Floor Loudspeaker Reviews

Resolution: Jim Thiel's "White Paper" on the CS5 makes much of the importance of phase coherency, and JA's measurements verify that Jim has been unusually successful in satisfying his design criteria in this respect. How important is phase coherency? No one's produced the same speaker in both a coherent package and a non-coherent one—in fact, it would probably turn out to be impossible to produce even the same tonal balance in both coherent and non-coherent forms—and the tonal differences between speakers make it impossible to compare simply the presence or absence of phase coherency between different ones (footnote 3).

The kind of resolution offered by the Thiel CS5, however, argues the case of phase coherency so forcefully as to beg the question. Not only is it very good; I've never heard anything like it before. Never has any component introduced in any system I've had set up told me so much I didn't know about the recordings I play. This degree of added resolution could be compared to that available going from the naked eye to a microscope, or from an optical microscope to an electron microscope. This may be a slight exaggeration, but I mean to say that the CS5 gives you detail about your recordings that no other device I know of can. You hear into the sounds of instruments, and into the texture of voices, much more than you have before. You hear a large number of sounds on records that you never heard before, little details that were there but covered from your attention by the obscuring effects of inaccurate speakers.

It adds up to greater realism. I say that the challenge is for those who maintain that phase coherency is of little importance to match the achievement in resolution of Jim Thiel—then the debate will have two sides.

Music: Generally speaking, speakers are not laboratory instruments; only reviewers and fanatics use them primarily for hearing differences between amplifiers or cables. And detail about your recordings is a fine thing, but in fact most people buy speakers to listen to music, not to the medium that carries the music to them. If all the CS5s allow you to do is to evaluate the different colorations of different microphones, or the differing character of tape hiss, it is a hollow achievement.

For some people, in fact, the Thiel CS5s will provide too much information. This can sound like a condescending remark—after all, what self-respecting reader of this magazine doesn't want to know everything that's on his or her records?—but it's true: depending on your nature, and on the kinds of records you have, you may be much happier with a speaker which covers up faults or creates beauty where there was little.

The noble hobby of high-fidelity sound reproduction, however, contains in its name the answer to the question—the higher the faithfulness to the original, the greater the achievement. I found the Thiels to be immensely American (at least, in our highest aspiring) in their willingness to accept all comers. Beautifully made recordings sounded just that; old recordings sounded scratchy, but the music rang through (many of my favorites date from the early '60s and are not in such good shape); old RCAs sounded bright, but the dynamics of recording and performance overcame my aversion to brightness; the power and beat of rock music, not normally a favorite of mine in home reproduction, overcame the inevitably screechy bright tonal balance and compelled me to listen (and even be moved). I found myself loving the sound of a singer's voice more than I had before, especially those favorites I listen to all the time and have become accustomed to.

As I said earlier, the CS5s were remarkably evenhanded in accepting CD or LP as a source (I, alas, am without open-reel tape). For the first time I have been able to appreciate CD as having real musical advantages over LP in some areas—though, to be honest, I suspect the Stax D/A processor is more responsible for this than the CS5s. Nevertheless, the Thiels allowed me to hear those subtleties of soundstage information which can peek out from behind the black veil of CD silence when you're using something as good as the Stax. They also could tolerate the sharpness of CD high-frequency peaks—which can be a characteristic of live music—with no off-putting exaggeration. LP, of course, was excellent, though I'm used to that. The differences between the early, 155gm 3-step version of our LP and the just-now-available 182gm 1-step version were dramatically apparent to me, as were the differences within each record in microphone usage. Most important, the music came closer as the medium got better.

Larry Archibald Closes
This review has discussed various people's reactions to the CS5, as well as my own, and has detailed shortcomings: places where the CS5s don't live up either to the standards they set in other areas, or to mine. This diversity of opinion, combined with some recommendations for improvement, should not distract readers from my central point: the CS5 is an extraordinary achievement in speaker-making. In quite a few respects it is the best loudspeaker I have heard: by a wide margin in resolution and preservation of detail, significantly in terms of dynamics and evenness of tonal balance, as well as in communication of soundstaging and imaging. Its various excellences are combined into a convincing whole. Both JGH and DO were amazed that a speaker with this many drivers, and with such convincing dynamics from the midbass on up, could paint such a convincing sonic picture. JA simply said, "Boy, can they do space! Wuuhh!" (This last exclamation is the highest praise JA can heap on anything, but you have to hear it live—or, maybe, we could put it on our next test CD—to get the exact character.)

One of the problems of reviewing is that you're given a limited amount of time—one to three months, basically—to make a judgment about something someone has worked on for a really long time, frequently several years. That person's knowledge of the product is inevitably much greater than your own. Every little problem and discrepancy the critic hears is probably, in the case of the best designers, the tiny still-protruding tip of what had originally been an entire iceberg. The designer knows in great detail what compromises had to be made and how inevitable compromise itself is; the reviewer only guesses.

I, along with most of our reviewers, can hear 70 to 80% of a product's problems and potential in a matter of hours, once the product is correctly set up. Usually the one- or two-month review process uncovers another 15 or 20%. In the case of the CS5, I feel that there's more left undiscovered than usual after the review process; unfortunately, I think my discovering what's left will take the next three to six months, and it could take a year. What, for instance, would the result of this review have been had I not had the particularly well-matched (to the CS5) Krells on hand? And what if there's an even more auspiciously capable amplifier as yet unauditioned? In spite of the concreteness of my conclusions, you must realize that I will continue to try for the best from this product, and I'm sure I'll find more.

The CS5 is a great speaker, one for the few rather than the many, even were it financially accessible to the many. Compared to a recent favorite of mine, the Mirage M-1, the CS5 is a collection of many excellences combined with a few flaws—flaws that may really bother some people. Ironically, the excellences of the CS5 will also bother people: they won't want to hear that much about what's on their records. The Mirage is more readily appealing to many people, and less revealing. I suspect I will find it strongly lacking when to it I return. (Couldn't resist that turn of phrase—I'm listening to Julianne Baird sing Elizabethan songs as I write this conclusion!)

Please use this review to examine whether the CS5's excellences are ones that you value highly, and whether you're willing to put out the effort in choosing associated equipment and effecting room setup that will allow them to shine. I hope that Jim Thiel can take my criticisms as signposts on the road to creating further greatness, either in the form of a new speaker or in the form of subtle improvements to this one. I, in the meantime, will be working my way through my entire record (and CD!) collection, auditioning them through the greatness he has already achieved.—Larry Archibald

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Footnote 3: Actually, a paper by Richard Greenfield and an old mate of mine from HFN/RR days, Dr. Malcolm Hawksford, that was presented at the 88th AES Convention in March (full report next month), discussed this very test. A computer applied a pair of digital amplitude-response correction filters in real time to the signals being reproduced by a pair of Celestion SL700 loudspeakers, resulting in speakers that were flat on-axis to a very tight tolerance above their LF rolloff. Although the speakers' phase responses were still not minimum-phase, these were equivalent to an appropriate amount of excess phase being added at each frequency to a minimum-phase response. A second pair of digital all-pass filters operating in real time could therefore be designed to compensate for that excess phase. Listeners compared the stereo sound of the flat-amplitude-and-phase loudspeakers with that produced by loudspeakers that had the same flat amplitude response but that were non-time-coherent. Interestingly, the listening panel seemed to prefer the latter!—John Atkinson