Despite its decades‑old design, the Rogers LS5/9 can still compete with some of the best monitors around today. We put this faithful recreation to the test.
Going back over half a century, high‑quality, professional audio equipment simply wasn’t available ‘off the shelf’, and so most of the major record companies and broadcast organisations had to design and build their own bespoke equipment. Nowhere was this truer than at the BBC, which established phenomenally innovative ‘R&D’ and ‘Equipment’ departments to design and build, respectively, pretty much everything that was required, often setting world‑class benchmark standards.
When it came to monitor loudspeakers the BBC evolved over many decades a particular approach to the design of both bass drive units and loudspeaker cabinets. The acme of the BBC’s in‑house loudspeaker heritage was undoubtedly the LS5/8, which was developed at the end of the 1970s to address a growing requirement for higher control‑room monitoring levels. The Beeb’s quirky naming scheme used LS to indicate that the product was a loudspeaker, ‘5’ to signify a ‘grade‑1’ monitor speaker for studio applications, and the ‘8’ simply meant it was the eighth‑generation design.
Excellent though the LS5/8 was, its physically large cabinet (110 litres) was simply too big for some of the BBC’s more compact control rooms. At the time, outside broadcast (OB) vehicles often used another well‑known and highly regarded compact BBC monitor speaker, the LS3/5A, but that was considered too small for a studio control room (and was officially classed as a ‘grade‑2’ monitor, anyway). So a few years after the LS5/8’s introduction the BBC boffins set about developing a more modestly sized grade‑1 studio monitor to bridge the capability gap and, logically, that was assigned the product label LS5/9.
Its design goal was to match the tonal accuracy, midrange transparency and production consistency of the LS5/8, while accepting the inevitably reduced bass‑extension and SPL capabilities of a more compact (28‑litre) cabinet. The prototype LS5/9 was trialled in 1983, and there’s a typically detailed BBC design report available online at http://downloads.bbc.co.uk/rd/pubs/reports/1983-10.pdf. Production LS5/9 monitor speakers were initially built under licence for the BBC by Rogers, although later on other manufacturers were also licensed to build it.
By the mid‑1990s, high‑quality, consistent monitor loudspeakers were available off the shelf from a number of manufacturers, and it became uneconomic and unnecessary for the BBC to continue developing its own speakers and drive units. Consequently the LS5/9 was the last monitor speaker to have a BBC‑designed bass driver, and also the last to be developed exclusively by the BBC’s R&D department at Kingswood Warren in Surrey.
Given its unique pedigree and domestically acceptable size, the LS5/9 developed a strong following as a hi‑fi speaker, particularly in the Far East, and in recent years there seems to have been something of a resurgence of interest leading to the LS5/9 being reincarnated by several UK manufacturers — notably Rogers, whose LS5/9 Classic SE is reviewed here.
Although originally a UK manufacturer, Rogers were sold to a Chinese company in the early ’90s and their speaker production subsequently moved to the Far East. However, a few years ago the owner was persuaded to build the revered LS3/5A and the LS5/9 speakers under BBC licence back in the UK. As a result, the cabinets and passive crossovers circuit boards are made entirely in the UK and to the original BBC design specifications, and the whole speaker is assembled and tested in the UK too.
The fairly elaborate passive crossover is mounted alongside the tweeter behind the front baffle, and uses 27 elements — 17 resistors and 10 reactive components (capacitors and high‑power dust‑iron‑cored inductors) — to create third‑order (18dB/oct) slopes. The crossover frequency is 3kHz (the original design was 2.4kHz, a change presumably due to the revised bass driver’s characteristics), and the speaker presents an easy 8Ω nominal load (with a minimum impedance of 6Ω). With a low‑ish sensitivity of 87dB/W/m, Rogers recommend using power amps of 30‑100 Watts, connected via a single pair of silver‑plated 4mm ‘banana’ sockets (XLR/Neutrik connectors are available as an option).
Compared to many modern project studio monitor speakers, the LS5/9’s cabinet is still quite large, at 275 x 460 x 285 mm (WHD), and each unit weighs 12kg. In contrast to the modern vogue of exposed drive units, the LS5/9’s front baffle is recessed slightly to allow for a front grille covered with black tygan fabric. This grille is held in place by Velcro around the edges, and a fabric tab at the bottom aids its removal if necessary — although the speaker is voiced with the grille in place, and the nude baffle isn’t the most attractive anyway!
