666thielcs1.promo.jpgKentucky manufacturer Thiel has acquired a reputation for the coherence of sound presented by its range of distinctive, sloping-baffle, floor-standing loudspeakers. Designer Jim Thiel gives a high priority to linearity of phase response; as a result, he chooses to use phase-linear, first-order crossovers in his designs, the target response being the combination of electrical and mechanical filtering. As the out-of-band rejection is then only 6dB/octave, it places demands on his chosen drive-units to be well-behaved, not only in their passbands, but also outside of them. In effect, the loudspeaker has to be designed as a whole system, the interaction between the drive-units and crossover being considerable.

The CS1 ($950/pair) is the least expensive in the Thiel range, combining a Norwegian plastic-cone, diecast magnesium-chassis woofer with a 1″ soft-dome tweeter in a well-built, heavily braced cabinet, finished in real-wood veneer. The woofer is reflex-loaded with a 2.5″-diameter, 4″-deep port placed just above the name-badge trim. The complex crossover features separate legs in parallel for the two drivers, and is constructed from high-quality components, with air-cored inductors and all electrolytic capacitors bypassed with film caps and polystyrenes. Electrical connection is via high-quality, gold-plated 5-way binding posts on the base of the cabinet.

Unusually in a speaker at this price, considerable attention has been paid to the construction of the grille, in order to minimize deleterious diffraction effects. The cutout for the tweeter, for example, is profiled so that the soundwaves never see a sharp edge. The CS1s were therefore auditioned with grilles in place.

Set-Up
The speakers were used over an extended period of time for all my recreational listening; once I had become happy that I was getting the best sound, a more critical series of listening tests was performed using an identical selection of music to get an idea of the comparative strengths and weaknesses of each design. The tracks used were as follows: Chopin Waltz in C-sharp minor, HFN/RR test CD (my own recording, made with the Calrec Soundfield mike in crossed figure-eight mode); the drumkit recording on the HFN/RR test CD (again recorded with the Soundfield mike); Beethoven “Pathetique” sonata, Performance Recordings PR-5 (recorded with crossed figure-eight ribbon mikes); Stan Rogers’ Northwest Passage (Fogarty’s Cove Music FCM-004, a naturally recorded collection of Nova Scotian-style songs sung by a baritone, recommended to me by Mission’s Armi Leonetti); Ray Noble’s “The very thought of you” (Ken Kessler’s favorite test track, the incomparable Ella Fitzgerald backed by a naturally miked big band, recorded in 1962 when engineers didn’t know enough to spoil the music); and Stravinsky’s Firebird suite, on Sheffield Lab CD-24 (pure Blumlein-miked orchestra, using Coles ribbon mikes). Particularly useful for judging accuracy of timbre on voice was the Freehold, New Jersey, recording of “Papa-oom-mow-mow” (Rhino RNLP 70827).

The two things these recordings have in common, apart from the fact that I know them all intimately, is that they all were recorded in such a way as to produce a tightly defined, tonally neutral soundstage, and that none have been “doctored.” As I have pointed out before, how on Earth can a reviewer make valid value judgments if he doesn’t know what to expect from the recordings he uses to make those judgments? Somehow he or she has to break the circle of not knowing what a recording sounds like apart from judging it using loudspeakers, the properties of which he or she doesn’t know apart from judging them using the unknown recording.

A comment on the nature of my subjective assessments will be in order. There is no doubt that both readers and manufacturers prefer bold, definitive statements of opinion, all black and white with nothing in between. With speakers in this price range, however, we are dealing very much with assessing the quality and quantity of different shades of gray. My subjective comments will therefore tend to concentrate on departures from neutrality and ideal behavior, but this doesn’t mean that the models reviewed were bad; rather, the compromises inherent at this price level will be more obviously audible than with speakers costing, say, $2000/pair. Nevertheless, in the right system and room, at least half of these speakers will shine, musically.

A note to those who condemn tweakery out of hand: At the start of the auditioning, I had the other loudspeakers I was reviewing for this issue in a pile in the corner of my listening room, some 10 feet from the left-hand speaker. Sitting listening to my chosen test tracks, I starting noting down adverse comments regarding stereo imaging: unstable center imaging, different image width at different frequencies, etc.

The penny dropped; I removed all the other speakers from the room; now, the imaging was actually very good. So I advise you to insist upon auditioning loudspeakers one pair at a time before making a final purchase decision. Dealers won’t like you, but only then will you get a true idea of the soundstage capability of a pair of speakers. Reviewers also hate auditioning loudspeakers one pair at a time, particularly if the speakers are heavy, but I can assure you that that will be Stereophile‘s policy.

Sound
With the CS1s placed well away from room boundaries, there was an immediate impression of a light, airy tonal balance, coupled with excellent low-frequency definition. The woofer alignment seemed to be well-nigh perfect, with very good bass transparency. This speaker should work well with classic tube amplifiers. Midrange timbres were excellent, though strings were a little thin-sounding, and bass guitar was somewhat reticent. High frequencies were a little excessive in level, with surface noise and recorded tape hiss “whitening” a little. Breath and key noise on woodwind instruments was slightly accentuated, and snare drum acquired a few more snare wires than usual.

The slightly tilted-up HF balance seems to be an inherent feature of a Jim Thiel design; while not unmusical in itself, it does make demands on the rest of the system that there be no treble nasties. If you use a Quad 34 preamplifier, then I would recommend applying a little down tilt; otherwise, it’s very easy to knock up a little passive network to fit between pre- and power amplifier or in the preamplifier’s tape loop (see fig.1). As shown, this gives a response hinging down above 2kHz to level out as a –3dB shelf above 8kHz: increasing the value of the 6800 ohm resistor (use metal-film types) reduces the depth of the shelf; increasing the size of the capacitor (use a polystyrene or polypropylene dielectric) lowers the hinge frequency.

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Fig.1 Simple HF shelf filter to fit in a preamplifier’s tape loop.

Imaging was very precise, laterally as good as the Celestion SL6S, but there was slightly less depth apparent than with the British loudspeaker. That tilted-up HF response projected vocal sibilants forward a little, and treble depth was shallower than midrange. Instrumental delineation was excellent, however, and the CS1s were never less than musical.

Conclusion
The CS1 is truly an affordable high-end loudspeaker, offering a well-balanced performance with no significantly weak areas, and losing out to the more expensive competition in terms of midrange/treble transparency, low-frequency extension, and ultimate loudness.