“This one is in excellent cosmetic condition and working 100%. It has just been serviced and with a lot of restoration. It is ready to be played and needs nothing! I doubt there is another here on Ebay that is as nice cosmetically and that has had the same amount of restoration. Please mail with any questions. Not sold as-is! California residents to pay state tax. Shipping to most countries!” Click here to search for synths on eBay
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“The Sequential Pro One is a wicked little monosynth! It comes from the same period and genre as the Roland SH-101 and Moog Prodigy. The Pro One was basically Sequential’s attempt at taking their legendary Prophet 5 poly-synth and packing it into a compact, inexpensive, monophonic analog synth! It has two VCOs, a great 4-pole lowpass filter, two ADSR envelopes (one for filter), and a compact three-octave keyboard. With a Pro-One, you can easily create punchy analog bass-lines and leads or quirky analog synth effects.
“Sequential Circuits Pro One
“Sequential Circuits Pro One J-Wire Version. Condition is “Used”.” 
“Vintage Sequential Circuits Pro-One analog synth. Recently serviced and fully cleaned by Takeshi at Main Drag Music in Brooklyn. Fully working J-Wire keyboard and several upgraded and restored pots, keyboard bushings and wiring. Unit is in AMAZING sonic, mechanical and cosmetic order and we are reluctant to part with it. We have a Prophet 5 so most of our vintage SCI sound is covered, but this unit takes CV and Clock I/O as well as External Audio, which is a big part of the way we work with synths. You can bring anything into this filter and control the filter CV externally!! Can route tons of modular gear through this and it BLOWS AWAY most of the modular. The keys on this unit are a joy to play and rock solid. The arpeggiator works along with, basically, a legato mode on the keys that plays at the same time, and can be set to either transpose or add notes. It is a great feature and there is tons of tweakability on this synth – which makes it very special and why prices are only going up right now. There is one piece of gaffer tape we put over part of the fuse box, as it is inherently a bit flimsy and having it prevents any issues from fuse popping out for any reason. ” 
“Sequential Circuits Pro-One, J-wire Keyboard, Recently Refurbished. Condition is “Seller refurbished”.
” Vintage Sequential Circuits Pro-One analog synth. Recently serviced and fully cleaned by Takeshi at Main Drag Music in Brooklyn. Fully working J-Wire keyboard and several upgraded and restored pots, keyboard bushings and wiring. Unit is in AMAZING sonic, mechanical and cosmetic order and we are reluctant to part with it. We have a Prophet 5 so most of our vintage SCI sound is covered, but this unit takes CV and Clock I/O as well as External Audio, which is a big part of the way we work with synths. You can bring anything into this filter and control the filter CV externally!! Can route tons of modular gear through this and it BLOWS AWAY most of the modular. The keys on this unit are a joy to play and rock solid. The arpeggiator works along with, basically, a legato mode on the keys that plays at the same time, and can be set to either transpose or add notes. It is a great feature and there is tons of tweakability on this synth – which makes it very special and why prices are only going up right now. There is one piece of gaffer tape we put over part of the fuse box, as it is inherently a bit flimsy and having it prevents any issues from fuse popping out for any reason. ” 
“This keyboard is priced to sell. It turns on and does have most sounds, but will need a refurbish in order to have it’s original quality sound production. It’s been in storage for 20 years and was in an 80’s band before that. I was going to refurbish and sell for more, but don’t have time.” 
“Sequential Circuits Pro One Synth
“I am the original owner of this Pro-One. It’s in excellent condition. I had SynHouse MIDI installed in the late 90s. It has The more reliable & preferred 37-note J-wire style keyboard. Recently is was serviced/refurbished by vintage synth repair specialist John Paul Bohon of Double Heart Audio in Austin. You can see more of his work at SwitchedOn vintage synth shop in Austin. The synth and the MIDI work perfectly. The synth comes with its original user’s manual and SynHouse MIDI manual. Also included is a receipt for the recent work done.
“Sequential Circuits Pro One
“Sequential Circuits Pro One
“We are open 6 days a week for local pick up at //ARMENS MUSIC/REPAIR SHOP//.Hard to find in this condition .Nice working condition ,works fine, very clean ,plays fine ,calibrated ,comes with power cable 120 volt. No Modifications ,Original condition .This one has the j-wire keyboard,not membrane one. See pics actual item pics.” 
“Refurbished Sequential Circuits Pro One, with midi in and out.
“Synth was used by original owner (whom I am selling on behalf of) until the 90s and then stored until being brought out to test earlier this year. This synth has been used is 8/10 cosmetically. The serial number is 3898 meaning it has the more stable J wire keyboard rather than the later membrane type.
“Supplied serviced and in full working order. In superb cosmetic condition with minimal signs of age or wear to the face. The end cheeks are clean with some scuffs and scrapes. See photos for more information on cosmetic condition.”
“If you’re unfamiliar with this synth, it’s essentially a single voice version of the popular Prophet 5.
“Sequential Circuits Pro One. Needs a good home. Condition is Used. This is a very special synth and is in full working condition with a few minor cosmetic flaws.There are so many things that make this synth special. These two Curtis 3340 VCOs (that so many modern analogue synthesizers have tried to replicate) allow for thicker bass notes and richer, more colorful, piano like Mids. The modulation matrix is capable of adding even more to the Pro One’s sound including countless timbral possibilities through FM synthesis, up to two LFOs, and a filter envelope that can also modulate pulse width and oscillator frequency as well. The Pro One also has an additional VCA envelope, and both envelopes have a re-trigger mode. Oscillator B can serve as an LFO or audio rate modulation source, and can generate frequencies independent of the keyboard. It has a sequencer and arpeggiator as well. The serial number for this unit is right in the sweet spot where Pro Ones had good power supplies and keys. That said even the better of the two key beds will need to be occasionally serviced. These keys have recently been serviced and none stick currently. They will begin to stick over time though, and the key bed will need to be routinely cleaned. The keys are just a bit stiff, as is the nature of all Pro Ones.” 
