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MIDI Control for Electro Harmonix Cathedral Stereo Reverb

MIDI Control for Electro Harmonix Cathedral Stereo Reverb

The Cathedral Stereo Reverb from Electro Harmonix is an excellent reverb guitar effect with infinite reverb („freeze“) and  tap tempo function. Unfortunately, it has not got any MIDI control.

Using our electronic kit it is possible to control the Cathedral by Program Change or Control Change MIDI command. The principle of operation is that the built-in MIDI controller electronically simulates turning and pressing the white control knob (encoder) and replaces an activity which would have to be carried out during the guitar playing. Instead, just by pressing a button on a MIDI footswitch controller, the Cathedral is automatically set to the preset corresponding to the number of Program Change/Control Change (1-8) or set to a sound corresponding to the momentary parameters of the black control knobs without preset (Program Change 9 or more or Control Change value 0 or 9 or more).

This small electronic kit facilitates controlling the Cathedral using a foot MIDI controller or from a computer by DAW software. The module doesn't affect neither the original sound nor functionality. It works in parallel with the knob. Moreover, if you move the knob, the mod isn't lost and after receiving appropriate MIDI message it sets correct program regardless of the previously set program.


How it works


Setting receiving MIDI channel

1) DIP switches

According to required MIDI channel, set the DIP switches this way:

Set MIDI channel on EHX POG2


2) Software configuration

The MIDI channel and all other parameters can be changed even using MIDIConfig web-based configuration tool.

  • Setting the MIDI channel using the DIP switches is active only if the MIDI channel is not set by software configuration.
  • The software configuration has higher priority than the DIP switches.
  • When the MIDI channel is set to default 1 by software configuration, the MIDI channel is read from these DIP switches.
  • When the MIDI channel is set to higher number by software configuration, the status of DIP switches has no effect.


Default MIDI control commands

Program Change 1 - 8 --- Set program 1 - 8 Can be reconfigured to Control Change  
Program Change 9 - 128 --- Set program off - the effect corresponds to the positions of the buttons
Control Change 96 64 - 127 Program increment  
Control Change 97 64 - 127 Program decrement
Control Change 21, 22, 23   See the next table


Tap Control Changes

There are three options for controlling the Tap/Freeze function by Control Change (CC) MIDI messages:

Default CC numberFunctionValues
CC#21 Momentary

64 - 127: Press
0 - 63: Release

Suitable for full control of both Tap tempo and Freeze function by a computer or by any MIDI controller that can send CC commands.

CC#22 Pulse

Any value (0 - 127): Press immediately
Release of the Tap switch is carried out after 10 miliseconds from receiving the CC.

Suitable for controlling Tap tempo by a computer or by any MIDI footswitch controller that can send CC commands.

CC#23 Toggle

Any value (0 - 127): Toggle the state of the switch: first CC carries out pressing, second CC carries out releasing of the footswitch. And so on: press, release ...

Suitable for controlling Freeze function by any MIDI footswitch controller that can send CC commands.

The CC numbers can be reconfigured from default values to any other numbers (0 - 127).


Variants and prices

We offer this module as a standard product with short delivery times in different variants:

MIDI module for build into the effect 65.00 USD
Building the MIDI module into customer's own Cathedral sent to us 120.00 USD
New Cathedral with built in MIDI module 420.00 USD