You always take for granted what you experience growing up. Unlike many people, I had a variety of keyboard instruments available to me in my formative years. One of the instruments I fondly remember is pictured at left: a 1970 Conn electronic organ (Prelude Theater model 305), which I got to play whenever I visited the farm where Mim, my maternal grandmother lives (and is still going strong at the age of 90).
When she was younger, she used to play often for me. I wish I could remember more of the songs she used to play. One of her favorites was "Rose of Washington Square," here presented in a Dixieland jazz arrangement by Red Nichols and His Five Pennies:
Unfortunately, this instrument no longer works. It may have fallen victim to a lightning strike. I suspect that the problem may be as simple as a failed power supply, since there are two power switches to the organ (one for the sound and one for the lights), and both are equally dead. It's a shame that I can't share a sample of what this instrument sounded like.
The Conn organs do not have the panache (or resale value) of the legendary Hammond B3, but they have much to recommend them. The Prelude Theater had a wonderful sound that I associate with baseball and roller skating. The key to the sound was a shimmer produced by a rotating Leslie speaker (much like in the Hammond B3), as well as a deep reverb produced by a set of coiled springs inside a metal box (also found in many guitar amplifiers of the era).
(At the end of Deep Purple's 1972 song "Highway Star," the crash you hear is caused by kicking or dropping a reverb unit, causing the springs to rattle violently inside the metal box.)
On YouTube there are several videos of Conn organs of similar vintage. This one has just the sound I remember from my grandmother's instrument, though this instrument has more bells and whistles (including a buggy whip effect, apparently triggered by a toe button). It also has a full pedalboard and larger manuals.
The Prelude Theater 305 also had a drum machine, the Min-O-Matic. Amazingly, someone has made a digital emulator of this drum machine. The sound is a little tinny compared to what I remember, but I'll take it. "Teen Beat" is a rhythm often used in 50s rock 'n' roll: a backbeat with snare drum doubled on beat 2. "Latin" is the familiar 3+2 clave. "Metro" is a metronome. "Double Beat" caused the bass drum to sound twice as often. There's no "Fatback" or "16 beat" button, sadly.