Left panel

Manual for MIDI Control for EHX x9

1. Overview


Connect a MIDI cable from any MIDI controller (eg. the Microdesignum MIDI Grande footswitch controller) to the MIDI IN connector of the EHX (Electro-Harmonix) effect pedal equipped with this MIDI module. Connect a power supply adapter to the EHX pedal.


To prevent misunderstanding in terms - the term "preset" in this manual do not correspond to the term "preset" used in the original EHX pedal manual. The original Electro-Harmonix C9 (or B9/Synth9/Mel9/etc.) manual's term "preset" is here called "EHX program" or sometimes "factory preset"! (eg. for the C9, EHX program number 1 is "Tone Wheel", EHX program number 4 is "Shimmer".)

There are 128 user presets + 9 factory (read-only) presets.

User presets

Each preset contains stored values for all knobs: EHX program number, values for all effect potentiometers (parameters) and default state for the bypass footswitch. All 128 user presets can be edited, the user can prepare a different combination of EHX pedal's knobs (parameters) values in each preset. The current preset number can be changed by the PC (Program Change MIDI command) or by the buttons ▲ and ▼.

Only the user presets (1 - 128) can be activated by Program Change.

Factory presets

The factory presets PG1 - PG9 correspond to the original EHX programs 1 - 9. When any of the factory presets is active, the corresponding EHX program (the names are printed on the case) is used and the actual physical values of the knobs (potentiometers) are used. The Pgm dot on the display indicates when a factory preset is active.

The factory presets can be selected only by the buttons ▲ and ▼ (hold the button until the PG prefix appears on the display). The factory presets in the menu are located before the preset number 1, they act as a "playground" when creating a user combination of effect's parameters. After the user adjusts all effect knobs properly to hear the desired sound, this combination can be saved to any of the 128 user presets (see the "Create a preset" chapter).

Controls and functions

MIDI Presto x9

Pgm indicator The indicator lights up when scrolling outside the user presets, when any of the factory presets PG1 - PG9 is selected (active). The indicator goes off when the selected preset is a standard user preset.
Value indicator Lights up when the display is showing the value of touched knobs.
Edit indicator Indicates the Edit menu (lights up when editing a user preset).
∙∙ Lock indicator In the Edit menu mode is showing whether the actual selected knob is locked or not. During normal operation (in preset menu), when the user tries to touch a locked knob (change potentiometer position) no value is showed on the display, but only the Lock doubledot light up to warn the user, that the touched knob is disabled and instead of physical knob position, the device is still using the value ("virtual" knob position) stored in the memory of the current active user preset.
button Preset + (when selecting a preset number); parameter value + (in Edit menu or Global settings menu)
button Preset - (when selecting a preset number); parameter value - (in Edit menu or Global settings menu)
Edit/Save button Many functions depending on the current menu or device mode
On button with indicator This button copies function of the EHX pedal's Bypass footswitch. The indicator: effect is turned on, effect is turned off (bypass mode).
Exception: in the Edit menu and when selected the parameter PA1 or higher (it means the first knob or any of the next knob), the button On toggles lock for the current knob (parameter).

2. Preset menu (normal device operation)

When the device is powered on, the preset menu appears the display. The user preset 1 is active as default, so preset 1 data is loaded from memory. Usually it does not matter the state of the knobs because they are used only when creating or modifying the presets.

A preset number corresponds to the MIDI Program Change number. The current active preset number is shown on the display.

Every time the preset number is changed, the device loads stored effect parameters from the selected preset memory. During normal operation of the device, physical knobs positions are not applied, but some "virtual" values are loaded from the preset memory and used instead of physical values.

The user has to prepare (create) some user presets before normal usage of the device and set every parameter of these presets to the desired value while listening the resulting sound. After some presets are properly prepared, during performance, the user only switches between these user presets by the Program Change MIDI commands.

