The Pedal That Makes Every Other Pedal Sound Better: MXR M108S Ten Band EQ

Most guitarists obsess over drives, delays, and reverbs. They’ll spend hours dialing in a fuzz tone, chasing the perfect shimmer, hunting down the right modulation speed. But ask the session player at Capitol Studios, the touring tech who keeps a stadium rig alive eight nights a week, or the bassist who has held down the bottom end for Primus for three decades, and they’ll tell you the same thing: the most important pedal on a professional board often isn’t the most exciting one. It’s the one that makes everything else work.

The MXR M108S Ten Band EQ is that pedal. Ten sliders, each covering a carefully chosen slice of the frequency spectrum, each capable of adding or removing up to 12 decibels of that slice. On its face, it sounds technical, even clinical. In practice, it’s the difference between a rig that fights you every night and one that sounds exactly right regardless of what room you’re in, what amp you borrowed, or what pickup configuration you switched to three songs ago.

This isn’t the flashiest pedal MXR makes. It doesn’t do harmonic shimmer. It won’t add chorus or phasing or reverb. What it will do is fix every frequency problem you didn’t know you had—and several you knew about but couldn’t solve. It sits on the boards of Grammy-winning session players, surgically precise metal guitarists, ambient experimentalists, and bass players who need to anchor a 90-minute set without losing the plot on the low end. That’s not bad for a box with sliders instead of knobs.

Origin: MXR’s EQ Legacy and the M108S Upgrade

MXR built its first graphic equalizer pedals in Rochester, New York during the late 1970s, at the same time the brand was developing the Phase 90, the Distortion+, and the DynaComp. The original Ten Band EQ—known simply as the M-108—became a fixture on professional rigs almost immediately. Studio musicians used it to shape a guitar’s frequency response the way a mixing engineer shapes a channel strip. Live players used it to compensate for stage acoustics, speaker cabinet resonances, and the brutal unpredictability of a PA that changes character in every venue.

Dunlop Manufacturing acquired the MXR brand in 1987 and continued producing the classic EQ pedals, but the original M-108 had limitations that became increasingly apparent in professional use: its noise floor wasn’t ideal for high-gain rigs, it lacked true bypass, and its housing wasn’t the most road-durable. The M108S addressed all of that. The “S” suffix signals a significant internal overhaul: noise-reduction circuitry was added throughout the signal path, the bypass switching was changed to true hardwire relay bypass (so the pedal has zero effect on your signal when disengaged), the housing was upgraded to lightweight die-cast aluminum, the LED indicators were made brighter for stage visibility, and—crucially—a second output was added. That extra output transforms the M108S from a tone-shaping pedal into a signal routing tool, enabling wet/dry setups, parallel amp rigs, and direct-to-board splits without a separate DI or router.

The M108S now runs on 18 volts rather than 9, powered by the included ECB004 adapter or compatible Dunlop power supplies. That higher voltage increases headroom across the circuit—more important in an EQ than almost any other pedal type, since clipping at an EQ stage produces distinctly unpleasant results and is frequently mistaken for gain staging problems elsewhere in the chain. At 18V, the M108S has substantially more headroom than its predecessors and handles hot active pickups and boosted signals without complaint.

Specifications

How It Works: The Ten Bands and What They Control

Understanding the M108S means understanding what each frequency band actually does to a guitar signal. Unlike a Tone knob, which sweeps a broad and somewhat ill-defined range, the M108S gives you ten precision windows into your sound—each one octave wide, centered on a specific frequency.

The two lowest bands, 31.25Hz and 62.5Hz, govern subsonic and bass fundamentals. For most electric guitars these bands live below or at the bottom edge of what the instrument physically produces, but they’re critical for bass guitar, seven-string rigs in low tunings, and for cleaning up woofy bottom end that makes a cab sound muddy at volume. Boosting 62.5Hz with a Les Paul in drop-D tuning adds physical weight to palm-muted passages. Cutting it fixes a room that’s turning your clean tone into a directionless rumble.

The 125Hz band covers upper bass and lower midrange—the zone where a guitar’s body resonance lives, where “thickness” is generated, and where mud accumulates on high-gain rigs. A small cut here can transform a boomy-sounding channel into something that sits in a mix. A boost adds weight to single-coil pickup rigs that feel thin through certain amps.

