Spendor S100 loudspeaker John Atkinson December 1991
When I see the word "monitor" applied to a loudspeaker, I flinch. Years of working as a musician in studios where the balance of the monitor speakers had been optimized both to play loud without strain and to throw detail in the engineer's face so that he could immediately tell what was wrong have left me with a defensive reflex. Whatever the actual model of monitor—I worked with JBLs, Tannoys, Meyers, UREIs, Westlakes, even those ancient grey-and-black Altecs featured in the inside photograph of the Band's second album—the words "listening pleasure" hardly came to mind. And when those monitors were driven by early solid-state amplifiers—such as the antique Quad 50E monoblocks that were ubiquitous at London's Abbey Road Studio in the early '70s—I used to drive home from the sessions with a headache the size of Nebraska.
Which doesn't go any way at all toward explaining the anticipation I felt when Sam Tellig told me he was going to send me his Spendor S100 monitors (footnote 1). The inestimable Sam wrote about the S100 in Vol.13 No.6, concluding that it was one of the finest products he had reviewed, yet the S100 comes from a long line of loudspeakers intended to be used as recording monitors.
A paradox? Actually, no.
Spendor was founded in the early 1970s by an ex-BBC engineer, Spen (Spencer) Hughes, and his wife Dorothy (Spen...Dor...get it?) to manufacture a range of professional monitors based on Spencer's work at the BBC and intended to be tonally neutral rather than ruthlessly revealing. These included the large three-way BC3 and the smaller BC1, which were sold in relatively large numbers to both British radio stations and West German Radio. The BC1 in particular, which coupled the classic Celestion HF1300 soft-dome tweeter with a Bextrene-cone midrange/woofer, was perhaps one of the three finest loudspeakers to come out of Britain in the '70s. (The other two were the Rogers LS3/5a and the Linn Isobarik, of course.) It offered superbly accurate imaging and an astonishingly uncolored midrange, these virtues offset by a somewhat restricted dynamic range and an underdamped reflex bass that worked better with direct microphone feeds and master tapes than it did with LP playback (footnote 2).
Spencer Hughes, who with Dudley Harwood did much of the early work into the use of polypropylene as a cone material at the BBC Research Department, sadly passed away in June 1983; his son Derek, also trained at the BBC, took over the design reins. The S100, a large, somewhat visually imposing speaker introduced in 1989, is the culmination of Derek's attempts to produce a monitor to rival the BC1 in midrange neutrality but with a higher sensitivity and a considerably greater dynamic range capability, coupled with a low-frequency tuning that will give a good balance between bass extension and articulation in a typical listening room.
The S100's woofer is a large unit, constructed on a 13" diecast chassis using a 1.75" (44mm) voice-coil and a doped Bextrene cone with an approximate radiating diameter of 9.5". Unusually, this driver is mounted behind the aperture in the front baffle. The reflex alignment is provided by two ports either side of the centrally mounted tweeter on the baffle, these 2.5" in diameter and 7.5" deep. The ports have a slightly flared profile to lower wind noise at high levels and are lined for most of their depth with absorbent foam to minimize duct resonances, a design wrinkle that first appeared in the BC1 some 14 years ago.
Covering just under three octaves, from 600Hz to 4kHz, the midrange driver is mounted above the tweeter, rabbeted into the baffle to give a flush mount. It uses a mixed polypropylene-polymer cone, this coated by hand with a damping compound. The tweeter is used to cover just the top two octaves of the audio band, and is a version of the venerable 19mm fabric-dome unit from Scanspeak. Its faceplate is covered in foam and loads the dome with a slight flare.
Three pairs of binding posts allow the drive-units to be driven individually if so desired, while the crossover is constructed on a printed circuit board attached to the rear panel by those six posts. Transformer-core inductors are used, with plastic film capacitors in the midrange and tweeter feeds and non-polarized electrolytics in parallel with more film caps shunting the woofer. There are also a couple of power resistors in the midrange filter. Electrical filter slopes appear to be second-order low-pass for the woofer and midrange, second-order high-pass for the midrange, and third-order high-pass for the tweeter. The internal wiring appears to be 18-gauge, with push connectors used to connect it to the crossover board.
