Listening #188: ASR Emitter II Exclusive
The Emitter II Exclusive integrated amplifier, from German manufacturer ASR Audio, challenged my idea of what I could expect from a solid-state amplifier and my thoughts of what might be the best amp for driving a pair of Quad ESL loudspeakers—revelations that were more or less inseparable. After hearing my friend and former neighbor Neal Newman drive his own ESLs with a ca 1975 sample of the Quad 303—a solid-state amplifier rated at 45Wpc into 8 ohms—and after my experiences, in 2016, driving my ESLs with a borrowed sample of the 18Wpc, solid-state Naim Nait 2, I began to think that Quad-friendly transistor amps are easier to find than their tubed counterparts.
The ASR turned supposition into certainty: Of the many tubed amps I’ve tried with my Quad ESLs, only the Lamm Industries ML2.2 and Miyajima Laboratory 2010—the former a monoblock, the latter a stereo amp that sounds best when strapped for mono—equal or surpass the musicality and the clarity of sound I’m enjoying right now with the ASR.
The Emitter II Exclusive also challenged my ideas of what constitutes an integrated amplifier. In choosing electronics for review, I often gravitate toward integrateds, if only because I like writing about things that offer a certain level of thrift while taking up as little space as possible—and so it was when I accepted the offer of a review loaner from Gideon Schwartz of Audio Arts, ASR’s distributor and sole retailer in North America. I was shocked when Schwartz arrived at my house with four very large boxes, none of which I could lift by myself, and one of which I could scarcely handle with assistance. And that’s to say nothing of the price: $27,000, as configured for this review. This four-box amplification system—five boxes, if you count the compact but chunky, Corian-encased remote-control handset—was unlike anything else my system has hosted.
Description
ASR makes two basic amplifier models, the Emitter I and Emitter II. Both are solid-state stereo amplifiers, both have three active stages—input, driver, output—and both are fitted with source-selector switches, stereo volume controls, and multiple pairs of line-level input jacks.
Sounds like an integrated amp, right? That was my thinking—although on ASR’s website, Friedrich Schaefer, the company’s cofounder and designer of all their products, seems to chafe at that label, instead describing the Emitters as power amplifiers with sensitive front ends and very-high-quality volume controls (more on the latter in a moment).
Consider that ASR’s amps also use outboard power supplies—not just wall warts, or little boxes you can hide on the floor behind your equipment rack, but steel-and-acrylic enclosures each measuring 16.9″ wide by 5.9″ high by 15.6″ deep and weighing 71 lb. The basic version of the Emitter I requires one of those outboard supplies, the Emitter II needs two, and the Emitter II Exclusive presently in my system adds a third—a battery pack, including a built-in automated charging system, that powers only the amp’s input stage, and is identical in size and similar in weight to the other two.
The amplifier itself sports an acrylic enclosure with generously sized aluminum-alloy heatsinks and much-larger-than-average dimensions of 22.4″ wide by 9.1″ high by 17.3″ deep. It weighs 103 lb. I don’t know if that weight spec includes the three 8′-long, multiple-conductor umbilical cables—each 0.625″ in diameter and terminated with its own industrial-style, cast-aluminum-encased, clamp-on connector—that are hardwired to the rear panel and reinforced at that juncture with a massive strain-relief nut. The entire Emitter II Exclusive system weighs over 300 lb and takes up about 4.75 cubic feet. If you’re considering buying an integrated amplifier because you want something small and easy to handle, this is perhaps not your best option.
One of Schaefer’s design goals, as stated on ASR’s website and in the very comprehensive manual supplied with my review sample, is to avoid contaminating the audio signal with electromagnetic radiation from mains transformers and rectifiers—hence the outboard power supplies. But he also believes in the virtues of stiff power-supply circuitry that can supply abundant current with ease, and in which that current is kept clean not only by means of buffering capacitors but by power transformers that are themselves resistant to noise. For that last reason, Schaefer builds his power supplies around enormous frame-style transformers made by the Philbert Mantelschnit company. He says that these step-down transformers are made and wound in such a way that they also act as isolation transformers, thus preventing high-frequency AC line noise from breaking through to the audio circuitry.
None of the above explains why the Emitter II amplifier unit is itself so large. Schaefer is on record as favoring signal paths that are as short as possible, yet the amp’s main circuit board, made from FR4 glass-reinforced epoxy laminate, measures a healthy 14″ square. That said, the board is not only one of the most cleanly laid-out and well-constructed I’ve ever seen, it’s also strangely beautiful, from its gold-plated traces—juxtaposed against the green of the PCB material, they gleam a beautiful mustard yellow—to the neatly executed logo and Schaefer’s signature. Its beauty is enhanced by the use, throughout various portions of the circuit, of multicolored LEDs—dozens of them. At first I didn’t know whether the LEDs were chosen for their electroluminescence or simply their aptness as low-voltage diodes, but as I read through the manual, I learned that each combination of colors tells a story. Several pages of the manual are devoted solely to explaining what each color in each unique position means—associations I’m scarcely capable of comprehending as I read the explanations, let alone of remembering.
