Integrated Amp Reviews

"You are going to freak out."

In February, that prediction was offered to me by Alex Brinkman, the usually understated sales manager for Ayre Acoustics. The suggested catalyst for my otherwise unforeseen psychotic episode: A new edition of Ayre's AX-5 integrated amplifier, the original version of which I reviewed for Stereophile's September 2013 issue. I was impressed with the first edition—a zero-feedback, solid-state design that I described as being no less than "one of the three best, most musical, and most human-sounding solid-state amps I've ever heard"—but, as far as I can recall, it utterly failed to compel me to run naked through the streets of my village.

The original Ayre AX-5 sold for $9950 and produced 125Wpc, and in it chief engineer Charlie Hansen debuted a modern implementation of a heretofore obscure 1960s output architecture: the diamond circuit, an arrangement of four bipolar transistors that's well suited for operating above electrical ground. (To a designer who favors balanced audio electronics—a category that includes the AX-5—the appeal of such an approach is obvious.) Ayre also claimed for the diamond circuit such strengths as high speed, high power gain, high reliability, and, best of all, good sound.

Another gem in the AX-5's tiara was Ayre's own variable-gain transconductance (VGT) circuitry: a means of controlling loudness not by attenuating maximal gain—which willfully hobbles the only operating condition under which an amp can perform at its best—but by creating, for each of its 46 volume-control settings, a distinct amount of input-section gain. Each turn of the AX-5's volume knob enacted a parts substitution that created a distinctive circuit: a control system that required of its designers a great deal of electrical and mechanical ingenuity.

All of the above was built into a foursquare aluminum-alloy case whose rear panel offered one stereo pair of loudspeaker connectors and six pairs of line-level inputs—four balanced (XLR), two single-ended (RCA)—and on whose front panel were two large knobs, for source selection and volume, and two soft-touch buttons that performed a variety of jobs.

The AX-5 Twenty ($12,950), named in honor of Ayre's 20th anniversary, looks identical to its predecessor. But my review sample sounded a bit different from the AX-5—a point to which I'll return—and even felt noticeably different. The AX-5 ran quite hot, but the Twenty has an output-stage revision—called the double diamond circuit—for which a 35% reduction in heat is claimed. I didn't bother taking the Twenty's temperature: Although unabashedly warm, the top of the Twenty's case was definitely cooler during operation than the AX-5's had been. Ayre also claims that the double-diamond version is "slightly more powerful" than the previous version, although the published output spec, on both their website and in the Twenty's owner's manual, holds steady at 125Wpc.

According to Ayre, the AX-5 Twenty's all-analog, zero-feedback power supply has also been refined, and now benefits from the company's AyreLock technology, which adds extra discrete components to the regulation circuitry in an effort to "lock" the output voltage under all performance conditions. Additionally, trim pots in the AX-5's input section have been replaced in the Twenty with a servo unit that Ayre describes as "much better sounding." Just as important, this servo is claimed to keep DC offset to less than 15mV, and even to compensate for DC that may be present in the outputs of some source components, making accidental damage to loudspeakers even less likely than before.

Installation and Setup
Perhaps it's only because I'm two years older than the last time I had an Ayre product in for review, but this time around I really chafed at the AX-5's setup procedure, which I've come to regard as pointlessly complex. Out of the box, the AX-5 Twenty is unusable: Before listening to music, the user must configure at least one of the amp's six inputs. In and of itself, that's not a huge deal; the problem lies in the 40-page instruction manual's presumption of the reader's very high level of interest in reading about Ayre's way of doing things—high enough not to blink when told, without apparent irony, that the information required to get a "quick start" on using the AX-5 "is contained in the [first] three chapters." And I was frustrated that, in the chapter on input configuration, the user is instructed to assign to each input a unique name, lest said input remain nonfunctional—yet no indication is given as to which of the AX-5's front-panel controls performs the select function. Granted, with only two knobs and two buttons on its front panel, the AX-5 Twenty is hardly a Klingon Bird of Prey, and I stumbled upon the correct procedure within a minute. Still, why should the buyer of a $13,000 amplifier have to proceed by trial and error?

Once I had the AX-5 Twenty up and running, all was well. With no balanced components on hand, I limited myself to two single-ended sources: my Sony SCD-777ES SACD/CD player, and the line-level outputs of a Leema Acoustics Essentials phono preamplifier. I labeled their respective inputs CD and PH, then proceeded to enjoy the more pleasant aspects of the AX-5 Twenty's user interface: control buttons on the large, sturdy remote handset are clear and well organized; when switching between sources, the AX-5 Twenty did not force me to toggle through unused inputs; the amp's Cardas speaker connectors accommodated well the Z-plug–style bananas on my Auditorium 23 speaker cables; and the 48-lb AX-5 Twenty—which is 17.25" wide by 4.875" high by 18.75" deep—fit nicely atop my Box Furniture D3S rack.

As with the original AX-5, the build quality of the AX-5 Twenty is mostly superb, my only quibble being the slightly rough manner in which metal screening is affixed to the underside of the top panel. Otherwise, everything was first-class: Ayre bows to no one in the neatness of their circuit boards, and the AX-5 Twenty's motorized, belt-driven, resistor-array volume control is indeed a small masterpiece of engineering.

