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- Written by Erich Wetzel Erich Wetzel
- Category: Full-Length Equipment Reviews Full-Length Equipment Reviews
- Created: 15 August 2017 15 August 2017
Note: Measurements can be found through this link.
Audio Research Corporation (ARC) and its reputation for high-quality audio equipment are well known to audiophiles. The company was founded in 1970 in Minneapolis, Minnesota, by William Z. Johnson, who had a plan to forward the state of the art of music reproduction. ARC was sold in 2008 to Fine Sounds SpA (since renamed the McIntosh Group), which owns other well-known audio brands, including McIntosh Laboratory, Sonus Faber, and Wadia.
But ARC still designs and manufactures its products at the company’s home in Plymouth, Minnesota. Outsourced components such as power transformers are mainly built by American suppliers, while circuit boards, made to ARC’s specifications by a nearby supplier, are still populated with electronic parts hand-soldered by ARC staff.
One of the newest products to emerge from Plymouth is the VT80, the sole stereo power amplifier in ARC’s new Foundation series, which also includes the PH9 phono preamplifier, DAC9 digital-to-analog converter, and LS28 line-stage preamplifier, each priced at $7500 USD. The Foundation VT80 costs $8000.
The Foundation VT80 has a large footprint of 19”W x 19.4”D, though at 10.3”H with supplied tube cage or 8.6”H without, it’s not particularly tall. In the context of the solid-state amps I’ve reviewed recently, the VT80 is a middleweight at 45.7 pounds.
Visually, the ARC VT80 is attractive. The thick faceplate of my sample had a finely styled natural aluminum finish that ARC calls Silver (it’s also available in Black), with subtle references to classic ARC design. The front panel has rounded corners, and a thin groove that runs around its perimeter. Half of the faceplate’s surface area is occupied by a glossy black display that roughly matches the proportions of the entire panel, as well as the area circumscribed by a groove in the face of my reference power amp, ARC’s D300. Centered at the bottom of the display is a thumb-tip-size power button, and above that is a green power-indicator LED. There are also rack-mount handles, long an ARC tradition. The thick side panels of extruded ten-gauge aluminum are emblazoned with the ARC logo, and bend smoothly into the top and bottom plates.
Sticking up from the front of the top panel are two small 6H30 input tubes surrounded by ventilation holes. Almost halfway back are two matched pairs of large KT120 output tubes, and at the rear hulk three black transformers. The mains power enters through the larger central transformer, and the amplified signal exits through the two smaller transformers, each placed directly over its associated speaker binding posts. For most markets, and to receive CE approval for the European Union, a color-matched cage is provided to cover the tubes and transformers, though in my opinion this detracts from the VT80’s visual appeal. The cage adds $500 to the final cost in the markets where it’s required, but here in the US we have no such requirement, and get to see the VT80 in all its beautiful, industrial glory.
At the far left and right of the rear panel are balanced (XLR) and single-ended (RCA) inputs for the right and left channels, and below them two sets each of three multiway binding posts for ground and for 4 and 8 ohms. Centered on the rear panel is an IEC inlet for the heaviest-duty stock power cord I’ve ever seen. There’s a mains-power fuse, an RS-232 connector, a 12V trigger port, and a toggle for switching between balanced and single-ended operation. Particularly useful will be the resettable Hours counter, to keep track of tube life, and the toggle for Auto Shut Off/Defeat. With Auto Shut Off engaged, the VT80 turns itself off after about two hours of detecting no input signal. With this feature Defeated, the VT80 shuts down only when the front-panel Power button is pressed.
ARC claims that the VT80’s transformer-coupled output generates up to 75Wpc into a 4- or 8-ohm speaker load. They specify the amp’s hum and noise as -112dBV with no signal and the input shorted, and its total harmonic distortion (THD) at 1kHz at about 1% at 75W output, and 0.05% at 1W. Compared to ARC’s more expensive Reference amps, the VT80’s THD is slightly higher at full output, and identical or slightly higher at 1W.
ARC says that the VT80’s circuitry is derived from and shares many parts, such as the power and output transformers, with the Reference 75. However, the VT80 also includes two features never before used in an ARC amp. First, a new auto-biasing circuit eliminates any need for the user to adjust the bias of a newly inserted power tube. According to ARC, that is done automatically, in real time, without affecting the sound. They also state that the VT80 can use 6550, KT88, KT90, KT120, or KT150 output tubes, but it’s no surprise that they suggest that the best results will be obtained only with matched sets bought from ARC. These tubes are tested and matched at ARC’s factory and burned in for 48 hours before being sent to the customer.
All tubes supplied with my review samples were made in Russia: 6H30 input tubes from Sovtek, and KT120 output tubes from Tung-Sol. ARC estimates that the input tubes will last 4000 hours, the output tubes 2000 hours. Either way, that’s a lot of listening with little maintenance. A complete set of six replacement tubes costs $600 from ARC, including new tube dampers; a single KT120 tube runs $100.
