Three years ago, when I first heard Audionet's Max monoblock power amplifiers, I described their pairing with YG Acoustics Hailey loudspeakers "an absolute winner" and "definitely one of the finer systems at T.H.E. Show Newport Beach." At subsequent audio shows, no fewer than four other Stereophile Contributing Editors enthused about different pairings of YG loudspeakers with Audionet amplification. Herb Reichert, at the 2014 Rocky Mountain Audio Fest: "Everything had a kind of just right quality. Totally impressive!" Sasha Matson, at RMAF 2015: "Marvelous" on vocals, "rockin' and tight" on bass and drums. John Atkinson, at T.H.E. Show 2016: "Duke Ellington's classic Jazz Party in Stereo . . . was reproduced with terrific dynamics." Larry Greenhill at the 2017 Consumer Electronics Show on the sound in the YG Acoustics room, which included Audionet's Max monoblocks: "the sound on playback of Jake Shimabukuro's ukulele wizardry came closer to matching his live performance than in most rooms."
I visited the same room later during CES 2017, and wrote that it produced a huge soundstage, "with the low frequencies remarkably fleshed out and layered. Everything was perfectly controlled, with the speed, power, and weight of bass response astounding. Highs, however, were a bit recessed, and lacking in brilliance, and strings briefly turned wiry on the track's loudest passage" (footnote 1). What we didn't know from these auditions was how the Maxes might sound with other gear. A review would answer that question.
Description
The Audionet Max ($30,500/pair), which was designed and are manufactured in Germany, costs almost the same as that of another German monoblock, AVM's Ovation MA8.2 ($29,900/pair), which I reviewed in the April 2017 issue.
The Max is based on what Audionet calls an Ultra-Linear-Amplifier (ULA) topology, originally developed for medical applications. The company claims that the technology "delivers results that nudge the boundaries of what is feasible with current measuring technologies. Even under conditions of maximum strain or in other borderline situations, any incidence of signal impurity remains almost undetectable, while the outstanding feedback damping ensures that the loudspeakers crisply perform to the limits of their capacity." I wonder what JA's measurements will have to say about that.
The Max has four separate power supplies—one each for the controller and input/driver stages, and one each for the output section's positive and negative half-cycles. The supply for the input/driver stage has its own 80VA toroidal transformer, with separate secondary windings for positive and negative voltages, while each of the two output-section supplies has its own very hefty 1000VA toroidal transformer—one for positive voltages, the other for negative. The controller stage—which is powered by its own toroidal transformer—monitors temperature, DC offset, and other parameters, and controls all amplifier functions. Should a fault occur, it is announced on the front-panel display, after which the Max disconnects from the mains supply. The Max's FET-based input stage is configured as a cascaded and bootstrapped differential amplifier. The output stage is equipped with eight hand-selected MOSFETs, with actively controlled bias current. For all that, the Maxes didn't run hot—the pair of them didn't heat up my well-insulated, 20' by 16' by 9' listening room, as do the Pass XA200.8 monoblocks ($42,000/pair) that usually drive my Wilson Alexia speakers.
On the rear panel are balanced and unbalanced inputs—the former are gold-plated XLRs of unnamed provenance, the latter are gold-plated, Teflon-insulated Furutechs—and two pairs of Furutech rhodium-plated speaker terminals (for biwiring). Also on the rear panel are a 15-amp power-cord input and, right above that, a small rocker power switch. The power receptacle, power switch, and speaker outputs are all so close together that, if both your power cord's input termination and speaker-cable spades are wide and your fingers are thick, you may have trouble accessing the power switch. I'm sure there's a reason for such cramped ergonomics, but it's not user friendly.
Equally disturbing, the positive and negative speaker terminals are close together. Bill Parish of distributor GTT Audio advised me to insert a piece of Styrofoam between my Nordost Odin 2 speaker cables' spade terminations to ensure that they would never touch. I made sure the lugs were tight, and checked them often.
The Max's Spartan front panel is far better designed. On it are an LED display, and a Power button that also controls a number of other functions. Once all inputs and outputs are connected and the mains power switch is turned on, the Max is in Standby mode. When you press the front-panel Power button, the message "Waking up . . ." is displayed. the polarity of the amp's AC cord be reversed—perish the thought—you're informed of that, too. Assuming all is in order, once the Max flashes which of its inputs is in use, you're ready to go.
Switching back to Standby triggers a sequence of messages: "Going to sleep . . . ," followed by "DISCHARGING NOW please wait . . ." When that message disappears, the Max is in Standby. If you change your mind and press Power once more, "RE-STARTING" is displayed. Parish recommended that I leave the Maxes on 24/7. Since they use very little electricity when no music is playing, and took quite a while to sound their best from turn-on, I followed his advice.
