Paia 2720 + 4700 (1970's DIY modular synthesizers)

video upload by Tinfoil Cat

"I've been telling myself for too long that I should post more Paia videos. This is an old video shot before I fixed the keyboard on the 2720 (broken sample and hold as you might hear). The main part is 4700, the 2720 helps out with a fourth VCO. The spring reverb is a little noisy.

These were available as kits from Paia starting in the 1970's. The 2720 is closely related to the 2700 that arrived on the market over 50 years ago!"

Interesting side note via sdiy.info:

"Frac rack, FracRak or Frac, from Fractional Rack, is the modular synthesizer format designed by John Simonton of PAiA. It has a mainly USA following largely through the popularity of Blacet modules.

Like the Eurorack format, Frac is considered a 3U format..."