Do non-speaker sources encounter phasing problems?

[Vomitorator]

when i mic'ed a drumset i had close mics and room and high overhead mics and i balanced the closer mic's in as needed. I then wondered why phasing was not a problem because i know it was hell to put two mics on my guitar cab. I havnt tried to mic an acoustic guitar with two mics, but my guess is that it wouldnt phase out. What is the reason for this?

[brandondrury]

Phasing occurs with EVERY source where 2 different times are summed together. This can even be caused by a reflection being out of phase with the instrument and a single mic. (See comb filtering and room modes).

The difference in time between the two signals is everything in terms of phase.

Usually, drum sets are some of the most sensitive to phasing, but this has a lot to do with your setup. If you are using 17 mics all with a few feet of the drum set, you can set yourself up for a phasing nightmare.

I've gotta run, but I'll get back to this one. Good thread!

Brandon

[Vomitorator]

Originally Posted by brandondrury

Phasing occurs with EVERY source where 2 different times are summed together. This can even be caused by a reflection being out of phase with the instrument and a single mic. (See comb filtering and room modes).

The difference in time between the two signals is everything in terms of phase.

Usually, drum sets are some of the most sensitive to phasing, but this has a lot to do with your setup. If you are using 17 mics all with a few feet of the drum set, you can set yourself up for a phasing nightmare.

I've gotta run, but I'll get back to this one. Good thread!

Brandon

well, i guess i have to go back and check these individual tracks because i didnt even realize. I have my overheads spaced out and i basicly only used 5 mics. (sm57 snare, audix i5 bass, two overheads and one in between the high and middle toms (all cheap radio shacks but they sounded pretty great))

[brandondrury]

I plan on writing an "Everything You Need To Know About Phase" article this week. I'll get in depth with it to make the concept more clear.

Without all the technical jargon, you can understand phase pretty easily by duplicating any previously recorded track in your recording software and then delaying the copied signal by 1ms, then 2ms, until you get to 50ms.

Brandon

[Vomitorator]

Makes sense, thank you! If what i learned in physics class is correct, what prevents us from comming up with a phase correcting plugin(for the multiple mic aplication at least)? Do they have those? Couldnt it be done manually?

[brandondrury]

To a degree, we can correct phase. The IBP phase correct is hardware box. Voxengo makes a phase corrector as well.

However, these tools are not meant to be used aggressively. In other words, you have to be pretty damn close for these to work, but if two mics are very close, these tools help tremendously in getting them to align.

These tools haven't been around that long, so keep that in mind. There is still no replacement for great audio engineering.

Brandon

[robbyho]

If you're using a DAW, there's no reason I can see why you shouldn't move the tracks to align the waves. This wouldn't always be possible if you have many mics at different distances, but at least you can know just how out of phase they are by looking at their alignment.

Rob

[brandondrury]

If you're using a DAW, there's no reason I can see why you shouldn't move the tracks to align the waves.

I can think of one reason. Sometimes it sounds like crap. ( Sometimes it doesn't.)

The problem with fixing phase problems with "time" is that it only puts one frequency in phase but shifts others out. This is more of an issue when using 2 mics on a guitar cabinet or something like that.

Brandon