The Max offers several options each of operation and display: AutoStart, which permits timed operation; Auto On/Off, which turns the amp on from Standby whenever a signal is detected; and a warm-up countdown that enables the user to enter an amount of time, between 15 minutes and 99.45 hours, after which they intend to begin their listening. Also adjustable are the display's brightness and various other control functions. All of this is easily done by holding down the Power button longer than two seconds, then navigating the menu and making selections from it with short presses of Power.
If you leave the display on, you can choose to have it announce the input selected or the Max's temperature. Since the display text changes locations randomly every 12 seconds, I found it utterly distracting and switched off the display. That meant that, once the "Waking up . . .," etc., sequence was completed, the display went dark. Thank God.
"I have the time!"
When I first installed the Max monoblocks, Bill Parish urged me to replace the balanced (XLR) interconnects that I usually use with unbalanced (RCA). "For the balanced input Audionet uses an op-amp, which is just another piece of circuitry," he explained by e-mail. "While it is the best op-amp out there, you can still hear it. I don't want to make this a big thing, but I assure you that you will greatly prefer the RCA (or at least I do). BTW, I'll bet most of the equipment made today falls into this camp; they just don't know or tell you."
Given such strong advice, I switched to unbalanced interconnects, and stuck with them when I reinstalled my Pass amps for comparisons. While the Audionet Maxes don't require that shorting pins be installed in their balanced inputs when using their unbalanced inputs, the Passes do.
The first time I listened to the Maxes in my system, they sounded disappointing. I suspected there was some sort of incompatibility between them and all of my Nordost Odin cables—even though I've used Nordost Odin 2s with a wide variety of amps and speakers, and the sound has always been excellent.
I immediately contacted JA, and asked if it would be kosher if I borrowed a full set of Kubala-Sosna Elation! wires for this review. With his assent came a warning: I would need to establish, as a benchmark, the sound of the Pass/Kubala-Sosna combo before moving on to the Audionet/Kubala-Sosna, and "That will take a lot of time."
"I have the time!" Famous last words of Serinus the Idiot.
Footnote 1: The music was by Mason Bates, from his Works for Orchestra, with Michael Tilson Thomas conducting the San Francisco Symphony (SACD/CD, SFS Media 65). See www.stereophile.com/content/sonja-xv-loudspeakers-yg-acoustics.
The Audionet Max ($30,500/pair), which was designed and are manufactured in Germany, costs almost the same as that of another German monoblock, AVM's Ovation MA8.2 ($29,900/pair), which I reviewed in the April 2017 issue.
On the rear panel are balanced and unbalanced inputs—the former are gold-plated XLRs of unnamed provenance, the latter are gold-plated, Teflon-insulated Furutechs—and two pairs of Furutech rhodium-plated speaker terminals (for biwiring). Also on the rear panel are a 15-amp power-cord input and, right above that, a small rocker power switch. The power receptacle, power switch, and speaker outputs are all so close together that, if both your power cord's input termination and speaker-cable spades are wide and your fingers are thick, you may have trouble accessing the power switch. I'm sure there's a reason for such cramped ergonomics, but it's not user friendly.
The Max offers several options each of operation and display: AutoStart, which permits timed operation; Auto On/Off, which turns the amp on from Standby whenever a signal is detected; and a warm-up countdown that enables the user to enter an amount of time, between 15 minutes and 99.45 hours, after which they intend to begin their listening. Also adjustable are the display's brightness and various other control functions. All of this is easily done by holding down the Power button longer than two seconds, then navigating the menu and making selections from it with short presses of Power.
If you leave the display on, you can choose to have it announce the input selected or the Max's temperature. Since the display text changes locations randomly every 12 seconds, I found it utterly distracting and switched off the display. That meant that, once the "Waking up . . .," etc., sequence was completed, the display went dark. Thank God.
"I have the time!"When I first installed the Max monoblocks, Bill Parish urged me to replace the balanced (XLR) interconnects that I usually use with unbalanced (RCA). "For the balanced input Audionet uses an op-amp, which is just another piece of circuitry," he explained by e-mail. "While it is the best op-amp out there, you can still hear it. I don't want to make this a big thing, but I assure you that you will greatly prefer the RCA (or at least I do). BTW, I'll bet most of the equipment made today falls into this camp; they just don't know or tell you."
The first time I listened to the Maxes in my system, they sounded disappointing. I suspected there was some sort of incompatibility between them and all of my Nordost Odin cables—even though I've used Nordost Odin 2s with a wide variety of amps and speakers, and the sound has always been excellent.
I immediately contacted JA, and asked if it would be kosher if I borrowed a full set of Kubala-Sosna Elation! wires for this review. With his assent came a warning: I would need to establish, as a benchmark, the sound of the Pass/Kubala-Sosna combo before moving on to the Audionet/Kubala-Sosna, and "That will take a lot of time."
Footnote 1: The music was by Mason Bates, from his Works for Orchestra, with Michael Tilson Thomas conducting the San Francisco Symphony (SACD/CD, SFS Media 65). See www.stereophile.com/content/sonja-xv-loudspeakers-yg-acoustics.
