After recently taking an in-depth look at the latest BOSS offering in the guitar synthesis realm (GM-800 Guitar Synthesizer and GK-5B Pickup, May 2024), I was excited to put BOSS’ latest bass-specific effects powerhouse through its paces. The ME-90B is the latest in a series of digital multi-effects processors for bass that spans decades (remember the yellow ME-6B from the ‘90s?), and the company has instituted new tech and tricks with each new revision. The ME-90B is lightweight, and dare I say somewhat diminutive, given all that it features – such as eight multi-function footswitches and a built-in expression pedal – and boasts 61 varied effect algorithms tuned specifically for bass. Ten bass preamps have also been included, within a dedicated preamp section, and the unit processes its 36 factory and 36 user presets via impressive 24-bit AD/32-bit DA conversion, utilizing an internal 32-bit floating architecture. It can function as a USB-C audio interface. And as the cherry on top, it can be powered by four AA batteries! Which, in fact, it will be, unless you already own or also purchase the recommended BOSS PSU.

A Closer Look

Let’s dive right into tones and textures! Effects all live in one of six effect categories, with additional options available for exchanging out the last effect type in a category with another from a short, predefined list, often from a different category (allowing you to stack two modulation effects, for example, by using the user-selectable last slot option in another category). This can be achieved with BOSS’ Tone Studio for ME-90B desktop or mobile app, although the latter requires a separate Bluetooth communication add-on that is not included. Here are some of my more notable experiences with the tones on tap:

PREAMP/EQ: Studio Bass stood out as exceptional. The Selectable 3-band EQ had tons of options for midrange frequencies, which I wholeheartedly applaud! SW-Tour also sounded excellent through my rig and monitors.

MOD: Analog Delay was awesome, and the selectable variations on Slicer; having a separate version that deemphasizes and another that overly emphasizes your attack characteristics yielded some fun results!

COMP/FX1: M-Comp was much more lively than Comp, in a very good way. This was my favorite compressor model, due to its more aurally exciting characteristics. It didn’t seem to darken my tone.

Octave: While it’s not a polyphonic effect, it is a lot like the OC-2 in timbre and response. Poly Octave works with no perceptible latency, which is great, yet it doesn’t have quite the same charm of the physical BOSS OC-3’s polyphonic mode.

BOSS ME-90B Multi-Effects Pedal

Pitch Shift: This effect does a much better job than Octave in sounding like an actual detuned string, however it does add some latency. I actually mainly use pitch shift and octave effects for an octave up (makes sense right? We’re already pretty dang low…), but I strongly preferred the tone of the octave down, here, over that of the octave up.

FILTER/FX2: I always love the sound of BOSS’ phasers. I released a whole song that grew out of the Step Phaser mode of the venerable PH-3! The Phaser algorithm here is no exception; Glassy, wide & beautiful.

Overtone is the surprise, standout hit! A new BOSS effect type for me, Overtone gives you control over your dry level, a modulated octave down, and another modulated tone an octave up. Sounding quite unique and very different from a simple harmonist or pitch shifter, it excels at creating an organ-like effect, especially with minimal dry signal mixed in. BOSS explains, “This effect uses MDP technology to add new harmonics to the sound, producing resonance and richness that was not present in the original sound.” This sounded so good for an octave-up along with dry signal, I preferred it to the other pitch-based effects.

DRIVE/SYNTH: Distortions and overdrives in general sounded great. Boost sounded like a tube preamp signal booster, which I liked quite a bit. In general, I think all of the drive sounds would have benefited from having a midrange control in addition to, or maybe even instead of, a simple tone control.

DLY/REV: Plate reverb is my all-time favorite type of reverb, and BOSS’ implementation here is good. Shimmer is pretty as well, but not quite as multidimensional as users who have had firsthand experience with purpose-built reverb pedals with shimmer modes may desire.

BOSS ME-90B Multi-Effects Pedal

BOSS once again provides an excellent PC-based app – Tone Studio – which makes programming and saving presets on the ME-90B considerably easier and a more visual affair. Unfortunately, I experienced considerable trouble getting BOSS’ ME-90B Windows 11 driver to recognize the unit, requiring several uninstalls/reinstalls and a number of other troubleshooting steps with assistance from Support. Ultimately, the installation was not successful on the initial computer I was using, but was successful on the first attempt on my music production system (also running Win 11). Once I was able to run Tone Studio with access to the USB-connected ME-90B, it was smooth sailing.

The ME-90B is one of the only floor effects processors of its size and feature set I’ve used that has the ability to be powered by batteries! Considering this unit can also function as a fast USB-C audio interface, phrase sampler, and more, the level of portability that can be achieved here is inspiring. But the flipside is that BOSS does not include an AC adaptor (while they do include your first four AAs). I went through that original quartet of alkalines in about 5 days, but I admit to having discovered I’d left it on for a few hours longer than intended on one or two occasions. The ME-90B smartly has an On/Off switch, so unplugging its input doesn’t disconnect it from power the same way it does on a typical battery powered, single stompbox, and I found I forgot to make use of that switch once or twice in the beginning.

