MMR Gáe Bolg: Get It On – An In-Ear Monitor Review



MMR’s 2020 Gáe Bolg is a bold, full and fairly warm-sounding monitor. It’s driven by a 2kHz peak, which generates larger, chestier-sounding instruments with weight and gusto behind them. It leans further towards baritones, trombones, cellos and the like, positioning them closer to you than their higher-pitched counterparts. And, at the same time, it imparts this heavier, less vibrant, less breathy tonality towards the latter too. Violins will have more body to them, trumpets will seem less bright and direct, and electric guitars will have more distortion or chug than presence or bite. Despite that, to MMR’s credt, the Gáe Bolg is able to achieve its response while deftly avoiding mushiness or congestion. Relatively-relaxed lows and low-mids give those instruments room to breathe. And, despite its tapered upper-treble, it sports enough extension to let clean air flow as well. Ultimately, it’s a rich, hearty, mid-biased sig with enough articulation and air cutting through.

Spatially, I feel, is where this Gáe Bolg has furthest exceeded expectations. Though it doesn’t necessarily have the largest space I’ve ever heard, as Joseph Mou’s IEMs previously have, it makes fantastic use of the real estate it’s been given. This Gáe Bolg is a precise imager with striking left-right separation. The two drum kits on Snarky Puppy’s Gemini, for example, are panned gorgeously. And, the ride towards the end of Tarova (from the same record) showcases superb accuracy too. When it comes to depth, as mentioned in the previous paragraph, it’ll depend on which frequency range that instrument occupies. Tracks led by female vocalists or flutes will have a more even, spherical stage to them, while male vocalists and trombones will instantly leap out at you; certainly more on the intimate side. But, again, that precision and stereo spread ensures that it’s all as tidy and tightly-layered all the while. Lastly, while the in-ear has a more relaxed, back-foot tone, it is able to eek out a fair bit of contrast, especially in the mids. So, its smoothness comes with good punch and precision too.


I’d argue the Gáe Bolg’s bottom-end will be better-remembered for its timbre and character than physicality or impact. It wasn’t tuned to be a crowd-pleaser, necessarily, with exaggerations in rumble or punch; not the kind to thump the chest or rattle the skull. I’m personally more taken to its melodic qualities. A slightly longer decay allows the bass to sing a hair more, almost, which is a pleasure to hear with toms. And, it’s a superb tool for discerning between kick drums too; really helps bring out those individual characteristics. These lows also work particularly well with contra basses. It balances the grunt of the string plucks with the actual notes resonating off this instrument quite nicely. Then, it’s also got that realistic scale, where they grow louder as the bassist travels further down the range. Though it’s still a ways away from a true DD in raw verve, the Gáe Bolg ultimately delivers lows that excel in nuanced musicality with an organic, character-filled tone.

With all that said, however, the Gáe Bolg is by no means a flimsy performer down low either. The IEM actually showcases a fair amount of low-end extension, which serves as a tactile, guttural foundation for the melodic qualities I described up above. With the vibrant tonality of the kick drum comes the thump as well, and the same goes for tom-toms and acoustic basses. So, though, again, it doesn’t quite match the texture or physicality of a genuine diaphragm, that blend it is able to achieve between tactility and melody still elevates it beyond most all-BA woofers I’ve heard in the price level. Clarity-wise, MMR have cleverly included a light drop throughout the upper-bass, which separates this Gáe Bolg’s lows from its lower-mids. As a result, you get a clear bass that’s encased in clean air; minimal in bleed, despite its longer decay. That extends all the way down to the sub-bass, which shines through the ensemble cleanly, even with its closer-to-neutral positioning.


