Infinity IRS Beta loudspeaker Larry Archibald, December 1989

Larry Archibald wrote about the IRS Beta in December 1989 (Vol.12 No.12):

There I was in audiophile hog heaven, faced with the greatest collection of amplifier pulchritude I could imagine—plus four pieces of masking tape. Amplification was by Vacuum Tube Logic (VTL 500s), Krell (KSA-200), and Mark Levinson Audio Systems (No.20.5s); tape was by 3M. The amplifiers retail for over $25,000, the tape for less than 5 cents—but each side of the equation was equally important.

Now, I already knew from JGH's experience with the Betas (Vol.11 No.9) that choice of amplification was crucial, particularly on the midrange-tweeter panels. And, prior to the measurements he carried out for his Vol.12 No.6 "Follow-up," JA confirmed this importance when he fired up the Betas in my living room using the exemplary Levinson 20.5s. No go! Unbearably bright sound—I listened for 30 minutes, then gave up. (In fact, that experience was daunting enough that it took me until late August to try again—see October's "As We See It.")

Fortunately, David Manley found a pair of VTL 500s to send out; their sister amps, the Reference 300s, had made the difference with JGH's original Betas, but are now with JGH in Colorado. (JA surmises that the interaction of a tube amplifier's higher-than-normal output impedance with the very low impedance of the Betas above 10kHz—which drops the absolute amplitude response above that frequency—is what makes the VTLs such a good match for the Betas. It's for sure that the Betas were designed by Arnie Nudell with strictly tube amps in mind.) Almost at the same time, our purchased Krell KSA-200 arrived, and we already had the Levinson 20.5s on hand for JA's review in the September issue (though I doubt I could have pried them away from him were it not for this follow-up). Such riches!

Let me define which pair of Betas I'm talking about here. If you remember JGH's review, he had just about decided the Betas were the best speaker in the world when he discovered that the two midrange-tweeter panels he had didn't sound very much the same (footnote 1). The area of difference was right in the range where a speaker sizzles, or doesn't. Critical to his up-till-now rave was the fact that the unsizzly (dull) speaker had been on the left (where the violins play), and the sizzly one had been on the right. JGH's most severe test of speaker tolerableness-under-stress is massed violins, virtually always found on the left of the orchestra. In other words, by accident JGH's Betas were "rigged" to sound good. JGH felt hoodwinked—though inadvertently, he was sure.

Infinity immediately supplied a third speaker, which unfortunately fell between the other two in tonal balance, making it even more difficult to determine what standard production sounded like. Then they sent out John Miller, their key speaker designer/technician, to make sure everything was all right, but the changes he made caused even more confusion. Finally, a completely new production pair of midrange-tweeter panels were sent, the sound of which JGH reported in his Vol.12 No.1 "Follow-up." Disappointingly, the replacements never quite attained the magic possessed by the first pair, with their one "dull" midrange-tweeter panel.

My job was to find just how good this new pair could sound, since JGH's efforts to do so were abbreviated by his move to Boulder, Colorado. (JGH's new listening room is, at present, too small to accommodate the Betas.)

By the time I got around to this "Follow-up," though, I had an advantage JGH didn't: the four pieces of masking tape. (You can use black electricians' tape for least noticeability, or sticky-backed foam tape for maximum effect.) This tape has provided the greatest return for the least investment since the first person used Mortite to keep a Shure stylus body tight to the cartridge body.

If you're a Beta owner (and it probably works to great effect on other Infinity models, most of which use EMIT and SEMIT drivers), here's what you do: vertically cover up half the tweeter and half the forward-firing supertweeter. I experimented with covering either inner or outer half of the tweeter. Which side you choose affects the overall soundstage presentation, but which will be better in your system depends on your speaker placement and room. I ended up with the tape on the inside half of the driver elements, effectively giving me a little extra separation. That's it! But do it before you spend $25,000 on amplification, buy a new cartridge, replace your preamplifier, and exhaust your dealer's supply of exotic cables. This one move brings the Betas into the realm of listenability with a wide range of equipment.

The next step is to have the most skillful and well-equipped dealer in the country, or at least in your state. You'll need him (or her), because you will need to be able to audition a variety of amplification, CD players, cartridges, and cables—for all I know the first thing they'll tell you to do is remove the tape. (You could use black tape and leave the grilles on; no one will notice.) Beg their indulgence; you'll still get to buy lots of expensive gear from your dealer to make your Betas sound their best, but you'll enjoy the journey more, and your choice of associated equipment will be wider.

