July 2010

Audience adeptResponse aR2-T Power Conditioner

Requesting an Audience 

Audience has turned into a rather rare enterprise in the world of high-performance audio. But for a source component or two, an Audience-exclusive system is now possible: the company designs and manufactures power and speaker cables, interconnects, power conditioners, a preamplifier and power amplifier, and a whole line of speakers. Only a quick review of the firm’s history is needed, however, to determine that power-related products are the foundation of the Audience line. Winning rave reviews over the past decade-plus, as well as residence in recording studios and hi-fi systems, Audience’s line of adeptResponse power products has expanded and evolved to meet the needs of almost any system. So when I wanted to build a Chinese Wall of power between my main system and the combination of computer and external hard drive I use to store and manage my library of +1400 CDs, I naturally thought of Audience.

After a conversation with Audience’s head honcho, John McDonald, an adeptResponse aR2-T power conditioner was on its way, along with a sample of Audience’s new Au24 powerChord. Representing the state of Audience’s art, the aR2-T is the first adeptResponse product to incorporate their new ground-plane architecture, and also includes all of Audience’s other power-conditioning features, including Teflon capacitors and bidirectional filtering. With the Au24 powerChord connecting the aR2-T to the wall outlet, I could now tap into the latter’s two ne plus ultra outlets of Audience-approved power. 

Rather than an attempt to improve the performance of connected devices themselves -- unrealistic in the case of a computer and hard drive -- McDonald and I were interested in how well the aR2-T would fare when the principal goal was to prevent the radio-frequency-interference (RFI) nasties generated by the switching power supplies in the computer and hard drive from contaminating the power feeding the audio system. Because this is not how the aR2-T is generally used, I agreed to also use the conditioner to feed my monoblocks, source, and preamp.  

Two outlets, no duplex 

Consistent with the important role Audience believes power products play in any ambitious audio system, physically the aR2-T less resembles a mere accessory than a standalone component measuring 10.5"W x 5"H x 8.5"D, and is accordingly priced: $4200 USD with the standard powerChord e, or $5650 with the Au24 powerChord of the review sample. (A version without Teflon capacitors, the aR2, is available for $2300.)  

Built on the same aluminum chassis used for its six-outlet aR6 stablemate, the aR2-T’s boxiness is offset by the gently rounded edges and corners of its case: two wraparound, clamshell panels, one forming the chassis bottom, the other the cover. Its substantial, 3/8"-thick aluminum faceplate has similar rounded corners. The review sample came in the brushed-silver finish (anodized black is also available), the only forward-facing adornments being the silk-screened "adeptResponse: High Resolution Power" logo and a small, blue LED to indicate whether or not the unit is on. The chassis rests on white, low-profile feet that are somewhat squishy and appear to be made of silicon. They certainly did a good job of gripping the surface beneath without leaving any mark or mar. 

On the rear panel are the two individual outlets (not a duplex pair), well spaced to easily accommodate not only audiophile-grade power connectors, but even large wall warts such as the one feeding my 2TB external hard drive. At the left side of the rear panel are the power switch and the power input jack, which deserve some explanation. 

The On/Off switch is neither a toggle nor a button. After testing many such devices, Audience selected a low-resistance, heavy-duty, magnetic circuit-breaker switch to keep the power path as clean as possible. Rather than a standard IEC input, the power inlet is the female half of a Neutrik PowerCon, a locking device that looks to me like an industrial BNC connector for AC, and strong enough that it should never become dislodged. John McDonald told me that it makes for a better, more secure connection. The downside, of course, is that while Audience’s own powerChord (included) sports the correct male counterpart, any other manufacturer’s cord will need to be specially terminated, which made it impossible to compare AC cords for this review.

