just mix down different tones. Sometimes I may use a condenser and the e906 instead.

I am just now learning about phasing. If the mic's are far apart do I need to hit the reverse phase switch on my MPA pre amp or do I need to keep it as normal.

Would I hit the Phase button on both channels with both microphones or would I only need to do this with one microphone? Would it be ideal to use 3 mic's? One being a condenser mic further away which I would have to plug into the interface instead of the pre amp and then mix them as needed?

I have a 6505 half stack, blackstar ht-40 combo and a vypyr 60 combo all which I will be using.
 
if you're using two mic's close to the grill then (i.e 57 and e609) and aren't sure if they're in phase or not then hit the polarity inverse button on one of the channels and listen. which ever variant sounds like it has more low end is normally right, e.g if you're listening and then invert one channel and the guitar sounds thin and weedy then they were already in phase so leave it as it was. if you hit the polarity inverse on one channel and the guitar suddenly sounds big and phat then the mic's are out of phase so leave the button in.

if you invert the polarity of both channels at once then it'll sound the same as if you had left the buttons unpressed.

If you use three mics (an extra condenser further back) then, as a rule of thumb that still gets debated, the 3:1 rule can be a good start. i.e if you have a mic 1 inch from the grill then the next mic should be at least 3x the distance from the source to the next mic (i.e 3 inches). This is probably a better explanation with some diagrams.

There is also a lot to be said for just using one mic at a time on a guitar amp. a well placed 57 or e609 can sound outstanding and you won't need to worry about phase issues. I'm a big fan of using one mic at a time but double tracking the guitar using a different mic or mic placement for the double track
 
nagol5178 said:
... I am just now learning about phasing. If the mic's are far apart do I need to hit the reverse phase switch on my MPA pre amp or do I need to keep it as normal. ...
Click to expand...
Play something continuous like a keyboard or strumming one chord through a speaker.
With two mics at the same volume panned mono, head phones on, put one mic up on the grill, the second right next to it. Then begin to slide one back and forth. You'll hear the phase tone effects.
Do it. :D

There's is only one condition where all of the frequencies can be in phase and that is where the sound from a source arrives at both mics at the same time. Ie the same distance, or close enough to not matter.

All other unequal arrival times will be different in and out of phase frequency combinations- basically you're getting a lot of interesting and perhaps useful phase effected tones to play with if you like.

The polarity switch inverts the signal 180 degrees, for a mic is wired backwards for example. In the case of mixed mic distance phase effects' it just gives another set of tone variables (for close distances likely worse or quite a bit more odd then in polarity.
Try it. You'll hear it easily.

If it's for 'one close one farther' forget 3:1 that's not what it's for. '3:1 is for attenuating -by move the mic away, bleed you don't want to hear. In you scenario you will be using and mixing the tone affects.

The short ver is put the mics where they sound good together.
But it does help to understand what the variables are.
 
The phase, or polarity button on gear inverts the incoming waveform.
If you recorded a pure sine wave which started at zero, climbed to one, and fell back to zero, inverting polarity would make it go 0, -1, 0.

Typically you'd use it on ONE of two mics if they are on opposite sides of a source.
Imagine top and bottom of a snare. When you hit down, the skin goes down. The top mic is 'sucked' downward while the bottom one is pushed.

One is reporting a negative and the other a positive. Wr invert one of them so that the signals compliment eachother, rather than cancelling.
 
You must log in or register to reply here.
Back
Top