Model:         Syntovox 221 
Bands:            20
Retail price   6000 Euro
Produced:     ?
Size:              4 HE
Features:     High end model with noise & VCO, matrix panel, voiced & unvoiced inputs, attenuator per channel.

Expander 1220

The 1220 vocoder expander unit pictured above this 221 is a one-off piece Synton built for Dutch broadcasting company NOS. It houses a pitch to voltage converter, CV freeze function and a ‘presto-patch’ edge connector for making analyzer-synthesizer patches.

Used parts

TDA 1034/NE5534
syntovox 221 Manual,   Review 221 sono france

VCO 221 schematics, 221 PSU schematics 221,_input schematics 221, Vocoder output mixer,

Only a small amount  of these were made. Users include Wendy Carlos (who owns a 221 & SPX 216), Bruno Spoerri, various electronic studio’s in Europe.  Best suited for studio use due to complex control.

The 221 has a 50-pin connector on the back which provides CV in and out for each channel, and other functions.

221 block diagram

A spectrogram of the 20 filters, spaced in minor thirds.The four bands per octave create a diminished chord.

The sample below is a polysynth chord on carrier, a S&H sine on the speech input.
One channel is without voiced/unvoiced detection, the other switches to internal noise on unvoiced sounds.
The left and right sounds are recorded in different passes.