The instrument
The Yamaha CS-15D is one of the partly preset, partly variable monophonic analog synthesizers that Yamaha released in 1979. It is a single VCO synthesizer. The preset section is divided into two channels. Channel 1 has 15 sounds with instrument imitations and channel 2 has 14 synthesizer sounds as well as a button to activate the manual section of the synthesizer. The channels can be mixed, channel 2 can be detuned.
Details
The CS-15D has two independent channels, each with its own preset selector and inputs/outputs for CV/gate control. The manual section includes a VCO with variable control between pulse and saw waves. The two waveforms can be crossfaded. There are also controls for pulse width modulation, noise and footpoints (32' - 2'). The 12dB filter has cut-off and resonance as well as its own ADSR envelope. The modulation is shared between the two channels. There is only one LFO, which can be routed to the pitch, the filter or the amplifier.