Eurorack via Expert Sleepers ES-9 — Gamepad to CV

The Expert Sleepers ES-9 is the bridge that makes the rest of this guide series make sense. It is a USB audio + MIDI interface that lives inside a Eurorack case, exposing eight DC-coupled CV outputs and fourteen inputs. Drive it from a gamepad over MIDI and you get an ES-9 gamepad CV rig that can address the whole rack — gates, 1V/oct pitch, bipolar modulation, all of it. The ES-9 is the cleanest, lowest-latency way to get gamepad data into a modular without buying a separate MIDI-to-CV box.

Why the ES-9 is the right bridge for modular

Other MIDI-to-CV converters (FH-2, Hermod, etc.) sit alongside the rack and consume HP. The ES-9 is a rack module. It draws power from the bus board, fits in 14HP, and gives you eight CV outs that respond in real time. Because it speaks USB MIDI and USB Audio simultaneously, you can drive gates from gamepad MIDI on one channel and pipe audio from a soft synth into the rack on the same cable. The bridge to make all this happen on the gamepad side is Universal Controller MIDI.

We covered the cheaper FH-2 path in the gamepad-to-modular guide. The ES-9 is the upgrade when you want eight independent CV destinations from a single controller. The ES-9 product page covers the full spec.

What you'll need

• Expert Sleepers ES-9 (firmware 1.7+ for best USB MIDI behaviour)
• Eurorack case with 14HP free, +12V/-12V supply
• USB-B cable
• Universal Controller MIDI v1.0+ — download
• ES-9 Controller app (free, macOS + Windows) or Silent Way plugin for CV routing config
• Patch cables and a few envelope / VCA / VCO modules to receive the CV

Step-by-step setup

1. Install and power up

Slot the ES-9 into the rack, connect the supplied power ribbon, screw the front-panel rails in place. Power on. Plug USB-B from the ES-9 to your laptop. The unit enumerates as both an audio interface and a MIDI device. We only need the MIDI side for this workflow.

2. Open the ES-9 Controller app

Launch the Expert Sleepers ES-9 Controller (download from the Expert Sleepers site). Confirm the unit is detected. The Controller app is where you tell the ES-9 which MIDI events drive which CV outputs.

3. Route MIDI to CV outs in the Controller app

The ES-9 doesn't have an opinionated default MIDI-to-CV map — you build it. Set up something like this:

# ES-9 Controller — MIDI to CV out mapping
CV OUT 1  <-  MIDI Note CH 1, pitch (1V/oct, 0V = C-2)
CV OUT 2  <-  MIDI Note CH 1, gate (5V high while note held)
CV OUT 3  <-  MIDI Note CH 2, gate (5V) — face-button trigger 1
CV OUT 4  <-  MIDI Note CH 3, gate (5V) — face-button trigger 2
CV OUT 5  <-  MIDI CC 1 CH 1, unipolar (0V to +10V)
CV OUT 6  <-  MIDI CC 11 CH 1, bipolar (-5V to +5V)
CV OUT 7  <-  MIDI CC 7 CH 1, unipolar (0V to +5V)
CV OUT 8  <-  MIDI Velocity CH 1, unipolar (0V to +10V)

4. Point the bridge at the ES-9

Universal Controller MIDI → Settings → Output Port → Expert Sleepers ES-9. The bridge sends MIDI to the ES-9, the ES-9 turns it into CV.

5. Face buttons fire gates

With the routing above, Cross sends note-on on channel 2 → CV out 3 goes to +5V → patches into an envelope's trigger input. Square on channel 3 → CV out 4. Etc.

# Gamepad → MIDI → ES-9 → gate trigger
button.cross    -> note 60 ch 2   # Gate 1 (CV out 3)
button.square   -> note 60 ch 3   # Gate 2 (CV out 4)
button.triangle -> note 60 ch 4   # Gate 3 (CV out remap — see Controller app)
button.circle   -> note 60 ch 5   # Gate 4

Now patch CV out 3 into a Maths EOC trigger, CV out 4 into a Plaits trigger, etc. Four percussive voices fire from four face buttons.

