Sounds Of The Rare PAiA 2720 Modular Synthesizer

This video, via Tinfoil Cat, explores the sounds of the rare PAiA 2720 Modular Synthesizer.

PAiA Electronics, founded by John Simonton in 1967, pioneered synth DIY in an era where commercial modular synthesizers were as expensive as cars. The PAiA 2720 system was advertised in electronics magazines, and available as a collection of kits.

This particular 272 features these modules, left to right:

  • Power supply with mults, attenuator, and 2 variable voltage sources
  • VCO (saw core with triangle and pulse, manually adjustable)
  • Triangle to Sine and PWM converter
  • VCA (two inputs, 0 db and 3 db amplification)
  • AD envelope generator
  • LFO (3 ranges, sine/trianglish wave, roughly 1 – 25 hz). Noise output
  • Band pass filter with Q control
  • Low pass filter (fixed cutoff point, variable slope 0-12 db/oct)
  • Buffer/inverter (buffer/amplify 0 or 20 db)
  • Envelope follower (outputs variable voltage and gate/trig)

If you built or have used a PAiA 2720, leave a comment and share your thoughts on it!

14 thoughts on “Sounds Of The Rare PAiA 2720 Modular Synthesizer

  1. built and owned a 2700 circa 1975. Pretty similar to the one you’re showing as I remember. Same case, same fairly unstable and lame sounds. It was an experience though (building and owning) a modular synth at that time.

  2. Yep, I lordered and built one back in my high school electronics class around 1975. Loved the whole process and enjoyed the resulting synth for many years. Regrettably I lost track of it in one of my many college day moves. Affordable in its day, educational and loads of fun.

  3. I own this instrument and can confirm it sounds like that, and has the same tuning instability and glitchy coarseness shown in the video. The modules all come with full schematics and you built them yourself and learned a lot in the process. Is it usable in a professional context? I never got it so, nor have I heard it used as such. Like a lot of educational systems, that wasn’t its reason for being. On the other hand the 2600 was designed as an educational instrument but actually ended up being an absolutely fantastic pro instrument. So designer intent isn’t everything.

  4. They ran the schematics of the 2700 in popular electronics back in the 70’s. I built my first PIAA from television caps, resistors, and pots. The semi’s and jacks I had to buy. Used perf board and panels from an erector set. Good stuff.

  5. I have a PAIA Fatman analog rack-mount synth (purchased already built at a ham radio convention flea market). It’s noisy but fun to fool around with. Also have an Oz keyboard, put together by engineering school dorm-mates from a kit I bought online.

  6. PAIA kits were horrid things, shipped with missing parts most of the time, and including instructions that made no sense. The dodgy things required massive amounts of delicate soldering and the ability to diagnose and correct manufacturing mistakes. But, when properly assembled (against all odds), they had that genuine MOOGy sound.

  7. I had a friend who was insane over his modular PAIA project. We’d blend our ARP-y/Korg-y rigs for a couple of weeks and make fun noises, trying to make unrelated gear play nice together. Sometimes we even succeeded. He cussed his PAIA while building, using and repairing it. It did make some nice sounds, but it was mostly Night of the Living Steering Failure. Made a VCS3 look stable. All the same, I echo the others who got some good from theirs, despite the wobbles.

  8. I built mine in high school. It was a life changing event. Went to college for electrical engineering after that. John Simonton is one of my personal heroes. The 2720 was hard to tune. As I recall, you had two tuning knobs, one to tune the low “C” and the panel mounted one to tune the high “C”. It was an iterative process, and you had to tune several times. I eventually bought the 4700 series power supply and VCO, which had a lot better onboard voltage regulation and tuning stability.

    I didn’t have some of the issues that people mentioned- I thought the documentation was great. PAIA never claimed that this synth would compete with a Minimoog. In fact, I remember a statement in the docs that their filters were “glorified tone controls.

    So circa 1975, I was in a prog rock band, where I hauled a Hammond M3, Leslie and my trusty PAIA synth to gigs. Played Lucky Man and Roundabout, using this setup. So, all in all, I am a huge fan of PAIA.

    I still have mine, stored in the basemen, haven’t turned it on in years. I built an Eurorack mod synth over the past few years that sounds great. Maybe when I retire in a few years, I will restore the PAIA.

  9. Yep, built one, was able to tune it just fine (tricky, but remember getting quick at it). But once I realized it still wouldn’t still be in tune when I turned it back on, at least right away, I moved on, built a large Aries system and on to personal design. But Simonton’s further writings, much of which is encapsulated in Friendly Stories About Computers/Synthesizers, was great Food for thought.

  10. I had a high school buddy in electronics class who built a 2720 but couldn’t get it tuned no matter what. He got fed up and gave it to me and I got it tuned. My buddy did a good job assembling it because it was stable & reliable enough for me to use regularly on gigs. My road base was a blanket and a couple of old belts. I was (and still am) a Jan Hammer fan so I needed a pitch bender. I swapped the pitch pot with a long-shaft version and glued a disposable razor handle to the knob to make a pitch bend lever. It looked wacky but worked great. My favorite trick was holding the red button at the end of a solo – it would do a long descending glide down to zero Hz. I never figured out why this worked but it was really cool. Sadly the synth is long gone.

    1. Interesting comment about the red button – the manual trigger for the ADR function generator; holding it while playing a note would somehow discharge the CV from the keyboard and glide the note down! I am refurbishing a 70s 2720/A i built in HS,learned a lot, long stored away and now refurbishing* it and then explore some eurorack fun! Also had troubles getting and keeping keyboard in a tunable state.
      *looking at

  11. I bought a 4700 system with separate keyboard at a pawnshop in the early eighties
    and have used live and in many recordings. It works great with Korg sq-1!

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