Advice on a measurement microphone? (1 Viewer)

[Dave Milne]

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?

 

[JohnRG]

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
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