Lifting the hood

According to McDonald, the adeptResponse approach to power conditioning is based as much on what is avoided as on what is accomplished. In general, the bane of power conditioners is that they tend to mask the true power of recorded music by diminishing dynamic headroom. Sometimes PCs roll off transients, sometimes they leave bass performance gasping for breath, but far too often they do both. Another common failing of power products is nonlinear filtration; i.e., they do a good job of getting rid of the power-related hash that affects some frequencies, but not all frequencies, and even then, they don’t do the job evenly. The goal of the adeptResponse project was to cure such common failings (these products weren’t intended to be sold, but rather used only within the company), retain and even enhance the full effect of dynamic transients in reproduced music, all while applying significant, evenhanded filtration across the audioband and providing protection from power surges. This would be done by minimizing any resistive effects of the circuitry, enhancing power delivery, and maintain the lowest ground impedance possible. Here are the details. 

The aR2-T is the first product in the adeptResponse line to incorporate a new copper-plate grounding system. (It has since been used in the aR6 and aR12 models, and is available as an upgrade for earlier models.) A "raft" of solid copper, affixed to the chassis bottom, acts as an internal subchassis to support all internal components not attached to the rear panel; tied to it is the ground for each outlet. As a result, not only is the grounding scheme for the device improved (to keep the ground impedance as low as possible), but the subchassis architecture attenuates the effects of vibrations on performance. Removing the aR2-T’s cover confirms Audience’s claim that an optimized layout of subcomponents is a priority -- there’s nothing haphazard in sight -- and this newly added feature furthers such objective.  

The more firmly established adeptResponse strategy for providing superlative power includes the use of partial power-factor correction (i.e., adding power-transfer efficiency to better satiate current-hungry amplifiers), star wiring to ensure that each outlet is independently filtered (which results in two levels of bidirectional filtration between connected devices), and high-efficiency, low-resistance filtration components on each outlet (with only highest-quality Teflon capacitors deployed in the T versions of adeptResponse components). Rather than printed circuit boards, point-to-point wiring is used throughout. The built-in surge suppression avoids any performance-depleting sacrificial devices, in particular that bad penny of the power-product world, the metal-oxide varistor. Finally, all electrical circuitry is cryogenically treated to maximize electron flow without resistance. 

In sum, Audience couples sound electrical engineering with best-in-class parts and attention to detail in layout and build quality. 

System 

After I’d run-in the aR2-T with several weeks of continuous use in my backup system, I installed it in my main audio system and left it there for most of the past year, in two different capacities. I first used it as I’d initially intended to -- to provide filtered power to my MacBook and external hard drive, and an extra layer of separation from the wall outlet feeding my source and preamplification equipment. Later, and more in keeping with the aR2-T’s intended use, I fed its clean power to my Ayre Acoustics MX-R 300Wpc monoblock amplifiers. While from time to time the equipment in my audio rig included interlopers in for review, it primarily comprised a Wavelength Crimson Cobalt Balanced USB DAC, a VPI Scout turntable, an Aesthetix Rhea Signature phono stage, Vandersteen 5A loudspeakers, and three Ayre products: D-1xe disc player, KX-R preamplifier, and the MX-R monoblocks. 

The speakers and monoblocks are arrayed along the front wall of my listening room; everything else is along the sidewall, in or on my Harmonic Resolution Systems MX-R rack with M3X shelves. With the exception of a single-ended cable linking the turntable and phono stage, the rest of the system is run truly balanced, culminating in biwired speaker cables. Those cables were, consecutively, Ayre Signature Series, Cardas Clear, and AudioQuest Wild. Except as displaced by the aR2-T, power was delivered by Ayre L-5xe power conditioners via Cardas Golden Reference AC cords. 

A history with power conditioning 

I’ve used many different power products over the years. While recognizing the benefits they often yield in certain areas, I’ve usually found that the power-conditioning sword has two edges, and have ultimately eschewed active devices such as power regenerators. Until my experience with the aR2-T, I felt that the best overall solution was Ayre Acoustics’ purely passive L-5xe, essentially a star-wired, four-outlet power strip with independent passive filtration for each outlet via the patented Ayre Conditioners, which dissipate high-frequency interference (RFI and EMI) as harmless thermal energy -- the same devices that follow the IEC input inside all of Ayre’s R-, 5-, and 9-series components. The L-5xe may not be the last word in removing power-line garbage, but it operates without side effects: no uneven filtration artifacts or unevenness, no castration of system dynamics.  

