I have a pair of 315-C's with one unit showing what seems to be a HF
resonance possibly caused by a defective diaphragm. As far as I know
there are no spare parts available for the 315-C's but it may be possible
to find a replacement diaphragm in a University stand-alone tweeter.

I saw one note saying that the 315-C's tweeter was similar to the T50, but
the size difference seems to make that unlikely. I haven't disassembled the
315-C (yet) and haven't eliminated things like bad "unpolarized" electrolytic
caps in the crossover (the only other repair I've done like this, a Jensen
G610B which I repaired ca 1970 had this problem).

I tried emailing Great Plains Audio some time ago, but haven't heard anything
back.

This is not a fatal problem, as I have a complete spare 315-C on the shelf which
I haven't put into service yet.

Any ideas would be happily accepted.

Mike Squires
mikes at cs dot indiana dot edu
--

Mike Squires (mikes at cs.indiana.edu) 317 233 9456 (w) 812 333 6564 (h)
mikes at siralan.org 546 N Park Ridge Rd., Bloomington, IN 47408