Audio ResearchReference 75usedAudio Research Reference 75 stereo amplifier in very good / excellent condition. Operationally perfect, like new, with a sweet, open, warm sound. Glowing reviews can be found everywhere about thi...3800.00

Audio Research Reference 75 silver

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Ships fromAlbuquerque, NM, 87110
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Package dimensions27.0" × 24.0" × 19.0" (65.0 lbs.)
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Audio Research Reference 75 stereo amplifier in very good / excellent condition.  Operationally perfect, like new, with a sweet, open, warm sound.  Glowing reviews can be found everywhere about this amplifier, below are just two from Stereophile and What Hi-Fi.  Conservatively rated 8.5/10 condition with no dents, dings, scratches that I could find.  Matched set of KT120 Power and 6H30 Driver tubes with 900-1000 hours on them.  Comes with original box, owner's manual, sonic information sheet, quality assurance card, factory screwdriver and alignment tool, and original, heavy gauge 20A IEC power cord. We ship the same day payment is received, shop with confidence and look at our hundreds of positive feedback transactions over the past 14 years.  Herndon Audio can take all credit cards, PayPal, AudioGon Express Checkout (Stripe), check, etc.   Price includes shipping, insurance, and transaction fees, everything to your door.     
 <from Stereophile>

Audio Research Reference 75 power amplifier

Robert J. Reina  |  May 7, 2013 

After I read Brian Damkroger's rave review of the Audio Research Corporation's Reference 5 SE line stage in the November 2012 Stereophile, I was excited about getting the review sample into my system so that I could do a Follow-Up (February 2013). However, the sample had already been returned to the factory, so I called ARC to see if it could be rerouted eastward to me. Chief Listener Warren Gehl answered the phone.

"Sure, you can listen to the Ref 5 SE, but I'd assumed you were calling about the Reference 75 amplifier."

"Reference 75? What's that?"

"It's our newest amplifier—a half-power version of the Reference 150."

Hmmm. Erick Lichte had reviewed the Reference 150 in July 2012 and in December, Stereophile had named it Product of the Year for 2012. The Ref 150 had replaced the Ref 110 in ARC's lineup; I'd reviewed the Ref 110 in August 2007, then bought one for my reference system. It would be interesting to compare the References 75 and 110 . . .

"Would you like to review it?"

Design
The Reference 75 ($9000) is similar to the Ref 110 and Ref 150 in that all three use input circuits using direct-coupled JFETs and a 6H30 tube. However, the Ref 75 has only four Tungsol KT120 output tubes (in ARC's ultralinear "partially cathode coupled" topology), compared with eight in the Ref 150, and eight 6550Cs in the Ref 110. Warren Gehl told me that, compared with the 6550C, the KT120—apparently the first output tube specifically designed for audio applications—is more robust and powerful, with greater dynamics, lower distortion, better tonal balance, a larger soundstage, and a greater sense of presence. The Ref 75 shares the same oversize power supply (520 joules of energy storage) as the Ref 110, but has improved interstage coupling capacitors, and more damping material on its capacitors and heatsinks.

I asked Gehl what makes the Ref 75 special.

"Its simplicity."

The circuit design is straightforward, and careful attention was paid to ensure that signal paths would be as short as possible. Removing the cover and looking inside confirmed the simplicity and elegance of the circuit layout. In fact, with only one pair of output tubes per channel, there's no need for a cooling fan. Weighing only 47 lbs, the Ref 75 is the lightest tubed stereo power amp I've had in my system.

One aspect of the Ref 75's design particularly intrigued me. Some audiophiles hold that a single pair of push-pull output tubes is capable of greater sonic purity than multiple pairs of tubes, which, when ganged, can create a subtle smearing; because tubes are never precisely identical, they can't work in perfect concert. This effect can worsen as the tubes age, each deteriorating at a different rate. The advent of the more powerful KT120 provides the opportunity for avoiding this potential problem because two KT120s can replace four 6550s or EL34s in push-pull topologies.

