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How to avoid phase issues when using more than one mic?

Discussion in 'Recording' started by J-3, Dec 23, 2004.

  1. J-3

    J-3 Active Member

    Jul 20, 2004
    Below is a quote from "recorderman"

    Take a sm57 and a 451. (or a 57 and any other small diaphram /pencil style condenser). Put some head phones on. Hold them together so that they face the same way and the capsules are about even. In a normal voice talk into the both of them, alternately muting and adjusting levels until they're of equal loudness. Now flip one out of polarity. Hear the "phase-y ness?" Slide the 451 Along the sm57 until you get the most out of phase sound you can (your voice gets thin and loses volumn). Now if you tape the two mic together at this point; put them both in polarity together you now have a two mic set-up that can be held on one sm57 mic clip and will give you the top two snare mics, of a three mic set-up (two top/one bottom) that is somewhat common in some circles. Mainly you gotten to hear how you CAN hear effect of "phase". If you adjust the balance of your mic's, in you headphones you can extrapolate this principle until you become allergic to phase. All your mics will be in , relative too each other, as much as you want.[/quote]

    Recorderman above was talking about a 3 mic set up on a snare. I too enjoy doing this 57 and a condensor on the snare top (or snare shell). I find that the condensor adds a nice top end that the 57 dosn't but alone is anemic.
    I have always thought that if you have 2 mics next to each other with the diaphrams lined up. (ie try your damndest to put two mics in the exact same position) that they would be IN PHASE I have seen this many times on the Royer website (and elsewhere) where engineers line up a 57/R-121/md421 setup on gtr amps etc. Is this type of settup not in phase? When i set up my snare I put the 57 where I want it then put the LD Condensor right next to it just almost touching. I also make shure the diaphram (not end of mic) is as close to being lined up as possible. I also do this when testing to see which mic I want to use for a source, put 'em in the same spot and a/b. That way I know what the mic is saying and not what the positioning is saying.

    I'm just trying to figure out the "correct" way to place a LD condensor and 57 on a snare top (or anything else) and not be out of phase with each other. Also, any rules for putting a 57 top and a LD condensor on the snare shell? Any help would be great. Thanks

  2. RecorderMan

    RecorderMan Distinguished Member

    Mar 28, 2001
    how about re-reading my qoute. it works perfectly..and the best. you can't get two mics closer than that (other than matbey tweaking with an IBP on top of that.) You tape the small diapharm condenser to the sm57 after alignment and palce the sm57 in it's mic clip..the one mic clip holds both mics this way. Uber-close
  3. RandomGuest

    RandomGuest Guest

    Feb 10, 2001
    In reading what 'recorderman' wrote and your question... I think the answer is along the lines of that what he's describing is lining up the diaphragms in a slightly more precise manner than just visaul representation... I don't believe he's talking about the 451 being halfway down the body tube of the 57, I think [reading cmprehension vs. personal experience] that he's talking about moving the 451 in like millimeter increments.

    Of course... I could be wrong...
  4. veatch

    veatch Active Member

    Feb 16, 2004
    I think the difference in position on the two mics is due to the different style capsules: 1 dynamic, and 1 condensor. An audio signal into a dynamic mic will generate an electrical output that is 90 degrees out of phase with the input. A condensor's electrical output is in phase with its input.

    So, the mics will have to have different positions to be "in phase".

    Note that the two will only actually be perfectly in phase for 1 frequency - who's wavelength will be 4 times the distance between the two capsules.... For this application, it should be the most prominant frequency of the snare.

    Either that, or what i think i know about mic theory is wrong... which is always possible. :)
  5. therecordingart

    therecordingart Well-Known Member

    Jul 28, 2004
    Has Recorderman taken a picture of his drum mic setup? I really want to see it because I can't see it in my head.
  6. J-3

    J-3 Active Member

    Jul 20, 2004
    Hey thanks guys, honestly i havn't tried this "slide/listen/tape" method yet but will today. Perhaps your are right Fletcher in that it's a very small amount of movement to get in phase. So on Royers website where they have 3 mics stuck on a gtr cab they arnt just visually lined up? Did they mostly likely start with one mic sounding good then move the others (one at a time) untill they sound right with the first? (see link below) I'll take some time and do some experimenting.


    On snares lately I've been doing a sm57 on top a Rode NT-2 on bottom and a TLM 103 on the snare shell (under the hats). Any sugestions on how to properly place mics in this fasion??? I try to get each mic the same distance away from the snare about 3" to 4" to help with phase. I like the fact that the 57 adds body and the TLM adds top end clarity.

    One more question. How do you align a DI signal and a mic signal without having too much phase craze? Say a bass di and mic to blend in the DAW. Sometime when I try to blend these signals I have phase phunk so often I just use the mic alone. Thanks so much guys.

    Hey Fletcher, sell me a pair of SD condensors for overheads and ac gtr's. I've got a grand plus or minus a few hundred bucks. Seriously!


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