Sequential Circuits · Analog monosynth · Pre-MIDI classics
Sequential launched the Pro-One in March 1981 and asked, right at launch, why anyone would make another monosynth. The answer was price. Sound On Sound described it as essentially one voice of a Prophet-5, with two Curtis CEM3340 oscillators and a CEM3320 four-pole filter, so you got the Prophet sound for a fraction of a Prophet. Dave Smith said over 10,000 were sold. There are no patch memories, so everything lives on the panel, along with an arpeggiator, a 40-note sequencer you can transpose while it runs, and CV and gate jacks for driving it from MIDI through a converter. Oscillator B can sit an octave down or turn into a second LFO, and the envelopes are fast enough for snappy drums. Vince Clarke made nearly all the backing for Yazoo's Only You on one, bass drum included, and Aphex Twin, Brian Eno, Herbie Hancock and New Order have used them. The keyboard and switches are what wear, so the best buy is one where both still work cleanly.
Sound On Sound found that Pro-Ones eventually double-trigger as the keyboard mounting bends with age, a quick fix with a shim. Knobs and switches go crackly, and some units hum mechanically from the transformer, though the hum stays out of the audio.
Buying guide
We'd buy the Pro-One titled Pro-Serviced w/Restoration at $2,919 delivered, at the top of the band but with the work already done. There are about 9 for sale and most ask $2,275–2,925 delivered; a service claim, the original box or a MIDI retrofit pushes an ask up, and the cheapest at $1,700 delivered comes from a seller who doesn't know how to test it. Whatever you buy, ask for a video playing each key slowly, because Pro-Ones double-trigger as the keyboard mounting bends with age, and have the seller flick every switch while a note holds to check for crackle.
$1,940.00est. delivered
The cheapest Pro-One with no stated problem, at $1,940 delivered, about $335 under the band. It isn't titled tested, so ask for a video playing each key slowly, since an aging keyboard mount makes Pro-Ones double-trigger.
1982 Sequential Circuits Pro-One Vintage Monophonic Analog Synthesizer
$2,919.00est. delivered
Titled Pro-Serviced w/Restoration at $2,919 delivered, just inside the top of the band. That's about $625 more than the cheapest plain unit in the band, for a synth that's had the work done.
Sequential Circuits Pro-One - Analog Synthesizer - Pro-Serviced w/Restoration
$2,919.00est. delivered
The service and restoration are done per the title, so it's the one to buy if you'd rather not start with a repair. Ask what the restoration covered.
Sequential Circuits Pro-One - Analog Synthesizer - Pro-Serviced w/Restoration
$2,980.00est. delivered
Titled serviced and listed with its original box, which collectors pay for, at $2,980 delivered, $55 over the band.
Sequential Circuits Pro-One Analog Synthesizer Vintage Rare + O.G. Box Serviced
$1,699.98est. delivered
The seller says they don't know how to test it, so treat $1,700 delivered as the price of a repair job. It's about $575 under the band, which leaves room for a tech's bench time.
Sequential Circuits Pro-One Monophonic Analog Synthesizer DONT KNOW HOW TO TEST
Delivered prices include shipping as eBay quoted it to a US address on Oct 5, 2026. Many sellers charge by distance, so your total may differ. eBay shows yours before you pay.
Snapshot
Checked . Some may have sold.
Delivered prices include shipping as eBay quoted it to a US address on Oct 5, 2026. Many sellers charge by distance, so your total may differ. eBay shows yours before you pay.
Used$1,940.00est. delivered
$1,900.00 + $40.00 shipping
Buy It Now$1,900.00
This seller takes offers, and many sellers accept less than the asking price.
Fine if you might miss it? Send an offer first. Someone else can still buy it while you wait for a reply.
Want it for sure? Use Buy It Now.
Good buy
Titled 1982. No test claim, so ask for a key-by-key video.
Seller: cutedrummergirl
100% positive
Refurbished$2,919.00est. delivered
$2,799.00 + $120.00 shipping
Buy It Now$2,799.00
Good buy
Titled Pro-Serviced w/Restoration.
Seller: analog_u.s
100% positive
Serviced$2,980.00est. delivered
$2,900.00 + $80.00 shipping
Buy It Now$2,900.00
Good buy
Titled serviced, with the original box.
Seller: retrogearshop
100% positive
Used$1,699.98est. delivered
$1,599.99 + $99.99 shipping
Buy It Now$1,599.99
This seller takes offers, and many sellers accept less than the asking price.
Fine if you might miss it? Send an offer first. Someone else can still buy it while you wait for a reply.
Want it for sure? Use Buy It Now.
Project piece
Seller says they don't know how to test it. Price it as a repair job.
Seller: tiffanbaldwi-1
99.8% positive
Used$2,292.20est. delivered
$2,200.00 + $92.20 shipping
Buy It Now$2,200.00
This seller takes offers, and many sellers accept less than the asking price.
Fine if you might miss it? Send an offer first. Someone else can still buy it while you wait for a reply.
Want it for sure? Use Buy It Now.
Our take
No service claim. Ask about double triggers and crackly switches.
Seller: koivu.ray
100% positive
Used$2,374.99est. delivered
$2,199.99 + $175.00 shipping
Buy It Now$2,199.99
Our take
Titled 1982 Model 100. No service claim.
Seller: mmguitarbar
99.5% positive
Used$2,780.00delivered
$2,780.00 · free shipping
Buy It Now$2,780.00
This seller takes offers, and many sellers accept less than the asking price.
Fine if you might miss it? Send an offer first. Someone else can still buy it while you wait for a reply.
Want it for sure? Use Buy It Now.
Our take
Titled 1981. Ships from Japan, so check the voltage plate.
Seller: asterisk_llc
99.6% positive
Serviced$4,074.00est. delivered
$3,899.00 + $175.00 shipping
Buy It Now$3,899.00
Our take
Titled with a Techsmechs TM-2 Turbo CPU and MIDI, pro serviced. The retrofit is why it asks over the band.
Seller: analog_u.s
100% positive
Prices change daily. The live eBay search shows everything listed now, including anything new since Oct 5, 2026.
See every listing on eBay ↗eBay search
Sequential Circuits · Analog polysynth
Sequential Prophet-5
1978–1984 · 5-voice polyphonic
Asking $8,900–$16,175 on eBay
Moog · Analog monosynth
Moog Minimoog Model D
1970–1981 · Monophonic
Asking $9,225–$12,400 on eBay
Roland · Analog monosynth
Roland SH-101
1982–1986 · Monophonic
Asking $1,475–$2,100 on eBay
Korg · Analog monosynth
Korg MS-20
1978–1983 · Monophonic
Asking $1,975–$2,450 on eBay
Moog · Analog monosynth
Moog Prodigy
1979–1984 · Monophonic
Asking $1,400–$1,600 on eBay