“These are great synths. The Ensoniq esq-m is the rack mount version of the esq1, it’s the same synth except it doesn’t have the outdated sequencer or the terrible keybed. All of the good stuff and none of the bad!
There’s plenty of information about these online so you can look them up if you’re unfamiliar but at its core it’s a hybrid synth (digital waves and analog filters) with a simple modulation matrix, multi timbrality (layer/ split), responds to polyphonic aftertouch, etc. It’s a great sounding synth, think late 2nd era skinny puppy (too dark park and last rites in particular).
This one is in pretty good shape for its age but certainly not perfect. It has plenty of dings and scratches and what not. Also the data slider is really jumpy, I was just testing the synth and I could use the slider but I’d want to address it if I was keeping it since it’s very difficult to get it to any specific value. It might just be dirty (possibly fixed by cleaning and lubricating the slider) or it might need to be replaced. Everything else works as far as I can tell (midi, audio, display, buttons, volume slider is scratchy but working), I even replaced the internal battery a couple years ago so as long as it gets turned on now and then that should be fine for many many years, likely decades. It even has the rack ears!
I’m including two voice cards in this auction. One is a vintage “voice crystal 2” card full of presets (rom/ read only) and the other is a modern rewritable one (ram) made as a retrofit for this synth. The rewritable card has a very large capacity and is pre-loaded with a ton of patches but is freely writable which is essential with these older synths as their internal memory was pretty limited. ” Click here to visit listing on eBay
“This ESQ-M has been serviced with New Battery, New Audio Output Jacks and the famous SQ80-M modification. All SQ-80 Waveforms are now present and selectable. The only function not implemented is the Envelope second release.
“If your looking at this you probably know what it is and how amazing it sounds, the unit works 100% the internal batter has been replaced so should last another 30 years also included the memory cartridge with an additional 80 patches which doesn’t sound like a lot but in 1986 it was alot.
” ENSONIQ ESQ-M with new battery, rack ears and manual. Mint condition sound module that has never left my home studio. Comes with power cord, Pristine manual, and rack ears included (no, I won’t sell those separately for $40!!) I actually sold this unit a couple of years ago and broke the data slider when I was packaging it to ship! Bummer! I had the shorted slider replaced last week along with the back up battery. Now the unit works like new.” 
“ENSONIQ SQ80-M (Professionally Modded ESQ-M) Power Supply Recapped w/ Audio Grade Capacitors!
“You are bidding on an Ensoniq ESQm hybrid analog / digital synthesizer. It is the rack-mount version of the well known Ensoniq ESQ-1 keyboard.