In any event, those LEDs are visible through the amp’s translucent front, top, and rear panels—as are the lights inside the outboard power supplies, albeit only through their front panels. From my listening seat, especially with the living-room lights dimmed, the effect was charming. I see from their website that ASR offers a version of the Emitter II with a fully transparent acrylic case; were I to spend almost 30 large on an ASR, that’s surely the version I’d buy.
More Description
The Emitter II Exclusive lacks a phono stage, but does offer far more than the usual number of options for connecting line-output sources. (ASR offers two different outboard phono stages.)
Of the amp’s seven inputs, 1 and 2 are for are unbalanced sources, and have gold-plated RCA jacks. Inputs 3 and 4, with gold-plated WBT Nextgen RCA jacks, are also for unbalanced sources, and are described as offering “the shortest signal path to the amplifier part.” Dual-mono DIP switches on the main circuit board let the user select, for inputs 1–4, one of five input impedances, ranging from 500 to 22k ohms.
Inputs 5 and 6 have XLR jacks (pin 1 ground, pin 2 positive, pin 3 negative), and are for connecting balanced sources. (As Friedrich Schaefer notes, the amp itself is an unbalanced design.) Another dual-mono pair of internal DIPs lets the user choose a balanced-input impedance of 1k or 10k ohms. Input 7 is labeled D, for Direct. Another unbalanced input with WBT Nextgen RCAs, Direct is subject to the same impedance-setting DIP switches that affect unbalanced inputs 1–4. It bypasses the amp’s source-selector relays and is connected, via solid-silver wire, straight to the Emitter II’s volume-control system.
That volume control is something of a technical tour de force. Similar to the Variable-Gain Transconductance system found in Ayre Acoustics’ KX-5 Twenty preamplifier and other Ayre products, the ASR system adjusts the volume not by resistively discarding gain, but by working with the amp’s input stage to produce different amounts of gain. This volume system, its large control knob connected to an optical rotary encoder with no limit to its travel in either direction, offers the user two ranges of loudness, depending on the setting of the amp’s four-position power switch: Set to O, the amp is off. Set to S, it’s in standby, in which state its signal-switching and volume-control circuits are active but the output section is not. (Hypothetically, one could record from a source to a tape recorder in this mode.) Set to 1, the Emitter II is in an “energy-saving” mode in which the outputs of the power supplies are reduced, the driver and output stages operate at half their normal voltages, and a volume range of 0–61dB is available. And, set to 2, the amp functions at full power, with a volume range of 0–76dB.
The Emitter II’s input stage is built around dual-mono sets of FET-input op-amps mounted on the undersides of chunky brass blocks. The driver stage uses MOSFETs, and the 10 output transistors per channel are also MOSFETs, each with its own ceramic isolator for electrical and mechanical isolation. These are mounted to solid brass bars that run the full depth of the amp and make contact with the large, side-mounted heatsinks, which are available in a variety of colors. (Going by the photos on the ASR website, the chrome-plated sinks are my favorites.) The Emitter II Exclusive’s specified output is 250Wpc into 8 ohms, 500Wpc into 4 ohms, 900Wpc into 2 ohms, and 1400Wpc into 1 ohm, operating in class-AB. Given that the two loudspeakers I used with the ASR were my DeVore Fidelity Orangutan O/93s (93dB sensitivity, 10 ohms nominal impedance) and Quad ESLs (low sensitivity and wildly varying impedance, but usually happy with solid-state amps rated between 20 and 100Wpc), I believe that power was not an issue in my system.
Setup
Installing the Emitter II Exclusive was no small chore, given the size and weight of the four enclosures, the smallness of my listening room, and the physical stiffness of the power-supply umbilicals. Gideon Schwartz and I wound up placing the three power-supply enclosures on the inner shelves of my Box Furniture rack—they barely fit—but the amplifier itself was too big to fit on the rack’s top shelf and still leave room for my turntable, let alone my phono preamp and step-up transformer. Ultimately, we set the amp atop a half-height, half-width Box Furniture rack placed next to the main rack.
Another complication: The living/listening room of my 1936 house has relatively few electrical outlets, and only one double outlet on the wall behind my equipment rack. Each of the three power-supply boxes needs to be connected to the AC—the review system came with three of ASR’s Magic AC Cords, in their standard 5′ length—so we were forced to rely on my trusty AVOptions outlet strip, in contradiction to Friedrich Schaefer’s advice to avoid extension cords of any sort. Later in the review period, Schaefer express-mailed three 14′-long Magic AC Cords, but even those weren’t long enough to reach the next-nearest available AC outlet. The AVOptions strip remained on duty (footnote 2).
Footnote 1: ASR Audio, Hohe Strasse 700, Haus 5a, D-35 745 Herborn/OT-Herborn-Seelbach. Germany. Tel: (49) (02772) 4-29-05. Fax: (49) (02772) 4-04-88. Web: www.asraudio.de. US retailer: Audio Arts, 210 Fifth Avenue, New York, NY 10010. Tel: (212) 260-2939. Web: www.audioarts.co.
Footnote 2: Having a new, audio-system-only circuit installed in this room is at the top of my home-improvement to-do list—but even a quadruple outlet wouldn’t have been enough for the three ASR power supplies, my Garrard 301 turntable, and the Sentec EQ11 phono preamplifier I used for this review.
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