The Ref 75 also sports a pair of VU meters, which give the amp a bit of the vibe of ARC's classic D79 amplifier, from the 1970s. These double as adjustment meters for biasing each of the four tubes individually. Setting bias was a snap (a bias adjustment tool is provided), and the settings remained very stable throughout my listening. ARC claims that the tube biases should need to be adjusted only when the amp is moved from one house to another (the voltages fed the different houses may vary), or when output tubes are replaced. The meters are illuminated, and their lights can be turned off; I noticed no difference in sound with lights on vs off. The Ref 75 comes with a burly, detachable, power cord fitted with a 20-amp plug. It has 4 and 8 ohm output taps, as well as 12V triggers for input and output. My review sample was in ARC's standard silver finish; black is available.

Listening
It was difficult to get a handle on the Reference 75's sound—after many weeks of listening to a broad range of recordings, I'd heard no shortcomings whatsoever. I never noticed a single coloration, or any deficiencies in dynamics, transient articulation, soundstaging, or retrieval of detail and ambience. I decided it would be most revealing to use specific reference recordings to focus on those areas in which the Ref 75 exceeded the performance of every amplifier I've heard in my reference system.

I first noticed the articulate manner in which the Ref 75 delineated the dynamic envelopes of all instruments. In all tracks of Bill Evans's At Shelly's Manne-Hole, Hollywood, California (CD, JVC JVCXR-0036-2), the unique personality of his technique was perfectly captured—every low-level nuance of the pianist's phrasing shone through across the instrument's entire register. Transient articulation was crystal-clear and lightning-fast with all recordings, and those with significant percussion textures were stunning. Drummer Paul Motian's Selected Recordings (CD, :rarumECM 8016) includes several tracks featuring solos by him. Through the Ref 75, every subtle drum and cymbal texture of the late master was clearly delineated with a wide dynamic envelope; it was easy to visualize just where Motian's sticks were striking each instrument.

I listened to the 2009 remastering of the Beatles' Abbey Road (CD, Apple 3 82468-2) in its entirety, and marveled at how dynamic Ringo's drums sounded, from his crash cymbals in "Come Together" to his floor toms in "Maxwell's Silver Hammer." The ARC's transient articulation combined with its superb dynamic capabilities to make many recordings sound more dramatic than I'd ever heard them. I've described before the Ellen Test: With components capable of reproducing a broad dynamic range, I put on a recording at a normal volume level and wait for the music to hit a fortissimo passage—and for my wife to say, "Turn that down!" I expect a great component to pass the Ellen Test when I put on a big orchestral work, or even a great electronic jazz or rock recording, but I didn't expect to hear those three words during Ringo's drumming in "Octopus's Garden," as I did with the Ref 75.


Not only was the Reference 75 capable of rendering dynamic swings on great recordings from pppp to ffff; I was also able to hear 10 to 15 dynamic intervals between pp and p. In short, the amplifier was able to reveal musically meaningful dynamic variation in recordings I'd previously thought sounded rather flat. Even soloist János Starker's performances in the cello concertos of Saint-Saáns (CD, Mercury Living Presence 432 010-2) and Dvorák (CD, Mercury 432-001-2), both with Antal Doráti conducting the London Symphony Orchestra, were presented with thundering dynamics, every attack of Starker's bow on his instrument kicking like a gunshot.

The ARC had superb detail resolution, especially in the critical midrange, which added a startling degree of realism to While You Are Alive, my favorite of the recordings by Cantus engineered by John Atkinson (CD, Cantus CTS-1208). The opening passage of Erik Whitacre's Lux Aurumquehas several very-low-level passages in which the choir resolves on a major chord, and the ARC was able to delineate these masterful singers' precision of pitch. With "Prana," from Liam Sillery's Outskirts (CD, OA2 22050), it was very easy to follow the two melodic lines of Sillery's trumpet and Matt Blostein's alto saxophone. Three male choirs sing on Psalms of Consolation and Hope, with George Guest directing the Choir of St. John's College and John Scott on pipe organ (LP, Argo ZRG 892): one each of adult males, older boys, and younger boys. Through the ARC, each group was easy to distinguish on the wide, deep soundstage—the Ref 75 separated the men from the boys.

