BBC LS3/5a loudspeaker Stirling LS3/5a V2, 2007

John Atkinson wrote about the Stirling LS3/5a V2 in April 2007 (Vol.30 No.4):

Back in the early 1970s, the British Broadcasting Corporation needed a physically unobtrusive, nearfield monitor loudspeaker for use in remote-broadcast trucks. A team led by T. Sommerville and D.E. Shorter, of the BBC's Research Department, developed the two-way, sealed-box LS3/5, based on a small monitor they'd designed for experiments in acoustic scaling. That monitor used a B110 woofer with a doped Bextrene 5" cone and a T27 SP1032 1" Mylar-dome tweeter, both sourced from British manufacturer KEF. The only limitations were intended to be those arising from the necessarily small enclosure and the absence of the need for a wide dynamic range under close monitoring conditions.

The speaker showed much promise, but problems with the drive-units led to a detailed redesign, carried out by H.D. (Dudley) Harwood, also of the Research Department, and Maurice E. Whatton and R.W. Mills, of the BBC's Designs Department. (I was surprised to learn that one change was to move the tweeter to the top of the baffle, footnote 1.)

The design was licensed to a number of commercial manufacturers: Rogers and Chartwell at first, then Harbeth (formed by Dudley Harwood, the "father" of the polypropylene woofer cone) and Spendor (formed by Spencer Hughes, the "father" of the Bextrene woofer cone, and who had been the chief engineer on the BBC's acoustic scaling speaker). The Rogers version was the first to appear, in 1975, and remained in production until early 1993. Other licensees included Audiomaster (whose designer, Robin Marshall, went on to found Epos and now works for Harman International), RAM, Goodmans, KEF (who also assembled the crossover circuit boards for all production speakers), and, more recently, Stirling Broadcast.

The design was revised just twice. In 1988, the woofer's surround was changed from Neoprene to a more lossy vinyl compound; and the crossover was redesigned, not to change the response, but to bring the production response window closer to target and to make the impedance a little less demanding. In 1990, the BBC approved a biwiring option, provided the performance in single-wired mode met the original specification.

To the probable surprise of its designers, the LS3/5a proved commercially successful. More than 60,000 pairs were manufactured up to 1988, 43,000 by Rogers alone. J. Gordon Holt reviewed the original LS3/5a for Stereophile in the spring 1977 issue (Vol.3 No.12), and his report, along with subsequent reviews of the Spendor, Rogers, Harbeth, and KEF versions, is available in our free online archives.

Why is it that almost all speakers from the 1960s and 1970s sound as dated, particularly regarding severe coloration and poor stereo imaging, as you'd expect, whereas the LS3/5a remains a competitive design? Perhaps it was the fact that the LS3/5a was intended to be a monitor (though many professional monitors are even more colored than good domestic designs). Perhaps it was the BBC's unique assembly of speaker-engineering talent in the early 1970s, which I don't think has been matched since. Perhaps it was the fact that the design was thoroughly and unusually worked out. (A BBC white paper by Harwood, Whatton, and Mills, "The Design of the Miniature Monitoring Loudspeaker Type LS3/5a," report RD 1976-29, is available at the BBC's website.) Perhaps it was serendipity.

The acquisition of KEF by Kinergetics Holdings in 1992 led to some concern that the drive-units would no longer be available. In the event, KEF continued to supply B110s and T27s throughout the 1990s, but stopped doing so at the turn of the century. The news in late 2005, therefore, that Stirling Broadcast had begun manufacturing the LS3/5a, combined with the fact that Acoustic Sounds began in 2006 to distribute what Stirling was calling the LS3/5a V2, triggered this Follow-Up review. I also decided to give a second listen to Harbeth's replacement for the LS3/5a, the HL-P3, in its current ES-2 guise.

Stirling Broadcast LS3/5a V2 ($1695/pair)

Stirling still manufactures the LS3/5a under license from the BBC, but their current V2 version uses SEAS and Scan-Speak drive-units rather than the original KEF models (footnote 2). Like the original, the SEAS woofer is mounted to the rear of the inset front baffle and the tweeter is surrounded by a rectangle of thick felt to reduce the levels of close reflections. The crossover, described by Stirling as "SuperSpec," is said to be of higher quality than the original, and the 12"-tall cabinet is of a thin-walled construction similar to the original, with a screwed-in rear panel. The snug-fitting grille is made from the same Tygan material as the original, and two pairs of binding posts are fitted to the rear panel to allow biwiring.

The $1695/pair price is for Cherry or Walnut veneers—a far but inevitable cry from the mid-1970s price of £52 each! My review samples (serial numbers LE88105A and B) were finished in striped ebony veneer (add $100/pair)—very flash!

