Audio Research Reference 110 stereo tube power amp

$10,000.00 $3,295.00

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Audio Research Reference 110 stereo tube power amp in excellent condition.
Note: Local pickup only

From Stereophile’s review:

This 110Wpc amplifier is based on a push-pull, fully balanced circuit using two matched pairs of 6550C output tubes per channel. The input stage, trickled down from ARC’s flagship amp, the Reference 610T, uses direct-coupled JFETs with a driver stage based on 6H30 tubes, one for voltage gain and one used as a cathode-follower. Output tube biasing is accomplished using trim pots and insulated test points on the left and right circuit boards. The output-stage coupling is a combination of ultralinear and ARC’s “partially cathode-coupled” topology, which the company claims yields better sound than conventional triode or pentode operation.

ARC pays more attention than most firms to circuit-board layout and wire routing. The Ref 110’s right- and left-channel boards are mounted horizontally and flank the transformers, which are mounted on a raised central channel running from front to back. A small LCD display indicating the number of hours the tubes have been run is mounted on the front of one board and is visible though the top panel. Every tube amp should have such a display. The speed of the two small fans mounted on the rear panel is controlled with a three-way switch. The input is balanced XLR only, and there are pairs of ARC’s rugged, proprietary speaker binding posts for the 4, 8, and 16 ohm taps. Two 12V triggers (input and output) allow remote turn-on. The Reference 110 is the first power amplifier I’ve had in house with a 20A IEC power cord.

Over my many weeks of listening to the Reference 110, two things made it extremely special with all recordings.

First, the 110 could unravel layers of inner detail. This, combined with its extraordinary ability to convey hall ambience and low-level dynamic inflections on a wide, deep soundstage, rendered all good recordings with startlingly lifelike realism. With every one of my very familiar reference discs, I noticed many subtle nuances for the first time. Listening to Timothy Seelig and the Turtle Creek Chorale’s recording of John Rutter’s Requiem (CD, Reference RR-57CD), it was easy to tell where the choirs were standing within the recording space. The wall reflections of the church were easily discernible, and the blend of voices and pipe organ had an incredible sense of bloom. I’m used to the male choir on Brian Wilson’s Smile (CD, Nonesuch 82946-2) sounding like a mass of identically replicated voices, but through the Reference 110 I could hear each singer’s individual vocal signature so distinctly that I almost felt I could write out each vocal line on a sheet of music paper. The 110’s dead-neutral midrange certainly helped. On Antal Dorati and the London Symphony’s recording of Stravinsky’s The Firebird (CD, Mercury Living Presence SR 90226), I noticed, buried way down in the mix toward the rear of the soundstage, delicate flute lines that were easy to follow no matter how complex or loud the surrounding orchestral passages.

The second of the 110’s remarkable strengths was its ability to render high frequencies with a clean, pristine, extended presentation totally devoid of electronic artifacts. This was also my reaction to the high frequencies of ARC’s Reference 3 line-stage preamplifier (see my Follow-Up in the June issue, p.139); in this region, clearly, these two designs were cut from the same sonic cloth. I tested the Reference 110 with both the Reference 3 and Audio Valve Eklipse’s line stage, and the amp’s high-frequency strengths shone through both (although the effect was notably greater with the ARC preamp). Soloist Tom Chiu’s violin in David Chesky’s Violin Concerto, on Area 31 (SACD/CD, CD layer, Chesky SACD288), revealed natural but biting extended partials, and the instrument’s vibrancy seemed to pop out of thin air. Similarly, Carol Wincenc’s flute, in Tomiko Kohjiba’s Transmigration of the Soul, from Festival (CD, Stereophile STPH007-2), was appropriately metallic, extended, and airy, with all subtle low-level dynamic inflections intact.

The Reference 110’s organic presentation of dynamics made it superb for jazz recordings. On “House Party Starting,” from Herbie Nichols’ The Complete Blue Note Recordings (CD, Blue Note CDP 8 50352 2), I fixated on the interplay of Max Roach’s snare and bass drum with Al McKibbon’s woody, warm, and vibrant walking bass line. I’d hoped that, during bombastic dynamic blasts, the Ref 110’s over-engineered power supply (520 joules of storage is unusually large for a 110W amp) would make it sound more powerful than it actually is, and the ARC did not disappoint. On John Atkinson’s recording of Robert Silverman’s performance of Beethoven’s 32 piano sonatas (CD, OrpheumMasters KSP830), I listened to the Largo of Sonata 2 in A, Op.2 No.2 (which is one of my favorite pieces to play as well). This delicate work from Beethoven’s early twenties has a surprise near the end, when a sudden ff passage bursts forth without warning, using the piano’s entire ranges of frequency and dynamics. My listening notes read “thunder, drama, and no strain.”

