STIRLING BROADCAST BBC LS3/6 loudspeakers – extensive review

In 2011, the Stirling Broadcast BBC LS3/6  loudspeakers were re-launched after 40 years by English proprietor Doug Stirling of Stirling Broadcast Inc. Doug subsequently employed loudspeaker designer Derek Hughes, son of Spencer and Dorothy Hughes (Spendor) to take on the design work of this loudspeaker – and I can firmly acclaim, “would there be anyone more knowledgeable to engage in a project such as this?  I have had the opportunity to evaluate these loudspeakers now for many months and can confirm that they are quite a special product, indeed! 

PERTINENT and HISTORICAL SETTINGS 

The original Spendor BC1, now somewhat of a vintage classic in audiophile circles and still used by myself for critical loudspeaker midrange comparisons, was a pre-derivative of the LS3/6, but not a BBC licensed model.

The late, great Spencer Hughes was working as a lab technician at the BBC on the development of the 12-inch drive unit that was one of the drivers in the BBC LS5/5, which may have ultimately been the finest BBC monitor using Bextrene in terms of sound accuracy of its time  

Spence, being quite inspired by this experience, later developed the first 8-inch Bextrene cone drive unit at home using an improvised setup, which, with the addition of the then esteemed Celestion HF1300 upper mid/tweeter, became the original prototype BC1. (early 1969). This 8” bextrene driver proved to be somewhat “magical” within its frequency range, particularly concerning its still to this day, exceptional mid-band quality. 

Hughes offered his design to the BBC (initially out of courtesy) but they ultimately turned it down because of its somewhat limited power handling. However, eventually, the BBC decided they could use the loudspeaker as a smaller monitor and started working on it; designating it the LS3/6. For some reason, they stopped mid-stream and Spencer kept working on his own to develop the BC1 and starting his renowned company.

The BC1 was originally a 2-way system with just a Celestion HF1300 mid/ tweeter which was amazingly useful (and accurate) from around 3khz and up. Unfortunately, it dropped off sharply at about 11-12 kHz.  Although the speaker was already quite adorning in its original design, a year later Spencer added the Coles (STC)  super tweeter to further extend the loudspeakers uppermost frequency range.

Meanwhile, the BBC started on the LS3/6 again making some changes, most notably the addition of a large auto-transformer to allow the overall sensitivity of the unit to be adjusted and they finished it.                            

(Jim) Rogers took on the manufacturing of the design and at his suggestion, proposed morphing the LS3/6 also into a 3-way system. However; he decided to replace the Coles super tweeter in exchange for the Celestion HF2000 super tweeter, which the BBC licensed and approved. This eventually became the original Rogers BBC monitor loudspeaker (LS3/6) which was initially released on or about 1970-1971.

Quite a bit of a complicated story, would you say? Yes, without any doubt! Not many people around today have heard and /or compared these original two loudspeakers as to subjective sound quality differences but past reviews perceived them to be quite small—that is until they were ultimately auditioned in familiar home auditioning comparisons. There were noticeable intrinsic differences; most significantly, in the mid-upper mid-range and high-frequency response, as well as overall power handling, bass quality, and their average impedance’s respectively.

STIRLING BROADCAST

Fast forward to 2011, we now had the release of the newly designed, BBC-approved version of The Stirling Broadcast LS3/6. It is still a 3-way reflex full range, freestanding assembly, designed to meet the needs of high-quality studio monitoring at much higher sound levels. The speaker contains 3 drive units, custom-built specifically for this loudspeaker and mounted in a 45litre reflex-loaded cabinet, together with a crossover/equalizer unit to match the units and to give the overall level frequency response needed for critical listening.

The system has an IEC268 power handling of 90watts continuous, 150watts short term, and a frequency response of 45Hz – 17kHz +/-3dB, with crossover points of 3kHz and 13kHz. Although the loudspeaker possesses a somewhat lowish sensitivity of 87dB for 1watt at 1metre, its maximum output of 107dB is extremely forthcoming.

The LS3/6 will accommodate very high sound levels in just about any room other than an auditorium. As for the drivers, the loudspeaker utilizes a 22cm, polymer LF drive unit designated the SB-4432, a 27mm HF unit- SB-4434, and a 19mm SHF unit named the SB-4436, all manufactured in Norway by SEAS to Stirling Broadcast specifications. The nominal impedance is 8ohms. This 8.6″ woofer is a polymer cone 6.5″ in diameter, and has a compliant half-roll surround, a ferrite magnet, a really well-made cast-alloy frame, and a dust cap made of a very soft pliable rubber surround.

