1) an echoplex is not an instrument, the echoplex is one of the progenitors to the modern delay pedal. i quote from wiki:
Many delay processors based on analog recording, such as the Maestro Echoplex or Roland Space Echo, used magnetic tape as their recording and playback medium. Electric motors guided a tape loop through a device with a variety of mechanisms allowing modification of the effect's parameters. Thin magnetic tape was not entirely suited for continuous operation, however, so the tape loop had to be replaced from time to time to maintain the audio fidelity of the processed sounds.
2) the echoplex use by comets on fire is the same as the keyboard in acid mothers temple music and are acid mothers temple noise? no!
3) i have blue cathedral, avatar, their split with burning star core, their split with major stars and the sub pop promo with live tracks.
they can get noisy but they are not noise. if any band who uses some distortion and feedback were to count then we'd have dinosaur jr and husker du in here.