The 250Hz and 500Hz bands are the most powerful and dangerous controls on the pedal. These frequencies define the midrange character of a guitar more than any others. The 250Hz zone is where honk and boxiness live—a notch here cleans up the nasal quality of a boxy-sounding combo. The 500Hz area covers the thickest part of the guitar’s midrange: boost it and you move toward a compressed, warm lead tone; cut it and you add clarity and note separation to complex chord voicings.

The 1kHz band is where presence begins. This frequency sits right in the center of the guitar’s “attack” region—where a pick’s transient is defined, where single notes articulate, where a chord’s structure becomes readable in a dense arrangement. The famous “mid scoop” of many classic metal tones involves cutting here (and at 500Hz) while boosting the surrounding frequencies.

From 2kHz through 4kHz, the pedal controls the upper presence range—where guitar solos cut through a mix, where the pick noise and string “chirp” that defines a clean Strat tone lives, and where harshness accumulates when gain is stacked. Boost 2kHz for a forward, singing lead voice. Cut 4kHz to tame a pedal that bites uncomfortably through stage monitors.

The 8kHz and 16kHz bands govern treble sparkle and “air.” Boosting 8kHz adds brightness without the thinness associated with boosting at higher frequencies. At 16kHz, the M108S reaches the very top of musical hearing range—boosting here adds a sense of open, airy treble that can make a guitar sound more lively and dimensional. Cutting here softens a brittle-sounding amp without the fundamental brightness being affected.

Above all that frequency control, the Input and Output level sliders give you independent management of how hard you’re hitting the circuit and how hot the signal exits. This transforms the M108S into a clean boost (all band sliders flat, output slider up), a volume cut for sections that need restraint (output slider down), or a gain compensation tool after heavy EQ cuts have reduced overall level.

Famous Players: Confirmed and Honest

The M108S has 29 documented users on Equipboard, but as always, the spreadsheet claims and community databases require verification. Three prominent attributions—Josh Homme, Tom Morello, and David Gilmour—do not hold up under primary source scrutiny. Homme’s documented EQ pedal is the Boss GE-7 (confirmed via multiple rig documentation sources, including Custom Boards Finland’s detailed Josh Homme gear history). Morello’s EQ pedal is the DOD FX40B, used flat as a clean solo boost—confirmed via Premier Guitar Rig Rundowns and multiple gear documentation pages; the MXR 10 Band is mentioned only as a modern alternative for players seeking to replicate his approach, not as Morello’s actual pedal. David Gilmour has no confirmed MXR M108S primary source in any rig rundown, interview, or official documentation. These three are legitimate EQ users and fascinating subjects for tone discussion—but they didn’t play this particular pedal.

Two confirmed users are worth examining in detail.

Jerry Cantrell

The Alice in Chains guitarist and primary songwriter has the most well-documented M108S connection. In Premier Guitar’s “Jerry Cantrell’s Pedalboard & Amps for I Want Blood Tour 2024” video, Cantrell’s full touring board is shown at the 1:48 mark, with the M108S clearly visible as a core component. This is the same rig that produced the material on I Want Blood (2024), Cantrell’s third solo album and a record notable for its layered, compressed, deliberately weighty guitar tones.

For Jerry Cantrell, the M108S is part of a broader approach to tone that treats the signal chain as a precision instrument rather than a collection of colorful stompboxes. His board on the I Want Blood Tour includes MXR Smart Gates, an MXR Timmy, a Strymon Ola, MXR EQs, a Boss DD-500, an MXR EVH Flanger, a Boss CE-5, an MXR Poly Blue Octave, and an Ibanez TS808HW—a rig that demands careful frequency management at multiple points. The M108S handles the macro-level frequency shaping: the fundamental EQ curve that makes every other element sit correctly relative to the amp and the room.

Cantrell’s guitar tones, both with Alice in Chains and solo, are defined by a specific midrange emphasis combined with controlled low-end weight. The M108S’s ability to dial in precise boosts at frequencies like 500Hz (for body) and 2kHz (for presence) without introducing the coloration of an overdrive pedal makes it the right tool for that kind of precision shaping.

Les Claypool

The Primus bassist and gear eccentric has a documented relationship with MXR’s Ten Band EQ series confirmed directly on the Jim Dunlop website, which lists Les Claypool as an MXR Ten Band graphic EQ user. Claypool’s use case is different from a guitarist’s but arguably more instructive: his approach to bass tone involves layering multiple signal chains, heavy filtering, and precise frequency management to maintain clarity across an extremely wide dynamic and registral range. The Ten Band EQ gives him the control to prevent low-frequency information from overwhelming the arrangement while preserving the midrange punch that defines his slap and pluck articulation.

