Calibration mic (or parts for one)

[Spasticteapot]

I'd like to buy an inexpensive calibration microphone, or parts for one. I've had a great deal of trouble finding any WM-61A capsules, and I have a feeling I'd likely make a hash of removing the internal FET if I did.

[bwaslo]

why do you want to remove the FET?
I have some capsules if you need one.

[Spasticteapot]

Originally posted by bwaslo
why do you want to remove the FET?
I have some capsules if you need one.

The internal FET, according to Sigfried Linkwitz, severely limits the performance of the microphone element. I wouldn't know, but Linkwitz is probably as good a source of info as any.

[Shaun]

The biggest performance gain of SL's mod is max SPL. It is not done by removing the FET, but by reconfiguring the connection (cutting a track). It is very delicate work, but do-able.

[zlast]

bwaslo - your email is not enabled. How much for a WM-61A ? Digikey has them but has a $25 minimum order.

[bwaslo]

The FET is the limiting element, but that doesn't mean it can work without one. (Like, a battery is the limiting element of a flashlight, but because it's not enough, not too much!)

The Linkwitz mod is good, but not easy to do. If you are only measuring frequency response at normal listening volume (and not right at a speaker cone) it isn't needed, though. The mod increases signal handling and lowers distortion (but raises noise level), the frequency response isn't affected.

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