Each output tube has its own fuse, which can be easily and cheaply replaced if a fault occurs or a tube fails, rather than the amplifier destroying some of its resistors, or causing other damage that requires it to be sent back to ARC for repair. Replacement fuses were included with the review sample. The Foundation VT80 is designed for tube aficionados who don’t obsess over maintenance.
Extracting the Foundation VT80 from its high-quality shipping carton was easy, and setting it up required only a bit more time than a solid-state amp would have. ARC preinstalls rubber dampers on the input tubes to reduce vibration-induced ringing, and each tube is labeled for a specific socket, making installation simple: Match the labels, match each tube’s pins with the holes in its socket, and press down. Repeat five times.
My sources were iTunes and Tidal’s streaming service, both running on my Apple iMac computer, which sent data to my Benchmark Media Systems DAC2 HGC digital-to-analog converter via a Nordost Blue Heaven LS USB link. Dynamique Audio Shadow balanced interconnects sent analog signals from the DAC to my Hegel P20 preamplifier, and from there to the VT80.
Connecting the VT80 to my KEF R900 speakers with Transparent Audio MusicWave Ultra cables required a bit more thought and a bit of testing. As mentioned, the VT80 has three binding posts per speaker: the post labeled “0 ohm” is used for the “-” cable connection, and the two “+” posts are labeled “4 ohm” and “8 ohm.” KEF specifies the R900 as having a nominal impedance of 8 ohms. However, in looking at a graph of the R900’s frequency vs. impedance, I estimated that the speaker’s average impedance over the entire audioband is closer to 6 ohms. At first I went with KEF’s spec, and connected the “+” lead to the VT80’s 8-ohm post. Then, taking the recommendation of SoundStage! founder Doug Schneider, I listened to the 4-ohm post as well. After comparing them, I stuck with the 4-ohm post, through which I heard subtly more detail over the 8-ohm post.
The VT80 ran warm enough that I could feel the heat rising from the exposed output tubes as I stood over the amp to set up my iMac (it’s at head level) for listening. The amp burns through 230W at idle, and up to a maximum of 500W when making music. It warmed the place a bit, but probably isn’t quite up to the task of heating your listening room in winter. In their thorough owner’s manual, ARC says that no burn-in is needed -- the VT80 should work optimally right out of the box. I did a little preliminary comparison of the balanced and single-ended inputs, but heard nothing that inspired me to prefer one over the other. I wound up using the VT80 in balanced mode only because my other components are hooked up that way.
Before unmuting my preamp, I listened for the Foundation VT80’s noise floor. I’d anticipated a lot of noise from the output tubes, and was surprised to hear how quiet the VT80 was. A bit of “wind” emanated from the Uni-Q coaxial tweeter-midrange array of each of my KEF R900s, but even that I could hear only when I put an ear within a couple inches of the drivers. Impressive.
My first reaction to hearing music through the VT80 was how clear and musical everything sounded. Throughout the audioband, instruments and voices sounded essentially unfettered by the amplifier, indicating a high level of transparency. I tried Borodin’s Polovtsian Dances, with Neeme Järvi conducting the Gothenburg Symphony Orchestra (16-bit/44.1kHz AIFF, Deutsche Grammophon). Over the course of its 11 minutes, this 1991 recording of this work for full orchestra and chorus, often playing and singing fortissimo, places huge demands on an amp -- but I could easily hear that each passage, whether instrumental or vocal or both, comprised individual players and singers spread broadly between the speakers and layered from front to back. The quiet voice of the male soloist, bass Torgny Spolsen, was three-dimensional and dead-center in front of the chorus, while percussion accents subtle and not so subtle, high strings, horns, and woodwinds were all clear, appearing in their usual positions in standard orchestral seating: respectively, at the rear, left, right, and center. The VT80 reproduced this dynamic, complicated performance and recording with ease. The re-creation of the acoustic of the recording venue, the 1300-seat Gothenburg Concert Hall, was well defined and articulated, without the obvious ether of warmth or softening sometimes produced by tubes.
My secondary reaction was that the VT80 did not have a stereotypically “warm” tube sound. And that midrange “tube bloom” that can make some recordings sound cloyingly sweet? I couldn’t hear it, and as a result enjoyed this amp that much more -- I prefer neutrality over coloration. In the Borodin, the upper-register instruments and singers never sounded shrill or piercing; rather, each instrument or voice was just an immersive image of itself. Neither did the low end become sloppy or in my face; it was just right, with a proper amount of slam from the deep percussion. The VT80 didn’t try to adjust my heart rhythm with excessive or too-sharp bass, nor did it overstimulate my lively room with floor-vibrating power. If you need those qualities, this is not the amp for you. What it did do was provide a level platform for all performances and recordings, from top to bottom of the audioband.