Whereas the classic Spendor BC-series speakers used cabinets constructed from mass-loaded plywood, that of the S100 is made from ½"-thick high-density fiberboard, to the inside surfaces of which are affixed bituminous pads covering almost the entire surface area. There is also an internal lining of 2" acoustic foam, while a horizontal brace joins the two side panels. The midrange unit is loaded with its own sub-enclosure formed by an angled horizontal brace running the full depth of the cabinet, and the black-painted front baffle is reinforced in the area of the ports by a horizontal 2" by 4" strut that runs behind the tweeter. The very tight-fitting ¾" rear panel, again painted black, is fixed with 16 wood screws, allowing access to the speaker's interior in cases of dire emergency. (Remember the Spendor's professional lineage; sound engineers know that if things can go wrong, they will.)
The hex-head bolts securing the two upper-range drivers stand proud of the baffle while, unusually in a modern design, the baffle is set back into the cabinet, giving a lip some 9mm deep around it within which the grille sits. This would be expected to result in some early reflections of the midrange and treble sound that experience suggests would smear the accuracy of the speaker's imaging.
Setting up the S100s didn't prove particularly problematic. Though I was at first bothered by a hollowness in the speaker's midrange balance, listening to pink noise showed me that I was sitting too high. With the speakers supported by the 13" Chicago Speaker Stands stands, the tweeter axis was placed around 30" from the floor, some 6" below the level of my ears in my favorite chair. The smoothest transition from the midrange to the treble seemed to be on or just below the tweeter axis rather than level with the midrange unit, so I discarded the spikes and propped up just the fronts of the stands with German Acoustics brass cones to bring my ears on to that axis.
With the possible exception of the ProAc Response Threes that I heard chez Jack English, it's a long time since I've heard a moving-coil loudspeaker as uncolored through the midrange and above as the S100. Looking through my listening notes, I have almost nothing to say about the speaker's "sound." Instrumental tonal colors seemed to be preserved intact, the speaker neither imposing its own formant structure on their sounds—no "eee," "aaah," "oooh," "oww," or "awww" vowel sounds being apparent—nor popping some notes out of the stage at the listener. Female voice was about as neutral and musical as I have heard. Everything sounded smooth, though the speaker's overall balance did seem to favor the upper midrange somewhat. This gave the S100 a somewhat forward rather than laid-back presentation, more noticeable with the Levinson and YBA amplifiers than either the Audio Research Classic 60 or Classic 120. (It also meant that the speaker was a better match with the VTL D/A processor than the already forward-sounding Krell.) Nevertheless, the high frequencies were, if anything, slightly reticent. The S100 is not an "audiophile" speaker in that respect.
Lower down in frequency, in the region covered by male speaking voice, for example, there was a touch of congestion, as well as a feeling of excess fullness to the sound. Sam Tellig's admittedly chocolatey speaking voice on the Stereophile Test CD, for example, acquired too much chest tone, as if he had been speaking a little too close to the microphone. This coloration manifested itself on piano by adding a slight woodiness to the sound. The already warm-sounding Steinway on Stereophile's Intermezzo LP became more so (though the thunderous character of the pedal D-flat 9:35 into the Brahms sonata's second movement was about as realistic as I have heard it sound since the original sessions).
These observations were with the speakers single-wired. Bi-wiring, so that the woofer was driven separately from the midrange and tweeter, significantly reduced the feeling of lower-midrange congestion, although the warm balance to piano and Sam's voice was unaffected. Nevertheless, my experience would suggest bi-wiring to be mandatory with the S100s.
Getting the musically optimum bass balance required some fooling around with both speaker placement and amplification. With the speakers in the positions that gave the smoothest response with the Wilson WATTs and Puppies (see June 1991), the upper bass was exaggerated in absolute terms. Though this lent the sound a sense of power, the lower bass sounded shelved down in comparison. Leaving the speakers in those positions but replacing the Mark Levinson with the tube amplifiers dropped the level of upper bass, presumably because of the interaction between the speaker's impedance curve and the output impedance of the amplifier; but the low bass remained depressed. The low frequencies overall sounded a little lean as a result.
Footnote 1: During the writing of this review, I was informed of the sad death of Richard Schaus of RCS. While I am not certain, therefore, of the current state of Spendor distribution in the US, I felt the S100 to be an important enough product internationally to publish the review.
Footnote 2: If any readers out there still have BC1s, hang on to them. You have classic speakers that the advent of CD as a source has brought into their own.