” This is a Pro One analog monophonic synthesizer Packed with features and a ton of modulation routings. This keyboard has the earlier, more reliable J wire keyboard. It is in good working condition. I’ve owned and used this keyboard for many years, always keeping it in my home studio. I was disappointed to find that after a recent move, one sliding switch was knocked off. Although moveable with a pen, the switch should be replaced. This part is still available from Wine Country Productions for under $10. This damage is shown in one of the photos. Because of this damage, I am offering this synth for less than it is worth. Although I have tested and confirmed that all features and functions work, it is sold AS IS. This synth is about 37 years old and these synths do occasionally need service although the Pro Ones are some the most reliable synths I’ve owned. ” 
“This Pro One features the more desirable J-Wire keyboard, and is in good condition. The wood grain siding is black and is missing a screw. There is calk at the base of the power cable.” 
“The original Pro-One monophonic synthesizer from 1981. Please refer to online reviews of this legendary instrument for detailed technical specifications. Suffice to say this is a classic analogue synth with extensive modulation capabilities, powerful filter with the SCI unique resonance, two oscillators, sequencer and arpeggiator. There is only one Pro-One in terms of build and sound quality; naming no names, recent clones are decent enough machines but simply that: machines rather than instruments. It was mostly triggered by a MIDI converter box rather than played direct during its working life, so the keyboard is responsive and without the triggering problems which some examples exhibit. There are slight though noticeable abrasions on the right-hand wooden sides (see photos) but otherwise it’s in a fine condition.
“Very good condition and comes with Turbo CPU/MIDI, plus a top of the line Fatar keybed installed. this work costed around £450 just for the parts and so the synth is priced higher than the usual selling price to account for these highly functional upgrades.
“The Good: This vintage Pro One is in very nice shape and comes securely packed in a heavy duty keyboard case. I’ve owned this for about 20 years, and it’s spent much of the time inside the case, so it’s in nearly the same great condition as when I bought it. No sticky knobs or dents, the end wooden pieces look nice, and it comes with the original manual. There are a couple of small scratches on the underside.
“You are bidding on a vintage Sequential Circuits Pro One monophonic synthesizer from the early eighties. The Pro One is famous for it’s snappy envelopes and is essentially one voice from the famous Prophet 5. With the step sequencer you can enter up to 40 notes/rests and play that sequence back while transposing it.” 
“Sequential Circuits Pro One. Owned since new. Serviced by Synthrestore. Condition 9 out of 10. Some age related marks. Also has the original manual & guide sheet. ”
“Sequential Circuits Pro One J-Wire Vintage Analog Mono Synthesizer Synthesizer in excellent condition. This is an amazing sounding vintage synth with two oscillators with cross mod sync. It also has a built-in sequencer. Very flexible modulation matrix. J-wire keyboard for easy cleaning, and they don’t wear out like the newer rubber keycap designs. All controls, functions, and keys work flawlessly. You won’t find one in better condition – it’s almost like new! ” 
“Super clean, unmolested/unmodified original Sequencial Circuits Pro One model 100 !
“Sequential Circuits Pro-One Synthesizer. Condition is Used. This synth is in excellent condition all around. It sounds great and all features work. It was professionally serviced a few years ago.” 
“The original Pro-One monophonic synthesizer from 1981. Please refer to online reviews of this legendary instrument for detailed technical specifications. Suffice to say this is a classic analogue synth with extensive modulation capabilities, powerful filter with the SCI unique resonance, two oscillators, sequencer and arpeggiator. There is only one Pro-One in terms of build and sound quality; naming no names, recent clones are decent enough machines but simply that: machines rather than instruments. It was mostly triggered by a MIDI converter box rather than played direct during its working life, so the keyboard is responsive and without the triggering problems which some examples exhibit. There are slight though noticeable abrasions on the right-hand wooden sides (see photos) but otherwise it’s in a fine condition.” 
“The original Pro-One monophonic synthesizer from 1981. Please refer to online reviews of this legendary instrument for detailed technical specifications. Suffice to say this is a classic analogue synth with extensive modulation capabilities, powerful filter with the SCI unique resonance, two oscillators, sequencer and arpeggiator. There is only one Pro-One in terms of build and sound quality; naming no names, recent clones are decent enough machines but simply that: machines rather than instruments. Sure, the keyboard, or rather, keybed, is notoriously flakey, but not on this example. It was mostly triggered by a MIDI converter box rather than played direct during its working life. There are slight though noticeable abrasions on the right-hand wooden sides (see photos) but otherwise it’s in a fine condition.” 
“Absolute perfect condition! Recently tuned up to %100 by experienced technician. Very clean, calibrated, comes with power cable. Sounds amazing! This model has the desirable j-wire style key contacts” 
“Sequential Circuits PRO-ONE Analog Synthesizer. Condition is Seller refurbished – Keyboard has been leveled and the J wires reset/repaired. Comes with custom flight case.” 
“Nice! vintage original Sequential Circuits PRO-ONE Analog Synthesizer mono moog. Condition is Seller refurbished – Keyboard has been leveled and the J wires reset/repaired. Comes with custom flight case. ” 
“Nice! vintage original Sequential Circuits PRO-ONE Analog Synthesizer mono moog. Condition is Seller refurbished – Keyboard has been leveled and the J wires reset/repaired. Comes with custom flight case.” 
“Sequential Pro One analog Synthesizer