Exorcising computers’ power gremlins 

Running a computer and hard drive on the same electrical circuit feeding a high-performance audio system can hinder the latter’s performance, and unequivocal evidence of that was provided by listening to records with and without my computer and hard drive inserted into the listening room’s electrical circuit. When these were plugged in, the noise floor rose, the soundstage collapsed as low-level signals were lost or blurred, and upper-register frequencies hardened. The same thing happens whenever my plasma video display is plugged in. Turning the plasma "off" doesn’t remedy the problem -- it remains in standby mode, in which its switching power supplies continue to infect the power line with a backwash of impurities. One solution would be to plug the computer, hard drive, and display into a power strip with a hard Off switch. But while entirely effective, this has two big disadvantages. First, continually powering these components up and down is a royal pain. Second and more important, I want my audio system to be working at its very best when I’m watching movies on the display, or listening to music stored on and managed by my computer. 

Through experimentation, I have determined that even when my system’s audio components are receiving conditioned power, better results occur when the computer, hard drive, and display are also being fed power from the conditioners. I suspect that this is because of the double level of separation between the conditioners’ individually filtered outlets; if connected directly to the wall, only a single filter in the conditioner separates these problematic devices from my audio equipment. As a control, I’ve stored several exemplary music files on my laptop’s hard drive, which I can play using only the computer’s battery power. When I used one Ayre L-5xe to power the computer, hard drive, and display, and another to feed my preamplifier, phono stage, disc player, and USB DAC, the difference in performance with and without any of the three RFI/EMI offenders in the loop was significantly lessened but not eliminated. With total elimination my goal, I turned to the Audience adeptResponse aR2-T. 

I unplugged the computer and hard drive from the L-5xe and attached their power cords to the aR2-T. Immediately, a further narrowing of the performance gap occurred. While the L-5xe seemed to eliminate at least 75% of the offending RFI/EMI, the aR2-T got rid of closer to 90%. When I plugged the adeptResponse into the Ayre, that rose to about 95%, although decoupling my audio equipment from those switching power supplies’ backwash was getting to be an increasingly expensive proposition. Absent complete elimination (100%) of RFI/EMI, I couldn’t justify spending $4200 on an aR2-T in this application. 

While I considered having a custom linear power supply built for my hard drive, I knew it would address only one of the three offending sources of power-line noise. Admitting to myself that it was time to explore more "active" power solutions for this problem, I turned to Furman Sound, who make power conditioners for the professional audio industry. Their IT-Reference 20i model uses a center-tap on a massive toroidal transformer to create "symmetrical balanced power" to take advantage of common-mode rejection and largely eliminate high-frequency power-line contamination. Further, each duplex pair of its balanced-power outlets originates from separate windings on the transformer. With this and the inclusion of a floating ground, Furman claims to entirely eliminate intercomponent interference, which is exactly what I wanted. 

I plugged the plasma display into one bank of the Furman and the computer and external hard drive into another. My goal was attained. As far as the sound from my audio system was concerned, it no longer made any difference whether the switching power-supply devices were plugged into or entirely removed from the electrical circuit. Given the effectiveness of the Furman, I suspect that their IT-Reference 7i, a four-outlet unit using the same symmetrical balanced power approach as the 20i and costing less than $1000, would be a perfect way to build that Chinese Wall of power I wanted. 

That the aR2-T did not prove the ideal tool for this particular job isn’t surprising, given that its raison d’être is something else entirely. 

