Well, the Fender Rhodes had a sound of it's own did'nt it. Great stuff, especially when Stevie Wonder played it. If you hit the keys fairly hard, it had an amazing distortion to it. Disadvantage was it was big and heavy. Smaller and lighter was the Wurlitzer EP10 made famous by the Carpenters etc. Again, a very distinctive sound, but my fave would be the Fender Rhodes stereo electric piano. There were any number of 'Hammond' copies - Farfisa, Vox, Elka etc etc but no-one ever caught the drawbar sound like Hammond. It was produced by a motor turning a shaft on which were mounted 'cog' wheels running adjacent to electric pickups. The pitch of the note was derived by how many 'teeth' were on the cog. Hammond went away from tone-wheel generators, as they were called, in about the 80's and tried to catch the sound electronically. They got close, but you can always tell the real thing. The originals were designed in, I think, in the 20's and stayed exactly the same for about 50 years. The Mellotron was totaly unique and I sold a few in the 70's when they were disappearing from fashion. They derived their sound from magnetic tape sections upon which had been recorded from the pure instrument,(flute, choir etc) one tape for every key. When you depressed a key, it operated a pinchwheel which then pulled the tape past a recording head into the amp circuitry. If I remember correctly, 8 seconds was the longest you could hold a note down before the tape rewound. They were a nightmare to change tapes and the stability of the thing was what finally killed it. Groups like the Moody Blues for instance, used to have a roadie permanently 'assigned' to the Mellotron when they were on stage to keep it in tune. The heat from, mainly, the stage lights, affected it enormously. But, hey, what a sound !! One keyboard I really liked was the Hohner Clavinet. This was a stringed instrument, plucked, by the keyboard a la harpsichord. It had a series of guitar pickups mounted under the strings and you could get very authentic guitar sounds through the spectrum to real funky stuff. Again, Stevie Wonder really introduced it and I've still yet to hear anyone play it better than him. Yep, and the Mini-Moog really got things going. It was monophonic (only one note at a time) but was, I think, the first one to have two oscillators which could be tuned separately. You still hear one now and again - it's quite a unique sound. ARP kinda copied it with the Odyssey and it did'nt take long after that before synths became polyphonic, computer chips became available and the rest is history.
Good days eh!!
Jim