While Claypool isn’t in the guitarist database, his use of the pedal points to one of the M108S’s most important characteristics: it’s not exclusively a guitar tool. Any instrument benefit from ten bands of precision frequency control, and the pedal’s 18V headroom makes it safe for active electronics and hot bass signals.

Adam Jones

Tool’s guitarist is listed on Equipboard as an M108S user with 29 documented pro artists, and the connection is credible given Jones’s documented approach to using EQs as precision control tools in his multi-amp rig. However, multiple independent gear documentation sources list his documented EQ pedals as the DOD FX40B and Boss GE-7 rather than the MXR M108S specifically, and no Premier Guitar Rig Rundown confirms the M108S explicitly on his board. Adam Jones is included here with an honest caveat: the M108S attribution is plausible and widely documented in community sources, but primary-source confirmation from a Rig Rundown or official interview was not found. His documented approach—using EQ pedals to bridge tonal differences between multiple blended amps—is exactly what the M108S excels at, making the connection functionally credible even if the specific model attribution remains secondary-source only.

Tone Recipes and Practical Settings

The M108S’s value isn’t in one “good” setting but in the range of specific problems it solves. Here are seven documented approaches, each targeting a real use case.

Signal Chain Placement

Where you put the M108S in a signal chain determines what it does. Placement before drives and overdrives shapes what tone goes into those gain stages—boosting low-mids before a Tube Screamer makes it progressively darker and more compressed; cutting them makes it tighter and more aggressive. This is effective but requires understanding that the EQ is now part of your gain structure, not just your tone.

In the effects loop, the M108S operates post-preamp, shaping the amp’s output response rather than its input gain. This is the most common professional placement and the one most analogous to the studio mixing engineer’s use of a channel EQ. The pedal here compensates for room acoustics, adjusts how the amp’s inherent voicing sits in a mix, and provides the clean boost function without interacting with any gain pedals. It’s also where the dual-output capability becomes most useful: the secondary output can feed a DI or a second amp while the main output continues to the primary cabinet, all with the same EQ curve applied.

Bass in front of the amp (before the input, in a guitar’s traditional pedal chain) affects everything from preamp saturation to the behavior of downstream pedals. For bass players and guitarists using the M108S as a fundamental tone-shaping tool rather than a gain-staging device, this placement provides the broadest control at the cost of influencing every gain stage that follows.

How It Compares

The MXR M108S sits at a specific intersection of band count, professional build quality, and price that sets it apart from its closest competitors.

Against the MXR M109S Six Band EQ, the M108S’s advantages are clear: four additional bands, particularly the extended low-frequency coverage at 31.25Hz and 62.5Hz that the six-band version omits, plus the dual output. The M109S is smaller and costs less ($125.99 MSRP) and is the right choice for players who only need to address midrange and upper frequencies. For bass players, extended-range guitarists, or anyone who needs to manage genuine low-frequency content, the M108S’s extra bands are essential rather than optional.

Against the Boss GE-7—the most common alternative and Tom Morello’s documented choice—the comparison is closer than the price difference ($159.99 vs. ~$99) suggests. The GE-7 has seven bands and runs on 9V (battery or adapter), making it more pedalboard-friendly for players with limited 18V outputs. Its noise floor, however, is a known issue in high-gain rigs—the GE-7 in a loop behind a high-gain preamp can introduce significant hiss, particularly if the sliders are moved more than a few dB from center. The M108S’s dedicated noise-reduction circuitry addresses this directly. For clean-to-moderate-gain rigs, the GE-7 is a legitimate and less expensive option. For high-gain or effects-loop applications, the M108S’s quieter operation is worth the premium and the 18V requirement.

Against the Source Audio EQ2, a digital two-channel EQ with app-based editing and MIDI control, the M108S trades digital precision and programmability for analog simplicity and hardware interaction. The EQ2 allows precise recall of settings, stereo operation, and 10-band control with far more granularity than the M108S’s physical sliders. If you need MIDI recall or true stereo EQ for a complex rig, the Source Audio unit wins. If you want to grab a slider on stage and adjust by ear without navigating an app, the M108S’s physical interface is the right tool.

The older MXR M-108 Ten Band Graphic Equalizer (the pre-S model, listed separately with 61 documented Equipboard users) shares the same frequency layout but lacks the noise reduction, true bypass, and dual output of the M108S. Used examples of the original M-108 trade for less than new M108S units, but the professional improvements in the S version are meaningful enough that the price premium is justified for regular use.