The connections offer a bi-wired screw terminal configuration accepting both 4mm plugs and bare wire availability. After a considerable amount of discreet evaluation time, I have concluded that there is virtually no difference in the sound reproduction quality when using a single vs. bi-wired setup. In fact, in the end, I found single-ended wiring preferable to bi-wiring when employing my Silversmith Audio Fidelium ribbon loudspeaker cables.

I happen to be well familiar with the sound of the SEAS high-frequency drivers, as they generally offer a superb upper mid-high frequency response, being uncommonly smooth at its frequency extremes. The newer 8.5-inch bass/mid driver is new to my ears and I will describe it in greater detail further into the review.

SUBJECTIVE OVERVIEW

Although I have been unquestionably intimate with the “BBC” sound (I overtly despise this term) going back some four decades, I was not at all familiar with the original LS3/6 monitor, (nor knowing anybody who was) as it did not have a huge following even in its prime years on the hi-fi market. What I am definitely familiar with, however, are various models of the LS3/5a’s, the original Ls5/9 (as well as Graham Audio’s latest BBC specified design (also by Derek Hughes), and few of the Harbeth models.

Nonetheless, and of most importance, I have considerable knowledge and experience with numerous samples of the Spendor BC1 and the SP1, the latter, being Spencer Hughes’ last design as it used a polypropylene bass/mid driver. (The change from Bextrene was to offer much higher power handling as well as a measurable and more powerful subjectively defined bass response.)

As to the setup for the Stirling’s Ls3/6 in my listening room, they couldn’t have been more straightforward as they conform to the standards set then and continuing today by the BBC for the ultimate monitoring and sound quality of any high-definition loudspeaker design.

Stirling properly advises the use of 14” high open-frame metal stands, with the initial high-frequency driver at just about ear height. However, as with the Ls5/9, in this case, I found these speakers brought forth their “ideal” sound attributes sitting 12” of the ground with dedicated spiked feet. stands. One should remember when setting up the Stirling’s to obtain their best, and smoothest sound quality is that you should listen with your ears no higher than on axis with the lower (physically and frequency-wise) tweeter. Anything above this may push the treble response a tiny bit higher (though by no means brighter) than one MAY prefer.

The speakers were set at almost 4 feet from their front baffle to the wall behind them and toed in, naturally, to about 15-20 degrees which formed the isosceles triangle at my 11-foot listening distance from the loudspeakers themselves. They were situated 8.5 feet apart within the width of my 14-foot back wall.

Initial listening tests quickly took me a bit by surprise; not by the stupendously open sounding, smooth and neutral tonality of the 3-driver bass/midrange tweeter integration, but by the exceptional quality of the SEAS high-frequency driver. This driver is crossed over at the traditional 3khz range, followed by the super tweeter which handles the frequencies up to and above 13khz. (Similar to the BC1). The combination of these two tweeters displays an in-room subjective frequency response that is foremost in neutrality, accurate tonality, and indeed, exhibits a sound quality that is beautifully balanced in almost every way.

Right off the bat, some of my finest digitally ripped files and CDs of orchestral music became an exquisite experience to listen to! The upper mid-high frequencies reproduced massed strings as well as the solo violin with exceptional clarity, fine string uniformity, and concert hall ambiance that was virtually second to none! With proper acoustical room considerations, there was a lush, rich, and superbly natural, yet never bright quality to most orchestral program sources as well as the most incisively displayed instrumental uniformity to the array of wind and brass instruments that were presented to it. As presumed, the sound emerged generously away from the 12 by 25-inch cabinets and reached far back into the soundstage with outstanding depth and discreet, solidly placed stereo localization image effects.

The classic design attributes of this new BBC model appeared to conform quite truly to its original design specifications as it continually dished out some of the finest stereo image effects, with depth, layering, and stage width that has been the trademark of the most classic BBC designs historically.

VINYL TO START

Ironically, for me, I started off listening to a 180-gram vinyl recording of two Mozart Piano  Concertos with Maria Joao Pires  playing with the Wiener Philharmoniker and Claudio Abbado. On loan for review was SOTA’s newest Comet 5 turntable; quite beguiling at its price with the Dynavector high output moving coil. (review forthcoming). The overall innate sound through the Stirling LS3/6 was duly transparent with a marvelous piano tone, timbre, and dynamics as it portrayed the preeminent orchestral backing by the Vienna Philharmonic. The 2nd. Concerto K.537 happened to be recorded live.

