Description

The MB301 Bass Synth is MXR's bass synth pedal featuring a main oscillator with three different wave shapes, sub-oscillators, an envelope filter, a low-pass filter, and modulation. Designed in collaboration with bassist Ian Martin Allison, this pedal offers a wide range of synth sounds with precise tracking and high sustain. It has 8 recallable presets using the dedicated button.

OVERVIEW OF THE MXR MB301 BASS SYNTH

The MXR MB301 Bass Synth is a bass pedal that offers vintage analog sounds with a wide range of monophonic synth sounds reminiscent of hits by Stevie Wonder, Michael Jackson, Parliament Funkadelic, and more. Designed with bassist and sound connoisseur Ian Martin Allison, this pedal features a sub-octave section, an expressive envelope filter, and rich modulation effects, all with precise tracking and high sustain. The controls are easy to use, designed to sculpt the sound in detail. The SUB MIX knob adjusts the amount of low octave mixed with the main synth signal. The MOD knob adds liquid and brilliant modulation, ranging from subtle movement to psychedelic pulses. The ENVELOPE control governs the response of the envelope filter. The MIX knob adjusts the blend of dry and affected signals, the CUTOFF control sets the filter's cutoff frequency, and RESONANCE amplifies it for a sound with more impact. Finally, the VOICE button adds harmonically tuned oscillators for more complex sounds, while the SHAPE button allows you to select the waveform of the main synth signal: triangular, sawtooth, or square.

The MXR MB301 Bass Synth comes with eight pre-loaded presets, designed by Ian Martin Allison. Each preset is inspired by classic synth sounds, such as those heard in Michael Jackson's "Thriller", Herbie Hancock's "Chameleon", Peter Gabriel's "Sledgehammer", and Nine Inch Nails' "Head Like a Hole". To cycle through presets, simply press the PRESETS button.

The Bass Synth offers a range of advanced parameters, including oscillator and modulation mix, compression, and tracking modes. The pedal can be used in stereo mode, paired with an external switch like the MXR Split + Tap or the Tap Tempo Switch to cycle through presets, or use a volume pedal like the Dunlop Volume (X) to blend different sound configurations.

CONTROLS OF THE MXR MB301 BASS SYNTH

VOICE: adds harmonically tuned additional oscillators for more complex sounds
CUTOFF: sets the cutoff frequency of the 4-pole resonant low-pass filter
MIX: adjusts the mix between dry and synth signals
SUB MIX: adjusts the mix between the main synth signal and sub signals
SHAPE: selects the oscillator waveform: triangular, sawtooth, or square
ENVELOPE: controls the attack and decay time of the envelope filter; at low values, it offers a fast attack and quick response, while at higher settings, it creates a slow effect; setting the knob fully to the left deactivates the envelope filter
MOD: sets the amount of modulation
RESONANCE: increases gain at the cutoff frequency, adding a more expressive and biting effect at higher settings
PRESETS: allows cycling through the 8 internal presets

SECONDARY PARAMETERS

Holding down the VOICE or SHAPE buttons while adjusting other controls allows access to alternative parameters. The parameters accessible by holding down the VOICE button relate to the synth patch sound. Each can be saved to a preset and controlled with an expression pedal. The parameters accessible by holding down the SHAPE button are mostly usage settings rather than effects. None of these can be controlled by an expression pedal. Some of them are global parameters and affect all presets.