Buying Guide

The M108S is available new from all major music retailers at the $159.99 MSRP, with street prices running $129–150 USD in 2026. Used units in excellent condition appear regularly in the $80–110 range, which represents exceptional value given the pedal’s build quality and professional pedigree.

When buying used, confirm the ECB004 18V adapter is included or budget for a compatible adapter—the pedal does not run on standard 9V center-negative supplies, and standard guitar pedalboard power supplies often lack 18V outputs. Verify which Dunlop power supplies support the M108S: the DC Brick, Iso-Brick, and Mini Iso-Brick all have appropriate outputs; most other brands’ standard units do not unless they specifically offer an 18V tap.

The slider caps on used units occasionally show wear but rarely affect function. Check that all ten band sliders move smoothly and return to center correctly. Test both outputs with a known-good cable. With true bypass, the pedal should pass signal transparently when disengaged regardless of slider positions—if the bypassed signal sounds different from a direct guitar cable, the bypass switch may need cleaning.

The M108S is available as a single unit; no standard version or variant exists. The M109S (six bands) is the smaller sibling, not an alternative version of the M108S. The vintage M-108 is a predecessor, not an upgrade.

Ownership Notes

The bright blue LEDs on the M108S sliders are frequently mentioned in user reviews as genuinely intense—”they burn out your eyes,” as one Equipboard reviewer puts it. Multiple users have documented replacing the stock LEDs with orange or amber alternatives (EDGELEC 5mm diodes are the commonly recommended part) for more comfortable stage visibility. This is a personal preference modification and doesn’t affect the circuit’s function.

Noise behavior in high-gain rigs is markedly better than the older M-108, but the M108S isn’t silent. Running large amounts of boost (6dB or more on multiple bands simultaneously while also boosting the Output) in a high-gain effects loop will produce some noise floor rise. The documented community workaround is to use the pedal more as a cut-based EQ than a boost-based one: instead of boosting 2kHz and 4kHz for presence, try cutting 250Hz and 500Hz to achieve a similar balance relative to the boosted bands. This keeps slider positions closer to center and minimizes gain accumulation through the circuit.

The dual-output feature is more useful than it appears at first inspection. Beyond the obvious wet/dry amp split application, the secondary output can run to a DI box for a direct monitoring feed to front-of-house (useful in IEM-based live setups where the stage has no amp at all), or to a tuner for buffered signal splitting without a separate buffer or tuner pedal on the board. Players with loop switchers can use the secondary output to maintain a continuous tuner feed that bypasses the loop switcher entirely.

Keep the M108S away from single-coil pickup guitars if you’re running heavy boosts in high-gain chains—not because of anything inherent to the pedal, but because boosting the upper midrange and treble of an already-noise-susceptible single-coil in a high-gain loop amplifies both the desired signal and any electromagnetic interference in the room. The pedal’s noise reduction handles its own circuit noise; it doesn’t filter incoming noise from the guitar or other sources.

The Bigger Picture: EQ as Practice

Learning to use the M108S well means learning to listen analytically—not just appreciating a sound, but identifying what frequency behavior is causing problems and acting on that information with a slider rather than a replacement cable or a new amp. It’s a fundamentally different relationship with tone than most guitarists develop with drives and delays, and it takes time.

The standard recommendation from professionals who use graphic EQs daily is to start with all bands flat and the pedal on, listening carefully to whether the bypassed and engaged signals sound different (they shouldn’t, with true bypass and flat settings). Then introduce one change at a time—boost a band, listen for what changes, cut it back if it doesn’t help. This systematic approach is slower than grabbing several sliders at once but produces more reliable results and builds genuine frequency awareness that transfers to every other tool in the signal chain.

Jerry Cantrell’s precise, controlled guitar tones; Les Claypool’s extreme and highly individual bass sound—neither happened accidentally. Both players use EQ as an active compositional tool, not a last resort when something sounds wrong. The M108S makes that approach available at a professional level for $159.99 retail. That’s not nothing.

Internal Links

Related MXR pedals in this series: the MXR M300 Reverb for Jerry Cantrell’s spatial processing, the MXR M117R Flanger for classic MXR modulation, the MXR M104 Distortion+ for the pedal the M108S most commonly precedes in a gain chain, and the MXR M101 Phase 90 for another corner of the original MXR lineup. For players researching the artists who inform the M108S’s most famous uses: Jerry Cantrell, Adam Jones, Tom Morello, David Gilmour, and Josh Homme.

Frequently Asked Questions