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Audio Research Corporation Reference 5 SE Linestage Preamp, Reference Phono 2 SE Phonostage Preamp, and Reference 250 Monoblock Power Amp

William Zane Johnson, God bless him, may be gone and his pathbreaking company, the Audio Research Corporation, may now be owned by an Italian holding company, but in spite of the loss of its founder and the change in proprietorship (which, let me be clear, has not affected the way things are done at Audio Research—all of whose products are still manufactured in the good ol’ USA), ARC has done anything but lose its way over the last few years. Indeed, its latest electronics are better than ever.

While two of the three items I’m about to review are “Special Editions” of previously released components, don’t let the moniker fool you. Both are improved enough to qualify as entirely new pieces of gear. Indeed, the first of the two I’ll discuss, the Reference 5 SE linestage preamp, is a far bigger sonic leap ahead of the Reference 5 than the Ref 5 itself was over the Ref 3 that preceded it. I’d go so far as to say that the 5 SE sounds more like a slightly less holographic Reference 40 (ARC’s late, lamented, $25k two-chassis flagship) than a “souped-up” Reference 5.

As is the case for all three components under review, technical advancements—much higher power-supply capacitance, proprietary Teflon capacitors in key spots, and circuitry and board-layout improvements borrowed from the Reference 40— have resulted in substantial sonic gains. With the Ref 5 SE you hear them primarily in four specific areas.

First, the 5 SE is much denser in tone color than the Reference 5 (or any previous ARC preamp save for the Reference 40). As is the case with the Reference 250 (see below), this increase in tone color is particularly noticeable in the so-called power range from about 100Hz to 400Hz, where ARC preamps and amps have traditionally been lean.

Given the relatively recent seismic shift in the tonal balance of ARC gear—which, IMO, can be attributed largely to Warren Gehl, who does the voicing of all ARC products—it is easy to forget that this characteristic ARC leanness in the upper bass and lower midrange wasn’t an altogether bad thing, at least in comparison to the gross overripeness of contemporaneous tube gear in this same region and in the midbass. Indeed, along with ARC’s also-characteristic forwardness and added energy in the transient-rich midrange and upper midrange, it was a large part of the reason why ARC preamps and amps sounded so different than their competition—what gave them that sense of solid- state-like neutrality, liveliness, detail, and transparency.

This said, ARC’s traditional slightly lean, slightly brightish balance rather threw the baby, or part of him, out with the bathwater. Too many of music’s fundamentals and harmonics— and too much musical energy (hence the name “power” range)— reside in the very area that ARC gear leaned down, and while ARC’s slight power-range suckout and added midband brilliance may have created a greater sense of apparent detail and transparency (precisely as these same things do with loudspeakers), they also robbed music of some of its foundation.

That is no longer the case. Indeed, the difference the 5 SE makes in overall balance is so dramatic that, at first, you may think that ARC has gone over to the “dark” side, as opposed to the bright, light, airy one where it has long resided. In all honesty, the 5 SE is darker in balance than the 5, but that is because it is also, as noted, substantially fuller, richer, and more realistic in timbre than the Ref 5. Moreover, the sense of a darker balance diminishes with break-in and use, although it doesn’t completely disappear.

You won’t have any problem hearing the difference the 5 SE makes in timbre, particularly in the power range. Just put on any decent piano recording. Where upper-bass/lower-midrange notes and chords would sound quite clear but a bit too insubstantial via the Reference 5 on, say, the Nova LP of Paul Dessau’s First Piano Sonata—as if the concert grand had suddenly turned into a spinet—with the Ref 5 SE all that lifelike color is restored, as are the majesty of the instrument, the passionate Romanticism of the score, which fluctuates between the kind of melancholy lyricism that only a young man could summon up and the chromatic pounding of Fate (ditto), and the sheer power of Siegfried Stockigt’s performance (particularly on the sforzando chords in the piano’s lower and bottom octaves, without which, as I just said, the sonata loses half of its youthful fervor).

Those sforzando chords bring us to the second of the Ref 5 SE’s major improvements: the bottom octaves. Though ARC has steadily been acquiring better control in the bass and midbass, the Reference 5 SE is a new high point. In combination with the Reference 250, it reproduces the bottom octaves with better grip, definition, and extension than any previous ARC preamp save, perhaps, for the Ref 40, although I’m not completely sure of this.