The tape tip came to me not from my native genius, which lies in the realm of Mercedes-Benz car repair, but from an electronics manufacturer who, almost alone among CES and Hi-Fi Show exhibitors, has coaxed an excellent sound from Betas in those environments. In fact, at one CES almost the entire staff of Stereophile remarked on his achievement—we just couldn't believe it!

So, here's my tale of the tape (footnote 2) With tape installed, I started out driving the Betas on top with the pair of VTL 500s, and on the bottom with the Carver Seven T-mods, using the Conrad-Johnson Premier Seven as preamplifier. (Other system elements consisted of the familiar CAL Tempest II, the Well-Tempered Turntable, the AudioQuest AQ7000 cartridge, AudioQuest Lapis interconnects, and AudioQuest Clear Hyperlitz and Kimber 4AG speaker cables.) The VTLs were magnificent on top. As much as I loved the 300s that Gordon used, I have to give the nod to the 500s in terms of sheer effortlessness—which is, after all, one of the main things a $35,000 hi-fi system should be all about. With the system first turned on, the tape was essential: without it, there was just too much uncomfortable edge. As the system warmed up—which means, essentially, the VTL 500s, since the Premier Seven stayed on continuously—the tape became less and less necessary, until, finally, it got too dull. Off came the tape, and the natural bite and sheen of live instruments returned.

Through all this, though, the Carver Seven T-mods couldn't quite be made to work satisfactorily. In my room, the Beta bass towers proved hard to position; in fact, with the Carvers I couldn't find a combination of bass-control setting and tower positioning that yielded adequate bass without incipient bass heaviness. (In all fairness, Carver's attempt here is to imitate—he no longer claims identity—the sound of his tube Silver Sevens, which are unlikely to represent state-of-the-art control at the low end. Bob told me, during a recent visit, that he wouldn't expect the Sevens to sound good on the low end.)

Installing the Krell KSA-200 on the towers eliminated all problems, though still only with careful woofer positioning. I ended up with the woofers about 1–1½' behind the midrange-tweeter panels, and toed-in the way full-range speakers normally are: the midrange-tweeter panels faced straight ahead. The toeing-in of the woofers proved critical in limiting bass heaviness. Although a full review of the Krell awaits JA's soon-to-arrive ministrations, I have to say that it's unbelievable that this amp measures the same as other amps in the lower octaves: there seems to be at least an additional octave, and with almost unlimited supplies of power.

For curiosity's sake, I moved the Premier Seven out of the system and moved in the VTL Ultimate, which had arrived as a bonus with the 500s (give a camel an inch into the tent and he'll take a mile). What a change! I rushed for the tape. Along with a dramatic change in spaciousness (the Premier Seven is no slouch in this category) came a dramatic increase in mid- to upper treble. The tape, though, made this bearable—a superior presentation of spaciousness and ambient detail was rescued by the tape; without it, I'm afraid the virtues of the Ultimate would have gone unauditioned.

Further adventures in the tape wars came with the Levinson 20.5 amplifiers on the top end. As I mentioned earlier, the Levinsons, as originally set up back in April, simply made the Betas unbearable to listen to. Just too much treble. A combination of tape on the tweeters and better in-room setup make the 20.5 a suitable, if not ideal, amplifier with the Betas. Let me make it perfectly clear that I consider the 20.5s one of the truly great amplifiers of the late '80s. They have been both revealing and forgiving with all the other speakers with which I've tried them.

When first turned on with the Betas, my first move was to cover even more than half of the tweeter and supertweeter on each Beta—there was barely any radiating surface exposed! In addition, I used the double-sided foam tape, which is more absorbent than masking tape (as well as a pain in the neck to remove). After about two hours, it was necessary to move the tape back to the half-covering position; after six hours, I removed the tape from the supertweeter. Still, the sound was even better the following morning, so for the remainder of my listening I simply left the 20.5s on all the time. Truly, there is no better speaker on which to listen to the sound of the 20.5s warming up!

