Flaky 299

[hmole]

Looks like flakes of plating are coming off the phasing plug of my 299, it quit working after a test of 300hz, I opened it up checked resistance and found flakes in the gap after removing the diaphram.
I cleaned it out, and I am working for now but am wondering how to resolve this permanently or is it time this guy paid a visit to GPA?
Thanks
Harry

[bfish]

Hi, Harry,
Since 299s have plastic (tangerine) phase plugs, there should be nothing to flake off them. You may be seeing pieces of diaphragm if you're testing at 300Hz, which is below resonance unless really heavily loaded. Occasionally, a tangerine might come loose (they're glued in), but shouldn't contribute any foriegn material to the gap.

[hmole]

Well, the big dome the Diaphragm rests against then if it isn't the phase plug.