Used - $179.00
The ESX-8CV is an expansion module for the ES-4, ES-40 or ES-5, adding eight CV outputs from one expansion header.
In order to squeeze eight 12 bit channels through one 8 bit connection, the channels are time-multiplexed and so effectively run at between one-third and one-twenty fourth of the audio sample rate. For example, if the audio interface/DAW is running at 48kHz, the ESX-8CV's outputs are running at between 16kHz and 2kHz, depending on how many channels are active. This is still plenty fast enough for most CV purposes, except for audio-rate modulation and the very fastest envelopes. Because the outputs are still derived from the audio stream, they retain the advantages of the ES-3/4 over traditional MIDI-based interfaces, that is, rock solid timing and absence of jitter.
The outputs are hardware calibrated and so do not require the use of e.g. Silent Way's software calibration when used with standard V/octave synths/oscillators. That said, the ESX-8CV's 12 bit resolution is adequate to perform software calibration if required (e.g. to cater for misbehaving oscillators that don't track well to a standard calibration), or to support oscillators with a Hz/V response.