BK XXLS-400 Subwoofer Review

We get our hands on the newest subwoofer from little known UK manufacturer BK Electronics

by AVForums
Home AV Review

14

Highly Recommended
BK XXLS-400 Subwoofer Review
SRP: £400.00

Introduction

For those not resident in the world of online forums, BK Electronics is a name that may be less than household. Where the world of AV and hi-fi is concerned, they inhabit the semi-visible realm of the Original Equipment Manufacturer, or OEM. They are the people that actually manufacture a lot of other ‘manufacturers’ products, be it because the manufacturer is a really a design/marketing brand, or simply because that manufacturer lacks the expertise, facilities or economies of scale to gear up for the production of certain product types. It’s not hard to appreciate that the small cottage industry type brand beloved of British hi-fi, will find far more economic sense in subcontracting out the manufacture of cabinets, complex electronics like amplifiers and even the complete assembly of products. If you need someone to do this, then BK is such a company.

BK Electronics XXLS400

That BK manufactured all of the early REL products up to and including a lot of the Q Series is fairly common knowledge across the interweb, and a keen eye will pick out fairly obvious similarities between their own product range and a lot of high street brands. It was the list of the less obvious that surprised me, but suffice it to say that there were some surprisingly well known names in there. So far from being some start-up internet based retailer (in the UK that is the only way to buy their products), they’re a manufacturer of some pedigree.

The subject of this review is the latest in their own range of subwoofers, a product line that takes advantage of the fact they design and manufacture their own cabinets and plate amplifiers in house. The range starts with the diminutive 10” driver, 150w Gemini II at £199 and tops out at the rather large 12” driver, 300w Monolith at £430; The new XXLS-400 we’re looking at here, slips in at £399 and somewhere in between in terms of size and capability.

So what’s new and interesting?


BK Electronics XXLS400

Well, the XXLS-400 follows a tried and tested formula of a down firing sealed sub and whilst it’s a bit bigger than the norm, it's not actually big enough to be classified as large, at least not by me. Typically subs of this price and ilk sport 8 or 10” drivers in a 12 to 13” cube; The XXLS-400 sports a 12” driver in a 15” cube. Not massive differences on a tape measure, but as the old adage “there’s no replacement for displacement” holds as true as ever it did where subwoofers are concerned, it’s enough to make quite a difference in use. This is presumably why as BK state, customer demand demanded it.

The thick single skin box certainly had the added dimensions to make fitting it into a saloon car a test of ingenuity as indeed did the weight - You won’t tuck one of these under your arm whilst fumbling for keys. Opening the box finds the sub, a well written manual, a near three metre moulded IEC power lead and enough five metre signal cables to be able to connect the sub up in stereo via the low (RCA Phono) and high level (Neutrik Speakon) inputs. Although nothing to get too excited about, the stereo cable is properly screened and sports metal RCA Phono plugs, so in terms of sub-bass it is as much as you’ll ever need unless you need longer runs or are a cable fetishist. It is depressingly rare in this day and age to actually find everything you need to get up and running already in the box.

Turning to the XXLS-400 itself, a wide range of furniture and décor friendly real wood veneers and paint finishes are available and this example, as with all of the BK subs I've seen, is very tight in it's fit and finish. For the record, this one is in the photographically friendly Light Oak. Dare I say it, BK have been known to produce a few custom finishes for those that ask nicely or are prepared to pay a bit more, but over time some of the more requested non-standard finishes have become standard, even if they attract a small premium.

Turning the sub over reveals the driver from which the XXLS-400 draws part of it’s name. It’s a Peerless XXLS-12 (Expanded Extra Long Stroke) driver designed specifically for the purpose of subwoofery and is one of the few decent size, long stroke drivers that can be sourced without crossing the pond to America. A Nominal 12” driver, the treated paper cone is driven by a 51mm voice coil propelled by a 2.5kg double stacked magnet and all strung together in a tidy alloy basket.

BK Electronics XXLS400

The rear of the sub is home to BK's own plate amp neatly recessed flush into the cabinet. The amp delivers the remainder of the subs moniker and 400w RMS into the 4O of the Peerless driver. This is a class A/B MOSFET amp of the old school and that means a massive toroidal transformer and power reservoir. Is this inherently better than the lightweight 'digital' alternatives? Probably not, but being of an age, I like things that weigh a bit and the combined weight of the thick cabinet, large driver and massive amp combine to create a subwoofer that feels satisfyingly dense and solid.