Press and hold the VOICE button

MIX knob - VOICE MIX parameter: with the VOICE button pressed, the MIX knob adjusts the VOICE MIX parameter. Sets the mix between the main oscillator and additional oscillators when the VOICE function is active; at minimum, additional oscillators are removed from the signal:
SUB MIX knob - NOISE MIX parameter: with the VOICE button pressed, the SUB MIX knob adjusts the NOISE MIX parameter. Sets the mix between the oscillator and noise.
CUTOFF knob - FILTER ENVELOPE AMOUNT parameter: with the VOICE button pressed, the CUTOFF knob adjusts the FILTER ENVELOPE AMOUNT parameter. Sets the direction and amplitude of the envelope filter (adjusted by the ENVELOPE knob). Beyond halfway, the envelope opens the filter; below halfway, it closes the filter for a "ducking" effect.
RESONANCE knob - GLIDE parameter: with the VOICE button pressed, the RESONANCE knob adjusts the GLIDE parameter. Adjusts the time taken to move from one note to another for a legato effect.
ENVELOPE knob - AMP ENVELOPE parameter: with the VOICE button pressed, the ENVELOPE knob adjusts the AMP ENVELOPE parameter. Sets the fade-in time (or attack) of each note.
MOD knob - MOD BLEND parameter: with the VOICE button pressed, the MOD knob adjusts the MOD BLEND parameter. Sets the mix between chorus and LFO filter modulation.

Press and hold the SHAPE button

MIX knob - COMPRESSION parameter: with the SHAPE button pressed, the MIX knob adjusts the COMPRESSION parameter. Sets the amount of compression, from no compression to tight and "punchy" compression. Affects how the synth responds to playing intensity.
SUB MIX knob - OUTPUT GAIN parameter: with the SHAPE button pressed, the SUB MIX knob adjusts the OUTPUT GAIN parameter. Adjusts the output gain +/- 18 dB, with 0 dB at halfway.
CUTOFF knob - GATE SENSITIVITY (GLOBAL) parameter: with the SHAPE button pressed, the CUTOFF knob adjusts the GATE SENSITIVITY (GLOBAL) parameter. When playing, the pedal automatically determines the average signal level. This parameter adjusts the pedal's responsiveness when the input signal is lower than this level. The default sensitivity is designed for most situations and playing styles, but dynamic playing or legato works better with high sensitivity. Note: the sustain of a note is independent of the set sensitivity. The note will resonate as long as it is played on the instrument.
RESONANCE knob - TRACKING (GLOBAL) parameter: with the SHAPE button pressed, the RESONANCE knob adjusts the TRACKING (GLOBAL) parameter. Determines how the synth signal responds to the instrument's frequency range to ensure accurate note tracking.

• 5-STRING BASS: default, knob fully counter-clockwise. Tracks from a low B to a high C on a 24-fret 6-string bass.
• 4-STRING BASS: knob at 12 o'clock. Has a faster response than 5-STRING mode, but only tracks down to a low E.
• GUITAR: knob fully clockwise. Tracks the range of a standard-tuned 24-fret guitar.

ENVELOPE knob - DRY THRU FX parameter: with the SHAPE button pressed, the ENVELOPE knob adjusts the DRY THRU FX parameter. When active (knob fully clockwise), the dry signal passes through the filter, chorus, compression, and gate along with the synth signal. This parameter blends the dry and synth signals more completely, allowing the instrument's natural articulation to emerge when using the MIX knob.
MOD knob - OUTPUT MODE (GLOBAL) parameter: with the SHAPE button pressed, the MOD knob adjusts the OUTPUT MODE (GLOBAL) parameter. Selects the output signal routing.

• MONO: default, knob fully counter-clockwise. True bypass.
• WET/DRY: knob at 12 o'clock. In this mode, the affected signal is on the left channel (tip) and the dry signal is on the right channel (ring). Buffered bypass.
• STEREO: knob fully clockwise. In this mode, the pedal creates a stereo signal by panning the oscillators and activating a stereo filter and chorus. Buffered bypass.

PRESETS

This pedal features eight different presets (four Green and four Red), plus a Live mode, active when the preset LEDs are off. Live mode represents the current knob settings. When a preset is modified from how it was saved, its LED will flash slightly.

GREEN PRESETS

THRILLENGANES: inspired by Greg Phillinganes' ARP 2600 sound on Michael Jackson's "Thriller", this low-octave sound suits both 80s hits and contemporary music.
WONDERFUL: based on Stevie Wonder's left-hand sound on the TONTO synth, offering resonant funk sounds.
LIZARD SYNTH: modeled after Herbie Hancock's ARP Odyssey on the famous "Chameleon", this sound increases resonance for that 70s funky timbre.
SYNTHADELIC: open sound with octaver, based on Bernie Worrell's Minimoog tone on "Flashlight".