It’s at this point that I usually play the transistor card and say that the 5 SE has come even closer to solid-state’s virtues in the bass than previous ARC preamps, but, even though it has, it doesn’t really sound like solid-state on the bottom. It is bloomier (not plummier, mind you), more freed-up, richer in timbre, more immediate, less tightly wound, more like the real thing (at least on acoustic instruments) than much solid-state, with better presence and texture on instruments like piano, percussion, and low-pitched brass, winds, and strings than some solid-state. It is even quite remarkable on rock combos like Fender bass and kick drum, which it sorts out without (as in the past) leaning down tone color or cheating you of realistic speed, weight, definition, and impact.

Third, there is the Ref 5 SE’s magical way with the duration of notes. While tube circuits don’t literally slow music down, they can have the peculiar effect of seeming to stretch time out, where much solid- state—with its more discontinuous, on/off power delivery—sometimes seems to abbreviate it. When details flow at this seemingly more expansive pace, our appreciation of the sequence of musical events, of how one thing leads to another—the horsehairs on a bow, say, catching the ridges of a violin string and setting it into motion—is curiously expanded. It is almost as if we have greater leisure to hear the little details, as if tubes were “lingering” over them just a touch longer, making them more present.

The Ref 5 SE is superb at delivering this more expansive sense of time and the heightened resolution of micro-details of timbre, texture, dynamics, and performance that accompanies it. As I point out in my review of the Crystal Cable Absolute Dream (which is a superb match with ARC’s new gear, BTW), tiny touches like the whispery vibrato that Melody Gardot adds to the tail ends of certain notes as she runs out of one breath before taking another are simply clearer here because of the Ref 5’s more finely detailed and (to my ear) more naturally paced presentation. This is how live music sounds if you sit moderately close to the performers in a good hall.

Fourth, that the Ref 5 SE is superb at low-level resolution and duration (bespeaking very low distortion and coloration) does not mean it lacks punch. This is also the hardest-hitting Reference Series preamp I’ve heard, with (because of the improvements in power-range color and weight, and control in the low bass) tremendous speed, slam, and articulation on big orchestral tuttis or, for that matter, Chris Franz’s rifle-shot drumming at the close of “Life During Wartime” from Stop Making Sense.

While it may not have quite the same three-dimensional imaging of the Ref 40 (nothing I’ve yet heard has, although I haven’t heard ARC’s latest flagship, introduced at RMAF, the Ref 10, in my system), the Ref 5 SE certainly comes a lot closer to that kind of sonic holography than the Ref 5 did, with less persistent forwardness and an even broader, deeper soundstage. In fact, there isn’t an area of performance where the Reference 5 SE isn’t either a little or a whole lot better than the Reference 5, making it a no-brainer upgrade for Ref 5 owners, a must-audition for those of you in the market for a world-class linestage, and my new tube preamp reference.

Let me turn now to the Ref 5 SE’s companion piece, the Reference Phono 2 SE phonostage preamplifier.

Not only does the 2 SE look different than the Ref Phono 2, with its new circular push-button faceplate and special damped plastic (as opposed to metal) top plate—design features it shares, BTW, with the Reference 5 SE, and that are derived from the rather unbelievably short-lived Reference 40 Anniversary linestage preamp—but it sounds different, too. One look inside—and you will have to take the top plate off (and I advise you to leave it off, if kids, pets, or spouses don’t make that impossible) to install the tubes—tells you why: lots of large Teflon capacitors that weren’t there before. My first thought on seeing these caps was, “This is going to sound like a Ref Phono 2 on steroids.”