The amp's resolution of detail was such that I was frequently able to "see" into the performances of many recordings. In Derek Bailey's Improvisation(CD, Ampersand 2), the amp's unraveling of the guitarist's unique string attack and harmonic chiming was so clear and clean that I could almost visualize how he was executing these effects on his instrument. With Tom Chiu's performance of David Chesky's Violin Concerto, with Anthony Aibel conducting (SACD/CD (CD layer), Chesky SACD 288), I was able to follow each instrument of the Area 31 ensemble as it floated on a bed of air. I was virtually able to re-create the score in my head.

My most chilling experience was listening to Michael Riesman conduct the Philip Glass Ensemble in the final movements of Glass's Einstein on the Beach (CD, Nonesuch 79323-2). This is my favorite Glass work; I prefer this 1993 recording to the first recording, from 1978, and have seen three performances of the opera over the last 30 years. Although Riesman has so far conducted every performance and recording ever made of the work, I was floored by the level of musicianship he coaxed out of a 2012 performance in New York. I sat riveted throughout those five hours, but the highlight for me was the bus driver's narration in the final scene. The actor-singer's performance was so dynamic, riveting, and personal that it gave me chills. When I played the final passage from the Nonesuch recording through the Ref 75, l was stunned—not because the bus driver on the Nonesuch recording equaled that of the 2012 New York performance (he didn't), but because the Ref 75 gave such a realistic facsimile of the singer standing in my listening room that I was mentally and emotionally transported back to the Brooklyn Academy of Music. I relived my experience of that night, which remains the most moving classical performance I've witnessed in the last 20 years. When the recording ended, I began to cry.

The ARC's ability to render instrumental images holographically on a bed of air with extraordinary detail and ambience meant that I was frequently fooled into thinking a live musician was playing in my living room. I had that experience with János Starker's recording of J.S. Bach's Suites for Solo Cello (CD, Mercury Living Presence 432 756-2), as well as with the solo guitars on Mark Ribot's Silent Movies (CD, Pi PI34). What was even more remarkable with solo classical performers was that the ARC amp unraveled so much detail, delicacy, and transient accuracy that I was able to appreciate certain performers' technical virtuosity more than through other amps. I had this experience with Gina Bachauer's recordings of the Chopin piano concertos, with Antal Doráti and the London Symphony (CD, Mercury Living Presence 434 374-2), and with guitarist Pepe Romero's Flamenco!(CD, Mercury Living Presence 434 136-2).

The Ref 75's resolution of detail also let me more easily distinguish between greater and lesser recordings. Although I'm a huge fan of both John Coltrane's Stardust (CD, Prestige 7268) and Chick Corea's Early Days(CD, Laserlight 17082), and I know that the Coltrane is a spectacularly natural recording, the Ref 75 revealed that the gap in recording quality between these two was much greater than I'd realized, especially during Corea's piano solos. And unfortunately, with "Sex Kills," from Joni Mitchell's Turbulent Indigo (CD, Reprise 45786-2), my favorite recording from her late period, it was obvious just how much electronic manipulation and digital compression had been applied; in terms of sound quality, it was far less satisfying than any of Mitchell's recordings from the 1960s and '70s.

