Electro-Harmonix Mod Rex Polyrhythmic Modulator
Introduction
Congratulations on your purchase of the Electro-Harmonix Mod Rex Polyrhythmic Modulator. The Mod Rex is a powerful modulation tool designed for multiple instruments and uses, and is equipped with many features, including:
- Up to 4 simultaneous modulation sections synced together in time
- MOD section offers choice of Vibrato, Flanger, Chorus, or Phaser effect
- Standalone Tremolo, Modulated Panning, and Modulated Filter sections
- 9 tempo subdivision options for each modulation section
- 4 LFO shape options for each modulation section
- 100 storable presets
- Full stereo input and output
- Tap Tempo
- Tempo-Sync to an external device with MIDI Clock or an external pulse clock
- Full MIDI control of all parameters and recalling of presets
- External expression pedal input
- External foot controller input to bank up and down presets
- 9.6VDC/200mA power supply included
WARNING: Your Mod Rex comes equipped with an Electro-Harmonix 9.6VDC-200mA power supply. The Mod Rex requires 100mA at 9VDC with a center negative plug and does not accept batteries. Using the wrong adapter may damage your unit and void the warranty. Please do not exceed 10.5VDC on the power plug.
Overview
The Mod Rex is a powerful modulation unit that gives you a massive toolbox of modulation options. At the core of the Mod Rex are its four modulation sections:
- MOD: A choice of a vibrato, flanger, chorus, or phaser effect
- TREM: A tremolo effect
- PAN: A modulated panning effect
- FILTER: A choice of a modulated, low-pass, high-pass, or band-pass filter effect
Any of these sections can be on individually, and any combination of them can be on simultaneously. All four are linked to the same tempo in beats per minute (BPM), but each one can independently have one of nine tempo subdivision options. Each modulation section has multiple parameters to fine tune your sound, including four modulation LFO shape options: rising-sawtooth, triangle, falling-sawtooth, and square.
You can have a vibrato effect going at exactly twice the rate as a simultaneous tremolo effect. Have a phaser on the whole note while simultaneously having a tremolo on the quarter note and a modulated low-pass filter on the eighth note. Create a polyrhythmic effect with a quarter note tremolo and a dotted-quarter note modulated filter. These are merely a handful of examples of the nearly limitless possibilities with the Mod Rex.
In addition to these rhythmic-combination effects, you can also use the Mod Rex as a more traditional modulation effect, just with several non-traditional options. Apply falling-sawtooth flanger blasts, or use a tap-tempo stereo phaser. MIDI sync external tracks and apply a rising-sawtooth tremolo for a side-chaining effect.
The bottom left LED always blinks based on the quarter note. The tempo can be set manually with the tempo knob, via tap-tempo, or synced to an external device via MIDI clock or an external pulse clock.
The Mod Rex is designed to maximize your ability to precisely apply rhythmic effects to whatever you plug into it. Its tap-tempo allows you to continue to play while tapping, as all modulations (including any with uneven subdivisions) adjust fluidly to your tapped tempo without resetting upon each tap. Plug a drum machine, sequencer, or an audio interface from a laptop into the Mod Rex and sync the tempo with MIDI Clock to create perfectly-in-sync rhythmic effects.
The Mod Rex can store and recall 100 presets to maximize your ability to create and use a variety of effects. It features full stereo in and out. An external expression pedal or foot controller can be used to control the Mod Rex. The unit is fully MIDI controllable and integrates seamlessly into any modern MIDI setup. These options make the Mod Rex the ultimate rhythmic modulation machine.
Control Diagram
The following lists the controls and their functions:
- 1 - VOL
- Controls master volume of the effect (page 9).
- 2 - Digit Display and Display State LEDs
- Displays current mode and settings (page 5).
- 3 - PRESET SELECT/STORE
- Used to store and recall presets (page 10).
- 4 - TEMPO
- Used to manually set the master modulation tempo/rate (page 7).
- 5 - LOCK
- Maintains current tempo upon recalling a preset (page 11).
- 6 - MOD Section
- Section with option of four different modulation effects (page 8).
- 7 - TREM Section
- Section controlling a tremolo effect (page 8).
- 8 - PAN Section
- Section controlling a modulated panning effect (page 9).
- 9 - FILTER Section
- Section controlling a modulated filter (page 9).
- 10 - Shape LEDs
- Display LFO shape for one of the four sections (page 7).
- 11 - Shape SELECT button
- Used to change LFO shape of a given section (page 7).
- 12 - BYPASS
- Switch between effect mode and buffered bypass mode (page 13).
