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Dynaudio BM Compact MkIII & BM9S II

Active Monitors & Subwoofer
Published February 2015
By Paul White

We check out this compact yet powerful 2.1 speaker system from Danish makers Dynaudio.

Designed and built in Denmark, Dynaudio speakers may have slipped off the pro-audio marketing radar over the past few years, but they have most certainly not disappeared — and now they’re back with some new offerings that are very well suited to the project studio. The system we’re looking at here comprises a pair of BM Compact MkIII monitors teamed with a BM9S II sub, though these speakers are available separately. While not budget speakers, the price is not unreasonable for the quality on offer and is still well below what you can pay for more esoteric offerings that may offer little in the way of improved performance.

Dynaudio describe the two-way BM Compact MkIII as a premium-quality, small-format nearfield monitor, and they make special mention of its wide dynamic range. Both of its drivers use aluminium voice coils driven by Class-D amplification. Interestingly, the speakers come packaged with IsoAcoustics ISO L8R155 speaker stands, which offer both decoupling from the desktop and the ability to angle the speakers correctly. Though not included in the kit, the speakers are compatible with the optional Dynaudio Professional Volume Box, allowing precise level control in setups that have no dedicated monitor controller.

Dynaudio BM Compact MkIII & BM9S IIThe BM Compact MkIII is, as its name suggests, a small speaker (170 x 260 x 211 mm), and it comes loaded with a long-throw 5.7-inch woofer working alongside a 1.1-inch, Ferrofluid-cooled, soft-dome tweeter in a rear-ported cabinet finished in black simulated wood grain. Not only does the woofer use aluminium wire, but its one-piece thermo-formed MSP cone sits in a cast-aluminium basket, where its 38mm voice coil is wound onto an aluminium former. Its dust cap is vented — a feature of all the Dynaudio monitors I’ve encountered so far. The tweeter also uses an aluminium front plate, so it seems Dynaudio have definitely been trying to keep the weight down. A metal ‘roll bar’ protector is fitted over the tweeter, while the woofer sits slightly proud of the baffle within a thick aluminium trim ring. A power-on LED is fitted to the rear panel, but there’s no indiction from the front that the speakers are turned on.


As with an increasing number of active monitor designs, the input is converted to digital data, where a DSP fulfils all the necessary crossover (second order at 2.1kHz) and adjustment functions. A pair of 50W Class-D amps delivers the necessary power (these speakers are specified as being capable of SPLs of up to 116dB peak at one metre). Their frequency response is 49Hz to 24kHz (the cabinet itself is tuned to 58Hz), and there are high-pass, HF, MF and LF analogue filters to allow you to adjust the response to compensate for room placement, or for use with a subwoofer. These are all accessed via four three-way slide switches on the rear panel, where the high-pass filter offers 60Hz or 80Hz options for use with subwoofers that don’t provide a high-pass output. The input sensitivity can be switched to -10dBV, 0dBu or +4dBu to accommodate professional or consumer audio levels. Either balanced XLR or unbalanced phono input connectors can be used, but there’s no jack option. Note that the mains connectors are two-pin types, not the usual IECs.

The BM Compact MkIIIs offer extensive options for tailoring the sound to the room they’re in, as well as to user preference.The BM Compact MkIIIs offer extensive options for tailoring the sound to the room they’re in, as well as to user preference.While the BM Compact MkIII makes a perfectly capable stand-alone monitor for smaller rooms and desktop setups, it can also be paired with Dynaudio’s BM9S II sub to create a full-range system suited to larger spaces. Though other sub pairings are possible, the BM9S II was designed to work with the BM Compact MkIII (and also the BM5 MkIII monitors). Its fairly compact size, at a little under one cubic foot (290 x 290 x 300 mm), and its weight of under 10kg, should win it a lot of friends. A fabric grill covers the front-facing driver and the cabinet, like that of the Compact MkIII, features a simulated black wood-grain finish.

Fitted with a four-inch aluminium voice coil, the 10-inch, long-throw woofer is loaded into an unported enclosure and driven by 200W of Class-D amplification. The rear panel has all the controls and connections you’d expect to find on a larger sub, such as a polarity invert switch, a choice of LFE or slave mode, and continuously adjustable crossover filtering, from 50 to 150 Hz for the mains and high-pass settings of Off, 60Hz or 80Hz. Both the phase and volume controls are bypassed when the sub is switched to slave mode. Despite its diminutive size, the BM9S II reaches down as far as 29Hz and provides all the level needed to match the BM Compact MkIIIs.

All the sub’s inputs and outputs are on XLRs, and there’s adjustable input sensitivity as well. Both the sub and the BM Compact MkIIIs meet the now familiar European requirement to fall asleep when not in use for 20 minutes or so to save power, though this function can be disabled via a slide switch if not required. Power for the sub comes in on an IEC connector.


Because the BM Compact MkIIIs have switchable input sensitivity, and because the sub has a variable high-pass output to feed them, the balance between the tops and the subs needs to be set by the user — there’s no preset operating level. As usual I set it by ear so that there was just enough level from the sub that you miss it when it is turned off, but without enough to be too obvious. There’s also the issue of finding the best sub placement in the room, but in smaller studios that can actually help in smoothing the bass response as the sub can go where it works best, not necessarily where the main speakers are.

The subwoofer has all the connections you’d expect, as well as a  variable low-pass filter and a  polarity invert switch.The subwoofer has all the connections you’d expect, as well as a variable low-pass filter and a polarity invert switch.Firstly then, even used on their own the BM Compact MkIIIs still manage to deliver an impressive amount of low end given their size, as long as you don’t need very high volumes. As with all smaller speakers, they sound tighter and have a better sense of focus when mounted on good speaker platforms, so it’s great to have the IsoAcoustics stands included (you can read a separate review of these at Some of the DSP-assisted monitors I’ve tried have been a little noisy, but these fare pretty well. There’s a tiny amount of hiss if you stick your ear right up against the tweeter in a quiet room, but nothing that would be audible in normal use.

Overall, the sound has the expected Dynaudio attributes, which means it comes over as well balanced, with crisp and open-sounding highs that do not at all sound harsh. There’s also a creditable sense of front-to-back perspective in the sound, especially considering that these are not esoterically priced speakers. Importantly, the speakers are able to expose the flaws in poor mixes as well as sounding good on high-quality material. Voices come over as sounding extremely natural, which is always the hallmark of a good speaker.

Add the sub and the lows become deep and visceral, far belying the small size of the sub. Taking the low-end load off the main speakers also means you can work at an even higher SPL without the speakers sounding strained, though to be fair they can go pretty loud anyway before they start to sweat. Fortunately, the lows always manage to stay adequately tight-sounding, as the use of a sealed subwoofer cabinet helps reduce overhang.

Overall it’s good to see Dynaudio bringing products like these to the market, as there are many owners of smaller studios prepared to pay a little more for quality, and the BM Compact MkIIIs certainly deliver, whether used on their own or teamed with the sub.


There’s no shortage of monitors to choose from, but similarly priced 2.1 systems also known to perform well include models from Adam, Eve, Genelec and AVI.

Published February 2015