But the Ref 75's greatest strength was in the bass. If my past experience of tube amplifiers has inclined me toward a bias, it's this: I haven't been crazy about the bass performance of tube amps of less than 100Wpc, including the ones I've owned. I've found that lower-powered tube amps tend to lose definition and slam, particularly in the lower bass. Not so the Reference 75. In the midbass, acoustic instruments sounded clean and uncolored, with great articulation, speed, and definition. And in the bottom two octaves the ARC had so much slam and authority that it behaved more like a high-powered arc-welder of a solid-state amp. With jazz tracks such as "Chairman Mao," from Denny Zeitlin and Charlie Haden's Time Remembers One Time Once (CD, ECM 1239), and "Our Love Is Here to Stay," from Bill Evans's At Shelly's Manne-Hole, I could hear the strings resonating separately from the wood on the respective double basses of Haden and Chuck Israels. Listening to "Where Will I Be," from Emmylou Harris's Wrecking Ball (CD, Asylum Elektra 61854-2), I was able to follow Daniel Lanois's electric-bass line perfectly, even though it's deep in the mix.

Victor Wootten's bass-guitar solo in "Cosmic Hippo," from Béla Fleck's Flight of the Cosmic Hippo (CD, Warner Bros. 26562-2), was so dramatic, dynamic, and in-my-face that I scribbled in my notes "Bass My God!" I had a similar reaction to the bass-synth lines in "Hunter," from Björk's Homogenic(CD, Elektra 62061-2), and Chris Jones's "Midnight Sun" (LP, 45rpm single, Surface Tension STNS002). The Ref 75's bass capabilities were demonstrated most startlingly with "Artemisia Absinthium," from Absinthe, the final album by John Zorn's Naked City (CD, Avant 004). Here Zorn, Bill Frisell, Wayne Horvitz, Fred Frith, and Joey Baron forgo their usual axes to perform works in the ambient genre. I don't know what instruments they are playing on this track, but most of the sounds generated are in the 20–50Hz range. Through the Reference 75, while the music thundered and bellowed across the front of the soundstage and shook the room, it was still easy to hear the subtle percussion textures across the rear of the stage. By now my two shelties have heard just about everything in my listening room, but this tune bothered them a lot.

The recording that at last put the ARC Reference 75 together for me was of my favorite classical work, George Crumb's Music for a Summer Evening (Makrokosmos III), for two amplified pianos and two percussionists (LP, Nonesuch 71311). This 1976 recording, by pianists Gilbert Kalish and James Freeman and percussionists Raymond Des Roche and Richard Fitz, is, in my view, the definitive performance of this work, and I was fortunate to hear this group perform it at New York City's Symphony Space in 1979, followed by a question-and-answer session with Crumb. The piece is replete with ambience, decay, and huge dynamic swings that include very delicate textures and crashing percussion. (The pianos are amplified, Crumb explained, not to add distortion, but to give a single piano the dynamic range of an entire orchestra.) The recording is an acid test for how an audio component deals with transients, dynamics, detail, and ambience retrieval. I was so struck by how well the ARC created an involving reproduction of the work that I sat through its entire 40 minutes, which I hadn't done in 15 years. The dynamics were startling, and more forceful than I recall from the live performance (well, my seats weren't that good).

I mainly chose this recording to test the ARC's power capabilities. When my wife and kids are around, I play music at a lower level than when I'm alone—among my audiophile friends, I have a reputation for playing music at louder levels than most people like. I cranked up the volume to a level that was about the maximum I could stand, to hear how the Ref 75 would handle the two sections of the third movement, The Advent, which ends in simultaneously crashing pianos and full percussion blasts (footnote 1). The effect was startling, with no trace of strain, distortion, or compression. And the VU meters registered an output of only 25W.

Could that be? The loudest volume I could stand in my 10' by 35' by 11' (at its highest point) listening room was being created by only 25W? I decided to push the Ref 75 further. I put on "Walking on Sacred Ground," from Chad Kassem's remastering of Janis Ian's Breaking Silence (CD, Morgan Creek/Analogue Productions CAPP 027). (Time for reissues of this one, Chad, on LP and CD.) I turned it up louder than I could stand it. My ears started hurting and I ran out of the room. From two rooms away, I called my audiophile friend Dudley Smalls and told him I couldn't believe how loud the amp was playing. Dudley noted that the music sounded pretty clean and undistorted over the phone. He said he wondered how much power the amp was using. Holding my hands over my ears, I ran back into the room to check how far into clipping the meters were registering on the peaks—their scale far exceeds the Ref 75's claimed output of 75Wpc. "45W," they said.