To me, the Gáe Bolg’s tuning is midrange-driven; the centre-mids, to be exact. It has a palpable rise towards 2kHz, which imbues vocals with weight, thickness and size. Baritones like Michael Bublé gain presence – gusto – while female singers like Tori Kelly or Ariana Grandé will have a hair more smokiness to them; not as light or nasally as more neutral or clinical monitors may make them sound. Lead instruments span large, and they’re forwardly positioned too. So, it isn’t an in-ear for fans of tight, compact notes lining the rim of the stage. Neither is it for those who want their instruments on the drier side. But, those who like their trombones and saxophones meaty and hearty will find lots to love in this Gáe Bolg. It ends its 2kHz rise with a dip between 3-4kHz. That cuts out those brassy, tinny notes you may find on trumpets, as well as lots of the clang you may hear on snare drums. Again, if you like your horn stabs bright and zingy, it may not be ideal. But, to me, it does well to maintain balance across the spectrum and prevent the midrange focus from becoming too unnatural.

Technically, lots of credit has to go to how much control MMR have lent the Gáe Bolg’s mids, despite the thicker, chestier timbre. Instruments, while rich and full, don’t spill into or mask each other. Again, this IEM is an impressively tidy imager, which goes a long way with multilayer guitar parts, string quartets, etc. In terms of resolution and layering, the Gáe Bolg, despite the thickness, doesn’t come off veiled or mushy. Notes have definition to them, and they have good pace as well. So, this stage is always allowed to breathe; never saturated with too much going on at once.  Still, it’s definitely more of a single-focus IEM, rather than a big picture one. Its 2kHz-leaned sig naturally gifts it an up-close look at instruments, which, again, contributes to texture and detail. Horns, electric guitars and the like all seem rounded and complete; their ranges perceivably presented in full. Lastly, in tonal accuracy, it’s likely richer and thicker than what most would call neutral. The high-mids are flatter too. But, ultimately, I feel the Gáe Bolg does coloured right; unabashedly bold, yet clean and refined.


Up high, the Gáe Bolg’s got somewhat of an L-shape; a healthy 5-6kHz peak, which then gradually falls to 10kHz, where it peaks for the final time. The former is where it draws most of its articulation. It adds attack to snares and cymbals, and it lends guitars their bite too. It’s not the crisp, pointed kind of articulation, I’d say. There’s a wetness and body to the attack that softens it on the ear. It makes it more agreeable to different users and chains, but not to the point of feeling diffuse, I think. The upper-treble extends very well, adding air and integrity to its image. It’s definitely not overdone, which, again, trebleheads may not enjoy. But, I feel those after a more relaxed, uncoloured, unexaggerated tone will prefer this timbre. In terms of tone, I’m not the hugest fan of how the highs’ been integrated with the rest of the frequency response. The 3-4kHz dip means the mid-to-treble transition isn’t the smoothest; not as seamless as some of the more reference IEMs I’ve heard in the past. But, it’s a tiny nitpick that, in some ways, is an inherent compromise of the sig, so I won’t rail on it a lot.

In definition, these highs do well to pop against this monitor’s backdrop. Ride cymbals and chimes come through cleanly with good ring. Cymbal shimmers slide from soft to loud nicely too. So, while it’s not the sharpest treble in the world, you surely won’t be losing out on much nuance at all. The only sounds you might miss are those strong sibilants from vocals, or string plucks and half-open hi-hats; the tizzy-er, slightly more abrasive sounds. Whether or not that’s a good thing will, as always, come down to taste. In imaging and depth, the Gáe Bolg continues to impress up top with wide stereo spread and deep layering. Ride cymbals sound genuinely further away on softer jazz tunes. And, on drum duets like Dave Weckl and Jay Oliver’s rendition of Higher Ground, each drummer’s hi-hats and cymbals are precisely placed too. Lastly, in terms of texture, MMR have tuned these BAs nicely. Different ride bells sound distinct, and you can pick out different bows and violins in a string section fairly well. So, the Gáe Bolg caps the sig with highs as unselfish as they are melodic and refined.

Pairing with Eletech’s Prudence

Eletech kindly agreed to loan me this Prudence for the purposes of this review, and I’m extremely glad they did, because the difference I’m hearing between is much larger than I expected. The Prudence adds changes that counteract a few of the Gáe Bolg’s distinct flavour; the bold, intimate, meaty sound I’d been describing throughout the review. Much of it has to do with the cable’s upper-bass and lower-midrange dips. It tightens what was once a very loose, rich region and made instruments like toms and trombones a lot more controlled. There’s more bite to its mid-treble too, which adds clarity to snares and cymbals. I’d classify it more as a neutral tone now, so which variant to go for will depend heavily on taste too.

