Stand Loudspeaker Reviews

Let me tell you how I spent the month of May 1987: I had been musing about a comment made by J. Gordon Holt following the 1986 Summer CES that it seemed that the loudspeaker High End was populated exclusively by planar models: Apogees, Acoustats, MartinLogans, Magneplanars of various kinds, the Quad ESL-63, and an assorted Infinity or two. The problem is, however, that folks as a rule buy speakers made from boxes; boxes priced a little lower than the esoteric beasts so beloved of reviewers. "OK," said Larry Archibald, "how about reviewing some moving-coil loudspeakers? Tell you what. Let's make it interesting; make them box loudspeakers costing under $1000/pair. It'll give you a feel for the kind of affordable speaker that sells in quantity."

Little could I protest that two of my favorite speakers—the Celestion SL600 and KEF R107—are conventional; at $1600/pair and $4750/pair respectively, however, they hardly qualify as "affordable."

Thus it was that I asked for loan samples of the SL6S stand-mounted loudspeaker ($900/pair) from UK manufacturer Celestion.

Successor to 1982's very musical SL6, which pioneered the resurgence of interest in metal-dome tweeters, the SL6S replaces that system's copper-dome unit with a more sensitive aluminum-dome driver. Whereas the copper dome had a first-breakup mode fairly low in frequency, the lighter dome doesn't go off until above 23.5kHz, doing away with the need for an individually tuned notch filter. Although the cabinet dimensions are approximately the same as its predecessor, the '6S is a complete redesign: the MDF-walled cabinet has a horizontal figure-eight brace and an inset rear panel to increase rigidity.

Though the bass driver, designed with the help of Celestion's laser interferometry techniques, looks the same, it too is different, having reduced voice-coil inductance and a two-piece surround. The inner part of the surround is of PVC, to correctly terminate midrange traveling waves in the cone, while the outer half is of soft rubber, to give a freer action at lower frequencies; this results, hopefully, in better articulation. Both drivers are manufactured by Celestion.

The high-quality crossover features a 12dB/octave low-pass slope for the woofer, but an 18dB/octave high-pass function for the tweeter drive, with the nominal crossover frequency being 2.8kHz. Electrical connection is via Michell gold-plated binding posts, which have a knurled screw rather than one which can be fully tightened with a nut-driver.

I should point out that Stereophile contributor Martin Colloms acted a consultant to Celestion on the design of the SL6S: this in no way affects anything I have to say about the loudspeaker; indeed, upon reflection, it may be that I will be a little too critical.

The Sound
I am no stranger to the basic sonic character of Celestion's small-speaker range, having owned a pair of the original SL6s, lived with SL600s for five years, and used a pair of SL6S speakers for two months before moving to Stereophile from Hi-Fi News & Record Review magazine.

The original SL6 design was noteworthy for its musical qualities, though it suffered from a lack of lower-midrange transparency and a depressed HF response, and was perhaps too insensitive for use with low-priced amplifiers. The former defect was cured in the SL600 by the use of a ridiculously expensive Aerolam cabinet; the SL6S represents an attempt to increase sensitivity a little, and to deliver a more neutral HF balance, at a lower price-point than the SL600, or the even more expensive SL700 launched at Chicago in June 1986.

First impressions were of a lightweight balance, with a very neutral midrange. Piano timbre was quite naturally reproduced, with no undue emphasis of any notes through the tricky upper midrange. Voice was also neutral, apart from a little chestiness on baritone when compared with the SL600. Bass was well-controlled, if lacking a little weight; low-frequency instruments were superbly articulate, however, if not quite up to the standard set by the '600, and there was not quite as much mid-bass "thunder." There was a slightly hard coloration in the low treble which gave overall reproduction a slightly cold quality, something which bothered J. Gordon Holt more than it did me.

Where the SL6S excelled, however, was in its imaging and presentation of soundstage. The piano images on the naturally miked Boyk and Stanczyk recordings were superbly delineated, with no spatial blurring, and the imaging was consistent with frequency. Some dislike this holographic presentation, feeling that it too ruthlessly reveals the lack of true soundstaging on multimiked classical recordings, but I want to hear truth, not some collage of recorded inadequacies fudged-over by loudspeaker problems (even if that collage does then correspond to what the listener might expect to hear sitting in Row Z in the concert hall).

The drum-kit image, too, was natural, and the dynamics came over very well. In fact, I would say that the SL6S suffers less from compressive effects at reasonably high levels (up to 100dB) than any other small speaker I have auditioned. It is a small speaker, however, and it proved possible to bang the woofer against its end-stops with the very high-level bass drum notes in the Sheffield Firebird, the excellent dynamics giving no warning of incipient overload. (With other small speakers, you become aware that the woofer is working very hard well before it runs out of mechanical headroom.) There should be no problems with amplifiers of up to 100W power, however.

Conclusion
Though the SL6S lacks the LF extension of, say, the Thiel CS1, it has sufficient authority and lower-midrange transparency to make reproduction of bass instruments believable. Though it is neutral through the midrange, the slightly cold balance may not suit all tastes. Nevertheless, regarding overall performance, though it doesn't communicate the music as effectively as the almost-twice-as-expensive SL600, the SL6S is an excellent speaker by any standard.

The point has been raised by Anthony H. Cordesman, among others, that small British loudspeakers represent poor value for money, their price having to reflect the costs of transatlantic shipping and the increased overhead of running an extra distribution company. With a model like the SL6S, however, no excuse need be made.

Final Thoughts
Two loudspeakers stand head and shoulders above the others that I have reviewed in recent issues: the Celestion SL6S and Thiel CS1. Almost the opposite in tonal character—the British speaker a little subdued, the American having almost too much HF verve—both featured a lack of unmusical coloration, created solid soundstages with very well-defined width and depth, and revealed enough of the dynamic shadings of the music to produce an enjoyable sound.