Soundcore Boom Go 3i Review: Big Output, Untidy Treble

Ultraportable Bluetooth speakers are one of the busiest corners of the audio market, and the Soundcore Boom Go 3i arrives in it with a clear plan: put a genuinely loud, rugged, long-running speaker into a flat square that will clip to almost anything. Its acoustic architecture is inevitably limited by the format, but with 15 W of amplification and a BassUp 2.0 mode it sets out to sound unusually powerful, backed by a quoted battery life that stretches beyond 40 hours. Around that sit the things this class now takes for granted, such as shock resistance, a lighting show and a wrist strap, plus several it does not: Auracast support, a small indicator screen and the ability to work as a power bank. The Boom Go 3i arrived in March 2026 in four colours, black, white, blue and pink. The white unit assessed here ran firmware 2.5.0 with version 5.0.14 of the Soundcore app.

The Boom Go 3i does not try to reinvent the shape of an ultraportable speaker; it ticks boxes rather than springs surprises. It is a flat square with rounded corners, close in outline to a Bose SoundLink Micro (Gen 2) or a Marshall Willen II, and it is designed to lie flat, with no mechanism provided for standing it upright. By default, then, it disperses sound through 360 degrees.

On looks alone the rivals arguably keep the edge. Marshall's inimitable styling gives its speakers a real identity, and the slightly neo-retro Bose is the more pleasing object. Soundcore is not short of assets, though, and the main one is that tiny monochrome display, an element that immediately catches the eye.

Style aside, the build quality feels serious, with the Soundcore standing out for the density of its structure. Soundcore lists IP68 and a one-metre drop rating. Almost the entire chassis is wrapped in hard silicone, the remainder being the metal grille across the front. The one real complaint concerns the controls: the buttons are moulded into the silicone covering and feel very stiff as a result.

The speaker is easy enough to pick up by hand, but the supplied silicone strap is cleverer than most because it offers two attachment modes. The first loops around the back of the speaker so it can be hooked onto something thin, or simply take up less space; the second extends as a lanyard, to attach to a bag handle for instance. The strap stayed fastened during the recorded handling.

As so often, one of the few reservations concerns the USB-C port, which is not tucked behind a flap. Soundcore is evidently aware of the issue, because the display can flag up moisture detection. For visual entertainment, several strips of RGB LEDs are set diagonally into the front. The arrangement is surprisingly pleasant to look at and the lighting scenarios are numerous, but the mode remains heavy on power.

At 106 x 102 x 45 mm and 380 g, the Boom Go 3i is unquestionably an ultraportable, even if it is not the champion of the category. It is comparable to the Marshall and Bose models already mentioned and therefore bulkier than a JBL Go 5. It slips into any bag without difficulty, hooks onto almost anything and can be carried in the palm of one hand for very long periods. Small pockets, though, are out of the question; this speaker is no magician.

Unlike the Marshall Willen II it cannot stand upright, but its four non-slip feet keep it perfectly stable once laid flat. All would be well had the maker fully protected the product against accidental switch-on: a quick press of the power key is enough to wake the Boom Go 3i, which can easily happen if it is stored in a crowded bag.

Unsurprisingly for a portable speaker designed in 2026, the Boom Go 3i does without any wired input. There is no mini-jack, and no audio interface over the USB-C port. That port does go a little further than expected in one respect, however, because the speaker can double as a power bank.

Beyond the usual refinements of a modern Bluetooth chip, multipoint and Google Fast Pair chief among them, the speaker supports Auracast, allowing an unlimited number of units to be driven in mono. Only Auracast appears to be implemented from the LE Audio standard; the classic Unicast mode could not be detected directly from a compatible handset. Stereo has not been forgotten either, as a second Boom Go 3i can be paired either through the app or with a simple press on the Bluetooth key.

Anyone hoping for a microphone should move on. There is none, so there is no hands-free calling and no way to summon a voice assistant.

On the face of it the control layout is entirely conventional, split across two groups. One carries volume up, volume down and play, pause and track navigation; the other goes a little further. Alongside the usual power and Bluetooth pairing keys there is an Auracast shortcut and, more usefully, a multifunction button that steps through the lighting modes and the sound modes. The secret weapon of this small product is nonetheless the minuscule monochrome screen, well judged enough to show battery level, the active sound mode and special connections such as Auracast. It is not indispensable, but it is more practical and more complete than anything the direct competition offers.

The Soundcore app rounds things out. Clear and rich enough to add something real to ownership, it handles firmware updates as well as sound and lighting settings, while adding a few functions such as device location. As it stands, it is hard to ask for more: the lighting scenarios are plentiful, and there are several sound presets alongside a customisable nine-band graphic equaliser.

Soundcore is oddly reticent about the acoustic architecture of the Boom Go 3i. The product page limits itself to a very vague 15 W power figure and an exploded view in which a single circular driver of roughly 5 cm and one, possibly two, elliptical passive radiators can be made out.

The result is not at all bad, if not revolutionary: the sound is more energetic than it is genuinely balanced. There is real output, with obvious reserve in hand, but that power is not matched by perfect linearity.

The bottom of the spectrum, always the showpiece for a product of this kind, performs at roughly the level of a Bose SoundLink Micro (Gen 2). Extension is fairly good, the speaker reproduces the foundation of a track reasonably well and does not collapse too high in frequency. It also avoids excessive droning, at least in the standard mode. The BassUp setting is a little more pleasant to the ear, but also softer and less precise.

Soundcore has clearly taken the design to the limit of what it can do, which becomes apparent as the volume climbs. At 73 dB the Boom Go 3i copes without difficulty. Push harder and power falls away quickly, particularly from the transducer, which starts to suffer from 200 Hz. Beyond 80 dB, the imbalance becomes quite marked.

The midrange is reasonably even, giving a precise and natural account of voices, but the treble is more capricious, a range that runs through a series of oscillations. By ear a fairly clear imprecision appears up there, with instruments such as guitars sounding blurred, while a slight brightness is noticeable higher still, especially as the volume rises. That imbalance stands out against a JBL Go 5, which is not perfect in this register but is more even. The Boom Go 3i is rarely unpleasant to listen to, yet it is plain that a single wideband driver cannot cover both extremes without compromise, particularly as the decibels climb.

Technically, this is already more than respectable for the class. It is a shade more detailed than a Bose SoundLink Micro (Gen 2), if no better in dynamics, and what it mainly lacks is linearity, a shortcoming the equaliser unfortunately cannot correct. Spatialisation is a relative notion for a mono speaker, but the 360-degree dispersion is well handled, with acceptable directivity despite the flat placement. A conventional upright orientation, impossible here, would clearly improve the listening quality.

Soundcore makes much of the endurance of its creation, quoting up to 40 hours in Eco mode, which lowers the bass level, at 50% volume; 24 hours at 50% volume with BassUp; and six hours at full volume with BassUp and the lighting running.

Measured at 50% volume, with the lights off and the standard sound mode selected, the speaker reached 35 hours 30 minutes. With the volume pegged at 79 dB (1 kHz at 1 m) the figure came down to 19 hours, which remains exceptional. That places it among the best products of the type, and ahead of the Willen II, itself impressive for the format. The only disappointment is recharging, which is particularly slow and takes at least four hours.

Given the format, the closest rivals to the Boom Go 3i are the Bose SoundLink Micro (Gen 2) and the Marshall Willen II. The Soundcore has a less distinctive design and less treble finesse, but it holds its own on output and surpasses them in areas such as battery life and the usefulness of its display. The Ultimate Ears Miniroll struggles by comparison, mainly because it lacks power in the bass.