Create a preset

New presets can be created by the following process. First, select one of the factory presets PG1 - PG9 (located below the preset 1 in the preset menu). Every factory preset holds one of the EHX programs (eg. for the EHX pedal C9, PG3 means the EHX program No.3 called "Compact"). Then adjust all knobs' positions to hear the desired sound effect (instructions can be found in the EHX manual for that effect pedal). Press and hold the Save button until SAS ("save as") temporarily shows on the display. Then select the preset number (blinking number on the display) where to store the prepared preset data (all values adjusted by physical knobs). The selected preset is erased and the new values are stored. Then press the Save button to confirm saving data to the preset memory.

If the user wants to edit a previously saved user preset, it is possible by opening the Edit menu of that preset (see chapter 3. Edit menu).

By default, outside Edit menu each knob has an accidental touch protection. If the user does not change knob position by at least little amount, the knob is disabled. After exceeding this little amount the knob is enabled and temporarily overrides the preset saved "virtual" value for the knob, until another preset is selected (loaded).

Controlling the EHX pedal via MIDI

Everything can be controlled via MIDI commands - the number of active preset, bypass footswitch, all knobs and their "virtual" values (every parameter of effect), even global settings and any preset data in memory.

MIDI commandpossible valuesfunction
Program Change PC  1-128 Change user preset.
Control Change CC  20  0/127 CC#20 is remote control for the bypass footswitch (0 = bypass, 1 = effect turned on). The CC#20 number can be changed to any other number in the Global settings menu.
  CC  21/22/23/24..  0/127 Each knob (potentiometer) value can be remotely set (overwritten) by MIDI CC commands. The CC number for any parameter (knob) can be changed to any other value in the Global settings menu. By default, CC#21 is for the first knob, CC#22 is for the second knob, etc.
SysEx (too complex) Use MIDI config online tool to configure Global settings or any preset from a computer (with a USB-MIDI converter). (It is being prepared, not workable now.)

3. Edit menu

Select a preset in the preset menu, then press and hold the Edit button until EDI appears on the display (open the Edit menu for the selected preset).

Edit indicator is always on in Edit menu. The first menu item that appears is EHX program choice for this preset. The user can scroll through the menu items by short pressing the Edit button (every press moves the user to the next preset parameter).

Each preset contain the following parameters:

menu item (parameter)possible valuesmeaning
PGM - EHX program PG1,PG2,PG3,.. Which EHX program (1 - 9) is used in this preset.
PA1 - parameter 1 value 0,1,..,126,127,---  (+ lock indicator) Stored (saved) value for 1st knob (potentiometer) for this preset.
PA2 - parameter 2 value 0,1,..,126,127,---  (+ lock indicator) Stored (saved) value for 2nd knob (potentiometer) for this preset.
PA3 - parameter 3 value 0,1,..,126,127,---  (+ lock indicator) Stored (saved) value for 3rd knob (potentiometer) for this preset.
PA4 - parameter 4 value 0,1,..,126,127,---  (+ lock indicator) Stored (saved) value for 4th knob (potentiometer) for this preset.
... 0,1,..,126,127,---  (+ lock indicator) (number of knobs/parameters depends on the EHX effect pedal variant - see the next table)


When a menu item is selected, after 1 second (of item name showing) a number is shown on the display (as the selected parameter value). The value for the selected menu item (parameter value or EHX program number) can be adjusted by the buttons ▲ and ▼. When the user is in the Edit menu and touches any of the knobs (potentiometers), the menu automatically jumps to edit this parameter. So there are two ways how to edit each parameter in the preset. Precise adjustment by the buttons ▲ and ▼ (with Edit button) or directly by touching the knobs, but keep in mind that touching the knob overwrites its previous value with no chance of reading which "virtual" value the corresponding parameter had before, because the actual physical position of the knobs (before touching) is often different than their "virtual" value (used to create the actual sound effect of the EHX pedal).

After the editing is done, press and hold Save button (until SAV appears) to confirm and save adjusted preset parameters to the memory.

