Celestion SL6S loudspeaker

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 R107are 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.

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.

Celestion International Ltd.
Celestion no longer markets domestic loudspeakers (202O)

Anton's picture

These babies were true imaging champs.

The Hi Fi store demo speaker of a lifetime.

I am sure this was used almost universally....I am pretty sure it was this album...that Flim & the BB's track with a bicycle coming toward the listener on one side, then turning in front of the listener, and then proceeding away in the other channel.

It was pretty uncanny.

Thanks for the splendid memory.

And it positively oozed the audiophile look!

I still lust after them...I wonder they would hold up today?

tonykaz's picture

I read ( in the early 1980s ) about your experiences with these Celestian SL6 and bought a pallet full. I sold them thru a Classified Ad. in the back pages of Audio Magazine. I ( B&K ) Imports, probably sold over a couple hundred pair, ( all that I could buy from regional distributors in the UK ).

Interestingly, I didn't like them as much as the ProAc but they did compare quite favorably to our regular Saturday Audiophile Comparison group meetings where all the Smaller Loudspeakers were compared: LS3/5a, Linn Kann, Spica TC-50, Quad ESL63, SL6 & SL600, the still outstanding ProAc Tablette original, along with everything else we would toss into the mix. VPI Player, Sumiko Arm, Koetsu, Electrocompaniet, Audible Illusion, Conrad-Johnson Electronics, Monster & MIT-750 cabling.

I miss the camaraderie of those wonderful days of exploration.

and I miss the John Atkinson Editor of HFN&RR.

Tony in Venice

davehg's picture

I was working at a big box retailer in the late 80s and got these at cost - $650 was a lot to a poor college kid. They sounded great but were hard to drive loud. I enjoyed the heck out of them, and managed to get a pair of SL600s which were even harder to drive.

32 years later and Iā€™m still enjoying high end gear. I do miss the many SPhile writers who have left us too soon.

Zachary Cohen's picture

Amazing connection yesterday as since the 1970's and early 1980's I have used the Audio Research SP3a (pre-amp) and D70 (amp) with an original and similarly old Martin Logan speaker. But, in my piano playing room, I listened to my own (high amateur) and professional recordings with the Celestion 6s, that I had bought when new, and was played with a good but not great NAD and/or Rotel electronics. The Celestion 6s sounded good but not great in several ways as it was only a few inches away from a back wall. My Martin Logans had broken down a few weeks ago. The Celestion 6s was moved to work with Audio Research to be used until I ordered a Martin Logan replacement. I thought I would order Magnepan, but more and more I began to like the Celestion 6s at a high level (it not only had come off the wall in my piano room but now were about 5 feet from a wall in a 17 x 21 room and were working with great tube pre-amp and amp). I think I will order a KEF 350 or something that can go in either room because I may continue to use the Celestion 6s with the audio research amp and pre-amp (I mainly listen to cd and old records of classical piano but do listen to most classical music, some jazz, and some old rock music). Now the Celestion 6s produces music with emotional appeal. What a coincidence to be deciding this about a speaker I bought decades ago and get to be influenced now by an old Stereophile article (which I probably read back then!).

yourfriendfred's picture

I bought a pair of these in 1988 when I lived in England. I paired them with an Exposure X (ten) amplifier and loved the sound. It was my first "hi-fi" setup and I think cost about 1,000 pounds altogether.

I still have the speakers and amp though I haven't listened to them in many years. I remember writing a letter to Exposure asking them how to convert the amp to 110V. They responded - also by letter!

Ortofan's picture

... could instead have opted for the Spendor BC-1 or SP-1.
Or, the under $1,000 box speaker I preferred, at that time, which was the ADS L880/2.

zimmer74's picture

after a brief experience with the original SL6, I lived with the SL600 for many years in the 80s. And I believe we were both using the Audio Research SP10 preamp and D250-II amp (250 watts of tube power). I have moved on to various setups, some very expensive, but that SL600-based system was the most musically satisfying I have ever owned. All the small Celestions required a lot of power, but the Aerolam cabinet of the SL600 was magic. I've often wondered why no subsequent speakers from any company have used that material.

cedricchan's picture

Bought a pair in Hong Hong when it first came out. That was like 33 years ago. I still remember the Taxi driver warned me with the SL6s speaker stand. He goes "Make sure your stand don't scratch or damage my seat LOL.

Here is the latest picture of my SL6s along with the Wharfedale EVO 4.4

avrayman86's picture

We used to sell the Celestions at our HiFi store but they never did it for me.Hard to drive and the sounded compressed. I prefered the Spendor BC1 and SP1's as I recall for stand mount speakers. Just IMHO :)

thomasrhee's picture

These belong in any list of "Hall Of Fame" speakers. Truly classics.

ChrM1971's picture

The review is of the SL6S (aluminium tweeter 1987) but the pictures show the SL6 (copper tweeter 1982). ????