Comparisons
I compared the Reference 75 with my Reference 110 ($9995 when last offered), which has the stock 6550C output tubes. (Although all current ARC power amplifiers are fitted with KT120 tubes, the company offers Ref 110 owners the choice of retubing with 6550Cs. Not all of ARC's 6550C-based power amps will accept KT120s, however.) I could easily hear microdynamic inflections through the Ref 110, which also had the same delicate midrange as the Ref 75. However, the 110 conveyed less inner detail and decay. Transients were also somewhat less articulate, with a slight bit of sibilant smear.

The Ref 75's bass definition was fairly close to the Ref 110's, but bass attacks were more articulate and bass pitches more easily followed through the 75. The Ref 75 also had a much wider dynamic range, with more subtle gradations of dynamics, as well as more "jump factor." And despite the fact that the KT120 has the reputation of being a more neutrally balanced tube than the 6550, the 110 had a slightly more forward sound than the Ref 75 with high-level passages.

It would have been interesting to do a three-way comparison—my Reference 110 with KT120 and 6550C tubes vs the Reference 75 with KT120s—to see how close the sounds of the 110 and 75 might come when driven by the same output tubes. However, as the 6550Cs in my Ref 110 aren't anywhere near the end of their useful life, I was reluctant to buy eight new KT120s just to satisfy my curiosity.

Conclusions
The Reference 75 touched me on a deeply personal level. I enjoyed listening to music so much through it that every time I entered the listening room and saw its silvery hulk beckoning to me, I turned it on and played some music. More than with any other component I've reviewed, when the Ref 75 was in my system, I went out of my way to make sure, every chance I could, that music was playing.

I expect the Reference 75 will create some marketing problems for Audio Research. It has no flaws, and several strengths that exceed the performance of any amplifier I've heard in my home. And if it's true that amplifiers with a single pair of push-pull output tubes have a certain "magic" that can be lost when multiple pairs of tubes are ganged to create great power output, then I wonder how the sound of some of the higher-powered ARC amps will stand up to the Ref 75. And while the speakers I used with the Ref 75 were fairly efficient, I did play them at very loud levels in a very large room, and not once did I tax the amp's power-delivery capabilities. I would suspect that unless someone has very insensitive loudspeakers and/or a very large room, it would be difficult to make a case for why anyone would need an amplifier with more power than the Reference 75.

I wrote what was to have been this review's final paragraph some time ago:

"John Atkinson has said that there is no greater praise a reviewer can give a component than to purchase it for use in his own reference system. And although I loved my time with the Reference 75, and felt it equaled or exceeded the performance of my Reference 110 overall, I still love my Ref 110. With the decline of the financial-services industry in the recent meltdown, I'm earning a fraction of what I did 10 years ago, even as I have one child beginning college this year and another not far behind. I can't justify the luxury of purchasing a new stereo amplifier this year."

The hell with it. I'm buying the Audio Research Reference 75.


<from What H-iFi>

Audio Research Reference 75 review

A fabulous power amplifier capable of sonic magic Tested at £8495

By What Hi-Fi? February 28, 2013

OUR VERDICT

A fabulous power amplifier capable of sonic magic

FOR

  • A beautifully transparent and inviting performance
  • Lovely dynamics and excellent detail resolution
  • Easy bias adjustment

AGAINST

  • Care is needed in system matching to get the best performance

The Audio Research Reference 75 is the baby power amplifier of the company's top range and is intended for those who want top-quality sound but don’t need any extra power. (Those that do need the oomph can have the likes of the range-topping Reference 750 monoblocs, which output a spicy 750W and sell for an equally spicy rather hefty £27,500 each.)

