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Tom Technique

Discussion in 'Recording' started by Emmet, Nov 17, 2005.

  1. Emmet

    Emmet Guest

    Hi Guys

    Quick inquiry... I was assisting in a session today, doing Rock Drums, 2 toms on which we used Senheiser 604's, 1 top, one bottom per tom. When blending the two mics to multi-track on the console, the Engineer knew right away that he would have to reverse the phase on one of the mics, and sure enough phase reversal on the bottom mic resulted in proper allignment. Just curious why. I know that phase cancellation is caused by the same or very similar waveforms essentially working against eachother and that this must be occuring.... is it how the wave reacts in the tom, or just as simple as the distance of the mic from the skin and resonant? Just found it neat..... thanks for your time

  2. Fede

    Fede Active Member

    Nov 3, 2004
    It's very simple in the case with the toms. Just imagine how the to drumheads act together. Once the top head is pressed downwards by the stick, so is the bottomhead - but the top head is pushed away from its microphone, whereas the bottom head is pushed towards its mic. That's why the two mics will have their signals out of phase in that case.

    Apart from this I never saw the advantage of using two mics on toms...!? I'd say it just gives you a lot of extra phase-problems over the entire kit. What is it you'd want to gain from a bottom mic?

    Speaking of - I just did a little drums recording tuesday, to test my new kit (Yamaha Birch Custom Absolute Nouveau) and added some guitars to it. The toms (since this is a tom-thread) were miked with Audix D2 and D4 (top heads only, ofcourse) and I think they turned out pretty well.

    Caution! Heavy Metal.

  3. Emmet

    Emmet Guest

    Simple indeed, thanks. I also agree that 2 mics on a tom may be excessive, or a poor way to get around properly placing 1 mic, but in this case it was not my call. :(
  4. Emmet

    Emmet Guest

    Drums sound great, I love Birch. Nice Kik too
  5. Because the bottom, or non-beaten, head is the resonant head. That's where a large portion of the "tone" of the drum comes from.

    Prove it to yourself by listening to a drum kit played live. Then, remove the bottom heads from the toms and remove the front head from the kick. The tone of the kit will change dramatically.

  6. Cucco

    Cucco Distinguished Member

    Mar 8, 2004
    Fredericksburg, VA
    Well - that's a good question.

    A simple flip of the phase of the bottom mic is actually not correct. If the mics in question were equidistant from the head (IOW, the mic above and the mic below were exactly, say, 1 inch from the head) than this would be the case. Because, of course, the mics see (err, hear) the head moving in different directions at the same time.

    The more accurate thing to do would be to time-align the drums themselves - not to try phase reversal. On toms, due to their height and stronger fundamental, this is actually pretty easy. On snare, it's a little harder b/c the attacks on both mics are already pretty darn close and the tone of a snare is filled with strong overtones (think similar to white noise).

    In any case, viewing the wave in an exploded view and lining up attacks and zero crossings is the more correct method to time-aligning drums.

    J (the Mook) :cool:
  7. Emmet

    Emmet Guest


    Good call J! I brought the drum tracks into pro-tools from RADAR and was able to get a much more full sounding (correct/accurate) Tom nudging the bottoms rather than the simple 180 flip.

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