MXR MB301 Bass Synth bass guitar effects pedal

MXR MB301 Bass Synth bass guitar effects pedal
Product no: 9000-0141-5675 Bax Music Warranty: This product comes with a 3-year warranty.

General

The MXR MB301 Bass Synth offers a wide range of monophonic synth sounds inspired by legendary sounds from funk, pop and electronic music. Think Stevie Wonder's sub octaves, Herbie Hancock's aggressive filter moves or Deadmau's deep modulations5-all callable via eight built-in presets. In live mode, the pedal responds directly to the position of the knobs, allowing you to tweak in real time without the need for menus.

MB301 Bass Synth: Fully programmable

Each preset can be customised and stored, including secondary parameters such as envelope settings, oscillator balance, filter direction and noise blending. The pedal offers space for eight presets (four per bank, green and red), plus a live mode where all parameters are active. The MB301 also supports expression pedal control-per preset, you can control which parameters respond to movement, so that, for example, you open up the filter or increase the modulation intensity as you play.

Deep sound editing without the hassle

The MB301 combines direct control with advanced features. With knobs for filter cutoff, resonance, envelope shape, modulation and mix, you quickly set up your basic sound. Long presses of the VOICE or SHAPE buttons activate a second layer of parameters such as glide (for legato effects), compressor settings, output gain, gate sensitivity and routing options. These are partly adjustable per preset, partly global-ideal for those who want to tune their sound in detail.

Flexible integration and connection options

The pedal runs on 9V DC (330 mA) via mains power, but is not compatible with batteries. The TRS output supports mono, wet/dry splitting or stereo output with panning and stereo chorus. The additional CTR jack can be used for expression control or as a second audio channel. For switching between presets, you can use the footswitch itself or an external switch. The MB301 is built for live use, but offers enough precision for studio sessions where timing, tracking and tone are decisive.

Tips or comments about this product

Note: A power adapter is not included.

Specifications

Product features

Adapter included	no
Centre positive/negative	centre negative
Sustainable product	not specified
Extra guitar pickup required	no
Stereo output	yes
Power supply plug	barrel 2.1 mm (inner diameter)
Can be powered by battery	no
Voltage	9 V

Weight and dimensions including packaging

Weight (incl. packaging)	495 gr
Dimensions (incl. packaging)	15,0 x 12,0 x 7,0 cm

Product specifications

effect type: bass synth
controls: mix, cutoff, envelope, sub mix, resonance, mod
mini switches: voice, shape
connectors:
input: 6.35 mm mono jack cable
output: 6.35 mm stereo jack cable, suitable for stereo output or wet/dry split
CTR: switchable between expression/tap input or right-channel audio output (for stereo)
footswitch: hold down to scroll presets or activate freeze function
power supply: 9VDC (not included)
power consumption: 330 mA
country of origin: USA

controls

voice button: switches on additional harmonically tuned oscillators
shape knob: selects oscillator waveform (triangle, sawtooth, square)
cutoff: determines the cutoff frequency of the 4-pole low-pass filter
resonance: accentuates frequencies around the cutoff for sharper filter response
envelope: controls the attack/decay of the filter envelope (far left = off)
mod: determines the intensity of LFO modulation
mix: balance between dry and synth signals
sub mix: balance between main synth and sub-octave
presets button: switches between 8 user presets and live mode

secondary functions (via hold voice/shape button)

glide: controls portamento time for legato synth transitions
amp envelope: determines the attack/fade-in of each note
mod blend: mixes chorus and filter LFOs
voice mix: ratio of main oscillator to additional oscillators
noise mix: ratio of synth signal to noise generator
filter envelope amount: controls direction and intensity of the filter envelope
compression: variable compression of the synth signal
output gain: ±18 dB output level adjustment
dry thru fx: runs the dry signal through all effects
gate sensitivity: determines how sensitive the pedal is to signal detection (global)
tracking: tunes the note detection to 5-string bass, 4-string bass or guitar (global)
output mode: mono, wet/dry split or full stereo with panning and stereo effects (global)

presets

8 fully customisable presets (4 green, 4 red) inspired by classic synth bass lines from the likes of Stevie Wonder, Herbie Hancock, Trent Reznor and deadmau5
live mode reflects current state of the buttons and settings
presets can be easily saved, reset and scrolled with foot or external switch

expression possibilities

each preset and live mode supports expression pedal control
parameters for heel and toe position can be saved individually

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Frans May 15, 2026

Wrote the following about MXR MB301 Bass Synth bass guitar effects pedal

Geweldig apparaat. Wil je de echte mogelijkheden gebruiken dan moet je er wel diep induiken. De tracking is goed, maar dat vraagt wel netjes spelen met goede demping van snaren.