1979 Yamaha CS20M - 15 patches demo

video by Valmont

"8 user memory slots (!!!), 2 VCOs + VCA Sine, Multimode VCF, 2 EG, 1 LFO (Up to 100Hz!), Portamento and a bunch of parallel modulations.
It shares almost all the same chips as found in all the CS Serie (From the tiny CS5 to the huge CS80). Inside you can find: IG00150 LFO, IG00151 VCA, IG00153 VCO (Pulse/Saw), IG00156 VCF (HP/BP/LP), IG00158 Waveshaper (Sine/Tri) and the IG00159 EG.
All these chips cost a fortune now, I hope none breaks (: It's not like CEMs/SSMs were you can find reeditions, these parts were specially made for the CS and there are not many anymore.
Tho my unit has a noisy VCA distortion, that's the high frequency buzz you can hear. I'll service it soon! Notice how straight and thin this synth sounds - it is extremely stable, and thanks its memories, it seems like the perfect synth for live gigs.
The filter reminds me of the Oberheim SEM, but it's less bright, as Yamaha's engineers set the max cutoff frequency to... 7500Hz. So we get the same behavior as in some Arp 2600 revisions: a restrained filter spectrum! Tho this doesn't make the synth bad at all ;)
I'll also add the fact that this synth is probably of the best build quality I have ever seen. Super heavy, big comfy controls. Inside everything is made very cleverly, top quality electronics. Yamaha also explained the whole synth circuits in the harware manual, I mean... They really described how the VCOs work, the memory encoding, etc... (http://www.midimanuals.com/manuals/ya...​)
And despite being 42 years old, it is stable as hell, just like a brand new synth from these days. Japanese engineers were really good... Too good maybe ;)

0:00​ - Fonk Bass
0:13​ - 2-Lead
0:24​ - Synth 1
0:33​ - Synth 2
0:42​ - Multimode Bass
0:54​ - Saw Lead
1:10​ - Resonance
1:21​ - Moog-Like 1
1:29​ - Moog-Like 2
1:37​ - SnH
1:51​ - BP Arp
1:57​ - LP Arp
2:07​ - PW Bass
2:19​ - Chord Lead
2:41​ - HP Lead"