The LS3/6’s distinctively proportional soundstage presentation drifted far back into the concert hall of this live performance. Wide, discreet yet palpable instrumental stereo images were never overshadowed at the expense of the piano which was expertly displayed at the center stage. This vinyl recording was a good showpiece for the Stirling’s particularly in terms of their reproduction of the full live event that and the seductively persuasive piano reproduction which the Ls3/6 portrayed quite seductively. As my mind was working overtime and I loved the performance, I also bought and downloaded the WAV 16-bit as well as the WMA file to compare it directly to the LP.

The sound quality via the vinyl recording was a bit more “light’ in its overall body, with great depth, strong bass, and a bit more natural string tone compared to the digital recording. Interestingly, the WAV and WMA files brought out some incontrovertible subjective differences between the two. As both claim to be lossless, the results were far from similar! The WMA recording was more constrained and congested in its dynamics and sonic bloom using 3 different DAC’s it was tested with. (most notably, Wyred4Sounds 10^th anniversary). The ambiance and decay times of the recording were somewhat stifled and muted. This was quite surprising to me and as such, WMA should not be entertained for high-definition sound reproduction.

An even more outstanding “showpiece” for the LS3/6 and for that matter, any of the greatest audiophile loudspeakers available is the Claudio Arrau Beethoven’s “Emporer” Concerto with Colin Davis conducting. This will make your hair stand and its recorded sound is amazingly authentic with the LS3/6 at the helm.

Otherwise, both the vinyl and digital download of this recording showed Ms. Pire’s piano tone to be slightly forward with splendidly vivid piano tones as her hands hit the keys. Notwithstanding the quality of its mid to high-frequency reproduction, the real beauty of the speaker was exhibited by its glorious and seamless transitional execution from the midrange to high frequencies. Where was that crossover? It was not to be heard!

In comparison to both the Spendor loudspeakers, the piano tone was slightly more subdued in timbre as the Ls3/6 midrange possessed a touch of dynamic restraint on keyboard transient attack, both measurably and subjectively. This also corresponded to most other orchestral instruments presented on suitably recorded and executed program sources.

Another fine recording very recently performed in March of this year, again by Maria Joao Pires once again brought forth her excellent style, charm, and exquisite piano accentuation; a slightly left of center stereo image perception along with a resonantly, smooth orchestral acoustic from the Paris Mozart orchestra

Considering all the above, it can be firmly established that the LS3/6 in-room response from say 1.5khz and up are uncompromisingly polished and flat— yet as you move further up the frequency ladder, its subjective response possess some of the finest, beautifully reticent, and natural high-frequency tonal balances I have heard in a loudspeaker of recent memory.

One of the first digital recordings played was a PCM soundtrack of the now-famous Beethoven piano concerto live performance by the late Maris Jansons conducting the Bavarian Radio Symphony with Mitsuko Uchida at the piano. Here the speakers delivered a huge, wide, and exemplary resounding rendition of the Hall, and Uchida’s piano was centered slightly behind the stage level giving an inordinate amount of depth and authenticity.

Although the bass/mid driver response of the Ls3/6, as stated above, once in a while could be sonically understated in its “thrust” or translucency as compared to some of the other British monitors currently available, its velvet fluidity and clarity were nevertheless portrayed with ultra-finesse while singing voices emanated quite elegantly, satiny and clear from this wonderful midrange.

As for that midrange, particularly on acoustically recorded vocals and operatic music, the LS3/6 reproduced sopranos with fine, smooth neutrality while it also exhibited an understated, “touch” of harmonic “dynamics” than the Spendor SP1 but more significantly—from its original, forerunner, The Spendor BC1.

When comparing it to the former loudspeaker, comparatively speaking, a frequency response graph at similar positioning on-axis comparing the Spendor SP1’s to the Stirling LS3/6s defined an almost identical replication up till about 1Khz, with the SP1 being a tad brighter (maybe more natural?) there on up. This could attribute to the slight reticence of the Ls3/6 vocal reproduction and piano key intonation; namely, as the hammer hits the string–as compared to both of the vintage Spendors.

 FURTHER LISTENING

Continued listening to some favorite digital recordings surely did bring forth more of the LS3/6’s luxurious and neutral balance. I had a chance to audition some new music in CD format which was loaned to me by a notable high-end audio manufacturer of some prominence. Dermot O’Leary Presents The Saturday Sessions – 2013 is a 2-disc compilation album where musicians perform acoustic sessions and specially recorded covers.

One excellent example was the track “Never Let Me Go“ by Florence and the Machine. The LS3/6 reproduced Florence Welsh’s voice with such a nuanced and naturally recorded tone, as well as presenting her voice as emanating at the speaker plane with a distance likened to her being in the room before you.

