Solid State Power Amp Reviews

Can an audio brand maintain a "house sound" if the original creator of that sound is no longer among the living? If the brand in question is Ayre Acoustics, the answer is a resounding Yes.

When Ayre founder Charley Hansen passed in late 2017, Ariel Brown, who is now Ayre's vice president and chief technology officer, was ready, waiting in the wings. Brown has worked for Ayre since he was a sophomore in college. As John Atkinson wrote in his February 2019 review of Ayre's EX-8 Integrated Hub, "Brown says that for better or worse, he was indoctrinated in Hansen's way of thinking and design. 'I only know the Charley way! Charley never wanted to introduce a product unless we had something new to offer with that product. 'New–Better–Different' was his philosophy; every product had to be a step up from before.'"

To my way of thinking (and listening), the Ayre house sound is as visual as it is audible, or almost so. The sound of Ayre amplification, including the component I have in-house for review, the VX-8 stereo power amplifier ($6800), which debuted in April at AXPONA 2023, is supremely quiet, deep-space black, aerodynamic, even futuristic.

Speaking with Brown via email, I asked if in design terms, the VX-8 bears more of his fingerprints or Hansen's?

"I worked with and learned from Charley for 21 years, so my core design thinking is never going to radically diverge from the path Charley forged," Brown wrote. "The changes are more likely to be continued subtle refinements to the topology we already believe to be second to none.

"I believe that some of my bigger contributions, recently and upcoming, are in the power supply and implementation details. The X-8 series, along with the Codex"—Ayre's combination DAC/headphone amp/digital preamplifier—"and the recent QB-9 Twenty DAC upgrade, show off quite a bit of my design thinking in those areas.

"I have no intention of straying from the sound Ayre is known and loved for, but rather [to] strive to extract and reveal even more," Brown continued. "Every year, we surprise ourselves by lifting another metaphorical veil on the sound that we didn't realize was there. Without compromising the sound, we're continuing to design more reliable and relevant products."

At $6800, the VX-8 isn't cheap, but it's cheaper—cheaper, that is, than everything else in Ayre's amplification lineup: At its AXPONA introduction, it joined the VX-5 Twenty ($14,000) and VX-R Twenty ($37,000) stereo amplifiers. Starting at the cheaper end was an intentional strategic move, consistent with Brown's intention to make the Ayre sound "available to more music lovers by expanding our product line and expanding the markets we design for."

Achieving the Ayre sound
Ayre components sound the way a Concorde looks: Sleek. Silent. Distinctive. Powerful. They combine impressive spatial performance with tubelike texture and an organic presentation, with good bass but no sonic booms—unless it's on the recording.

"I give a lot of the credit for the 'Ayre sound,' as you describe it, to the zero-feedback design," Brown noted. "That is supported by attention to every detail in the design, from parts and materials selection to careful circuit board layouts. The thing I've noticed most in our year-over-year evolution in power supply improvements is the increased sense of low-end control."

Other aspects that carry over from Charley's design thinking: fully balanced, discrete circuitry; the Double Diamond output stage; the Equilock gain stage, a linear analog power supply; and the company's AyreLink communication system. I asked Brown to explain these technologies, starting with the Double Diamond.

"The 'Diamond Buffer' is a fairly well-known circuit block in general electronics, though less specifically in audio," Brown explained. "One of the drawbacks of the circuit is its relatively high bias current needs and the resulting power dissipation. This is perfectly acceptable for line-level signals in a high-end audio product but becomes problematic trying to implement it as a power amplifier output stage. The Double Diamond output stage combines multiple diamond buffers within the overall diamond topology to better delegate the power-dissipation needs to more appropriately sized transistors."

What about Equilock?

"The 'parasitic' characteristics of a transistor depend on the voltage applied to/across them," Brown said. "Therefore, changes in signal (music!) will modulate these parasitics, causing the transistors to be nonlinear and contribute distortion. Ayre's Equilock gain stage reduces these nonlinearities, hence distortion, by minimizing the voltage 'swing' seen by the transistors, attempting to use them primarily in 'current mode'."

