To my mind, the best of the early (pre-Buchla/Moog) electronic synthesisers was the Hammond Novachord. It's remarkable that a commercial record was released with a polyphonic synthesiser as the sole instrument in 1939, and even more remarkable that it was anything but a novelty - it sounds absolutely gorgeous.
A sackbut is a Renaissance/Baroque predeccessor to the trombone, often accompanied by cornettos[1]. Here's an example of a Gabrieli canzon https://www.youtube.com/watch?v=nWqFfDnV5KI
In that video the sackbuts are the three people at the back and there are 2 cornettos at the front.
So this is an early synthesiser that sounded a bit like a sackbut presumably.
[1] A virtuosic curved horn instrument with a trumpet-like mouthpiece but fingering like a recorder.
The interesting thing to me is that the timbre controls seem to have been intended to modify the instrument while it is sounding. An organist can do this by pulling stops, and is similar to setting patches on a Moog, but generally, you play the pitches with both hands and pause to change settings.
I wonder if this was done simply to aid the prototyping, or if the intention was that the performer would be changing the timber during the performance, while the instrument is sounding. This seems to be the effect you hear with the klaxon sound changing into a grunty, nasal timbre at the beginning of the Sackbut Blues.
My guess is that it was a prototyping convenience, but it would seem to have big implications for how the instrument is used in performance. A composer writing for it would have to think about mutable timbre not dissimilarly to planning pedal changes for a harp or even thinking about double-stops on string instruments -- there are practical limitations of the performer and instrument that has to be considered.
That actually makes the music a bit more interesting to me than an early 20th-century ideal of "liberating" music from the confines of catgut and sloppy wet wood and metal.
As mentioned elsewhere the Sackbut/sackbutt/sagbutt etc. is a predecessor to the trombone. All of these sound infinitely better than that atrocity. I know I'm supposed to be impressed at a pioneering effort and all that, but damn, modern instruments sound unbelievably good. The timbre is better than any time in history, the quality of a modern pro instrument is usually infinitely higher than on most older ones, and intonation is way easier to get right these days.
I know, I know, downvote me. But if you people had to be stuck on a desert island with a recording of that thing vs Tommy Dorse or Melba Liston or J.J. Johnson, you know which one you'd choose, and it's not the "electronic sackbut".
Looks like a power strip. Looks like there might be an amplifier built into the base. Most likely a much later addition, or even a temporary one, to make moving it around/displaying it/demoing it easier.
https://en.wikipedia.org/wiki/Ondes_Martenot
https://www.youtube.com/watch?v=yidV0HeVyCg
To my mind, the best of the early (pre-Buchla/Moog) electronic synthesisers was the Hammond Novachord. It's remarkable that a commercial record was released with a polyphonic synthesiser as the sole instrument in 1939, and even more remarkable that it was anything but a novelty - it sounds absolutely gorgeous.
https://en.wikipedia.org/wiki/Novachord
https://www.youtube.com/watch?v=h1xrofiEa4w