Those prices shouldn’t come as a surprise for those that know the company: Audio Research is one of the most revered brands in high-end amplification. Along with the likes of Krell and Mark Levinson it helped establish the prestige market, and to this day remains a go-to brand for top quality valve amplifiers.

Audio Research Reference 75 review: Design

As is usual for Audio Research products, build quality is best described as solid and functional rather than luxurious; the Reference 75 is designed as a tool to do a specific job rather than doubling as an objet d’art. It feels like it will last for years, though, so we won’t complain too much.

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Maybe it’s the inner nerd in us, but we can’t help but like the twin VU meters on the front panel. They have two uses.

Firstly, they show instantaneous power output, and it’s surprising just how low this can be: we rarely saw these meters register much above 5W per channel even at high volume levels. We suspect this is because they can’t react to transients (where the amplifier delivers lots of power for a very short periods) quickly enough.

Secondly, they indicate valve bias current. It’s a neat arrangement that makes routine maintenance easy.

Audio Research Reference 75 review: Controls and components

Valves, like transistors, usually need a certain amount of current – bias current – flowing through them to work. (This is what makes electronics warm even when they’re not actively in use.)

As valves are used, their electrical characteristics change gradually, and these changes mean that their bias current requirement changes, too. It therefore needs to be adjusted to gain maximum performance.

In a conventional valve amplifier this needs to be checked regularly – every few months if it gets heavy use. This is usually done by getting inside the amp and being handy with a multimeter but, understandably, many people aren’t comfortable with doing this. So either they don’t do it, in which case the amplifier’s performance suffers, or they have to get the dealer to do the job.

Audio Research has come up with a neat solution: twist the appropriate control knob and that front panel meter shows the bias current. There are useful markings showing where the current should be set, and the pair of small holes drilled either side of the knob give access to the adjustment screws. The company even provides a dedicated screwdriver to make the job easy. Not just a pretty fascia, then.

Round the back of the Reference 75, though, things are more conventional: you’ll find a single pair of balanced XLR inputs and a set of traditional screw-down speaker terminals, which are ideal for spade or bare wire connections.

At the heart of this amp beat a quartet of KT120 valves. They’re of a type that the company has only recently started using, and should work well for around 2000 hours. Unlike with transistor units, keeping valve amps continuously powered for ultimate performance isn’t a good or cheap (as far as electricity consumption is concerned) idea.

Even a look at the power supply shows the care Audio Research takes over its designs. As expected, the company uses high quality smoothing capacitors, a hefty transformer and careful circuit board layout to get the optimal performance.

Audio Research Reference 75 review: Performance

Spending almost £8500 on a 75W-per-channel unit doesn’t seem like great value, but use the amp as intended with conventional speaker loads and rooms that don’t qualify as palatial, and it positively sparkles.

We tried a range of partnering equipment, including alternate preamps such as Burmester’s lovely 808 and a range of speakers, from KEF’s LS50 to our reference ATC SCM 50s, without issue.

Certain valve-amplifier stereotypes ring true here. The Reference 75 is wonderfully fluid in the midrange, sounding totally free of hardness and as refined as they come. The treble in particular is a stunning mix of insight, power and smoothness; the way dynamics are delivered is incredibly graceful and subtle. But that’s not all.

Listen to The Dark Knight Rises soundtrack and the Audio Research uncovers a mass of fine detail. It sounds truly three dimensional, painting sounds with care and stability that little else we’ve heard can match.

In our opinion, most power amplifiers at double this price would have difficulty bettering the Reference 75’s transparency.

Accepting the relatively limited amount of power available, this power amp’s composure when pushed hard is pleasing, as is its refusal to sound harsh or aggressive, even when provoked by poor recordings. There’s no denying that it will reveal all the flaws – but likewise, it never overstates them.