One issue with the use of analog-style knobs on digital interfaces like this is that the physical knobs don’t indicate what settings are stored when loading a patch. And often, if you adjust them in hopes of discovering their current, hidden selection, their value/selection changes and you may not know what to change it back to if you want to backtrack. But BOSS has thought of this and has a solution! To reveal a knob’s stored setting, one simply holds down the [EDIT] button and turns the knob for the parameter to be checked. The knob’s value is shown in the display. When the knob’s position and value match, the tuning guides on both sides of the display light up. Kudos, BOSS! Aside from this super handy feature, there’s a user selectable option you can set via Tone Studio that alters the behavior of knob turns on a stored patch – from immediate alteration of that value, to change only occurring after the stored value has been reached.

The Bottom Line

At just under $400 street, The BOSS ME-90B is a very easy recommendation to make to anyone that can make use of even just two of the value propositions it offers, such as: multi-effects platform and audio interface, or phrase sampler and onboard treadle/expression pedal for Whammy effects, or even tuner and volume pedal and amp simulator – with user loadable IRs! BOSS has packed a metric ton of value into this little blue box, and it does much of what it can do very well. While it can’t be expected to compete with a flagship floorboard like the Line 6 Helix or Neural DSP Quad Cortex, it doesn’t aim to fill those shoes – and BOSS offers the GT-1000 for comparison in that category. Instead, it sits in more of a mid-market space between high-end, individual effect units and those fully featured and all-encompassing floor FX engines, but provides 75% of the value of a flagship at maybe only double the cost of a great single stomp. It’s hard to imagine any level of player not finding significant value in the ME-90B.


Sampling Frequency: 48 kHz
AD Conversion:24 bits + AF method
AF method (Adaptive Focus method) This is a proprietary method from Roland & BOSS that vastly improves the signal-to-noise (SN) ratio of the AD converters.
DA Conversion:32 bits
Processing:32-bit floating point
Effects:93 Types
Memories:36 (User) + 36 (Preset)
Phrase Loop:38 sec. (MONO)
Internal Tuning Detection Accuracy:±0.1 cent
Nominal Input Level:INPUT: -10 dBu, RETURN: -10 dBu
Maximum Input Level:INPUT: +7 dBu, RETURN: + 7dBu
Input Impedance: INPUT:1 M ohm, RETURN: 1 M ohm
Nominal Output Level:OUTPUT L/MONO、R: -10 dBu, PHONES: -10 dBu, SEND: -10 dBu,
Output Impedance:OUTPUT L/MONO, R: 1 k ohm, PHONES: 44 ohms, SEND: 1 k ohm,
Recommended Load Impedance:OUTPUT L/MONO, R: 10 k ohms or greater, PHONES: 44 ohms or greater, SEND: 10 k ohms or greater, BALANCED OUTPUT: 600 ohms or greater
Display:7 segments, 2 characters (LED), Tuning guides (LED)
Connections:INPUT jack, OUTPUT (L/MONO, R) jacks, SEND jack, RETURN jack: 1/4-inch phone type, BALANCED OUTPUT jack: XLR type, PHONES jack: Stereo miniature phone type, USB COMPUTER port: USB Type-C(R), Bluetooth ADAPTOR connector: Dedicated connector, DC IN jack
Power Supply:Alkaline battery (AA, LR6) x 4, or AC adaptor
Current Draw:195 mA
Expected battery life under continuous use:Alkaline battery – Approximately 6 hours
* This can vary depending on the specifications of the batteries, capacity of the batteries, and the conditions of use.
Accessories:STARTUP GUIDE, Alkaline battery (AA, LR6) x 4, Leaflet "USING THE UNIT SAFELY"
Options (sold separately):AC adaptor: PSA-S series, Bluetooth(R) Audio MIDI Dual Adaptor: BT-DUAL, Carry Bag: CB-ME80,CB-BU10
Width:443 mm / 17-1/2 inches
Depth:220 mm / 8-11/16 inches
Height:67 mm / 2-11/16 inches
Maximum Height:93 mm / 3-11/16 inches
Weight (including batteries):2.9 kg / 6 lb. 7 oz
Price: $399.99
author avatar
Sean Fairchild
Sean Fairchild lives and breathes bass. He has dedicated his life to the (illusive) pursuit of mastery of the bass guitar and the advancement of the instrument, and is constantly learning and growing as a musician. A bassist since the age of 13, Sean has spent nearly every day since with some kind of instrument in his hands. Beware: given the opportunity, he will talk your ear off about all his favorite tools of the trade!