The design goal of any speaker cabinet is that it should be acoustically inert, of course, and the usual solution is to make it as solid and rigid as possible. However, that typically also makes it heavy and expensive, and any panel resonances tend to be high‑Q and thus ‘ring’ for a relatively long time, which is not helpful. The BBC’s boffins took a completely different approach: based on their research from the 1960s, and driven by the need to reduce both manufacturing cost and weight, they applied good engineering principles to come up with the idea of the ‘thin‑walled cabinet’.
Thin panels obviously tend to vibrate — just as the body of a violin or cello does — so this was prevented by gluing on bitumous pads to provide ‘critical damping’. In technical terms, these bitumous pads both lower the panels’ resonant frequencies and broaden the resonance peak to have a low Q (shortening the duration of any ringing) — both being Good Things in the context of a loudspeaker. In addition, internal acoustic damping was added, originally in the form of 40mm‑thick rockwool slabs in porous fabric bags stapled to the cabinet walls.
Of course, different speaker designers have different opinions of the ‘thin‑wall cabinet’ concept, but the BBC employed it on many very successful speaker designs over the years, and it seems to me an elegant, practical, engineering solution.
Rogers have maintained the BBC’s design in their reincarnated LS5/9, using 9mm‑thick Russian birch plywood for the panels, with beech hardwood battens to strengthen the joints. The outside is veneered with either walnut, rosewood or olive as standard finishes, but the review model is the upgraded SE version which features amazaque wood veneer.
The cabinet is ported, with a 90mm‑deep tube (tuned to around 40Hz) opening at the top right‑hand corner of the front baffle above the tweeter. Modern bitumous damping pads are affixed to each panel, as in the original, while modern acoustic foams are used instead of the mineral wool — but the results are exactly the same. While the standard models use 9mm birch ply for the front baffle as well, the SE version reviewed here uses a 9mm‑thick Panzerholz baffle (see 'Panzerholz' box), which is claimed to improve the bass response — presumably because of its greater stiffness.
Dating from the 1960s, the BBC’s R&D department researched extensively to find a bass driver cone material that gave more consistent results than the traditional doped paper, and it was instrumental in the development of plastics in this role. An early success was a thermo‑formed rubberised polystyrene material called Bextrene, which produced less distortion than paper‑pulp cones. One well‑known application of Bextrene was in the infamous KEF B110 bass‑mid driver employed in the LS3/5A (and many other similar drivers of the age). Further research through the ’70s led to the BBC developing a translucent polypropylene material which could be formed easily into any desired cone profile, and the first BBC loudspeaker to use this kind of bass driver was the LS5/8. For the LS5/9, the BBC built a scaled‑down version of this polypropylene bass driver, resulting in an 8‑inch (210mm) bass unit codified as the LS2/14.
Perhaps not surprisingly, this bass‑mid unit is no longer available and, sadly, most original bass drivers have deteriorated badly over the years due to weak spiders and decayed PVC surrounds. This could have been a big problem as the specific plastic and the critical flare of the cone were fundamental to the performance and sound character of the speaker as a whole. Fortunately, the man charged with overseeing Rogers’ recreations of their classic BBC monitors, Head of Design Andy Whittle, was able to reverse‑engineer the BBC designs to create modern replacement drivers with virtually identical performance. A key element of the design of the LS2/14 was the inverted half‑roll PVC surround cone termination, which is absolutely critical to the mid‑band performance and that has been re‑engineered to match the BBC’s original specs. Rogers’ revamp of this unique bass driver is now built in the company’s facility in China, but is hand‑finished in the UK.
A few years ago, the original tweeter was unavailable too: the LS5/9 used the same 34mm fabric dome unit as its big brother the LS5/8, but commercial production of this tweeter ceased for many years. Thankfully, French manufacturers Audax recently restarted manufacturing their HD34 drive unit, although the frequency response is slightly different to original models. To achieve the required performance parameters for the LS5/9, Rogers fit an additional damping layer, as well as a perforated dispersion plate.