But the difference in sonics actually goes beyond the massively beefed-up power supply, which now has twice the energy storage of the original Ref Phono 2. The thing isn’t just faster (although it is faster), harder-hitting (although it is harder-hitting), or more extended in the bass and treble (although it is these things, too), with excellent bass-range grip and explosive impact on big transients—the benefits you might expect from a stiffer power supply. It is also markedly lower in noise and grain, higher in resolution (and the Ref Phono 2 was no slouch in the detail department), richer and more natural in tone color, more tightly defined in imaging, and more immersive when it comes to ambience retrieval. It is, in short, less tube-like (in the “coloration” sense), more neutral, less there-in-its-own-right than any previous ARC phonostage I’ve heard. (A further important word about the 2 SE and ambience retrieval: With the right speakers and electronics, this phonostage— along with the Ref 5 SE linestage that I just covered and the Reference 250 monoblock that we will come to in a few paragraphs—has the uncanny ability to reproduce voices and instruments as if they are embedded within an acoustic space that is audibly different than that of your listening room. These instruments and voices don’t sound, as they so often do with less high-resolution gear, as if they are standing in front of an acoustical scrim that stretches out behind them, like actors filmed in front of a projected backdrop in a 40s film. They are, instead, reproduced within the space, like actors filmed in a location shot. In order to reproduce the very air of a hall or club in this utterly realistic immersive way, a component must be capable of extraordinary resolution, as well as very very low noise. The Ref Phono 2 SE fits this bill better than any previous ARC phonostage or, frankly, any other phonostage I’ve yet tested.)

As is always the case when the presence of electronics (and if you’ve got good ones, source components and speakers) is diminished, the presence of what is actually on the recording is proportionately increased. For a fidelity-to-mastertapes/absolute sound listener like me this is paradise. With great LPs, you not only hear more of what is actually in those grooves (and recent experience suggests that we haven’t come close to the end of mining that vein, yet); what is in those grooves will, if the augurs are right, sound significantly more realistic.

I’ve already mentioned in previous reviews of turntables and cartridges the fine detail about instruments and engineering that the ARC Ref Phono 2 SE is capable of reproducing (when sourced by a truly low-noise, high-resolution front end like the Ascona/Kuzma 4P/Ortofon MC A90 or the Walker Black Diamond Mk III/Clearaudio Goldfinger Statement or the Da Vinci Mk II/Benz LP S-MR). This subtle but significant bonanza of added musical and recording detail is probably owed to the fact that, unlike the original Ref 2 Phono, the Ref Phono 2 SE isn’t very slightly softening (with very fine grain, somewhat less incisive focus, and reduced energy) and warming (with tubier bass) the astonishingly neutral and high-in-resolution (some might say slightly clinical) signature of the Ortofon MC A90 or, for that matter, the near equally high-in-resolution but more robust, more energetic, more gemütlich signature of the Clearaudio Goldfinger Statement or the sweet, gentle, diaphanous one of the Benz. It is reproducing what comes ahead of it with greater discernment and less editorialization than previous ARC phonostages.

As has long been the case with every successive iteration of ARC products, the Ref Phono 2 SE appears to be incorporating more of solid-state’s undeniable virtues (there, I said it)—its lower noise, its wider bandwidth, its superior transient speed, its dynamic impact, its tighter focus, its more neutral tonal balance— without sacrificing the tube’s ability to more fully and naturally reproduce very low-level details about instrumental and vocal timbre, texture, and dynamics, or its ability to see into the stage without flattening images or dimming the lights, or its magical way with instrumental bloom. When you can not only hear the obvious differences between the “chick” and the “shimmer” of percussionist Butch Miles’ stickwork when he plays with his hi- hat closed and open (on Reference Recordings’ swell From the Age of Swing LP), but can also actually hear him opening and closing that hi-hat as he plays, you’re getting the kind of resolution of instrumental detail, playing style, and lifelike timbre, texture, and dynamic that makes for astonishing realism. Ditto for Attila Bozay’s harp- zither on the Hungaroton LP that I’ve talked about in various reviews (sorry, Wayne). Double ditto for Joan Baez and her guitar on Joan Baez in Concert Part 2 [Vanguard]. Her occasional head movements (toward and away from the central vocal mike, which cause her voice to shift a bit right and left as it is picked up by the mikes on the audience/hall and on her guitar) are more apparent than ever before, as are her fingerwork and the timbre and texture of the separately miked guitar’s strings and resonant body. Triple ditto for the delicate harp pizzicatos in the second movement of Stravinsky’s Three Movements for Orchestra [Decca] or Steven Hunter’s marvelous chucking rhythm guitar on “Rock ’n’ Roll” from Rock ’n’ Roll Animal [RCA].

The new Ref Phono 2 SE is exactly $1k more than the original Phono 2—$12,995 instead of $11,995. As with these other ARC components, the sonic improvements are well worth the difference in price. So’s you know, the features of the original Ref Phono 2 remain the same, i.e., the unit still allows you adjustable RIAA curves (RIAA, Decca, and Columbia) and the convenience of remote-control operation and remote- controllable loading of moving-coil cartridges.