- 13 - Status LED
- Shows if the pedal is in effect or bypass mode (page 13).
- 14 - TAP
- Tap in quarter notes to set master modulation tempo (page 13).
- 15 - Rate LED
- Shows speed of current master tempo/rate (page 13).
- 16 - MONO/L Input
- Input for mono signal or left channel of stereo signal (page 13).
- 17 - R Input
- Input for right channel of stereo signal (page 13).
- 18 - EXP
- Input for expression pedal (page 14).
- 19 - MONO/L Output
- Output for mono signal or left channel of stereo signal (page 13).
- 20 - R Output
- Output for right channel of stereo signal (page 13).
- 21 - CLK/FC
- Input for external pulse clock or foot controller (page 14).
- 22 - MIDI IN
- Input for MIDI signals (page 15).
- 23 - Power Jack
- Power input, 9V DC, center negative (page 13).
Top Panel Display Screen
The four-digit display screen at the top of the unit has three main modes: DIVISIONS, TEMPO, and PRESET. LEDs to the left indicate the active mode.
Divisions Display Mode
In this mode, each digit represents the tempo subdivision of one of the four modulation sections (MOD, TREM, PAN, FILTER, from left to right). To enter this mode, turn or press/release a DIVISION knob. Ten possible settings for each digit:
- 0 = Modulation section is off
- 1 = Whole note
- 2 = Half note
- 3 = Dotted quarter note
- 4 = Quarter note
- 5 = Quarter note triplet
- 6 = Dotted eighth note
- 7 = Eighth note
- 8 = Eighth note triplet
- 9 = Sixteenth note
Example display: 1408 indicates MOD (1=Whole), TREM (4=Quarter), PAN (0=Off), FILTER (8=Eighth note triplet).
Divisions are changed by turning the respective DIVISION knob. The digit blinks when changing; press/release the knob to set the new division.
Tempo Display Mode
Displays the current tempo in beats per minute (BPM). Switch by rotating or pressing/releasing the TEMPO knob. Tempo can be set manually, via tap tempo, or external device. Displayed tempo is rounded to the nearest BPM, but modulation remains in sync with fractional external sources. Minimum tempo is 10 BPM, maximum is 500 BPM.
Note: When syncing with MIDI Clock, the displayed tempo may be off by 1 BPM, but the Mod Rex remains in sync.
Preset Display Mode
Displays the current preset number (1-100). Switch by rotating or pressing/releasing the PRESET SELECT/STORE knob. Rotate to select a number, then press/release to load. A dash in the first digit indicates no preset is saved. The rightmost decimal place lit indicates parameters have changed since loading and the preset has not been resaved.
Modulation Parameters
Each of the four modulation sections (MOD, TREM, PAN, FILTER) has its own parameters. The master tempo affects all sections. LFO shapes are shared but can be set independently per section.
Divisions
Each section has a DIVISION knob to set its tempo division and to activate/deactivate the section (0 is off). See Divisions Display Mode for details.
Tempo and Rate Knob Mode
Master tempo is set manually, via tap tempo, or external device. For traditional modulation pedal feel (less BPM-critical), switch the TEMPO knob to Rate Knob Mode. In this mode, turning the knob changes tempo more rapidly. To enter Rate Knob Mode, hold the TEMPO knob until its LED blinks; hold again until solid to return to normal mode.
LFO Shapes
Four LFO shape LEDs are shared. Hold a section's SHAPE button to see its current shape. Hold the SHAPE button and toggle the SELECT button to change the shape. The four LFO shape options are:
- RISING SAWTOOTH: Modulation rises from minimum to maximum, then resets. Good for side-chaining or reverse effects.
- TRIANGLE: Modulation smoothly moves between minimum and maximum points.
- FALLING SAWTOOTH: Modulation falls from maximum to minimum, then resets. Good for sharp rhythmic effects.
- SQUARE: Modulation alternates directly between maximum and minimum points with no smooth transition. Good for choppy effects.
MOD Section
Controls parameters for four effects: Vibrato (pitch), Flanger (sweeping), Chorus (warbling), Phaser (phase shifting). Use the TYPE button to cycle through VIB, FLN, CHR, PHS.
- DEPTH: Sets the amount of effect. For Vibrato, it's pitch shift amount. For Flanger/Chorus, it's effect depth. For Phaser, it's LFO size/phase modulation amount.
- FEEDBACK: (Flanger/Phaser only) Increases resonance.
- R INV: (Stereo) Inverts LFO in the right channel for a stereoized effect from mono input.
TREM Section
Controls tremolo effect (volume modulation).