And that linear analog power supply?

"The linear power supply begins at the power inlet, where we immediately apply our own radio frequency (RF) filtering," Brown wrote. "We use a custom EI-core transformer, which further rejects RF noise. Multiple secondaries are used to isolate power regions. Full-wave rectification uses discrete devices followed by a heavily paralleled pi filter for further noise and ripple rejection with very low equivalent series inductance and equivalent series resistance. Voltage regulation follows our audio-amplifier philosophies and other topologies, using discrete, zero-feedback circuits and ultralow-noise voltage references based on LEDs. Then the various power rails are distributed around the board using low-impedance internal circuit board planes."

Brown described the AyreLink communication system as "Ayre Acoustics' method for receiving control messages in our equipment. It allows us to not only send and receive simple triggers, but it will also communicate information that could be visible on a display upstream. Another unique product offering is our 'AyreLink Isolator,' which can take RS232 command data and send it via a RJ11 phone jack to integrate our products into pretty much any smart home/entertainment system."

The VX-8 is a purebred spinoff of the EX-8 integrated with less noise and power draw, achieved "by stripping the extraneous functions," Brown said. "The core amplifier circuit topology is nearly identical to our other current amps. Where the VX-8 is actually ahead of our other amps is in the latest iteration (evolution) of our discrete, zero-feedback, linear power supply regulation.

"It uses the same complementary junction field effect transistor (JFET) differential input circuit" as Ayre's more expensive amps, Brown added, "and the same Double Diamond output stage using identical output power transistors (just fewer in the VX-8). Obviously, parts quality is somewhat lower to be able to hit the 'entry level' price point. And being a newer and more evolved design, it has some technology that we hope to trickle up to our other amps."

The VX-8 boasts "FR4 equivalent" PCBs: high-spec, heavy fiberglass-plus-resin construction. Additionally, the amp uses custom transformers produced by Mercury Magnetics; all Ayre components come standard with Cardas wiring.

The VX-8 is available in silver- or black-anodized finishes. It weighs 24lb and stands 4.5" high, 17.25" wide, and 13" deep. Its slim aluminum case seemed to disappear into the sight lines of my Salamander rack. It outputs 100Wpc into 8 ohms or 170Wpc into 4 ohms; no rating into 2 ohms is specified.

A single power button decorates the VX-8's front panel; a tiny adjacent LED indicates whether the amp is powered on (blue) or in standby mode (green). The back panel of the VX-8 will seem familiar to an EX-8 owner; it includes a pair of slant-mounted Cardas patented binding posts (CPBP), which accept bananas, spades, or bare wire. Also on the back panel: a combination IEC receptacle and master power switch; pairs of balanced (XLR) and unbalanced (RCA) inputs; pairs of balanced (XLR) and unbalanced (RCA) subwoofer outputs; and two small sliding switches for selecting input type (balanced or single-ended) and subwoofer mode (stereo or mono). Two AyreLink Ethernet ports and a USB connection (for firmware updates) complete the connections.

Intentionally or not, the VX-8 evokes '70s-era American muscle cars, with the number 8 and, more subtly, with two 6" × 1½" top-panel, mesh-lined cooling vents. (Also evocative of 1970s muscle cars: The wire mesh on the EX-8 came unglued.)

Setup
Ayre sent along the K-5xe^MP preamplifier so that I could experience an Ayre amplification pair. Technical Editor John Atkinson reviewed the K-5xe^MP in July 2011, writing, "It offers much of the sound quality you can get from the megabucks solid-state preamps." The KX-5 complemented my Sugden LA-4 line preamplifier. Small for a power amp, the VX-8 easily slid onto the bottom tier of my five-shelf Salamander rack.

Oddly, if trivially, input and output connectors on the back of the amp aren't designated Left or Right. "Each half-side is one channel, and no signal crosses the middle, therefore each channel is whatever you assign it by connecting the input," Brown said when I asked him about this. "There is nothing stopping you from connecting the 'Left' channel input to the right side (referencing the front), so long as you also connect the left speaker to the same side."

The Ayre VX-8 ran hot.