Improvising a PZM or boundary microphone

Discussion in 'Live Sound' started by ElChupaNibre, Jan 24, 2013.

  1. ElChupaNibre

    ElChupaNibre Active Member

    Jan 24, 2013
    Munich, Germany

    I will be doing the sound recording for an upcoming "making of" of a large BluRay concert production. We want to be able to record as much talking amonst the artists as possible, whilst not disturbing them or their mood.

    For this project I will use a normal boom microphone where applicable, but I would like to be able to drop a boundary (layer) microphone/pressure zone microphone on the table without much ado where the situation calls for it.

    Being mobile will be essential, as we have to follow the musicians around. Thus, having less equipment will be easier and also not having to connect different mics to my mixer.

    I will be carrying two Sennheiser wireless lavalier microphones. My question is: Can the effect of a PZM be achieved by simply laying/taping a lavalier mic like this

    on the table? Or will I have to bring a true boundary mic with me?

    In theory, an 18kHz sound wave should be about 1.9cm long. The lavalier mic is probably 0.5cm high. Thus, I should be able to catch all relevant sound without it being reflected away and not get any reflections from underneath, correct?

    Will the microphone's omnidirectional characteristics mess my sound up?

    Thank you for any help!
  2. Boswell

    Boswell Distinguished Moderator Resource Member

    Apr 19, 2006
    Home Page:
    The key word is consistency. You can get away with recording a one-off conference by using an omni lav mic taped to a table to emulate a boundary mic, but for video shoots, you need to be able to reproduce the same sound quality and characteristics under different conditions. A low-cost boundary mic such as the AT U841A (omni) or the AT U851R (cardioid) is a good mic for speech and, because of the way boundary mics are housed, gives consistent sound quality across different positions and usage provided the table surface has at least the minimum area.

    I would not have thought that placing a boundary mic on a table and running the miniature cable back to your mixer would be any more of a disruption than taping a lav mic to the table. A real boundary mic would also look rather better if it happened to get into shot.

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