Advice on a measurement microphone?

Discussion in 'Archived Threads 2001-2004' started by Dave Milne, Dec 23, 2001.

  1. Dave Milne

    Dave Milne Supporting Actor

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    I'm having trouble getting the bass "right" in my new theater --thin at some frequencies and boomy at others. I suspect that my DIY speakers have some response "funnies" I just haven't noticed before. I have access to a Schlumberger response analyzer. It will analyze and plot out the gain and phase transfer characteristics of anything between its output and input. All I need is a good flat microphone to use it for room measurements (and maybe a mic preamp; the Schlumberger accomodates a wide range of input voltages, but microvolt-level inputs may cause noise problems).

    Josephson has some mics that are advertised to +/-1.0 dB, but they're $500 (ouch). I also have a Rat Shack SPL meter with mic-out jack but it's old (20+ years) and I don't trust it. Are the new ones really flat? Any other ideas?
     
  2. JohnRG

    JohnRG Auditioning

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    Panasonic Mic Capsules from Digikey are relatively flat. Most people find they are within about 2dB. This should allow you to find nasties. A single op amp is sufficient to amplify your signal, and the circuit for that is on the net in many locations
    http://www.gti.net/wallin/audio/preamp/preamp.html
    is one source
     

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