We come now to what might be the most improved component of this marvelous trio, the Reference 250 monoblock amplifier.

ARC has been designing, building, and marketing a roughly 200W amp for decades (its reputation was, in part, made by the D150, the first “high-powered” Audio Research amplifier), but it has never built a better one I’ve heard than the new Ref 250, which is everything that its most recent predecessors—including the Reference 210—were not.

I reviewed the Reference 210 and, like all contemporary Audio Research amplifiers, it was an excellent pentode power amp. It had the traditional ARC virtues of neutral balance, lifelike bloom, and mid-to-treble-range air and light, plus, like all ARC products from the SP-3 on, it was able to “breathe” life into instruments and voices in the midband and top end almost like an acoustic bellows, changing image size, projection, and presence with the ebb and flow of dynamics, just as instruments and voices do in a concert hall.

However, all you had to do was compare the Ref 210 side by side (as I did) with a really good triode amplifier, like the then-current Convergent Audio Technology, to hear what the ARC amp didn’t do. In spite of the fact that at 90W the CAT amp was, on paper at least, half as powerful as the Ref 210, it simply blew the ARC out of the water when it came to transient speed, dynamic range, midbass and low-bass definition and slam, density of tone color top to bottom, image focus, and ultimate SPLs. Of course, Class A triode and Class AB pentode amplifiers and the different tubes they use have fundamentally different presentations (the CAT for all its dynamo-like power and gorgeous tone color lacked the midrange-to-treble bloom, air, and lifelike “action” that I just commented on); nonetheless, the Ref 210 sounded like a wimp beside the CAT. It was also considerably grainier than the triode amplifier, producing sonic images that sounded the way “half- tone” photographs look, where the CAT’s images sounded the way “continuous tone” images look.

If you were to combine the virtues of the CAT amp with those of the Reference 210, while subtracting the flaws of each and adding even higher resolution of low-level detail and lower noise than either was then capable of, you would end up with something very close to the sound of the new Reference 250. Everything that I didn’t like about the Reference 210—its dynamic wimpiness that made it sound a lot less powerful than its on-paper watts would suggest, its graininess, its washed-out tone colors (particularly in the crucial power range from about 100Hz to 400Hz), its slightly sluggish transient response, its lack of bottom-bass definition and slam, its ill-focused images (too big with too little edge definition), its inability to play really loud without bumping its head against an SPL ceiling—is gone. Everything I liked about the Reference 210 and other pentode ARC amplifiers—their neutrality, their bloom, their air, their light, their incredibly expansive soundstage, and, above all else, their realistic way of breathing life into instruments and vocals (now including bass-range instruments)—has been improved.

I could cite musical examples from record after record that demonstrate the newfound virtues of the Ref 250, but as I’m running short of space and have already provided examples in my previous discussion of the Ref 5 SE and Ref Phono 2 SE, why bother? None of those instances of superior resolution, timbre, bass, treble, dynamics, soundstaging, imaging, and transparency would’ve sounded the way I’ve described them sounding without the Reference 250—it’s that simple. And so, BTW, is my opinion of this marvelous amp: The Reference 250 comes closer to sounding “realistic” on more instruments and on more kinds of music than any previous ARC amp I’ve heard (and I’ve heard them all, save one). Indeed, I would have to say that, ultimate power levels aside, it is a substantially better amp than the Reference 610T that was my tube reference for many years. (The Ref 250 is my tube reference now.)

In sum, what we have here are an amp, preamp, and phonostage that you positively need to audition, whether you’re in the tube camp or the solid- state one. All three compete fully with the best examples of either gain strategy, even in those areas (bass, low-level detail, speed of attack, noise) where solid-state has traditionally reigned supreme. This does not mean that the Reference 250, Reference 5 SE, and Reference Phono 2 SE are the only great electronics out there—we are, in case you missed it, living through a new Golden Age of High Fidelity that, particularly when it comes to low noise and high resolution, leaves most of the products from that first Golden Age in the dust. What it does mean is that when it comes to contemporary tube amplification and preamplification, ARC is the marque to beat. But then what’s new about that?


