about microphones and henns and eggs

[Mike Maloney]

They are fairly rare - I've seen one once. And if you'd like to buy one, I
know where you can get one for $2000 or so. It is over 30 years old, though.

The only reason I brought it up was that you asked about a "standard"
capsule.  I have a couple of NBS-traceable mics, and every calibration
report I have on them (by several different labs) traces to a Western
Electric 640. So I figured that qualified as a "standard".  I'm certainly
not suggesting that you should buy one. But if you do, can I borrow it?:-)

I think the real baseline calibrations for acoustics measurements are done
with pistonphones - they are only good for one frequency, but since the
piston displacement is pretty much absolute, its output at frequency is
guaranteed.

PS - it is really a 640 AA - I got a little too happy with the A's.

Mike Maloney


> :::Western Electric 640 AAA.
>
> Sorry, I couldn't find any information about these ?!
> But a lot about old Western Electric telephones...
>
>
> m.c.
>