ES-4 SPDIF/CV Interface

ES-4 - Introduction

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The ES-4 is a Eurorack format module which converts a standard S/PDIF input to five channels of control voltage.

Two of the five channels are calibrated to provide over 5 octaves of 1V/octave pitch CV. The remaining three channels are general purpose outputs (for use as e.g. gates, envelopes, LFOs) and each have a nominal range of 0-10V or ±5V (user selectable).

Since S/PDIF is a stereo-only format, the encoding of the five channels on to two is handled by software provided as part of Expert Sleepers Silent Way.

The ES-4 will connect to any audio device using the S/PDIF standard. This includes the digital audio output provided as standard on many recent Macs (more info here on the Mac connection).

The ES-4 also includes an S/PDIF output for sending data back to the computer. This output is used by expansion modules connected to the ES-4; currenty, the only such module is the ES-7 CV Input Expander.

Expert Sleepers ES-4 Demo on Vimeo

ES-4 Controller Simple Setup on Vimeo.


The ES-4's specifications are as follows:
  • Panel width: 8HP
  • Module depth: 51mm
  • Digital input: coaxial S/PDIF, standard rates up to 192kHz
  • Digital output: coaxial S/PDIF
  • Analogue outputs: 5x 3.5mm jacks, DC-coupled
  • Output voltages
    • Channels 1-2: 0-5.3V (when trimmed for 1V/octave response)
    • Channels 3-5: 0-10V or ±5V (jumper selectable per channel)
  • D/A conversion: 8 bit, using high precision Analog Devices DACs
  • Indicators: LED for S/PDIF sync lock; 2 LEDs per channel on channels 3-5 indicate output voltage (+ve/-ve)
  • Expansion
    • 5 headers for connecting ES-4 Gate Expander modules (see below)
    • Digital audio I/O header (I2S format) for future expansion
  • Current draw: 50mA on the +12V rail, 20mA on the -12V rail (70mA total)

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.

For more detail, please see the user manual.

Software Requirements

Unlike the ES-3, the ES-4 requires particular software in order to generate meaningful output signals. Currently, the only such software is the 'ES-4 Controller' plug-in, part of Expert Sleepers Silent Way, and our Max/MSP external (see below).

Silent Way is available in AudioUnit, VST & AAX 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 ES-4 - however, the ES-4 Controller plug-in functions in a licence-free mode, so ES-4 users are not forced to buy Silent Way. Such users can than evaluate the rest of the Silent Way suite in demo mode.

See the tutorials page for a selection of videos that illustrate the software side of the ES-4.

Max/MSP External

We provide an 'external' for Max/MSP to enable users of Max to easily integrate the ES-4 into their patchers. This can be downloaded from the downloads page.

Expert Sleepers es4encoder~ Max/MSP external on Vimeo.

ES-4 Gate Expander - Introduction

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The ES-4 Gate Expander is a Eurorack module which works in tandem with the ES-4 to offer 8 on/off outputs for use as gates, triggers, clocks etc.

Up to five ES-4 Gate Expanders can be attached to one ES-4 - one per ES-4 channel. (The 8 outputs of the Gate Expander reflect the 8 bits of CV information passed to the ES-4's DACs.) Therefore you can combine the modules to create a system with up to 40 independent gate outputs - all driven from a single S/PDIF connection.

The ES-4 Controller software (part of Expert Sleepers Silent Way) also allows the Gate Expander outputs to be used for DIN sync or MIDI output* (note - not just MIDI clock output, but as an actual MIDI port, capable of sending any MIDI messages). Since these outputs are driven from an audio connection (the S/PDIF port), they have sample-accurate timing, which no USB MIDI interface can claim.

* Note - the MIDI out feature is only officially supported at sample rates of 48kHz and above, though some users report success with specific hardware when running at 44.1kHz.


The ES-4 Gate Expander's specifications are as follows:
  • Panel width: 4HP
  • Module depth: 24mm
  • Analogue outputs: 8x 3.5mm jacks, DC-coupled
  • Output voltages: 0V/5V or 0V/12V, selectable via jumper in groups independently for channels 1-4 and 5-8
  • Indicators: LED per channel
  • Current draw: 5mA on the +12V rail, 0mA on the -12V rail (5mA total)

The front panel is drilled for both Doepfer and Analogue Systems mounting holes (using a 'slot' rather than a single round hole).

For more detail, please see the user manual.

Pricing & Availablity

The ES-4 and ES-4 Gate Expander are available now.

For purchasing links, please see the store.

Jitter-free MIDI from the ES-4 on Vimeo

DIN sync from the ES-4 on Vimeo.

ES-4 and Silent Way Voice Controller on Vimeo.

ES-4 Audio Demo on Vimeo.

ES-4 vs USB MIDI on Vimeo.