Reference 5 SE
Type: Tube linestage preamplifier
Tube complement: Four 6H30P dual triodes, plus one 6550C and one 6H30P in power supply
Frequency response: +0-3dB, 0.5Hz to 200kHz at rated output
Distortion: Less than .01% at 2v RMS BAL output
Gain: 12dB, balanced output; 6dB, SE output
Input impedance: 120k ohms, balanced; 60k ohms, unbalanced
Inputs: CD, Tuner, Video, Phono, Aux 1, Aux 2, Processor (XLR and RCA connectors)
Output impedance: 600 ohms, balanced; 300 ohms, unbalanced
Outputs: 2 main, 1 tape (XLR and RCA connectors)
Maximum input: 20v RMS, balanced
Dimensions: 19″ x 7″ x 15.5″
Weight: 30.4 lbs.
Price: $12,995

Reference Phono 2 SE
Type: Tube phono preamplifier
Tube complement: Four 6H30 dual triodes, plus one 6H30 and one 6550C in power supply
Frequency response: ± .2dB of RIAA, 10Hz to 60kHz; 3dB points below 0.3Hz and above 300kHz
Distortion: Less than .002% at 1.0v RMS 1kHz output
Gain: Selectable, 51dB (low), 74dB (high) at 1kHz BAL; 45dB (low), 68dB (high) at 1kHz unbalanced
Selectable loads: 1000, 500, 200, 100, 50 ohms and custom
Phono eq: RIAA, Columbia, Decca
Output impedance: 200 ohms unbalanced, 400 ohms balanced
Maximum inputs: 250mv RMS at 1kHz (680mv RMS at 10kHz)
Dimensions: 19″ x 7″ x 15.5″
Weight: 27 lbs.
Price: $12,995

Reference 250
Type: Tube monoblock power amplifier
Tube complement: Three matched pairs of KT120 (power output); one matched pair KT120 (driver); two 6H30 (gain stage and regulator); one 6550C (regulator)
Power output: 250 watts per channel continuous from 20Hz to 20kHz
Harmonic distortion: Typically 0.5% at 250 watts, below .04% at 1 watt
Power bandwidth: (-3dB points) 5Hz to 70kHz
Frequency response: (-3dB points at 1 watt) 0.5Hz to 110kHz
Input sensitivity: 2.4v RMS balanced for rated output
Input impedance: 200k ohms balanced
Output taps: 4, 8, 16 ohms
Overall negative feedback: 8.8dB
Slew rate: 20 volts/microsecond
Rise time: 1.5 microseconds
Dimensions: 19″ x 8.75″ x 19.5″
Weight: 73 lbs.
Price: $25,995

JV’s Reference System

Loudspeakers: Raidho C 4.1, Raidho C1.1, Estelon X diamond, MartinLogan CLX, Magnepan 1.7, Magnepan 3.7, Magnepan 20.7
Linestage preamps: Constellation Virgo, Audio Research Reference 5SE, Technical Brain TBC-Zero EX
Phonostage preamps: Audio Research Corporation Reference Phono 2SE, Technical Brain TEQ-Zero EX/TMC-Zero
Power amplifiers: Constellation Centaur, Audio Research Reference 250, Lamm Ml2.2, Soulution 501, Carver Black Beauty 305, Technical Brain TBP-Zero EX
Analog source: Walker Audio Proscenium Black Diamond Mk III record player, AMG Viella 12, Da Vinci AAS Gabriel Mk II turntable with DaVinci Master’s Reference Virtu tonearm, Acoustic Signature Ascona with Kuzma 4P tonearm
Phono cartridges: Clearaudio Goldfinger Statement, Ortofon MC A90, Ortofon MC Anna, Benz LP S-MR,
Digital source: Mac Mini/Wavelength Audio Crimson USB DAC, Berkeley Alpha DAC 2
Cable and Interconnect: Synergistic Research Galileo, Crystal Cable Absolute Dream
Power cords: Synergistic Research Tesla, Shunyata King Cobra, Crystal Cable Absolute Dream
Power conditioner: Synergistic Research Galileo, Technical Brain
Accessories: Synergistic ART System, Shakti Hallographs (6), A/V Room Services Metu panels and traps, ASC Tube Traps, Critical Mass MAXXUM equipment and amp stands, Symposium Isis and Ultra equipment platforms, Symposium Rollerblocks and Fat Padz, Walker Prologue Reference equipment and amp stands, Walker Valid Points and Resonance Control discs, Clearaudio Double Matrix SE record cleaner, HIFI-Tuning silver/gold fuses


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