- DEPTH: Sets the depth of the tremolo. Maximum depth mutes the signal; less depth creates a subtler effect.
PAN Section
Modulates signal between left and right output (stereo). In mono, it acts like an inverted TREM section.
- DEPTH: Controls modulation spread. Maximum depth is 100% left to 100% right. Lower depth pulls the modulation towards the center.
FILTER Section
Offers three modulated filter modes:
- Low Pass Filter (LPF): Frequencies above a modulated cutoff point are cut.
- High Pass Filter (HPF): Frequencies below a modulated cutoff point are cut.
- Band Pass Filter (BPF): Frequencies above and below a modulated center point are cut.
- MODE: Button to toggle between LPF, HPF, BPF.
- DEPTH: Sets the high point of the cutoff modulation
- RES (Resonance): Increases emphasis on frequencies at the cutoff point, enhancing the sweeping effect. In BPF, it also narrows the bandwidth.
- R INV: (Stereo) Inverts LFO in the right channel for a stereoized effect from mono input.
VOLUME
The VOL knob controls master output volume. This setting is saved and recalled with presets.
SIGNAL PATH
When all four sections are active, the signal path is: FILTER → MOD → TREM → PAN.
Presets
The Mod Rex can store and recall up to 100 presets. It loads the last used preset on power-up.
Loading a Preset
Rotate the PRESET SELECT/STORE knob to scroll through preset numbers (display blinks). Press/release the knob to load the selected preset. Loading a preset overwrites current parameters. Physical knob positions for VOL, DEPTH, FEEDBACK, and RES will snap to the recalled preset's values when the knob is next rotated.
If a parameter is changed after loading, the rightmost decimal place on the display will light. These changes are lost unless the preset is resaved.
Saving a Preset
To save the current settings, select the desired preset number (display blinks). Hold the PRESET SELECT/STORE knob until the blue PRESET LED blinks, then release. The current settings are stored.
Updating the currently loaded preset: In PRESET display mode, hold the PRESET SELECT/STORE knob until the blue LED blinks. Release. The preset is updated. If the rightmost decimal place was lit, it should turn off.
NOTE: A quick press/release of the PRESET SELECT/STORE knob reloads the current preset, losing any unsaved changes.
Blank Presets
Preset numbers with a leading dash indicate no preset is stored. Loading a blank preset loads an initialized state:
- Tempo: 120 BPM
- Divisions: 0 (off) for all sections
- LFO Shapes: Triangle for all sections
- Mod Type: Vibrato
- Filter Type: LPF
- R-INV: Off
- Knobs: Current physical position
This is useful for building effects from scratch and avoiding overwriting existing presets.
LOCK Button
Located under the TEMPO knob. When pressed in, loading a preset does not recall its saved tempo; the current tempo remains active. If not pressed, the preset's tempo is recalled. This allows tempo consistency when cycling through presets.
When saving a preset to the same slot (updating), with LOCK pressed, the preset's tempo is not overwritten by the current tempo. Without LOCK pressed, the preset's tempo is overwritten. Saving to a different slot always saves the current tempo.
What You See Is What You Get (WYSIWYG) Mode
When a preset is recalled, knob parameters snap to the preset's values upon the next knob rotation. To snap all knob parameters to their current physical positions simultaneously, hold the TREM DIVISION knob until three LEDs light and the display shows four dashes. Release the button to set all knob parameters to their physical positions.
Factory Reset
The Mod Rex ships with 20 factory presets. To restore these and erase all user presets:
- Unplug the Mod Rex.
- Hold down the BYPASS footswitch and the MOD DIVISION knob.
- While holding them, plug the power adapter back in.
- The display will show two dashes. Continue holding for 3-4 seconds until the display switches back to DIVISIONS display mode. The factory reset is complete.
NOTE: Performing a factory reset erases all saved presets permanently.
Footswitches and Jacks
Footswitches
- BYPASS: Engages/disengages the effect. Blue LED indicates effect is active. Features buffered bypass.
- TAP: Sets the master modulation tempo by tapping in quarter notes. The blue LED blinks with the tempo. LFOs sync to the nearest quarter note. A long press (over 1 second) and release hard resets LFOs to the start of a measure/song.
Jacks
- POWER: 9V DC, center-negative power adapter input. Requires 100mA. Does not accept batteries. Use only the supplied or equivalent adapter.
- INPUT JACKS (MONO/L, R): For mono or stereo input. MONO/L for mono or left channel. R for right channel. Plugging into MONO/L only imposes the signal onto the R input for mono-in/stereo-out.
- OUTPUT JACKS (MONO/L, R): For mono or stereo output. MONO/L for mono or left channel. R for right channel.