THE BASS/ LOWER MIDS

Almost all the music I auditioned on the Ls3/6 produced a fine, robust lower midrange to bass response from its 6.6 inch bass/mid driver in my listening room. There were a few times, however, when its overall subjective impact displayed a somewhat dissolute and less powerful amount of bass extension and weight than I was used to hearing, particularly in comparison to the Spendor SP1 loudspeaker.  However, I did find within the long period of time I had with the speaker, that a few changes in room acoustical (bass trap) treatment seemed to bring this slight problem more in line, thereby giving large orchestral bass drums a more solid transient force.

Most pop music program had less of an effect here, as pop/rock bands favor acoustic drum sets, usually made up of bass drum, snare, and multiple tam-tams. Presumably, some of these program sources were purposely balanced to show off their deep and discerning musical and instrumental attributes. In that sense, the LS3/6 displayed fine rhythmic energy and timing on these program sources.

SUMMATION

The Stirling LS3/6 loudspeaker was formulated as an updated version of its classic original older brother, which was designed some 50 years ago by the BBC. Although direct comparisons are all but nonexistent as of today, one must assume that its BBC licensed and approved overall parameters have been implemented, and indeed, met by designer Derek Hughes.

His expertise as an elite loudspeaker designer which includes his background with the BBC and his formative work with his father at Spendor has proved to be an invaluable asset as to the exquisite work he has done with the Stirling LS/.6 loudspeaker.

What has been captured here with the LS3/6 is a loudspeaker, that as far as subjective sound quality is concerned, can compete if not outclass, many current BBC licensed designs, (2 or 3 of which Derek has built for another manufacturer) or for that matter, any British or American loudspeaker currently available today of definitive standing at the LS3/6’s respective price point.

Even though its bass response around approximately 60-100hz is a touch “loose” in retrospect, it still delivers a warm, full, and comprehensively solid “slam” within its accepted design parameters.

The updated Stirling LS3/6 has combined a fully mixed recipe of “current day” improvements over some of the slight faults of its much older, vintage pre-derivative, the original Spendor BC1. Despite the fact that the LS3/6 still falls a bit short as to the BC1’s infinitely translucent midrange response (not many loudspeakers till this day can fill that void), the upper-mid to high-frequency response using its SEAS drivers is its forte— being exceptionally smooth, detailed, non-aggressive, and exquisitely “accurate” in every respect.

It’s midrange does possess a delightfully beautiful response that is silky, open, liquid (though maybe a cinch subdued), and tonally natural; a quality that classical music lovers will find hard to let go of. But don’t be fooled: this speaker can reproduce any type of music genre with superlative audible results!

Like its much older sibling, the Spendor BC1, the Stirling LS3/6 is a music lovers’ “dream come true” loudspeaker. As such, it is a resounding high-end loudspeaker success and at its asking price is worth its weight in gold.!

Equipment used in this evaluation: Digital ~~ Audio Note (UK) CD3.1×2 player /Wyred 4 Sound 10th Anniversary DAC/ Prism Sound Callia DAC● Innuos Zenith Mk.3 server/streamer Analog- SOTA Comet 5 TT/Ortofon X5 moving coil cartridge /Amplification ● Mark Levinson 5805 integrated amplifier/ Peachtree Audio Nova 300 preamp (2019) / CIA C- 100S stereo power amplifier / PS Audio M700 monoblocks ● PS Audio M1200 monoblocks Loudspeakers ~ Audio Note AN/ED loudspeakers / Spendor BC1/ Spendor SP1 ● Cables – Conditioners: Inakustik AC-3500p power station & LS-4004 speaker cables, AC-2404 reference Air Power Cord/ Silversmith Audio ‘Fidelium’ loudspeaker cables/ Audio Note (UK) Lexus bi-wired speaker cables/ Wireworld Silver Eclipse 8 bi-wired speaker cables/ Wireworld Silver Eclipse 8 interconnects & Electra 7 power cords/ Audio Art 1 e” AC Power Cord.

PRICING :

LS3/6 Cherry or Walnut ~ USD 6,498.00 pair.

LS3/6 Exotic veneers ~ USD 6,998.00 pair.

Specifications:

Power handling: 90w continuous, 150w short term, IEC268
Max sound level: 107dB, pair @2m
Input impedance: 8ohm nominal
Input connections: Bi-wire, 4mm terminals (plugs/wires to 4mm cross-sectional area)
Frequency response: 45Hz to 18kHz +/-3dB (on HF axis @1m)
Crossover frequencies 3kHz, 13kHz

Doug Sterling – Stirling Broadcast

Ty Llammarch Felingwm Uchaf

Carmarthen SA32 7PT UK

Phone: 01267 290990

E-mail: stirbro@aol.com

www.StirlingBroadcast.com