To ensure accurate HF balance and stereo pair matching, the original LS5/9’s crossover included a resistor ladder connected to solder terminals on the front baffle, which allowed the precise tweeter output level to be set in 0.5dB increments during the final QC process. This facility has been retained in Rogers’ reissue and it can be seen alongside the tweeter through the front grille. However, this is a factory setting; there are no user user‑adjustable options or controls on the LS5/9.
Rogers market the LS5/9 Classic SE as being built using the same techniques and specifications as the originals, matching the BBC’s exacting standards. However, in some small ways it actually improves upon the original, most obviously in its higher power handling and slightly greater SPL capability (106dBA). I partnered the review speakers with either a pair of Bryston PP120 Monoblock amplifiers, or a Bryston 4B stereo power amp, depending on which listening room I was using at the time. Both configurations worked very well and the speakers actually seemed to benefit from the tight control of a powerful amp. Rogers recommends a ‘break‑in’ period of around 50 hours, mostly to allow the PVC surround on the bass driver to reach its optimum condition, so I ran the speakers in the background for a couple of days before starting serious auditioning.
My memories of the LS5/9 from back in my BBC days were that it could be a bit fussy about placement, and I think that’s still true of these recreations. The spacing between the speakers is critical to optimise the stereo imaging, and proximity to the rear wall affects the bass response more obviously than in some designs. However, with good positioning the LS5/9s deliver a vast and realistic soundstage that extends well beyond the speakers, and I soon forgot the sound was actually coming from those physical boxes! That said, the stereo imaging is not as precise and sharply focused as many modern monitors can manage, almost certainly due to the old‑school design of relatively broad front baffles with sharp edges.
The clarity of voices and midrange detail was reliably consistent and, frankly, quite sublime.
Tonal accuracy was always the primary goal of the LS5/9, and particularly in respect of speech, of course. I’m pleased to report that Rogers’ LS5/9 reincarnation achieves that in spades! I always use a reference speech recording as a first test when evaluating any monitor speaker as it is such a revealing signal. Subtle colorations or distortions instantly become obvious when listening to speech, just because our brains are well tuned to spotting anything ‘unnatural’ — but the LS5/9 Classic SE passed that test with flying colours! Spoken words and singing voices both enjoy a vivid clarity and naturalness that many so‑called monitors fail to achieve. The LS5/9 could fairly be described as precisely analytical in this respect, and I’d opine that the midrange resolution and detail are easily benchmark‑standard, revealing the subtlest elements of complex mixes with great clarity.
A common criticism levelled at classic BBC monitor speaker designs like the LS5/9 is known as the ‘BBC Dip’ — a built‑in, broad and shallow (2‑3 dB) depression through the midrange, centred around 2kHz. The Rogers LS5/9 Classic SE seems to exhibit this characteristic too, although I can’t say it bothered me at all, and it certainly doesn’t detract from the transparency of the midrange. In comparison to some more modern monitors with a slightly forward midrange character, the LS5/9 could come across as less informative, but it’s really not at all — and it’s actually a lot less fatiguing to work with over extended sessions.
With such a large tweeter I was expecting a little less ‘air’ extension than smaller designs, but I didn’t hear any obvious limitations and the LS5/9 delivered a smooth and detailed high end, while the upper‑mid region was free of sibilance.
However, I did find the speaker’s low‑frequency performance oddly variable. As I mentioned earlier, room placement is critical and I spent considerable effort, in two different listening rooms, optimising things as far as possible. Nevertheless, some very familiar test tracks exhibited great depth and solidity, while others sounded unexpectedly anaemic. The published specifications suggest a frequency response of 50Hz‑16kHz (±3dB), although listening to my test track of descending bass notes my impression was of a slightly higher roll‑off frequency. And yet these speakers were still putting out very audible content down in the 30Hz area on some of my test tracks — low frequencies that many monitor speakers fail to reproduce at all. But despite the context‑sensitive variability I experienced in the low‑end, when the music suited the LS5/9s I found them exceptionally good and genuinely revealing monitors, and the clarity of voices and midrange detail was reliably consistent and, frankly, quite sublime.
So, despite being a 40‑year‑old design, the Rogers’ LS5/9s can definitely still challenge more modern alternatives, especially in showing how vocal clarity should be done! The elephant in the room, though, is that these are £5000 speakers, to which must be added the cost of a high‑quality power amplifier. It goes without saying that in the pro‑audio market there is some very strong competition from quite a lot of extremely capable active studio monitors at and below that price range.