- EXP (Expression Pedal): TRS input for passive expression pedals. Controls modulation rate. Has two expression modes (E--1, E--2) selectable via the FILTER DIVISION knob.
- CLK/FC (Clock/Foot Controller): Accepts external pulse clock (e.g., Electro-Harmonix Clockworks) or foot switch for preset up/down or tap tempo. Mode selected via MOD DIVISION knob: "- FC -" for foot controller (tip for up, ring for down), "CLOC" for clock/tap tempo.
MIDI and the Mod Rex
The Mod Rex accepts MIDI input via its 5-Pin MIDI IN jack for tempo sync (MIDI Real Time messages), preset recall (MIDI Program Change messages), and parameter control (Control Change messages). It does not transmit MIDI output.
MIDI Tempo Sync
Connect MIDI Out from an external device to the Mod Rex's MIDI IN. The Mod Rex syncs to MIDI Clock, MIDI Start, and MIDI Continue messages. MIDI Start/Continue hard resets all LFOs to align with song structure.
MIDI Program and Control Change Messages
To ensure proper communication, the Mod Rex's MIDI channel (1-16) must match the external device's. Set the MIDI channel by holding the PAN DIVISION knob until the display shows 1-16.
Program Change messages recall presets 1-100.
Control Change (CC) messages control parameters. MIDI data values (0-127) map to parameter ranges. For parameters with set values (like divisions or shapes), the first few MIDI values correspond to options. Values exceeding the maximum map to the highest option.
MIDI CC Message Assignments
| CC Number | Parameter |
|---|---|
| 04 | Expression* |
| 07 | Volume |
| 18 | MOD Type |
| 19 | FILTER Type |
| 20 | MOD Shape |
| 21 | TREM Shape |
| 22 | PAN Shape |
| 23 | FILTER Shape |
| 24 | MOD R-INV** |
| 25 | FILTER R-INV** |
| 26 | MOD Division |
| 27 | TREM Division |
| 28 | PAN Division |
| 29 | FILTER Division |
| 30 | MOD Feedback |
| 31 | FILTER Resonance |
| 92 | TREM Depth |
| 93 | MOD Depth |
| 94 | PAN Depth |
| 95 | FILTER Depth |
*Expression input via MIDI only works when nothing is plugged into the physical EXP jack.
**For MOD/FILTER R-INV, 0 is off, any higher number is on.
Factory Presets' Parameter List
A grayed-out parameter means it has no effect in that configuration and is set to a default state.
| Preset | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 |
|---|---|---|---|---|---|---|---|---|---|---|
| VOL | 60% | 65% | 50% | 55% | 50% | 65% | 55% | 55% | 60% | 60% |
| TEMPO | 120 | 130 | 110 | 100 | 100 | 100 | 95 | 110 | 130 | 96 |
| MOD Div. | 1 | 1 | 7 | 7 | 1 | 2 | 7 | 2 | 9 | 1 |
| MOD Type | PHS | FLN | VIB | PHS | PHS | PHS | VIB | CHR | VIB | PHS |
| MOD Shape | TRI | FALL | TRI | SQR | TRI | FALL | TRI | TRI | TRI | FALL |
| MOD Depth | 85% | 70% | 20% | 50% | 80% | 100% | 25% | 30% | 20% | 100% |
| Feed. | 60% | 65% | 50% | 10% | 60% | 60% | 50% | 50% | 50% | 50% |
| MOD R-INV | Off | Off | On | Off | On | Off | Off | On | Off | Off |
| TREM Div. | 9 | 4 | 4 | 0 | 0 | 5 | 6 | 7 | 5 | 4 |
| TREM Shape | SQR | RISE | TRI | TRI | TRI | TRI | TRI | TRI | FALL | RISE |
| TREM Depth | 90% | 70% | 50% | 50% | 50% | 100% | 50% | 50% | 100% | 100% |
| PAN Div. | 1 | 0 | 0 | 2 | 4 | 0 | 0 | 3 | 0 | 0 |
| PAN Shape | TRI | TRI | TRI | SQR | TRI | TRI | TRI | TRI | TRI | TRI |
| PAN Depth | 50% | 50% | 50% | 60% | 100% | 50% | 50% | 50% | 50% | 50% |
| FILTER Div. | 0 | 8 | 0 | 1 | 7 | 2 | 1 | 0 | 4 | 0 |
| FILTER Type | LPF | LPF | LPF | LPF | LPF | HPF | BPF | LPF | LPF | LPF |
| FILTER Shape | TRI | TRI | TRI | TRI | FALL | RISE | TRI | TRI | FALL | TRI |
