Audio Research REF 110 Power Amplifier

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If any series of products has served up with impeccable consistency the sort of behavior that leaves you awestruck, it's the Reference family from Audio Research. It possesses the kind of track record you associate with Porsche, Leica and precious few other dynasties: five-star performance again and again and again.

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Having completed the lineup last year with a CD player and phono stage, ARC decided to add a tang of populism by issuing a single-chassis, stereo power amplifier worthy of inclusion in this particular clan. So now the range is accessible to a few more with merely deep pockets, as opposed to those who own football clubs and Maybachs.

Admittedly, £8490 is still a heady price tag, but you must put it into context: it's less than half the price of the REF 210 monoblocks. Given the way the 110 drove the hungry Sonus faber Guarneris, you'd be hard-pressed to justify the extra power of the bigger REF offerings in rooms under five by eight meters. Well, unless your name is Lemmy, or you run stupidly inefficient speakers.

ARC's corporate missive is quite clear as to why the REF110 exists: "It is perfect for anyone who does not require the high power provided by our larger monoblock Reference amplifiers." It's that simple. While the REF110 is never going to be described as "compact," a stereo unit with measurements of "only" 19 by 8.75 by 19.5 inches (WxHxD) will cause far less consternation than a brace of similarly-dimensioned chasses. It is precisely the same size as a single REF210.

Blessedly, you're spared the grotesque vacuum-fluorescent display of the REF210. Lord knows that the information it provides is truly useful, and - keeping my prejudice in check - if I were ARC's product manager, I would be pushing for a REF110D with the info panel, for an extra grand, for those who crave a display. But who on Earth chose that noxious green horror? With all the cool LCD panels out there, ARC could have specified something far less bilious. But I digress: the REF110 is as pure an amp as you will ever find.

Look at it: an unadorned box, yet unmistakably a product of Audio Research. The thick front panel bears only an on/off rocker switch and a tiny green LED. The back? Nothing more than robust custom-made speaker terminals for 4/8/16-ohm operation, XLR-type balanced signal inputs, a mains fuse and a socket for a 20-amp detachable IEC AC cable adorn the back. Additionally, since this is the era of the custom installation, the REF110 also has two 12-volt triggers (input and output) to allow remote turn-on. That's it - all you need. Perfect. Just what an amplifier should be.

It's inside where you find the fascinating grubby bits that justify the "Ref" tag. Its internal layout resembles that of the REF210, with right and left channel boards mounted horizontally, on either side of the trio of transformers that ARC has mounted on a raised central channel bisecting the unit: the mains transformer is just behind the front panel, with the output transformers lined up behind it.

Those boards are filled with such niceties as a small LCD display indicating tube life in hours, mounted on the front of the right channel board and visible through the top. There are two small 12-volt DC fans on the rear panel, the heat exiting through apertures at the back. Listeners ultra-sensitive to their whisper-quiet operation will love this bit: a small internal switch allows users to set their speed to low, medium or high.

Like the model number suggests, this amplifier delivers 110 watts per channel, courtesy of a push-pull, fully-balanced circuit containing two matched pairs of 6550C output tubes per channel. The hybrid input stage employs direct-coupled JFETs with a 6H30 gain stage and 6H30 cathode follower. Biasing is not automatic, so here's a use for your digital volt meter. The procedure is explained in detail in the manual, and it is accomplished using insulated test points on the main boards. The output section is a combination of classic ultra-linear topology and Audio Research's "partially cathode-coupled" topology, which the company argues as capable of "yielding better sound than conventional pentode or triode operation."

As mentioned before, this unit adheres to Reference practice in providing only balanced inputs - 300K ohm impedance and via XLRs. It's non-inverting, too, but I trust that all seasoned audiophiles set polarity by ear. Better still, they use preamps with an inversion switch.

After manhandling this 67.4 pound beast into position, I connected it between the McIntosh C2200 preamplifier and my trusty Sonus faber Guarneris. I soon found out that the speakers prefer the eight-ohm taps, the bass tightening up considerably and the dynamic swings seeming more fluid and greater in spread from low levels to high. The dynamic range was, it turned out, one of the REF110's most seductive qualities, along with the most liquid and natural bass I've heard since the days of the original Class-A Krells.

Read more about the REF 110 on Page 2.

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