[TenTec] what is so special about heil microphone elements?

[Stuart Rohre]

No general purpose computer mikes are the flat response virtually high fi
types.   The electret element without special chambering is flat.   It is
cheaper to make a flat response electret element, than a tailored to the
voice element.  Hence, the price difference for controlled response Heil
elements.

Old crystal mike elements that are hydroscopic "might" be saved by gentle
baking.  I would not go above about 110 degrees F.   Might check on the
properties of Rochelle Salts crystals first, and heed whatever their
temperature rating says.

Replacement crystal elements are available from the manufacturers of the
D104.
-Stuart
K5KVH