However, the objective improvement I think the Prudence adds to the mix is space. The image completely opens up with the cable swap, and introduces quite a bit of holography to this IEM as well. Some hard-panned elements, say, on Dimas Pradipta’s 9 Range Road now sit out-of-head. And, there’s a lot more clean air between its notes too. If you can afford it, I personally believe the Complete package is worth that price hike. At the very least, if you already have aftermarket cables in your collection, swap the Gáe Bolg’s stock cable for one immediately. But, if you do prefer the meatier, bolder, warmer sig I’ve been describing throughout the piece and you don’t mind the stage, then you can save some cash on the Lite too.

General Recommendations

MMR’s Gáe Bolg lives somewhere between neutral and warm, making it a versatile universal that isn’t short on flavour or character. Below are what I feel to be its greatest strengths, and why it may potentially stand to be your next daily driver:

An intimate, meaty-sounding, yet versatile everyday-in-ear: The Gáe Bolg reminds me of in-ears like Stealth Sonics’ C9 Pro or Vision Ears’ EVE 20; not in tone, but in how versatile they are despite their colourations. It complements those rich, gutsy instruments with superb layering and precision, allowing that voicing to work with more genres than one would typically expect. It resembles Campfire’s Andromeda too in this sense, but on the opposite – warmer – end of the tonal spectrum.

A low-end that digs, but without excess rumble: This Gáe Bolg’s BA-driven low-end showcases a surprising amount of depth and tactility. It digs, but it never distracts like the stereotypical dynamic driver sound would. And, the mid-bass provides a musical melody to it at the same time. That is perfect if you want your kick drums to thud without thumping your skull in every half-measure, or if you like your acoustic basses nicely balanced throughout the entirety of their frequency ranges.

Richness and euphony with no compromise in articulation: Despite the Gáe Bolg’s fullness and warmth, it’s not an IEM that’s dark or rolled-off either. The high-end’s got plenty of snap for percussion or keys, and vocalists, though elevated in terms of chestiness and heft, still have a fair amount of balance between their fundamentals and their sibilants. So, if you need your rich, bold-sounding instruments to have bite to them as well, the Gáe Bolg should have enough of it to satisfy most.

This Gáe Bolg’s colourations, however, don’t come without compromise. Those bold, intimate, full-sounding instruments need accommodation too. So, if these following three are aspects you very much need, MMR’s latest is likely to fall short:

An expansive, three-rows-back soundstage: The Gáe Bolg’s boldness and intimacy naturally errs it away from those relaxed, laidback and distant-sounding profiles, where instruments line the outer rim of the space. It’s not a UIEM for audiophiles searching for a more holographic or out-of-head experience. So, do keep that in mind if you’re considering this Gáe Bolg.

Hard-hitting, chest-thumping, skull-rattling lows: Though the Gáe Bolg is capable of impressive low-end tactility and depth, they aren’t so much scene-stealers or show-stoppers either. They’re definitely above neutral in quantity, but, at the same time, they’re closer to neutral than basshead, for example. So, if you fall into the latter camp, the IEM may not be for you.

A generous helping of upper-treble presence and air: This Gáe Bolg, though nicely-extended and airy up high, doesn’t really push it in terms of quantity either. It has a tad of a taper, and I’d wager most audiophiles would sit it on the warmer side of the spectrum. So, if you are a treblehead, MMR’s Gáe Bolg – at least, quantity-wise – isn’t entirely guaranteed to please

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About Author

Church-boy by day and audio-obsessee by night, Daniel Lesmana’s world revolves around the rhythms and melodies we lovingly call: Music. When he’s not behind a console mixing live for a congregation of thousands, engineering records in a studio environment, or making noise behind a drum set, you’ll find him on his laptop analysing audio gear with fervor and glee. Now a specialist in custom IEMs, cables and full-sized headphones, he’s looking to bring his unique sensibilities - as both an enthusiast and a professional - into the reviewer’s space; a place where no man has gone before.

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