"They are never any kind of good quality, so other than the inventor's itch being scratched, why bother?"
These can sound just as good as a lot of vintage mics. You just need to use vintage (pre 1940 say) phones. Most of the old phone have carbon elements which are no good for harp. The speaker is what you want. They will be low impedance so you"ll need a transformer. Fun to make and one of mine holds it own against all of my vintage elements.
One of our "dearly departed" (banished) former members here, nastyolddog, made a really great video tutorial on this a couple of years back...
It's a cool idea, and one day I want to do it, but I have yet to actually come across one of these old phones in all the myriad thrift shops, junk shops, and antique stores I've browsed... It's always one of the things on my list (that and cool vintage suitcases to make into an amp) that I never ever find... ----------
shbamac: Yes I used the speaker too. It would be nice to try older phones like you did. Mine are from 1960s-70s.
atty1chgo: I think they could be of good quality. I have bullet mics with very good CR and CM elements and good stick mics. But it's a little different sound in the phone mic. I did a video to show a sample of thier performance, see below. I can say that this one is qualified to be in my mic collection.
In this video I played Hohner Marine Band DeLuxe harmonica in A through a speaker element from a telephone. Connected to multi effects processor DIGITECH Vocal 300 connected to recording equipment BOSS BR-1200CD.
This isn't exactly new stuff because I've seen more than a few players 30 years ago doing the very same thing you've done. ---------- Sincerely, Barbeque Bob Maglinte Boston, MA http://www.barbequebob.com CD available at http://www.cdbaby.com/cd/bbmaglinte