The Reference 75’s broad spread of talents means that it sounds comfortable with pretty much all types of music, too. True, this is no muscle-bound powerhouse, so if you want to pump out the likes of Kanye West’s Power at party levels and feel the bass wobble your insides, there are alternatives that do it better.

But, even on music like this, the Audio Research’s spellbinding resolution and dynamic finesse work wonders.

Audio Research Reference 75 review: Verdict

The Audio Research Reference 75 really does deserve to be considered a landmark product of its type. Consider us wowed, and very tempted.

<from Audio Research>

The Reference 75 is a stunning amplifier in every way – performance, styling and reliability combined to elevate your music listening to a new experience. Capable of controlling a wide variety of speakers, the Reference 75 will transport you into the musical performance unlike any other comparable amplifier. At the heart of the Reference 75 is decades of proven Audio Research vacuum tube technology, a legacy unrivaled by any other manufacturer of tube electronics. Developed through hundreds of hours of critical listening, the carefully selected components comprising the Reference 75 combine to provide an amplifier which transcends traditional hi-fi, instead relaying music with realism and tangibility.
Visually, the Reference 75 hearkens back to past Audio Research products, taking inspiration from earlier amplifer designs. With its two large VU meters, which display power output as well as provide bias adjustments, the Reference 75 has a timeless appearance resembling precision laboratory equipment and an overbuilt, industrious aesthetic. Offered in both natural aluminum and black finishes, the understated look will complement any system.

The KT120 vacuum tube delivers power from the amplifier to your speakers. Newly designed solely for the audio industry, the KT120 offers higher power handling and current delivery. A matched pair of tubes per channel run conservatively, ensuring stable operation and many hours of trouble-free listening. Custom designed capacitors couple the output of the tubes to the speakers for the purest signal possible.

The Reference 75 is the new generation from a lineage of amplifiers only Audio Research could produce. Experience real music and unleash the capacity of your system – music in High Definition®.


POWER OUTPUT

75 watts per channel continuous from20Hz to 20kHz. 1kHz total harmonic distortion typically 0.6% at 75 watts, below 0.05% at 1 watt. Approximate actual power available at ‘clipping’ 76 watts (1kHz). (Note that actual power output is dependent upon both line voltage and ‘condition’ i. e.: if power line has high distortion, maximum power will be affected adversely, although from a listening standpoint this is not very critical.)

POWER BANDWIDTH

(-3dB points) 7Hz to 60kHz.

FREQUENCY RESPONSE

(-3dB points at 1 watt) 0.7Hz to 75 kHz.

INPUT SENSITIVITY

1.4V RMS BAL for rated output. (25 dB Bal gain into 8 ohms.)

INPUT IMPEDANCE

300K ohms Balanced.

OUTPUT POLARITY

Non-inverting. Balanced input pin 2+ (IEC-268).

OUTPUT TAPS

8 ohms, 4 ohms.

OUTPUT REGULATION

Approximately 1.0dB 8 ohm load to open circuit (Damping factor approximately 8).

OVERALL NEGATIVE FEEDBACK

15dB.

SLEW RATE

10 volts/microsecond.

RISE TIME

4.0 microseconds.

HUM & NOISE

Less than 0.06mV RMS – 112dB below rated output (IHF weighted, input shorted).

POWER SUPPLY ENERGY STORAGE

Approximately 520 joules.

POWER REQUIREMENTS

105-125VAC 60Hz (210-250VAC 50Hz) 410 watts at rated output, 500 watts maximum, 230 watts idle.

TUBES REQUIRED

2 – Matched pair KT120 – Power Output; 2 – 6H30 Driver.

DIMENSIONS

19″ (48.3 cm) W x 8.75″ (22.2 cm) H x 19.5″ (49.5 cm) D. Handles extend 1.5″ (3.8 cm) forward.

WEIGHT

47 lbs. (21.3 kg) Net; 63 lbs. (28.6 kg) Shipping.


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