6. Sticks for continuous CV

This is where the ES-9 earns its price. CV out 5 and 6 can be unipolar or bipolar — gorgeous for modulation:

# Stick CV for filter sweeps and bipolar modulation
stick.right.x -> CC 1  ch 1   # CV out 5 (0–10V) → VCF cutoff
stick.right.y -> CC 11 ch 1   # CV out 6 (-5V to +5V bipolar) → VCO FM
stick.left.x  -> CC 7  ch 1   # CV out 7 (0–5V) → VCA CV
stick.left.y  -> CC 74 ch 1   # CV out 8 → another destination of your choice

Bipolar CV is the trick. With a -5V to +5V swing on CV out 6, you can drive a VCO's FM input either side of centre — push positive to detune up, negative to detune down. A gamepad stick is perfect for this because it self-centres.

7. Pitch CV with 1V/oct quantisation

If you want gamepad notes to play a melodic patch, the ES-9 outputs 1V/oct on CV out 1 (per the mapping above). Send a note-on with pitch 60 and CV out 1 sits at exactly 5V (C3 in 1V/oct). Patch CV out 1 into a Plaits / STO / Rings 1V/oct input and the rack plays the pitch your gamepad button fired.

Default ES-9 mapping

Gamepad input	MIDI	ES-9 CV out	Use
Cross / Square / Triangle / Circle	Note 60 ch 2 / 3 / 4 / 5	CV out 3 / 4 / 5 / 6 as gate	Percussion / voice triggers
D-pad up/down	Note pitch shift ±12	CV out 1 (1V/oct)	Octave-shifted pitch
Right stick X	CC 1 ch 1	CV out 5 (0–10V)	Filter cutoff sweep
Right stick Y	CC 11 ch 1	CV out 6 (bipolar)	VCO FM / bipolar mod
Left stick X	CC 7 ch 1	CV out 7 (0–5V)	VCA level
Left stick Y	CC 74 ch 1	CV out 8	Patch destination
L2 / R2 triggers	Velocity / CC	CV out 8 envelope	Note dynamics
Touchpad XY (DualSense)	CC 16 / 17	Re-routed in Controller app	Second XY pair
L1 / R1	Note 36 / 37 ch 6	Aux gates	Clock divide / reset

Common gotchas

• The ES-9 Controller app must be running. The mapping you build lives in the app — close it and the ES-9 reverts to its last saved profile. Save your profile to the unit so it persists across reboots.
• Bipolar CV needs DC-coupled patching. All ES-9 outputs are DC-coupled by spec; just make sure the receiving module accepts bipolar (most modulation inputs do; audio inputs sometimes don't).
• Gate voltage is 5V, not 10V. Most Eurorack envelopes trigger at 5V comfortably. If you've got an unusual module that needs 8V, patch through a Maths channel to amplify.
• USB MIDI vs ES-9\'s own clock. The ES-9 can act as a MIDI clock source if you've enabled it in the Controller app. Decide who's master — gamepad bridge or ES-9 — before live performance.
• Audio interface side draws CPU. The ES-9\'s audio interface mode (14-in/8-out) uses your laptop\'s audio bus. If you're doing CPU-heavy DAW work alongside, set the buffer size to 256+ samples.

Three patches that show off the ES-9

• "Four-voice modular drums": face buttons fire four separate envelopes/VCAs into a kick, snare, hat, and clap module. Right stick sweeps a shared VCF cutoff across the whole drum bus. Hands-on rack drumming.
• "Pitch CV + bipolar FM": D-pad transposes pitch CV (out 1), face buttons fire the gate (out 2), right stick Y drives bipolar FM (out 6) into the same VCO. A monophonic synth that detunes when you push the stick.
• "Generative ride": patch a slow LFO into Maths, Maths cycling end-of-cycle triggers a random Marbles output. Wire your right stick X (CV out 5) to Marbles' DEJA VU input — your thumb controls how predictable the generative pattern is.

The ES-9 is the cleanest gamepad-to-Eurorack path that exists. Eight CV outs, DC-coupled, sample-accurate. Drop Universal Controller MIDI in front of it and your modular rack now plays from a DualSense — gates, pitches, bipolar mod, and any future destination you wire into the Controller app.