Hardware Reviews

BK XLS300, a sub of delights

bk xls300 review

BK XLS300 active subwoofer

My take on the BK XLS300 has taken an inordinate amount of time to write. My life has been hectic of late and during any downtime that I’ve had, I’ve wanted to enjoy this product rather than sit down to write about it. But the time has finally come to commit my thoughts to text about a little-known subwoofer brand which really needs to be experienced by a wider audience.

The company

BK Electronics are probably a new name to many although they’ve been involved with subwoofer design and manufacture in Southend-on-Sea since 1992. They began by supplying REL Acoustics and production spiralled to a thousand units a month. Turnover was increased by involvement with five hi-fi brands and its designs have won countless awards. Among its successes is the acclaimed AB3A active sub from Rogers as an accompaniment for its LS3/5A mini monitor. Today they also operate in a parallel market and regularly supply sound systems to major cinema chains with what they term Big Boys’ Toys while also expanding their own BK brand which is sold direct to end-users to offer substantial savings over the standard distributor/retailer chain.

The company is proud that all BK logo products are Made in Britain with its Essex electronics centre, dedicated cabinet works and 6,000 sq ft spraying and powder coating facility. When sourcing components, BK selects local tradesman and specialist UK suppliers. The front panels, metal feet, PCBs and cartons are amongst some of the parts sourced within a 20 mile radius of the factory, while wood for the cabinets is carefully sourced from sustainable forests.

bk xls300 review


The BK XLS300 is described as a 300W sub-bass amplifier, although audiophiles would use the term active subwoofer. A refinement over the earlier XLS200, the unit remains committed to the Peerless XLS10 10-inch long-throw bass driver, downward-firing in an 18-litre enclosure to create both a tight and fast LF response in a compact design. It now benefits from the same Class-A/B amplifier circuit as the up-market Platinum range, and has been uprated to 300W.

The XLS10 driver is designed with an extra-long stroke and incorporates shorting rings that help to lower distortion. It also has a low Qts and, even in an 18 Litre enclosure, has a system Qb that is lower than 0.5; it is therefore critically damped for an excellent transient response with virtually no overhang.

By user request, the new BK XLS300-DF incorporates a filter bypass switch to manage the bass frequencies for home theatre use, leaving the built-in filtering to deal with the bass management on the high-level input for audiophile use.

The package includes a comprehensive manual, detailing connection and operation, plus necessary accessories such as a 3m RCA interconnect, a set of M8 spikes and mains lead. There is also the option of a high-level Neutrik lead to connect to an amplifier’s speaker terminals where there is no dedicated sub-output available.

bk xls300 review

Features highlighted included continuously-variable frequency control, audiophile-grade toroidal transformers, gas-tight Neutrik connection for long term consistency of sound quality, separate controls for high and low-level input adjustment, simultaneous connection of high and low-level sources, ASP automatic speaker protection for audibly transparent driver protection, four 16A output devices for effortless current control, auto switch-on function which can be disabled via a switch, and an IEC power socket – all covered by an two-year warranty.


The supplied manual is detailed to provide for a swift connection, using sub-out where provided (such as on my Denon 5.1) or to an amp’s speaker terminals as with my Hegel H190, using either BK’s RCA lead supplied or the optional Neutrik high-level connector which is offered in various lengths from 3m to 20m, as required.

I found the BK XLS300 easier to install than some other subwoofers and was soon up-and-running, connected to my Hegel 190 feeding my trusty Harbeth M30.1 monitors. Placement is also straightforward, helped by the unit’s compact design and downward-firing drive unit. The cabinet was easily accommodated in the listening room. I attached the feet supplied before making the necessary settings using the detailed instructions supplied. There is the choice of frequency at which the subwoofer takes over from the main speakers, and this can be adjusted to give a seamless integration. Then there’s the amount of output from the sub to decide on, finally there is an option to adjust phase, if required, to provide partial cancellation of the frequencies around the selected crossover point. The aim being to select the position which subjectively offers the tightest, cleanest bass. I soon found that, optimally, it was not a case of having the subwoofer operating at a high volume, rather to have it gently supporting the main speakers.

But why bother with a subwoofer? Well, my modestly sized BBC-style loudspeakers have stunning midrange performance coupled to a delightful treble. But they are not, in any way, known for producing seismic bass. In fact, in the BBC environment, they were designed for, an abundance of bass would have only caused interference to adjoining studios.