RED PRESETS

SLEDGE: inspired by Tony Levin's bass sound on Peter Gabriel's "Sledgehammer", this preset offers the classic analog octave sound with generous use of compression and chorus. Playing with a pick maximizes the potential of this sound.
ARMY OF SYNTH: modeled after the iconic synth bass line on Björk's "Army of Me". Use an expression pedal for greater intensity.
NINE INCH SYNTH: based on Trent Reznor's synth programming and tone on "Head Like a Hole", this sound is perfect for both rock and dance.
SYNTHMAU5: inspired by the sidechain technique used in electronic music production, this preset brings the dark atmospheres used by producer deadmau5. Playing precisely on the beat with a quarter-note kick drum makes it seem as if the kick drum triggers the bass notes.

Cycling through presets

You can cycle through presets using the dedicated button next to the LEDs, or an external switch like the MXR Split + Tap connected to the CTR jack, in addition to the integrated footswitch. Using an external switch, pressing once cycles forward through presets, while holding it down reverses the scrolling direction. To use the integrated switch, hold down the switch until the main LED starts flashing. At this point, pressing the footswitch will scroll forward. The SHAPE button LED will flash to indicate the active preset. Hold down the switch again to exit preset selection mode or wait for the scroll menu timeout.

Saving a preset

To save the current settings to a preset, you must first copy the settings by holding down the preset button for 2 seconds. The preset LEDs will flash for confirmation. Then, scroll through the preset bank to select the save location. Hold down the button again for two seconds to copy the settings to that bank. The preset LEDs will stop flashing. To exit the copy/save menu without saving, simply change the knob settings or wait for the timeout. Note: you cannot save a preset in Live mode.

Resetting a preset to default settings

To reset a preset to default settings, scroll through the presets to select the one to reset. Then, hold down the footswitch and the preset button simultaneously for 5 seconds. The preset LEDs will flash rapidly to confirm the reset. In Live mode, all preset LEDs will flash green after a reset.

Factory reset

Hold down the VOICE and SHAPE buttons simultaneously for 5 seconds when powering on the pedal to perform a factory reset. Once the reset is complete, the Bypass LED will flash rapidly several times.

EXPRESSION

Live mode and each preset can store their own expression state. To set the expression behavior of a preset, adjust all parameters in both the heel-down and toe-down positions of the expression pedal according to the desired settings. Then, move the expression pedal through its full range to confirm the desired behavior. Once the expression pedal settings are verified, follow the steps in the "Saving a preset" section. Note that the heel-down state also corresponds to the preset state when no expression pedal is connected. In Live mode, expression states are automatically saved and maintained as long as the expression pedal remains connected. If the unit is powered on without an expression pedal connected, the next time the pedal is connected, the heel position will be set to the current Live mode state. Note that each time Live mode is entered, the current settings are represented by the knob positions until the expression pedal is operated. Changes to expression settings in Live mode will not be recorded until the pedal is physically operated after entering Live mode.

CTR JACK

Expression/Tap Input

Set the CTR side switch to the TAP/EXP position (towards the OUT jack) to use the CTR jack with an expression pedal via a TRS cable or an external switch via a patch cable to switch between presets.

Audio Output

Set the CTR side switch to the AUDIO position (towards the CTR jack) to use the CTR jack as the right channel of the audio output. In this configuration, use two TRS cables in the OUT and TRS jacks or a single TRS cable in the OUT jack to use the pedal in stereo mode.

TECHNICAL SPECIFICATIONS OF THE MXR MB301 BASS SYNTH

Input Impedance: 1 MΩ
Output Impedance: 100 Ω
Maximum Input Level: +5 dBV
Noise Floor: -97 dBV
Current Draw: 330 mA
Power Supply: 9 volt DC