Audio Research Reference 5 SE line preamplifier
Rumor has it that in the mid-1990s, when William Z. Johnson set out to design the original Reference 1 preamplifier, his jumping-off point was the SP10. What's not a rumor is that the Reference 1 carried on the tradition and lineage of those classic preamps. It was fully tube driven, it was the best preamp that ARC could build with the technology available at the time, and, like its predecessors, the Ref 1 redefined what was possible in a tube preampand, to some ears, what was possible in a preamp of any type. It thus became an instant classic. Time and technology marched on, and the Ref 1 was replaced by the References 2, 3, and 5, each one in turn carrying on the lineage and setting a new standard of performance (footnote 2). The latest in this series is the Reference 5 SE ($12,995), introduced in late 2011 to replace the Reference 5.
The Reference 5 SE
The Reference 5 SE benefits from several advancements that Audio Research developed for the cost-no-object, limited-edition Anniversary Reference preamplifier ($24,995), including two readily visible changes from the Ref 5. First, the 5 SE's front panel mirrors that of the Anniversary: the buttons are now tidy, round, metal, and set directly into the faceplate, rather than the Ref 5's square, recessed plastic buttons. Added on the inside, to the left, is a vertically mounted circuit board, stuffed to the gills with capacitors to nearly double the Ref 5's already massive energy storage. Other changes include new Teflon and hybrid coupling and bypass capacitors, and changes in the internal wiring.
Otherwise, the Reference 5 SE's basic circuitry resembles that of the Ref 5: it's mostly contained on a single-sided board that stretches from wall to wall. Additional, smaller boards handle I/O, switching, and display functions. As in the Ref 5, the Ref 5 SE's transformersan R-core for the audio circuits, a toroidal for the display, relays, and microprocessor controlsare mounted on the sides of the chassis, above the board, to reduce vibration in the audio circuits. The audio circuitry's power supply is a hybrid-regulated design employing both FETs and a 6H30 dual-triode tube controlling a 6550 pentode tube. The audio circuit itself is "as simple and good as we could make it," according to ARC's David Gordon: a single gain stage with a cathode follower tube in a zero-feedback, fully balanced, pure class-A triode layout. There are six tubes: four 6H30s in the analog stage, and the 6550 and 6H30 in the power supply.
The Ref 5 SE's cosmetics and layout are handsome in Audio Research's traditional fashion, and it's the same goodly size and weight as the Ref 5: 19" wide by 7" high by 15.5" deep, and weighing 30 lbs. The chassis is of heavy aluminum, with a thick, elegantly machined aluminum front plate and two rack-mount handles. The review sample's top plate was of tinted polycarbonate, with slot vents. A cover of perforated aluminum is also available, but ARC recommends the polycarbonate, perhaps because of lower chassis resonances. The Ref 5 SE is available in natural aluminum or black.
Like the Reference 5, the 5 SE has at the center of its faceplate a large window that prominently displays the volume setting with both a bar graph and large numeric display. Also displayed, in far smaller characters, are the selected input, whether it's single-ended or balanced, and the status of several functions: mono/stereo, mute on/off, and polarity non-inverted/inverted. The display can also be used, via the remote control, to show the hours each tube has been used, handy for confirming what your ears will tell you: that you've reached the 600 hours of break-in time that ARC recommends. Via the remote, the display's level of illumination can be set to one of eight levels, from off through bright. But even when the display is fully dark, any change in status lights it up for 10 seconds to display the change.
Flanking the display are two return-to-center knobs, attached to a microprocessor, that turn through an arc of about 60°. The one on the left changes the volume across 103 steps; the one on the right selects among the six inputs. Below the display are six small buttons: Power, Mute, Mono, Balanced/SE (input selection), Processor, and Phase Invert. All front-panel controls are duplicated on the utilitarian remote control, which also includes buttons for adjusting balance and display brightness, and to display tube hours.
On the rear panel are six line-level inputs, a processor input that bypasses the volume control to allow the Ref 5 SE to be integrated into a home-theater system, a set of line-level output jacks for recording, and two sets of outputs. All inputs and outputs have both single-ended and balanced connections. For each input, the type of connection is selected with the Balanced/SE button on the front panel or remote.
Use, Handling, and . . .
The Reference 5 SE was a delight to use. All of its controls were intuitive and positive, and the single-ended and balanced connectors were all nicely solid. An interesting feature of the Ref 5 SE is that it's supplied with a 20A IEC power cord, not one of the standard 15A cords we're all used to. I would have liked to experiment with different power cords, but no dice: Although ARC's extremely heavy cord is removable, it takes a different type of IEC connector. I used the Ref 5 SE with both single-ended and balanced sources, and though I experimented with both types of outputs, I found that I marginally preferred the sound with the Ref 5 SE's balanced outputs driving my VTL amps. In any configuration and throughout my listening, the ARC was completely quiet.
The Audio Research Reference 5 SE's lineage and $12,995 price led me to expect a lot from it, and it didn't disappoint. I can sum up my impressions of it in one word: "Wow!"
The Ref 5 SE was no shrinking violet of a preamp. It was big, bold, brash, and brassy, in exactly the way live music is big, bold, brash, and brassy. While listening to Howard Hanson and the Eastman-Rochester Orchestra's Fiesta in Hi-Fi (CD, Mercury Living Presence 434 324-2), I was repeatedly taken aback at how the Ref 5 SE reproduced this recording's full dynamic spectrum and harmonic richness. Bass drums exploded and boomed with a wonderfully round, taut tone. Castanets cracked with perfect woodiness. Cymbals rang and shimmered, maracas hissed and clattered, violins sang, cellos swooned, basses groaned ominously. You name it, the Ref 5 SE nailed it.
Nor did the Ref 5 SE shine only with sonic spectaculars. It was equally impressive with small, intimate recordings, such as Doug MacLeod's Brand New Eyes (CD, Reference Fresh FR-703CD). Its incredible resolution and recovery of fine detail made it seem as if several layers of the recording chain had been wiped away and I was in the room with MacLeod.
Regardless of the genre or scale of the music, the Ref 5 SE brought about a fundamental, not-subtle jump in my system's performance. It was like hearing a good direct-to-disc record for the first time, or maybe an analog master tape. It wasn't just a question of being a little bit better, or better in one or two waysit was a broad-brush, wholesale improvement, like going from two dimensions to three, or from black-and-white to color. It was almost the sort of fundamental change in the fabric of the music that (dare I say it) separates live music from recorded. This isn't to say that my system magically became the real thing with the Ref 5 SE installed, but it was definitely a step closer.
The ARC's reproduction of timbres was uncanny; it seemed to be painting the music with a tonal palette both bolder and more nuanced than I'd heard before. Tonal colors were richer and denser, harmonic structures more complex. With the Ref 5, instruments sounded more like themselves, more alive. Violas were more distinct from cellos and violins, and each woodwind retained more of its inherent characteristics, whether it was the woody, airy tone of a clarinet or the reedier buzz of an oboe. The rich way the Ref 5 SE portrayed instruments also made it easier to discern individual musicians in a chorus or orchestra, the differences in timbre and texture enhancing the image specificity to create a nearly holographic effect. With recording after recording, I noticed more complexity in background voices and passagesand not just across the midrange, but from the very bottom to the very top of the audioband, and across the full range of volume, from the faintest pppp shadings to thundering ffff climaxes.
Footnote 1: I bought a sample of the Audio Research SP-10 after I reviewed it for the English magazine Hi-Fi News in May 1984. It was both the most expensive and most enjoyable audio purchase I had made at that time and I still have it, occasionally taking it out for an satisfying canter around my music collection.John Atkinson