So while it’s difficult to recommend the Rogers LS5/9 Classic SE purely on a cost/performance basis, it does have some impressive strengths. If I was setting up a spoken‑word studio these monitors would certainly be on my shortlist.
If your eyebrows raised at that unfamiliar term you’re not alone — I had to look it up too! The word Panzerholz was coined in the Second World War to describe plywood covered with sheet aluminium, creating an ‘armoured wood’ which the Germans used to protect delicate equipment during transport.
Today the name is trademarked and describes a panel made from compressed laminated hardwood impregnated with a phenolic resin. The result is a resilient material whose strength is comparable to metal, but it also has beneficial acoustic properties and so is ideal for use as a speaker baffle.
Rogers also use it for custom speaker stands to partner their LS3/5A and LS5/9 speakers.
BBC Loudspeaker Heritage
The BBC designed a lot of high‑quality monitoring loudspeakers over the five decades following the Second World War, simply because the few available commercial products just couldn’t deliver the accuracy, fidelity and consistency that was required. The oldest model in use that I can remember from my days with ‘Auntie Beeb’ in the ’80s and ’90s was the LSU/10 (Loud Speaker Unit 10), a design dating from the late 1940s with a huge oak cabinet housing a dual‑concentric 18‑inch bass driver and horn tweeter (which was supplemented by a separate ‘supertweeter’ to extend the HF response). Despite its age, it sounded very impressive to me!
Later designs adopted a different identification system. Models intended for outside broadcast applications — where speakers needed to be portable and, often, compact — were prefaced with LS3/. These were generally considered to be ‘grade‑2’ monitors and were primarily optimised for speech‑based programming. The first was the LS3/1 developed in the late 1950s; big, grey‑painted, with a pair of tweeters mounted on a perforated plate suspended directly in front of a 15‑inch bass driver (an arrangement intended to allow this huge speaker to be used in the nearfield!).
However, the LS3/7 was a more common sight during my BBC career, being a two‑way active unit using an 8‑inch bass/mid driver, each speaker being driven by a modified Quad 303 power amp containing an active crossover. Undoubtedly the most widely known speaker design outside of the BBC has to be the LS3/5, dating from the mid‑’70s (although there were at least three evolutions of that core design). This very compact, two‑way, sealed‑cabinet speaker evolved from a design intended for acoustic modelling applications. It was a stunningly accurate speaker for the time and quickly gained widespread use in smaller radio and TV studios, as well as in countless OB trucks, and in the hi‑fi world. In BBC use it was usually powered by a 50 Watt mono power amplifier (the AM8/12), built by HElectronics.
Studio monitors had the prefix LS5/ and were considered ‘grade‑1’ monitors. The early studio equivalent of the LS3/1 was the slightly larger LS5/1, introduced in the early 1960s. The excellent three‑way LS5/5 appeared a few years later, employing a 12‑inch bass‑driver, an 8‑inch midrange and a Celestion tweeter, all driven from a modified Quad 50D amplifier with a separate preamp/EQ control unit. This served as the primary studio‑quality monitor speaker right through the ’60s and most of the ’70s, but it could barely manage 100dB(A) SPL and that was becoming a problem in the Beeb’s music production studios.
Consequently, the LS5/8 was developed to provide a greater monitoring SPL — it could deliver around 118dB(A) SPL (although the limiting factor was actually the available amplifier power). This physically large (roughly 110‑litre volume), ported, two‑way design combined a 12‑inch bass driver with a Son Audax 34mm tweeter, and it was driven by a modified Quad 405 amplifier (AM8/16) containing an active crossover. A wonderfully detailed BBC report on its design is available at: http://downloads.bbc.co.uk/rd/pubs/reports/1979-22.pdf
The LS5/8 served as the flagship control room monitor speaker throughout the BBC’s studios and control rooms from the start of the 1980s extending well into the noughties, with around 1000 pairs being produced — any individual speaker being matched (theoretically at least) to any other within 0.5dB!