Electrifying the amps 

The two-outlet aR2-T essentially offers the full-out assault on power-line problems that Audience makes available in its six- and 12-outlet models, respectively the aR6-T ($5000) and aR12-T ($8000), both of which cost much less per outlet. The aR2-T is likely to be used only with a pair of monoblocks, or perhaps a simple system comprising a single source component and an integrated amplifier. Given that my system includes two monoblocks placed between the speakers, I was ready to subject the aR2-T to a more fitting test. With powerful, current-hungry amplifiers and relatively low-sensitivity speakers, I was determined to tease out every possible strand of the Audience’s nature. 

I’ve been using as a reference the 45rpm, 180gm edition of René Leibowitz and the Royal Philharmonic Orchestra’s The Power of the Orchestra (LP, RCA/Analogue Productions AAPC 2659-45). The dynamic swings captured on all four sides of this reissue are legendary. As Mussorgsky’s music ebbs and swells, everything from a solitary percussive stroke to the full cacophony of the united orchestra is presented in all its glory. With the aR2-T tethered to the Ayre MX-R amplifiers, nothing impinged on the music’s vibrancy or flow. Rather, the quiet passages emerged from a noise floor lower than I’d previously experienced in my system, enhancing the perceived dynamic range and better enabling soundstage cues to paint a three-dimensional soundscape. 

To challenge my system at high decibel levels, I turned to Pantera’s Vulgar Display of Power (CD, EastWest/Atlantic 91758-2), an album that, to be truly appreciated, demands that all amps be turned up to "11." On track 2, "A New Level," singer Phil Anselmo screams, "Dimebag" Darrell Abbott attacks his wailing guitar, and the demands on amps and speakers are extreme. My system never flinched, propelling forward all of the raw energy delivered by this quintessential metal band. Mesmerized by the caustic virtuosity of Abbott’s shredding, I was transported by the unexpurgated brute force of this album’s sound in my living room all the way back to 1994, when my brother and I careened across the floor of the sold-out Los Angeles Forum as Pantera belted out song after song. If anything, the power-flow-enhancing elements of the aR2-T elevated the headroom available from my amps.  

From the profane to the sublime, I then teed up some of the 45rpm discs in the 11-album boxed set of Bill Evans’ Riverside Recordings (22 LPs, Riverside/Analogue Productions AAPJ 0018). Given that the acoustic piano is the only instrument that spans nearly the entire audioband, music featuring the ivories provides a useful yardstick for assessing whether any nonlinear frequency effects are being introduced. I’ve listened to Waltz for Debby -- the album and the track for which it’s named -- dozens and dozens of times, and it has never sounded better than in this reissue. Whether focusing on Evans’ piano work, the double-bass efforts of Scott LaFaro (who died in an automobile accident only ten days after recording this classic), or Paul Motian’s percussive underpinnings, I heard no incongruities that I could attribute to the aR2-T or to any other component of my system. Song after song, hour after hour, the adeptResponse power conditioner let my amplifiers and system shower me with the riches of some of the greatest jazz piano recordings ever made. 

In sum: No matter what I threw at it, the aR2-T remained unfazed. 

Audience takes the Hippocratic Oath 

Though the phrase "First, do no harm" is not actually part of the Hippocratic Oath, my listening has convinced me Audience has not only taken that charge to heart, but successfully implemented it in the adeptResponse aR2-T. It is only the second power product with which I’ve had extensive experience that introduces neither dynamic limitation nor nonlinear filtration artifacts -- each a significant achievement. That the aR2-T also provides surge protection, significant suppression of power-line noise, and maximal power flow, thus enabling high-current amplifiers to perform at their absolute best, makes it easy for me to recommend it without reservation. 

There’s no denying that $4200 is a lot to spend for two outlets of exceptional power, or that Audience’s own six- and 12-outlet adeptResponse products provide more bang for the buck when more outlets are needed. However, for the specific function of feeding a standalone pair of high-current monoblock power amplifiers, the aR2-T is just about perfect. That this product was able to wrest another percentage point or two of performance from world-class amplifiers like the Ayre MX-Rs leaves me to conclude that the aR2-T provides value that justifies its price.

. . . Peter Roth
peter@soundstagenetwork.com