| FILTER Depth | 50% | 40% | 50% | 100% | 100% | 50% | 50% | 50% | 100% | 50% |
| Res. | 50% | 55% | 50% | 40% | 55% | 60% | 0% | 50% | 60% | 50% |
| FILTER R-INV | Off | Off | Off | On | Off | Off | On | Off | Off | Off |
| Preset | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 |
|---|---|---|---|---|---|---|---|---|---|---|
| VOL | 52% | 60% | 60% | 55% | 60% | 60% | 66% | 55% | 70% | 65% |
| TEMPO | 100 | 120 | 105 | 94 | 120 | 40 | 120 | 122 | 120 | 120 |
| MOD Div. | 2 | 4 | 4 | 1 | 7 | 1 | 6 | 9 | 3 | 1 |
| MOD Type | PHS | CHR | FLN | FLN | VIB | FLN | VIB | PHS | CHR | VIB |
| MOD Shape | TRI | TRI | SQR | TRI | TRI | TRI | TRI | TRI | SQR | TRI |
| MOD Depth | 80% | 20% | 50% | 45% | 25% | 15% | 15% | 60% | 35% | 50% |
| Feed. | 55% | 50% | 25% | 60% | 50% | 65% | 50% | 25% | 50% | 50% |
| MOD R-INV | On | Off | Off | Off | On | Off | Off | Off | Off | Off |
| TREM Div. | 9 | 7 | 9 | 3 | 4 | 0 | 4 | 4 | 9 | 7 |
| TREM Shape | TRI | FALL | FALL | TRI | RISE | TRI | TRI | TRI | FALL | FALL |
| TREM Depth | 85% | 80% | 50% | 100% | 75% | 50% | 50% | 50% | 100% | 70% |
| PAN Div. | 0 | 0 | 4 | 7 | 2 | 2 | 1 | 0 | 1 | 0 |
| PAN Shape | TRI | TRI | TRI | TRI | SQR | TRI | TRI | TRI | TRI | TRI |
| PAN Depth | 50% | 50% | 70% | 100% | 55% | 75% | 25% | 50% | 60% | 50% |
| FILTER Div. | 6 | 2 | 9 | 4 | 1 | 1 | 4 | 3 | 6 | 4 |
| FILTER Type | BPF | HPF | LPF | LPF | LPF | HPF | HPF | HPF | LPF | HPF |
| FILTER Shape | TRI | RISE | FALL | TRI | RISE | TRI | TRI | RISE | FALL | FALL |
| FILTER Depth | 40% | 25% | 100% | 100% | 100% | 15% | 10% | 20% | 40% | 50% |
| Res. | 30% | 75% | 50% | 25% | 70% | 25% | 10% | 50% | 50% | 50% |
| FILTER R-INV | Off | Off | Off | Off | Off | On | Off | Off | Off | Off |
Warranty Information & FCC Compliance
Warranty Information
Register online at www.ehx.com/product-registration or return the warranty card within 10 days of purchase. Electro-Harmonix will repair or replace products failing due to defects in materials or workmanship for one year from purchase. This applies to original purchasers from authorized retailers. Repaired/replaced units are warranted for the unexpired portion of the original warranty.
For service within the warranty period, contact EHX Customer Service at 718-937-8300 or info@ehx.com for a Return Authorization Number. Include a description of the problem, name, address, phone number, copy of receipt, and payment for service.
United States:
ELECTRO-HARMONIX
C/O NEW SENSOR CORP.
47-50 33RD STREET
LONG ISLAND CITY, NY 11101
Attn: CUSTOMER SERVICE
718-937-8300
info@ehx.com
Europe:
JOHN WILLIAMS
ELECTRO-HARMONIX UK
13 CWMDONKIN TERRACE
SWANSEA SA2 0RQ
UNITED KINGDOM
+44 179-247-3258
electroharmonixuk@virginmedia.com
FCC Compliance
This equipment has been tested and found to comply with Class B digital device limits per FCC Rules, providing reasonable protection against harmful interference in residential installations. It generates, uses, and can radiate radio frequency energy. If not installed/used per instructions, it may cause interference. No guarantee against interference in a particular installation.
If interference occurs, users are encouraged to correct it by:
- Reorienting or relocating the receiving antenna.
- Increasing separation between equipment and receiver.
- Connecting equipment to a circuit different from the receiver's.
- Consulting the dealer or an experienced radio/TV technician.
Modifications not expressly approved by the manufacturer may void the user's authority to operate the equipment under FCC rules.
Electro-Harmonix