The controls on the plate amp will hold no surprises for all but the greenest of subwoofer virgins. As alluded to, both high and low level connections are provided and owing to separate gain controls and the ability to defeat the crossover on the stereo/LFE low level input alone, the XXS-400 can be run with simultaneous low and high level inputs. This is excellent news for those with discrete stereo and home cinema systems as the sub can be connected to and optimized for both at the same time. This also suits AV Receiver owners who run their main speakers as ‘Large’ for music playback and the strange minority who like to connect their sub simultaneously to their centre speakers amplifier terminals as well as the LFE channel. Taking as read the On/Off switch and the two gain controls, the crossover is sweep-able from 40 to 120Hz and the phase control is thankfully a continuous 0-180 degrees type rather than a cheap one or t'other switch. There is no Auto On/Off, nor any custom install 12v triggers. Don't even ask about remote controls or other such frippery.

If there is a complaint relating to the feature set, I would like to see crossover over frequencies down to at least 30Hz, just to keep the stereo hi-fi boys happy.

For those with a technical bent, BK have boxed a bit clever with the internal tuning of the XXLS-400. The box volume of 50 litres is a bit smaller than the 65 litres recommended by Peerless' design notes. This would normally result in a slightly earlier roll-off of the frequency response and a slightly over damped response characteristic (Qtc). Through use of a Linkwitz Transform circuit, the driver is 'persuaded' to perform like it is in the bigger box and thus deliver a slightly deeper, flatter response and a Qtc closer to the theoretically ideal 0.707 ratio. The pay off is that the available power is used up slightly quicker, plus the greater cone excursions of an artificially extended response inevitably introduce more distortion, so there is a balance to be struck – there is no free lunch when trying to avoid using larger box volumes.

Set-up, as with any sealed sub that hasn't been mercilessly Eq'd internally to deliver a flat response, is easy. A bit of humping around found it happy in more or less the usual spots in my room and due to the naturally sloping response dove-tailing in with the rooms gain, it was the work of a moment to simply tune out the rooms modal contributions and get a nice flat extended response. Of course, a flat response at test tone frequencies is easy and it's only under real programme conditions that you find out how much of that depth is actually maintained at higher volumes.

Listening

The answer turned out to be quite a lot of depth, but more of that later. As per usual, I start with checking the set-up by listening to music; By luck or by judgement (I'd hope it was mostly the latter by now) I was pretty happy straight from the off and restricted myself to small gain adjustments. All the usual demo tracks were run through and then some and a few clear impressions were made that remained throughout my time with the XXLS.

The first thing I noted is that the clean upper bass music fiends crave to achieve a seamless blend with the bottom end of their main speakers was clearly evident, or rather not evident if you follow. Stare as I might, I couldn't convince my ears that the bass was coming from the sub rather than from the speakers and that is exactly what you want. This clean and extended high frequency response that the driver is capable of, delivers a really tight fast upper bass that drives strong beats with real snap and mid-bass kick.

I was actually quite shocked at the punch Gwen Stefani's 'If I Was A Rich Girl' was delivered with and it really tempted me into just cranking the volume up just to feel it more as the track bounces along. The fun would be short lived if the tunefulness suffered. Digging out an old favourite, Living Color's 'Stain', showed that there was no issue with either tracking the tune of the fast and deeper than I remember, electric bass lines, the dynamically plucked and slapped strings starting and stopping with real precision. This is real fast bass, not because of a lack of bottom end, nor because of a heap of mid-bass harmonic distortion, but simply because the transients are delivered in a fast and phase coherent manner. I had worried that the use of a Linkwitz Transform like any form of boosting equalisation might slur the attack slightly by impacting the phase response, but in this subtle implementation it's effects are benign.

