2 cabs 1 figure 8 mic?

Discussion in 'Recording Studio' started by kfowler8, Oct 17, 2017.

  1. kfowler8

    kfowler8 Senior Member

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    I was micing a 4x12 cab the other day and something occurred to me afterwards. I have two 4x12 cabs loaded with different speakers. I also have a ribbon mic with a figure 8 pattern that's my preferred mic to pair with a 4x12.

    So if I wanted to mic both, how do you think it would work if I placed the the cabs one on each side of the mic? Would I be creating one big phase issue that's irreversible?
     
  2. yeti

    yeti Senior Member

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    I don't know what it would sound like to have 2 cabinets firing at each other with the same signal. It could result in the speakers fighting each other or adding to each other. whether it's one or the other is frequency dependent. All in all it doesn't seem like a good idea unless the cabs are far enough away from each other. This is regardless of micing.
    As far as the figurer 8 mics go, the front and back of those are not out of phase with each other. Figure 8's are commonly used to pick up signals from both sides of the mic. The phase thing comes in when using them in MS stereo, where the igure 8 mic is routed to 2 channels, panned hard left and right and the right channel phase reversed. But a single figure 8 mic can pick up 2 speakers, singers or whatnot , one on each side without phase issues.
     
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  3. kfowler8

    kfowler8 Senior Member

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    I usually mic the cab about 32” in front of the cab so the cabs would be 64” apart. The cabs are similar to Freeman’s where the top row are two greenbacks and the bow rows are two Vintage 30s. The other cab is the same config but with WGS speakers. They sound huge together.
     
  4. yeti

    yeti Senior Member

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    I hope I did get my initial point across so let me clarify:
    When you have 2 (sets of) transducers and one audio signal there's always interaction between the two. 2 speakers radiating side by side will cause cancellation somewhere in the spectrum, creating that 4by12 or 4by 10 sound ( that plus the standing wave inside closed back cabinets) 2 speakers radiating at each other will most likely affect each others' ability to freely move in accordance with the incoming signal. If you have ever played an amplified acoustic guitar you'll know that under certain conditions the amplified tone thrown back at the player via floor monitors will choke the guitar top because it negates the movement of the top of the guitar, throw the phase switch and the guitar sounds free again. the same is true if you encounter feedback due to the amplified guitar signal enhancing the guitar top's movement, throwing it into a howl feedback, the phase switch will kill that feedback immediately. So it's all about phase relations between transducers and the instrument. Electric guitars are largely immune since there's no top vibrating but the speakers facing each other will take that role, either choking each other or oscillating. How bad it gets depends on volume, dampening factor, dispersion pattern, distance and EQ. Note that we haven't talked about microphones yet. the fig 8 mic picking up 2 speakers with the same signal will only arrive "in phase" at the mic and sum without coloration at the exact middle location. However, for non-correlated sources it will be in phase, always.
    To illustrate some of these concepts regarding multiple speakers ( mics work the same way in reverse) I find this video very helpful.
     
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  5. Freddy G

    Freddy G V.I.P. Member

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    Agree with yeti's summation. I would not recommend it either.
     
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  6. yeti

    yeti Senior Member

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    Speaking of micing guitar cabs with figure 8 ribbons, one of the best features of these mics is the difference between the front and back in terms of frequency response. The other is the rejection at the null, I frequently put a Princeton at 90 degrees to my control monitors and play an overdub without headphones, the mic rejects the speaker playback almost entirely.
     
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