Zoom B1 Four

The Zoom B1 Four is a digital bass multi-effects processor made by Zoom, a single compact pedal that replaces a whole board of separate units. It carries over 70 effects and amp models, covering the traditional bass staples as well as sounds like octaver, bass synth and fuzz, and it adds a looper and a built-in rhythm section for practice and songwriting¹. It was announced at Winter NAMM in January 2019, shown alongside its sibling the Zoom B1X Four²¹.

For a bass player building a first setup, the appeal is simple: one pedal, one power source, and a wide palette of bass pedal sounds to explore before committing to individual boxes.

What it does to your sound

Zoom describes the B1 Four as a bass multi-effects processor with over 70 effects and amp models¹. Within that count, the US product page breaks out more than 60 traditional and boutique effects, naming the octaver, bass synth and fuzz as examples⁶. That range spans the effect families a bass player reaches for most: compressor, overdrive and distortion, fuzz, chorus and other modulation, delay and reverb, plus octave and pitch effects and amp and cabinet simulation.

The amp and cab models matter here as much as the effects. In a February 2025 budget multi-effects buying guide, Guitar World's reviewer found the compressors to be particularly good and described the amp and cab sims as fantastic⁴. The same guide reports that you can save 40 presets, which it says can cover anything from clean, round and warm tones through to grinding bass tones with distortion⁴. Presets store a complete patched sound, so a whole chain of effects and an amp model can be recalled with one selection rather than rebuilt each time.

Alongside the effects, the B1 Four includes a looper and a built-in rhythm section¹. The rhythm section supplies drum patterns, so you can practice, loop a bassline, and play against a beat without any other gear. The looper puts the B1 Four in the same category as dedicated looping pedals, if in a simpler form.

Performance modes and connections

The B1 Four gives you two performance modes, which Zoom frames as a way to switch patches and effects seamlessly during live shows¹.

The difference is the mental model. PRESELECT mode lets you jump from patch to patch without affecting your current sound, while STOMP mode lets you turn individual effects on and off. Players who think in terms of "kick in the fuzz for the chorus" will prefer STOMP; players who think in complete sounds will prefer PRESELECT⁸.

On the back panel, Guitar World lists the sockets as one 1/4" instrument input, one 1/8" aux input, one 1/4" output, and one USB Micro-B port⁴. The aux input lets you play along with audio from a phone or player, and the USB port handles both the USB bus power option and the connection to Zoom's Guitar Lab software.

Power: batteries, adapter or USB

Zoom gives the B1 Four three power options¹:

• Four AA batteries
• An optional Zoom AD-16 AC adapter
• USB bus power

The battery option is the one that sets the B1 Four apart from most metal-box multi-effects units, which need a mains supply or a pedalboard power brick. Four AAs make it a genuinely portable practice tool, usable on a couch, a train, or a street corner¹⁶⁸.

Where it came from and how it compares

Zoom announced the B1 Four and B1X Four at Winter NAMM in January 2019, as the bass versions of the same four-series format Zoom built for guitar. In Sweetwater's demo video from the show, Mitch Gallagher and Zoom's John introduced the pair simply as the bass voices of the line: "we also have those voice for bass as well the B1 X4 and b14"²¹.

The B1 Four is not Zoom's first compact bass multi-effects pedal. The earlier Zoom B1on offered 100 bass effects and amp models, more than the B1 Four's 70-plus, but without the B1 Four's looper and built-in rhythm section⁹. The B1X Four, the B1 Four's sibling, adds an expression pedal to the same effects engine, which matters for volume swells and wah-style control.

What reviewers said

Guitar World's February 2025 guide to budget multi-effects pedals is the published review coverage of the B1 Four. Beyond the verdict on the compressors and amp sims, the guide notes the 40-preset capacity and the range it covers, from clean and warm through to distorted tones⁴. The guide treats the B1 Four as a budget option, which is the category it was built for: a first multi-effects pedal that lets a bass player try the whole effects landscape before buying individual units.

Sweetwater's NAMM 2019 demo video walks through the pedal at the point of announcement²:

In the video, Mitch Gallagher talks with Zoom's John about the B1 Four and B1X Four as the bass versions of the four-series format, covering the effects and amp models voiced for bass².

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