The ESX-4CV is an expansion module for the ES-4 or ES-5, adding four CV outputs from one expansion header.
In order to squeeze four 12 bit channels through one 8 bit connection, the channels are time-multiplexed and so effectively run at one-eighth of the audio sample rate. For example, if the audio interface/DAW is running at 48kHz, the ESX-4CV's outputs are running at 6kHz. 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-4CV'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.
The ESX-4CV's specifications are as follows:
• Panel width: 4HP
• Module depth: 26mm
• Digital input: connection from ES-4 or ES-5 module
• Analogue outputs: 4x 3.5mm jacks, DC-coupled
• Output voltages: ±5.33V, hardware calibrated
• D/A conversion: 12 bit, using high precision Analog Devices DACs
• Indicators: 2 LEDs per channel (+ve and -ve voltages)
Current draw: TBC
The front panel is drilled for both Doepfer and Analogue Systems mounting holes (using a 'slot' rather than a single round hole). The power connector is a Doepfer standard 16 way IDC, with -12V furthest from the top of the board.
The ESX-4CV requires software in order to time-multiplex the four output signals, and to encode them for the ES-4 or ES-5. Currently, the only such software is the 'ESX-4CV Combiner' plug-in, part of Expert Sleepers Silent Way.
Silent Way is available in AudioUnit and VST formats for Mac OS X and Windows. Use of Silent Way therefore requires a compatible host application (DAW). For Pro Tools users, Silent Way is known to work with the FXpansion VST-RTAS wrapper.
A Silent Way licence is not included with the ESX-4CV - however, the ESX-4CV Combiner plug-in functions in a licence-free mode, so ESX-4CV users are not forced to buy Silent Way. Such users can than evaluate the rest of the Silent Way suite in demo mode.