Completely warmed up, the 20.5s were most listenable, even enjoyable. In some respects the Levinsons were superior to the VTLs: they possessed a directness and clarity not there on the VTLs. (In fact, I found that excessive tape, such as I started out with, really screwed up this clarity; tape can be overdone.) Neverthess, I felt that the virtues of both amplifier and speaker were not being heard to their maximum. The Betas were designed to be used with excellent tube amps, and they should be; the 20.5s sound best with speakers possessing a more neutral upper two octaves than the Betas. More specifically, the 20.5s don't provide the draw-you-in luscious liveliness I heard from the VTLs. I suspect other great tube amps, from Conrad-Johnson, Audio Research, or Counterpoint, can perform similarly well; I've heard the latter two sounding good with Betas. Complementarily, the 20.5s sound best in other situations—almost any other situation.

I guess your big question is, Are the Betas worth all this trouble and expense? In fact, my biggest incentive in writing this follow-up has been to allay the anxiety I experienced every time I saw the Betas in Class A of "Recommended Components." After all, I'd heard them sound quite poor in a number of situations, and good in only a few. (Our writers, after auditioning the Betas in JGH's basement at our second "Recommended Components" conference, couldn't for the life of them imagine how they made it into Class A at all.)

When everything's right—right amps on top and bottom, right preamplifier, right cables, right tape—the Betas are the best speakers I've ever heard in my home. They're one of the best speakers I've heard anywhere; only some choice auditions of the IRS Vs (by The Audible Difference at the Bay Area Hi-Fi Show) and the Wilson WAMMs have clearly bettered them. Voices and instruments achieve a kind of immediacy that's uncannily like what I imagine it would sound like to have my favorite singers and players right in my living room. Reproduction of the details of recording spaces, particularly on LP with the VTL Ultimate preamp, leaps way beyond anything I've heard at home, and not just a little. This ability is addictive: I suspect I'll be unhappy with how hard it will be to go back to Mirage M-1s, Thiel CS1.2s, or Vandersteen 2Ci's—all excellent speakers.

At the same time, the Betas give you size—not the kind of size I've heard on IRS Vs, where modest voices sound overpowering, but the correct size of a guitar as well as (more or less, footnote 3) the size of an orchestra. There's enough visceral power to just about blow you out of the room, though I feel secure that a new generation of Infinity speakers will deliver tighter, better-controlled, and better-integrated (with the upper-range panels) bass. In fact, to reduce my anxiety about under-controlled bass, I ended up setting the bass-level control at a point where low bass seemed just a bit deficient. Over the next few weeks I will experiment with judicious and, I hope, unobtrusive distribution of Tube Traps to see if this corrects the problem.

There's one area where the Betas have a surprising limitation: right around 125Hz. Strong energy in this region, such as from organ, sets the lower midrange panels to rattling at little more than 100dB, a much lower limit than I would have suspected. (In this one sense, the Waveforms reviewed last month stand supreme.) The problem is much less severe when you adjust the Beta crossover so that the upper bass limit of the bass towers is set at 134 or 164Hz; for maximum coherence and least runaway bass, though, I generally had the LP Filter set for 60Hz.

I have a more difficult time deciding whether the Betas are worth all this trouble and expense. I find it annoying that Infinity insists on using drivers which have what look to me—if JA's impulse tests are any indication—like severe time-domain problems. Once they start moving, they have a hard time stopping. I assume that this is why they are so amplifier-sensitive, and why I needed the tape to block their sizzle. On the other hand, these same drivers, when driven placidly, offer as transparent a window on the music as I've heard.

When it comes down to it, I can't think of a less expensive way to get the kind of musical involvement offered by the Betas at their best. I have to say that, if you've got the money and the time and the patience and (especially) the right dealer, they're worth it. I look forward to a speaker which does as much with less trouble.—Larry Archibald

Footnote 1: Ever the stickler for thoroughness, JGH always checks how sharply focused a central mono image is (usually toward the end of the review process); with the Betas there was hardly any focus at all. Checking with pink noise, and alternating each speaker's position in the room—room anomalies are very commonly the cause of two speakers from a pair sounding different—JGH determined that the two speakers were markedly unalike in the mid- to upper treble.—Larry Archibald

Footnote 2: I read with interest reviews which imply that the true dimension and power of an orchestra has been captured by some hi-fi system. In my experience, reproduced sound has even suggested this only once, and a visit to a real orchestra quickly disabused me of that suggestion. Hi-fi systems can't yet capture the dimension and power of a piano or solo violin; they are equally, but more noticeably, far from doing it for an orchestra. How unutterably far we have to go!—Larry Archibald