Sound

Before I auditioned the Stirlings, I spent some time with my 1978-vintage Rogers LS3/5as. (I used both sets of speakers with their grilles in place.) There was a touch of nasality in the upper midrange, the treble sounded less smooth than modern contenders, and the upper bass was less well defined than audiophiles now expect from even inexpensive speakers. But the accuracy and stability of the stereo imaging and the sheer purity of the speaker's midrange reproduction were both still competitive with the best small speakers.

Replacing the originals with the Stirling V2s on the same 24" stands, with pads of Blu-Tack connecting each speaker to the stand's top plate (bypassing the LS3/5a's small rubber feet), I was struck by the fact that the upper midrange had lost its nasal character, but also by the feeling that there was now a slight lift in the treble region. It had been a decade since I'd auditioned a recent LS3/5a (the final KEF version), and that was in a different room, but I remember it as being a little more subdued at the high end. Having said that, I did adjust quite quickly to the Stirling's tonal signature, which was balanced at lower frequencies by a definitely rich-sounding upper bass, even with the speakers well away from room boundaries.

Of low- and midbass there was none, of course. But the upper-bass boost does give the illusion of there being more bass than there actually is. With appropriate recordings, such as the charming Bach-Malloch The Art of Fuguing (CD, Sheffield Lab 10047-2-G), or Antony Michaelson's performance of the Mozart Clarinet Concerto on K622 (SACD, Musical Fidelity SACD017), both of which use a small orchestra, the double basses were reproduced with a natural-sounding tonality, even at quite high playback levels. On larger-scale works, such as Vladimir Ashkenazy's 1983 recording of Rachmaninoff's Symphony 1 with the Concertgebouw Orchestra (CD, Decca 411 657-2), where the double basses are joined by timpani and bass drum, the illusion could be maintained only at modest volumes. The bass-drum blow that begins the fugal section in the symphony's first movement, for example, had superb definition, though it definitely needed to be played a little quieter than would be strictly required for optimal visceral stimulation. At more realistic levels, the speakers started to sound gruff and too warm.

But even with the Stirling's slightly exaggerated treble and the early digital sound of this Rachmaninoff recording, the upper strings sounded smooth and edge-free, and the brass had a most satisfyingly realistic crackle. Naturally recorded voices also sounded free from coloration. The CD I recently engineered of Minnesotan male-voice choir Cantus singing works about the sea (There Lies the Home, Cantus CTS-1206) features a variety of solo voices, each faithfully reproduced by the Stirlings. And the speakers' superbly stable, accurate stereo imaging allowed me to hear deep into the rich acoustic of Sioux Falls' Washington Pavilion, where I recorded the album.

Dynamics were never the LS3/5a's strong point, and the original always sounded a little "slow" on rock music, as though the body of the bass-instrument tone was lagging a little behind the beat. Following Steve Guttenberg's dissing of Bob Dylan's Modern Times (CD, Columbia 3826 87686-2) in his December 2006 "As We See It," I picked up a copy to see what the fuss was about. Well, this album does sound "modern," in that a thin, grainy scrim hangs between the musicians and the listener, and Dylan's voice has a distinct, cheap mike "quack" to it. But over the Stirlings I could hear a respectable amount of "room" around the drums and piano, especially in "Spirit on the Water," and the cymbals had decent HF extension.

The recorded balance was not as bad as I was expecting, and boy, that's one tight band. It may be heresy to say so, but I am starting to deplore the sloppy ensemble on much of Highway 61 Revisited (Columbia CK 9189), especially "Queen Jane Approximately," which the LS3/5a V2 reproduced with all its jangly, out-of-tune guitars intact. But play Modern Times too loud and Tony Garnier's use of double bass rather than the better-behaved electric bass pushes the Stirling's upper-bass bloom too far in the wrong direction. And it wasn't that hard to push the speakers hard enough that their tiny woofers crapped out, producing a slight pop at the beginning of each bass note.

Summing Up

I was very impressed by the Stirling LS3/5a V2, though its slightly forward treble balance is going to be less forgiving of treble problems in the rest of the system than was the original design, and those with larger rooms will easily ask for too much from it. Even so, it both lives up to the reputation of its illustrious ancestor and even, perhaps, improves on what the original LS3/5a had to offer.— John Atkinson


Footnote 1: The full history of this classic speaker can be found at the LS3/5a Enthusiasts website.

Footnote 2: The Stirling LS3/5a V2 costs $1695/pair in Cherry or Walnut veneer; add $100/pair for Ebony or Rosewood finish. Manufacturer: Stirling Broadcast, Somerset, England. Web: www.stirlingbroadcast.net. US distributor: Acoustic Sounds, PO Box 1905, 1500 S. Ninth Street, Salina, KS 67402-1905. Tel: (785) 825-8609. Fax: (785) 825-0156. Web: www.acousticsounds.com.

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