"Joel Koltner" wrote in message
...
Are crystal earphones called that because they're used with crystal
radios, or because they really do have some sort of crystal in them (seems
unlikely)?

---Joel



The crystal earphone is called that because it does contain a crystal,
similar to some microphones.

The crystal in a crystal radio is the diode that does the conversion from RF
to AF. It started off years ago as a real crystal. A semiconductive
mineral crystal, usually lead sulfide (galena) or cadmium sulfide.