The early 1980s were the first time a working musician could buy a programmable analog polysynth, and the machines from those years are still the usual way into vintage gear. They all sound good. They differ in what they ask you to live with, which comes down to whether there's MIDI, how many sounds they store, how many oscillators each voice gets, and which part is most likely to fail. Decide which of those you care about and the choice gets much easier.
The shortlist
- Roland Juno-60 (1982 to 1984). Six voices, each with one DCO plus a sub-oscillator, 56 patch memories, an arpeggiator, and Roland's DCB port instead of MIDI.
- Roland Juno-106 (1984 to 1988). The same one-DCO voice plan, now with MIDI, 128 memories and portamento. The arpeggiator is gone.
- Korg Polysix (from 1981). Six voices, each with one VCO plus a sub-oscillator, 32 memories, an arpeggiator, and built-in chorus, phaser and ensemble effects. No MIDI.
- Sequential Prophet-600 (from 1982). Six voices with two VCOs each, 100 memories, and one of the first synths sold with MIDI.
- Oberheim OB-8 (1983 to 1985). Eight voices with two VCOs each, 120 patches plus split and double programs. About 3,000 were made.
The Korg Mono/Poly often turns up in the same searches because of its name. It's paraphonic. Its four oscillators can play four notes, but they share one filter, so it isn't a substitute for any of the machines above.
MIDI
If you want to play the synth from a computer or another keyboard, start here. The Juno-106 and Prophet-600 shipped with MIDI. How much MIDI a Prophet-600 has depends on its software version, and later software brought fuller polyphonic MIDI. Some owners have since fitted the GliGli firmware, a remake that runs on a Teensy++ board. A listing that mentions it describes a modified synth, so ask what else was changed.
The Juno-60 has Roland's DCB connector, a precursor to MIDI. Roland's MD-8 box converts DCB to MIDI, Kenton sells a Juno-60 MIDI retrofit kit, and Tubbutec's Juno-66 kit replaces the processor to add MIDI and extra features. The Polysix has retrofit kits from Kenton, Tubbutec and Kiwi Electronics. The OB-8 arrived just before MIDI, and some were fitted with it later.
Kenton says its retrofits are a job for a competent synth technician. So when a Juno-60, Polysix or OB-8 listing mentions MIDI, look for the sockets on the back panel in the photos and ask the seller which kit is fitted and who installed it.
Memory
Thirty-two memories on the Polysix fill up fast if you like to keep variations of a sound. The Juno-60's 56 and the Prophet-600's 100 are comfortable, and the Juno-106's 128 is plenty. The OB-8 adds 12 split and 12 double programs on top of its 120 patches, which lets you play two sounds at once. Ask the seller whether the stored sounds are still there after the synth has been switched off. Lost memory usually points to a tired backup battery, and on the Polysix that battery is also the part that leaks.
One oscillator per voice, or two
The Junos and the Polysix give each voice a single oscillator plus a sub-oscillator an octave or two down. Roland and Korg both built in chorus to make up for it, and the Juno chorus became the Juno's signature. Roland's DCOs also keep the Junos in tune from the moment you switch them on, which Sound On Sound called a first for an analog polysynth.
The Prophet-600 and OB-8 give each voice two oscillators, so detuned sounds, sync sweeps and heavier brass come from the voice itself. The Prophet-600 also carries over the Poly-Mod section from the Prophet-5. Between the two Junos, the 60 can drive its pulse width from the envelope, which the 106 can't. Some players think that's part of why the 60 sounds a little punchier.
What usually goes wrong
- Juno-106: the six 80017A filter and amplifier chips, one per voice, fail with age. Replacements are made today. The Juno-106 voice chip guide covers the symptoms and the fix.
- Polysix: the backup battery on the KLM-367 programmer board leaks, and the fluid eats the circuit traces. Clone replacement boards exist. Ask for a photo of that board before you buy.
- Prophet-600: owners report keys that don't trigger and hum from the transformer. Ask for a video that plays every key.
- OB-8: owners report units that reset when several notes are played, voices at uneven volumes, and keys that respond unevenly.
- Juno-60: it uses Roland's IR3109 filter chip directly and has none of the 106's 80017A hybrids.
The stretch picks
The Prophet-5 is the synth the others were chasing. Sequential built it from 1978 to 1984 in three revisions. Only 182 Rev 1 units were made, all hand-assembled. Rev 2 used SSM chips, and Rev 3 switched to Curtis chips, which many players hear as a little thinner but which Vintage Synth Explorer calls the most reliable version. Rev 3.1 and later units can take a MIDI retrofit, and Rev 2 units can't. Sequential started making a new Prophet-5 in 2020, the Rev 4, with USB, MIDI, velocity and aftertouch. It's a new instrument and shouldn't be listed as vintage.
Vintage Synth Explorer calls the 1983 Prophet-T8 Sequential's finest analog synth. It has eight voices, 76 weighted keys with velocity and aftertouch, 128 memories and MIDI. Both are much harder to find than the synths above, so they aren't where most people start.
The digital alternative
The Yamaha DX7 came out in 1983 and sold more than 200,000 units, so there are plenty around. It isn't analog. It uses FM synthesis with six oscillators per voice and plays 16 notes at once, 61 keys with velocity and aftertouch, MIDI, 32 internal memories on battery backup and a cartridge slot. The sound is bright and glassy, and its E Piano 1 preset was on 40% of the US number-one singles of 1986. Programming is done through membrane buttons, one data slider and a small LCD. If you want a knob for every function, buy an analog.
Which one to buy
- If you want MIDI from the factory and lots of choice, buy a Juno-106. Prefer one whose voice chips have already been replaced.
- If you want the Juno sound with an arpeggiator and can live without MIDI or add a kit, buy a Juno-60.
- If you want two oscillators per voice and MIDI in a six-voice synth, buy a Prophet-600.
- If you want eight voices and the Oberheim sound, buy an OB-8, ideally one that already has MIDI.
- If you love the Polysix's effects, buy one only after you've seen the KLM-367 board in the photos.
Before you pay
- Ask for a video that plays single notes up the keyboard and then full chords, so you hear every voice.
- Look at the back panel in the photos for the sockets you need, MIDI or DCB.
- Ask for an inside photo of the part most likely to fail on that model.
- Ask when it was last serviced and by whom. What vintage synth service involves explains what that should cover.
For listing warning signs, read eBay seller red flags for vintage synths. Many of these synths were sold in Japan first, so see voltage and shipping before you buy one from overseas.