If you edit any parameter of the preset by mistake and want to revert the changes in the actual preset, disconnect the power supply of the EHX pedal, because any unsaved changes of the actual preset are not permanently stored in the memory until the user saves whole preset by holding the Save button.

Parameter/knob values

Normal mode: 0 - 127

"Realtime sync" mode:  ---

Normal mode values can be set by touching the knobs or by pressing the buttons. Special value --- can be set only by buttons ▲ and ▼ (increasing the value above 127 or decreasing the value below 0). If the "Realtime sync" mode (---) is enabled for the certain knob, instead of "virtual" saved value, the real actual knob value is used anytime the preset is active. This option gives the user the opportunity to create some knobs force set physical knob value regardless of used preset (if the "realtime" mode is set for the certain parameter in all used presets).

Any parameter can be locked (or unlocked) by pressing On button. This means that when this preset is active, the corresponding physical knob is disabled (even if the user moves it significantly). The user can see the ∙∙ Lock doubledot indicator when the parameter is selected in Edit menu.

Table for specific EHX pedal variants:

short nameC9B9Mel9Synth9Key9Bass9
PG1 Tone Wheel Fat & Full Orchestra OBX Dynamo Precision
PG2 Prog Jazz Cello Profit V Wurli Longhorn
PG3 Compact Gospel Strings Vibe Synth Suitcase Fretless
PG4 Shimmer Classic Rock Flute Mini Mood Mallets Synth
PG5 Lord Purple Bottom End Clarinet EHX Mini Eighty Eight Virtual
PG6 Mello Flutes Octaves Saxophone Solo Synth Tri-Glorious Bowed
PG7 Blimp Cathedral Brass Mood Bass Vibes Split Bass
PG8 Press Tone Continental Low Choir String Synth Organ 3:03
PG9 Telstar Bell Organ High Choir Poly VI Steel Drums Flip-Flop

4. Global Settings

Turn the pedal off, hold down the Edit button and turn it on. The display shows GLB and when the button is released, the user can edit individual global parameters. By short pressing the Edit button, the next global menu item shows and the user can edit the next global parameter.

The user can edit these parameters in sequence:

Channel number

The display shows C1 (default channel No.1). Using the buttons ▲ and ▼ select the MIDI channel number (1 to 16) on which the device receives the MIDI messages. Select the same channel on your MIDI footswitch controller or any MIDI controller that you want to connect with this device.

Then press shortly the Edit button to select the next parameter in the global settings menu.

Preset (PC) number display format PCr

The MIDI command Program Change is usually displayed in user format (in range from 1 to 128). But some devices or DAWs display these values in technical format (in range from 0 to 127). Depending on how your MIDI controller device works, you can change the displayed format of preset numbers (Program Change numbers) to technical format (0 - 127).

Using the buttons ▲ and ▼ select the user format 128 or technical format 127.

Then press shortly the Edit button to select the next parameter in the global settings menu.

Bypass footswitch CC number CCF

Change Control Change controller number. Default is CC#20 (as you can see in the 2nd row of the MIDI commands table in the Chapter 2 of this manual).

Then press shortly the Edit button to select the next parameter in the global settings menu.

CC number for each knob CC1CC2, ... (multiple menu items)

Depending on the specific EHX pedal, different number of parameters (knobs) can be visible. If the user wants to change Control Change controller number for the specific parameter (knob), he can change the value under CCx menu item (eg. for 2nd knob "ORGAN" of EHX C9 change CC2 controller number)

Default is CC#21 for the 1st parameter (knob), CC#22 for the 2nd parameter (knob), etc..

If you want to go to the beginning of the global settings menu, press shortly the Edit button, this will jump to the first menu item again.

Anywhere in the menu, the user can press and hold the Edit button until the display shows SAV to exit and save the global settings and go to the preset mode (normal device mode).


Device's MIDI OUT port resends every message arrived to MIDI IN port.