Thiel CS3 loudspeaker
The CS3 is time-aligned, phase-coherent (footnote 1), actively equalized to extend the low-end response, and designed for an unusually uniform impedance characteristic. As can be seen from the photograph, the enclosure is tapered and the edges rounded off. The taper provides the back-to-front offset for the drivers (to accomplish the time-alignment), and the rounding-off minimizes the effects of cabinet edge diffraction.
Also worthy of note is the fact that the teak panels on the bottom front of both speakers have virtual mirror-image patterns of graining. That's what I mean by attention to detail. The cabinets have nice proportions and clean lines. They're more attractive with grille cloths in place, but even without them, the speakers serve to decorate rather than intrude.
The CS3 has two sets of input connectors, which are supplied with straps between them. Removing the straps allows the system to be connected to two separate power amps for bi-amplifying. The connectors are so-called "5-way" binding posts, and for once the designer had the foresight to recess these far enough into the enclosure to accommodate the length of dual or single banana plugs. There is even enough space around the plugs to allow easy access to them. More attention to detail! I should not feel compelled to praise things like this, but such common-sense considerations are surprisingly often overlooked.
The CS3 comes with a little black box that must be connected in-circuit at some point, preferably between the preamp and power amp (although the Tape Monitor loop will do), and then plugged into an AC outlet, preferably unswitched. The box contains active circuitry which, as with the ITC-1 system reviewed last month, boosts the system's low end to compensate for the fact that each speaker has only a 10" woofer. Located late in the system's circuitry, directly ahead of the power amp, the equalizer is likely to contribute far less sonic pollution than it would if it were located, say, between the cartridge and preamp. When bi-amping, it is used only with the woofer amp and thus cannot possibly affect the higher frequencies.
This bass-boosting approach has been tried many times in the past, but it never caught on until recently because 1) few woofers could take that much LF boost without distorting or bottoming, and 2) amplifiers capable of producing enough power to yield clean low end at such elevated power levels were few and expensive. Times—and components—have changed.
Low-end boosting actually offers two advantages over the use of a large bass-radiating area. The smaller the woofer area, the easier it is to locate the woofer where it excites the fewest booming-up room resonances; I believe this is one reason why the CS3 behaves as well as it does at the low end. The second advantage is that one 10" driver stores far less energy than one or two 12" drivers. Energy storage and re-release (later in time) is one of the major factors in low-end coloration, and one of the principal reasons some speakers are described as "fast" (low energy storage) and others "slow" (high energy storage).
The CS3s were, in fact, very easy to locate for optimum sound. I started with them at a distance of about 10' from the listening area and aiming parallel. Better and more stable imaging was obtained by toeing them in so that their axes crossed about a foot behind a centrally seated listener, and this is the way they stayed for the balance of my listening tests. I felt no further inclination to fiddle with them.
My first reaction to this system was total incredulity! Never in my life have I heard such tight, deep bass from a speaker this small. In fact, rarely have I heard this kind of low end reproduced from anything at a comparable price. The Sheffield Drum Record heard through the CS3s was a tactile experience! I thought I had heard the lower limit on that disc, but it has more impact than I had thought. And with adequate amplifier power (I used a Threshold S/500 at 250Wpc and would not recommend much less), the kick drum was clocked at 100dB before the woofers started bottoming! Then I started to notice other things.
The CS3 seems better able to handle impactive bass (kick drum, bass drum, plucked double bass) than sustained bass. Bowed basses, for instance, seemed a little shy of that throom quality they have in real life.
The imaging on these speakers is nothing short of amazing. No matter where I sat, Amanda McBroom stayed centered between the speakers! Even when I walked to the right of the right-hand speaker she was centered. Sitting still, anywhere across the 6' spread of my sofa, I heard a balanced stereo stage and quite remarkable imaging stability from every voice in a performing group. I have heard this kind of imaging before, but never from a speaker that was this good in other respects. How good was it? Well...
Footnote 1: For the second issue in a row we must apologize for having no standard (other than our opinion) for evaluating manufacturer's claims of phase coherence. Again, we're not implying the manufacturer's claims are false.—Larry Archibald