Carver ALS Line Source Loudspeaker System

Unique Natural Beauty

Equipment report
Bob Carver ALS Line Source
Carver ALS Line Source Loudspeaker System

The Adjustability of the Speaker
Typically, a loudspeaker review describes first a whole lot of things that, however much they may be wrapped up in poetic language and in the code words of audio, really amount to reviewing the frequency response in broadband terms, the overall balance. You know how the code goes: “detail” = excess top end, “transparent” = hole in the 100–300Hz range, “PRAT” (pace, rhythm, and timing) = extended but lowered in level bass, “involving” = midrange forward, and so on. This code system arose when people stopped knowing or caring what the actual frequency response was—and of course largely stopped measuring it. But they were still reviewing it, just in different words and forms of description. [See my review of the Magico Q7 Mk II in this issue. It has an identical frequency response to that of the original Q7, but a decidedly different tonal balance as well as significantly greater resolution and transparency. —RH]

Now comes a surprise! To a great extent, you will have to give the whole balance question a miss with the ALS because it has a very considerable range and a variety of adjustments. There are controls on the bass, the upper midrange, and the high frequencies, with marks to indicate Carver’s own preferred settings but no obligation to stick to them. The speakers are quite well behaved in in-room smoothness—actually rather more so than many quasi-point-source speakers, especially in floor interaction. The ALS starts with the advantages of good driver behavior and elimination of the floor reflection (and everyone has a floor!), but of course one can balance the speakers in different ways to suit room conditions and tastes—and with the Carvers, one can compensate for room character.

Still, three adjustments are not anywhere near enough to modify the response of a speaker to one’s sonic preferences. In my experience, I could not quite get the ALS to be entirely neutral-sounding (to my ears) using only the adjustments provided. Getting in there with an eq device and just going for it led to satisfying results beyond what the adjustments themselves allowed—and by “satisfying” I mean sounding tonally like what I have come to believe is on the recordings. Part of this may be that in my room I could not get the speakers quite as far from the sidewalls as I would have liked (more on this below). In any case, there were other things going on (a 300Hz prominence and the dip above that, for instance) that were not directly adjustable with the speaker’s controls, though those are very useful indeed.

In a sense, the speaker’s native, natural balance—and what Carver had in mind, as I understand it—is to have a BBC-style “Gundry dip” in the 2 to 4kHz range or on up somewhat further. (There are theoretical reasons why this sounds good—the ear’s diffuse-field response in this region is much lower than its frontal direct-arrival response, and making stereo recordings effectively moves some diffuse field into direct arrival. So it’s a good idea to compensate for this perceived difference. One can see the figures on this in Bech and Zacharov’s book Perceptual Audio Evaluation. But if you do not like this, you can adjust the extent of it, or even adjust it away with the controls, though I doubt you will want to as the speaker really “likes” the Gundry dip in sonic terms.)

Incidentally, the ALS is a natural for DSP room correction and eq adjustments in general, if you feel you want to make changes beyond the ones offered (of an analog sort). If you do want to DSP, you will be free of the restrictions many speakers of limited dynamic range impose. One can never fill in an infinite null, of course, but otherwise one can do essentially anything one likes here, thanks to the ALS’s enormous dynamic capacity. Also the speaker is quite high in sensitivity, so big dynamic swings do not require huge amplifier power. The pair played quite loudly (not DSP’d) with a moderate-power tube amplifier (20Wpc) that Carver supplied, though higher-power amplifiers, both solid-state (Sanders Magtech) and tube (Carver’s 350Wpc monoblocks) of course made them stand up and salute even more. However, DSP control of this type of speaker is not a simple matter; measurements of line sources are complicated because the whole interaction with the room is different, and the subtleties of what is “right”—already tricky for quasi-point-sources—are likely to be equally complicated and different. Fastening up some automated program is not likely to give good results (except in the very bottom end). You will need to adjust by ear.

So once you have adjusted the speakers to what you perceive as the most natural and neutral balance in your room, what then? (Further discussion will pertain to the speaker adjusted.)

The Listening Experience
First of all, one overwhelmingly obvious and compelling attribute is how pure and resolved the sound is, without being top-end aggressive. Then there is the ALS’s full bandwidth, all the way from subterranean lows on out to forever in the highs. There is unlimited dynamic capacity, for all practical purposes. And the distortion does not rise as the level goes up. The speaker just soars like an orchestra or a big band. Loud, but without any stress at all. (Really loud—the ALS is supposed to be able to produce 120dB+ levels cleanly, though I did not even begin to explore this.)

Another striking aspect about its overall purity is the lack of perceived intermodulation (and I imagine, measured intermodulation as well, though I did not actually measure this). Speaker manufacturers and testers tend to quote THD figures, but even more crucial is intermodulation in the extended sense. Does action in the trombone modulate the trumpet line? Does the cello section interfere with the violas? Do complex things turn to mush? With all too many speakers one has to answer yes to these questions. But here, not a bit. Everything stays clear and effortless and resolved in the true sense.

I think the speakers are very close to unique in this regard. I doubt that this effect can be maintained from the lowest to the very highest levels by any speaker except a large line source, and few of those will do it as well as this one. (I do not say that none can because there are the aforementioned Steinway Lyngdorf LS Concerts, for example. In fact everything I am aware of that is comparable in these aspects costs more. But the Eminent Technology 8Bs, which are quite inexpensive, also have very low perceived distortion, within a somewhat smaller dynamic range.)

The first thing I listened to seriously was a recording on which I play in the orchestra, Music from the Left Coast. The first piece here, Wayolo Lamoni by Christopher Tin, is a complex mix of orchestra, vocal solo, and choir (the famous Soweto Gospel Choir). Naturally I’m more than familiar with this recording. I was there playing and listening as it was made (to the playbacks as well as to the playing itself). The ALSes presented this piece in a startlingly realistic way, like a photograph with higher resolution but without any edginess, and the voices were dazzlingly beautiful. Carver himself, who had come to set up the speakers, seemed quite overpowered, and so was I. I had heard this recording a great many times, but never like this.

While the ALS did very well on every type of material, the vocal reproduction, both solo and choral, proved to be a particular strength, if one had to choose a single genre from all that these speakers reproduce so well. Reference Recordings’ A Gaelic Blessing (from the Rutter Requiem CD) was a marvel. And the solo vocalist on another CD in which I was playing was just gorgeous and truthful, too. My wife Paige’s reaction was, “ I really like her voice.” Indeed, and very much the real voice it was. This reaction was typical of people encountering the ALS for the first time. They noticed how good the music sounded without being distracted by how the speaker worked. To me, this seems to truly define naturalness.

While Carver was here, I also did a live-versus-canned comparison of my own playing recorded with a very nearly neutral microphone, where I played alongside the speaker channel where most of the violin is on that CD. This was really convincing, one of those exciting moments when one realizes anew that yes, audio really can work in terms of the convincing presence of a real instrument in size, physical scale, and unconstrained dynamics.

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