A final setup note: For this review, I followed through on a suggestion I'd seen in the original AX-5's instruction manual, on how to customize the amp's overall gain by changing a single resistor per channel. Since both of the speaker models I used are considerably more efficient than average, I decided to try lowering the amp's gain, and requested the appropriate new resistors and instructions for their installation, which were duly supplied. Apart from the Allen wrench used to remove the AX-5 Twenty's top panel, the only tool required for the changeover was a very small, flat-blade screwdriver: The resistors in question are not soldered in place, but secured with miniature terminal blocks that were reasonably easy to access. That said, after replacing the original resistors (301 ohm) with the new ones (619k ohms), the change in gain range was extremely modest. That experience, especially when considered alongside the advantages of Ayre's VGT technology, leads me to advise prospective owners against bothering with this mod.

Listening
Right out of the box, the AX-5 Twenty hinted at greatness, with textures wildly good for solid state and a thoroughly convincing way with musical momentum and flow. But it also sounded somewhat compressed, somewhat lacking in the ability to break out of its cage—whether driving my DeVore Fidelity Orangutan O/96 or vintage Altec Valencia speakers. In the days that followed, the Altecs, with their higher efficiency and sometimes peaky low-treble range, proved the poorer match, so I stayed with the DeVores for the duration: a really excellent choice. After a little over a week of around-the-clock running-in, the Ayre opened up and showed what it could really do.

In my original review, I wrote that the very faithful AX-5 cut no slack for bright-sounding recordings, a category that includes Peter Rowan's eponymous first solo album (LP, Flying Fish 071). I expected the same this time out—and yet, though the Twenty was itself truthful on the matter of Richard Greene's hotly mixed and hard-sounding fiddle, what I heard this time was truth of a more generous-spirited sort. Selections such as "Midnite Moonlite" remained on the bright side of neutral, but were more tolerable than I remembered from my go-round with the first AX-5. I am very much in favor of tolerable playback.

In that same review I also mentioned how the original AX-5 played André Previn and the London Symphony Orchestra's recording of Tchaikovsky's Manfred Symphony (LP, EMI/Alto ASD 3018) with a degree of believable scale and spatial perspective that I described as "tube-caliber." The Twenty performed just as well in those regards, yet sweetened the deal with . . . well, with sweetness: This time, this excellent if occasionally slightly grainy and occasionally too-hot-on-the-crescendi recording had more saturated timbral colors and richer textures than I remembered hearing through the original AX-5. It was, simply and unambiguously, better—and I'm also on the record as preferring better, ten times out of ten.

The sounds of antique wind and percussion instruments in Musica Antiqua Vienna's Le Jardin Musical (LP, Supraphon 1 11 2126)—which, in that earlier review, I described as being "pleasantly tactile" through the AX-5—were, through the Twenty, joined in that regard by the sounds of the viola, the viola da gamba, and various singing voices, all reproduced with color, body, scale, melodic and rhythmic drive, and believable spatial presence. (I almost said "soundstaging," but caught myself at the last second.) With that record, the Twenty delivered the sort of best-of-all-worlds performance—musical rightness and sonic realism—that has been known to stir the complacent, if not to compel them to dance naked, checkbooks in hand.

That LP wasn't alone. Through the Ayre, I enjoyed: a recording of American classical music (Barber, Ives, Copland, Cowell, Creston) conducted and played by the very British Neville Marriner and the Academy of St Martin-in-the-Fields (LP, Argo ZRG 845); the Electric Recording Company's new and typically colorful LP reissue of D'ombre et de lumière, a recital of mostly Spanish music performed by pianist Magda Tagliaferro (LP, EMI/ERC 350 C 001); David Grier's wonderfully stringy instrumental collection Evocative (CD, Dreadnought 0901); and the uneven but ambitious and curiously satisfying Murder Ballads, by Nick Cave and the Bad Seeds (CD, Reprise 46195-2). All sounded wonderful, and served only to cement my impression that the AX-5 Twenty is inarguably more realistically colorful, impactful, and compelling than its predecessor.

Value
I don't know much about consumer psychology, so I haven't a clue whether the AX-5's crossing of the five-figure Rubicon will be seen as a good or a bad thing in the high-end marketplace. I do know that a 30% increase in price seems stiff for an integrated amplifier—something that most of us are conditioned to regard as an entry-level component. There are available, for $3000 or less, some awfully good one-box amps, though probably none as good as this. That said, it's worth noting that Ayre will upgrade to full Twenty status any older AX-5 for $3000: the same amount as the difference between the model's prices.

Did I freak out? The Ayre Acoustics AX-5 Twenty proved a consistently engaging, reliably musical, downright fun integrated amplifier; it improved on its predecessor in every way except the user interface; and it stands as one of the easiest choices in integrated amps on the market, with a pedigree that suggests superb reliability and freedom from obsolescence. Very strongly recommended, amp and upgrade alike.—Art Dudley