The Yamaha CS-05 is a single oscillator monophonic synthesizer, released in 1979, that has been described as “an unremarkable synth”:

It was a one oscillator job with a single ADSR envelope that controlled both the filter and the final amplifier. A simple LFO was provided for modulation and it also had a noise generator for sound effects.

Its saving grace was the multi-mode filter that offered low, band and high pass options which was unusual on a budget synth of the time.

Features:

• 1 VCO with pulse or sawtooth waveforms and noise-gen
• LFO with sine, sawtooth, sample and hold
• 12dB/oct High pass or Low pass; 6dB/oct band-pass

Resources:

• Yamaha CS-05 user manual
• Yamaha CS-05 at Fantasy Jack Palance
• Vintage Synth entry