“Mansour’s Gift,” from my jazz quartet Attention Screen’s Live at Merkin Hall (CD, Stereophile STPH018-2) includes huge dynamic swings. Drummer Mark Flynn coaxes a broad range of bombastic colors with soft mallets from his Korean puk drum, and near the end there’s a tutti crescendo that tested the dynamic limits of the recording process. The Reference 110 rendered these dynamic swells as we’d created them on the Merkin’s stage.

The ARC’s ability to render wide dynamic blasts on electronic recordings didn’t hamper in any way its ability to render subtle details within these recordings. In Kraftwerk’s Minimum/Maximum (CD, EMI ASW 60611), the low- and high-frequency transients were startling, detailed, and lightning-fast without being harsh, even at extreme volume levels, while preserving subtle programming details that I hadn’t noticed with other amplifiers. Similarly, Chris Jones’ original electronic works, on Snowflake’s Tea Lounge 6-04-06 (CD, private recording), blend powerful dynamic bass blasts with delicate kalimba samples—through the ARC 110, all were clear and pristine with no trace of mud or strain.

I had to look really hard to find any shortcomings in the Reference 110, and found only one very small one. With certain recordings, there was a touch of warmth or roundedness in the midbass region. This genuinely split hair—the music still sounded incredibly lifelike—was audible only when I compared the 110 with amplifiers that have an ultrafast, overdamped quality in this region. Ray Brown’s bass solo on “I’m an Old Cowhand,” on Sonny Rollins’ Way Out West (CD, JVC VICJ 60088), was extremely natural, but a touch warm only near the bottom of the instrument’s register. Similarly, the midbass synth lines on Sade’s Love Deluxe (CD, Epic EK 53178) were natural but just a touch rounded.

Jerome Harris’ arrangement of Duke Ellington’s “The Mooche,” on Editor’s Choice (CD, Stereophile STPH016-2), put all of the 110’s strengths together. The blend of alto sax and trombone was the silkiest I’ve ever heard from this track, and the musicians sounded as if they were in my room (or, more appropriately, as if I were in the recording venue, the recycled church sanctuary of Chad Kassem’s Blue Heaven Studios). My notes: “this amp blooms like nothing I have ever heard; I want to listen longer and longer.” I’ve never heard a male voice sound more natural than Hugh Masekela’s through the Reference 110, in his rendition of “Stimela (The Coal Train),” on Hope (CD, Triloka KAT 2020-2). Moreover, the natural dynamics of the percussion on this live pop recording, and the bite and burnished brass of Masekela’s trumpet, were startling.

Summing up
The Audio Research Corporation’s Reference 110 amplifier replicated, over many weeks of listening, the magic I’d experienced in those few hours of listening at Home Entertainment 2006. In certain areas the amplifier produced a level of realism startling enough to make me reluctant to turn the stereo off. I had this experience with all types of music, as well as with movies. Although the 110 was an excellent match for ARC’s Reference 3 preamp, I didn’t need an ARC preamp to hear its magic.

Those who’ve read my reviews for a while know that I rarely change reference components. In fact, at one point about 10 years ago, every piece of gear in my reference system had been discontinued. For me to even consider buying it, a new product must constitute a significant improvement over what I already own, as well as provide value for money. At the end of my listening sessions for the Reference 110, I put down my notebook and picked up my checkbook. This amplifier is not going back to ARC.


Description: Stereo tubed power amplifier with balanced inputs and 4, 8, and 16 ohm output transformer taps. Tube complement: 4 matched pairs of 6550C output tubes, 4 6H30 driver tubes. Maximum output power: 110Wpc continuous, 20Hz–20kHz at 1kHz with THD typically 0.3% at 110W, <0.03% at 1W; 120W at clipping (20.8dBW). Frequency response: 0.6Hz–90kHz, –3dB. Input sensitivity: 1.8V RMS balanced for rated output (24dB balanced gain into 8 ohms). Input impedance: 300k ohms balanced. Output polarity: non-inverting. Damping factor: approximately 12. Hum & noise: <0.2mV RMS, 106dB below rated output (IHF weighted, input shorted). Power requirements: 105–125VAC, 60Hz (210–250VAC, 50Hz), 630W at rated output, 800W maximum, 410W at “idle.”
Dimensions: 19″ (483mm) W by 8.75″ (222mm) H by 19.5″ (495mm) D. Handles extend 1.5″ (38mm) forward. Weight: 67.4 lbs (30.7kg) net, 83 lbs (37.8kg) shipping.