In 1992 Quad ceased manufacturing the 405 amplifier, and after evaluating a number of contenders the BBC selected a new British‑made amplifier for the later production LS5/8s, coded as the AM8/20. This was based on Chord’s SPM800, modified initially to incorporate the same active crossover PCB as used in the old Quad amps. This new amp had a slightly higher continuous power rating (160W into 8Ω) instead of the Quad’s nominal 100W, but with a peak capability of 1kW. It was also fitted with a different balanced input transformer to cure a slight HF roll‑off introduced by the one employed in the Quad amps! Neutrik Speakon connectors were also used on both the amp and speaker instead of the 4‑pin XLRs used on the originals. (A stereo rackmounting amplifier became available later, licensed as the AM8/21, based on Chord’s SPA four‑channel amp, and incorporating a revised crossover board which was also fitted to later AM8/20s).
Perhaps slightly embarrassingly, these new power amps gave the venerable LS5/8 a new lease of life, with significant improvements in bass control and definition, much improved dynamics and transients, and smoother midrange and top‑end!
While the earliest BBC speakers were built entirely in‑house, by the 1970s most were manufactured under licensing arrangements with established high‑end hi‑fi companies like Rogers, Kef, Chartwell, Harbeth and others. The same applied to the design of the drive units too — many bass units being bespoke BBC designs, latterly championing the use of polypropylene cones. These licensing agreements actually helped to fund much of the BBC’s own R&D development costs, while the manufacturers were allowed to market these designs (and variants of them) to the general public as high‑end hi‑fi speakers.
During its early development the LS5/9 was configured as an active speaker, just like its bigger brother, with a complex line‑level active crossover. However, advances in computerised circuit modelling techniques facilitated the design of an equivalent passive crossover, removing the need for an expensive dual‑channel power amplifier. In fact, during the speaker’s evaluation tests it proved to be very good at revealing the imperfections of the power amps in common use at the time, so the BBC designed a bespoke 50W single‑channel power amplifier specifically to drive the LS5/9 — codified as the AM8/17 and built under license by HElectronics.
I mentioned in the main text that the LS5/9 was the last in this lineage to have a BBC‑designed bass driver, as well as the last to be developed by the BBC’s R&D department at Kingswood Warren in Surrey. However, it wasn’t actually the last BBC in‑house speaker; that honour goes to the LS5/12 — essentially a mid‑’90s replacement for the LS3/5 benefitting from improvements in speaker technology to deliver greater dynamic capabilities and bass‑extension. Its rear‑ported cabinet carried off‑the‑shelf Dynaudio drive units, and that decision essentially opened the door to using commercial monitor speakers thereafter.
Since it was no longer commercially viable for the BBC to design and develop its own monitor speakers and drive units, in 2003/4 a lengthy evaluation process led to the BBC adopting Dynaudio’s Air Series of monitor speakers. Air 20s effectively replaced LS5/8s, while Air 6s and (passive) BM5s were used in smaller installations. That said, from my more recent visits to various BBC facilities there appears less ‘standardisation’ today, as I’ve seen many different monitor speakers from a wide range of reputable brands used in different parts of the Corporation.
The obvious contenders are Graham Audio’s BBC LS5/9, and Harbeth’s M30.2. The Graham Audio LS5/9 is built to the BBC’s original design in much the same way as Rogers’ model, with both using the Audax H34 tweeter. However, Graham Audio use a custom Volt bass driver developed specifically for this application by Derek Hughes (son of one of the BBC’s original designers, and an accomplished speaker designer in his own right). Harbeth’s M30.2 is much more of an evolution of the LS5/9, and although sharing similar sizing and fundamental concepts, it employs an altogether more modern approach with an in‑house‑designed bass/mid driver partnered with a smaller 25mm tweeter.
- Superb vocal clarity and definition.
- Capable of huge and involving soundstages.
- Constructed to original BBC specifications.
- Needs a very high‑quality power amplifier to reveal its strengths.
- Stereo imaging not as precise as more modern alternatives.
- Potential bass inconsistency.
- Can be fussy about positioning.
- High cost.
A well‑engineered revival of a BBC grade‑1 passive studio monitor speaker which excels on vocal clarity and tonal accuracy.
LS5/9 Classic £4800, LS5/9 Classic SE £5599. Prices are per pair, including VAT.
Retrotone +44 (0)7981 269404.
LS5/9 Classic £4800, LS5/9 Classic SE £5599. Prices are per pair, including UK VAT.