Producing sounds between, typically, 20Hz and 200Hz, subwoofers enable compact speakers to produce a fuller sound, improving the reproduction of instruments such as kick drums, bass guitar, and pipe organ, as well as movie sound effects. There is a sense of not merely hearing but ‘feeling’ sounds, and most important when trying to enjoy bass-heavy material such as hip hop, watching full-throttle action movies or, in my case, wallowing in heavy-duty organ recitals.

bk xls300 review

But that’s only part of the story. And, for a long time, I thought the only part. Adding a sub to a two-channel system improves the overall sound. Typically, the dynamics become more compelling, the soundstage widens, and the stereo imaging becomes more accurate. This is true with analogue as well as digital sources to help create a more vibrant, all-encompassing sound.

Sound quality

I have tried a number of different subwoofers in my system over the years and enjoyed the experience of them all. Most have been on the larger side, though, and not always easy to accommodate in the listening room. That’s why I was struck by the BK XLS300s compact nature, it can be slotted in without dominating the room and is domestically acceptable. The system improvement was immediate, and for such a modest outlay.

Larger subs have also produced rather too much in the way of LF boost for my liking. This might be ideal for those trying to create cinema sound in the home, but I simply want to extend the bass response of my monitors for two-channel enjoyment.

From the first notes of Mahler’s Second (CBSO/Rattle from 1987) I remembered just what it was that subs added to a simple system. The whole performance became much larger and grander than I am used to. The recording venue acoustics were better portrayed and it was easier to become immersed in the performance, as if the singers and orchestra were really at arm’s length. Yes, the bass was more noticeable, yet this was but one improvement provided by the BK XLS300.

On rock and pop, as well, the performances all became larger and more lifelike with involuntary foot-tapping on track after track. Bass-heavy material such as The Police’s Regatta de Blanc was just amazing with the subwoofer connected, the individual instruments easier to hear from what can be a something of a musical blur on lesser systems. With tracks such as Johnny and Mary (Robert Palmer) the wonderful bass lines around the choruses were superbly enhanced with the BK XLS300 in circuit on this track (made famous by those Renault Clio adverts in the early ‘90s).

While watching TV, the BK SLX300 revealed just how much production goes into the programme trailers and commercials. The basslines here really come alive with a sub connected and it’s a shame to realise that the vast majority of viewers are not hearing this, especially those reliant on the built-in speakers of flatscreen tellies. Over the Easter holidays we were treated to a TV screening of Johnny English Strikes Again which is not only highly enjoyable for its writing and acting but has a soundtrack which is vastly improved with the addition of the BK XLS300 subwoofer: effects were so much more dramatic and the entertainment level increased significantly.

bk xls300 review

The review period coincided with the Coronation of King Charles III and its celebratory concert which was just spine-tingling to listen to. Having the sub in circuit certainly enhanced the enjoyment from Nicole Scherzinger’s powerful performance if also highlighting Lionel Richie’s vocal difficulties on the night.

From track to track, genre to genre, I was blown over by what the BK XLS300 can add to the system in terms of enhanced sound. It makes my system sound so much bigger, more grown-up and has proved the perfect accompaniment for LF extension down to about 25Hz. Even at low listening levels the XLS300 cements the bottom end, providing a strong, tight bass while being in the thunderous class when required. I was impressed at how seamless the integration of the sub was, making my Harbeths sound as though they were on steroids.


Having tried a number of subwoofers over the years, from some of the major players, I was very excited to audition the BK XLS300. It is a well-designed and crafted, British-made compact sub which offers remarkably good value-for-money.

The compact cabinet is easy to site and the Peerless drive unit creates a beautiful sound which enhances not just two-channel systems but surround sound ones as well to bring a welcome sonic improvement for a modest outlay.

Congratulations are due to Barry and the team in Southend. They’ve used their knowledge and experience to create a masterpiece of a low-frequency engineering to improve the lives of audiophiles and home cinema lovers. I can’t praise the BK XLS300 enough.


Type: Down-firing, powered subwoofer with 18l infinite baffle cabinet
Driver: 254mm Peerless XLS10 long throw bass driver
Inputs: low level RCA, high level Neutrik
Low frequency extension: 17Hz at -6dB
Amplifier power: 300W RMS discrete bipolar
Controls: variable low pass filter, volume, phase (0 or 180 degrees)
Dimensions (HxWxD): 340 x 355 x 290 mm
Weight: 17.5kg
Finishes: satin black, cherry, gloss black, gloss white, light oak, mahogany, silver, walnut, white, black ash
Warranty: 2 years

Price when tested:
Manufacturer Details:

BK Electronics
T 01702 527572





Trevor Butler

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