Deciding to stop playing fair, I spun a Naxos sampler of J.S. Bach organ music in an effort to find the bottom end limits, because there isn't much to fault higher up the range. As expected, the really deep peddle notes whilst present, can't be delivered with the profound depth and power of a larger sub. The bottom end rolled off softly somewhere in the low 20Hz range which is still a creditable performance. In fact if there is a criticism to level, it's that the last half octave is slightly soft, lacking the fibrous texture of the very best (read much more expensive) subs. I think this is preferable to not attempting these frequencies at all, as at least the sense of scale is maintained and notes still stop and start properly thus carrying a tune, just with a little less detail resolution.

Moving onto movies showed again that the really big bass hits were slightly lacking, but the 30Hz and up bass was again delivered with such crisp attack that I found myself noticing the deep absence less and less. The phenomenal canons in Master and Commander didn't quite bend windows and rattle the fabric of the house in the way that a larger ported sub does, but by 'eck they pinned you to the sofa with their ferocity and impact. And so it went with the cave sequence near the beginning of Iron Man, the punch fest that is Kung-fu Panda; Fantastic upper bass kick, with only the really deepest effects tailing off.

That said, the deep pulsing heart beat of Tai Lung as he leaps between the falling rocks in the prison escape sequence in the Panda movie was very impressive. The room pressurized in a way that I hadn't quite expected and similar was experienced with the wind buffeting the plane in Flight of the Phoenix. The basso drop of the barrel roll, tailed off, but only once it had extended far deeper than I had imagined it would. Strangely, the slight softness noted with the very deepest of (real) musical notes seemed to be a non-issue with equally deep movie effects.

Unsurprisingly, movies with strong music soundtracks were particularly rewarding. Slumdog Millionaire was riveting in it's dynamic contrasts and rhythms and I'll even admit that Mama Mia didn't mange to drive me from the room for once and that IS saying something.

Verdict

9
AVForumsSCORE
OUT OF
10

Pros

  • Well considered balance of performance
  • Very clean upper bass, regardless of price
  • Large range of finish options
  • Small
  • Value for money

Cons

  • Not as small as some
  • Greater extension can be had for the price, but at a considerable size penalty.
  • Slight softeness at the very bottom end
  • Not at a showroom near you

BK XXLS-400 Subwoofer Review

BK Electronics XXLS400

Those with an irrepressible movie bias will still be best served by a bigger ported boxes and their room wobbling extra bottom end. That is big box efficiency making itself count low down. For most people wanting a movie/music balance and not terribly interested in getting involved in subwoofer equalisation, I feel the XXLS-400 to be a sweet spot in the BK range and in the larger pantheon of subs in general too.

It offers the nimbleness of smaller sealed subs with their easier room integration, plus a good portion of the grunt offered by the considerably larger ported boxes but without taxing the limits of acceptable domestic size. With the XXLS-400, you're giving very little away in order to achieve a very musical performance. That music capability is notably superior amongst it's price competition be it in the high street or online, the latter being obviously relevant to this sub.

That direct selling business model will also be the XXLS-400's Achilles heal. A lot of people will never get to hear it, some simply won't believe that this much capability can be had for so little and a few more still won't buy online, even though subwoofers alone amongst speakers, lend themselves to retailing this way. It's their loss, because I simply can't think of anything that comes close to such a complete performance for remotely similar money in such a WAF friendly package.

Highly Recommended

Scores

Value For Money

.
.
8

Sound Quality

.
9

Build Quality

.
9

Verdict

.
9
9
AVForumsSCORE
OUT OF
10

Our Review Ethos

Read about our review ethos and the meaning of our review badges.

To comment on what you've read here, click the Discussion tab and post a reply.

Related Content

BK Electronics P12-300SB-PR Subwoofer Review
  • By Steve Withers
  • Published
SVS SB-3000 Subwoofer Review
  • By Steve Withers
  • Published
REL HT/1205 Subwoofer Review
  • By Steve Withers
  • Published
Fyne Audio F3-12 Subwoofer Review
  • By Steve Withers
  • Published
SVS PC-4000 Subwoofer Review
  • By Steve Withers
  • Published

Latest Headlines

AVForums Podcast: 21st October 2019
  • By Phil Hinton
  • Published
AVForums Podcast: 14th October 2019
  • By Phil Hinton
  • Published
Canton DM76 and DM101 soundbases now available in UK
  • By Andy Bassett
  • Published
Top Bottom