Another of my favorite reference recordings is Rush’s Grace Under Pressure (16/44.1 AIFF, Mercury). Through the VT80, “Red Sector A” retained its driving pace, and kept pressing forward with no loss of urgency. The percussion had all the punch, speed, and complexity of Neil Peart’s virtuosic cadences, transmitted with no hint of blurring. The guitars were presented without bloating the sound of the bass guitar or thickening the midrange of the lead. The splash cymbal, higher keyboard notes, and the higher registers of Geddy Lee’s voice remained musical and clean.
As I write this, U2 is once again traipsing across America -- so I cued up “Running to Stand Still,” from the new 30th-anniversary edition of their The Joshua Tree (16/44.1 FLAC, Island/Tidal). Say what you will about Bono and his public persona (many find him pretentious and annoying) -- I find much of his singing on this album to be terrific. His voice was highly tangible through the VT80, suspended in air at center stage with great presence. His slightly pained singing exuded embodied passion without being artificially enhanced by the ARC amp, which reproduced his sibilants smoothly and with no emphatic hiss.
Female voices were reproduced exceptionally well. Amy Winehouse’s thick but slightly scratchy singing in the title track of her Back to Black (16/44.1 FLAC, Island/Tidal) had wonderful clarity, without sounding too sharp or too fat. This recording has a slightly hard edge that the VT80 conveyed clearly, without exaggeration. I hadn’t expected such neutrality from tubes, but the VT80 had it in spades.
My reference amplifier is Audio Research’s D300, a model from the mid-1990s that serves as a good point of comparison for the Foundation VT80. Each is a moderately powerful example of its type: the tubed VT80, producing 75Wpc into 8 or 4 ohms, vs. the solid-state D300, putting out 160Wpc into 8 ohms. Each is or was priced at the lower end of ARC’s range, the VT80 listing for $8000 today, the D300 for $3995 in the 1990s. Both amps are essentially maintenance-free: the VT80’s auto-biasing circuitry for its tubes renders it plug-and-play, while the D300 has been utterly reliable since I bought it new in 1995. It was the differences that made this comparison exciting: a state-of-the-art tube amp vs. a solid-state amp from the same tube-centric manufacturer, and new vs. classically aged.
The VT80 and D300 are solidly built and pleasant to look at. However, the VT80 in Silver won the beauty contest with its areas of contrasting silver and black and its exposed tubes; only Darth Vader could find the basic squareness of the all-black D300 truly pretty. The D300 is slightly easier to use, if only because there’s nothing to install or replace, ever. But the VT80 makes an outstanding statement in being a modern tubed amplifier that is, essentially, maintenance-free.
My comparison of the two ARCs’ sounds quickly devolved into nitpicking. Immediately, the D300 came across as sounding not harsh, but brighter in the highs -- high-pitched guitars, sibilants, and cymbals all sounded a bit more forward and drew more attention to themselves. Through the D300, the voices of Amy Winehouse and Bono lost some of the beautiful three-dimensionality they had through the VT80, and sounded rawer in detail and flattened in emotional range. When I tried to approximate the volume level of a rock concert, the D300 had greater deep-bass presence that I could feel through its stronger characterization of bass guitar, and the bigger-sounding drums and bass pedals in the Rush recording -- no doubt because of its much higher power output. In normal use, however, both ARC amps allowed for solid bass reinforcement while retaining the clarity of the recording. The two ARCs’ soundstages were equally wide, but the VT80s’ were deeper, especially with voices. These amps are not purely analytic devices, but neither veered far from what was contained in the recordings I played -- the descriptor neutral applied to both. However, outside the issue of power output, there was no question that the Foundation VT80 demonstrated audible improvements over my 22-year-old D300.
In the Foundation VT80, Audio Research Corporation has come up with a beautiful-looking amplifier with excellent fit and finish that is as hassle-free a tube amp as you’re likely to find. Standing behind it are ARC’s three-year warranty, nearly 50 years of experience, and a tradition of quality.
I appreciated the VT80’s clear, musical sound throughout the time it was in my system. It reproduced voices beautifully, without excessive tube bloom, and supported them with firm bass, while the treble end of the audioband was extended and clear, with no etch or hardness. The VT80 played everything I asked it to with ease, finesse, and a lack of coloration. In sum, ARC’s new, essentially maintenance-free power amp deserves attention from all audiophiles, and by those who only love tubes -- it’s definitely changed some of my ideas about tube amps.
. . . Erich Wetzel
- Loudspeakers -- KEF R900
- Preamplifier -- Hegel Music Systems P20
- Amplifier -- Audio Research D300
- Source -- Apple iMac running Mac OS 10.11.6, iTunes, Tidal music-streaming service
- Digital-to-analog converter -- Benchmark Media Systems DAC2 HGC
- Speaker cables -- Transparent Audio MusicWave Ultra
- Analog interconnects -- Dynamique Audio Shadow XLR, Transparent Audio MusicLink Super RCA
- USB link -- Nordost Blue Heaven LS
Audio Research Foundation VT80 Stereo Amplifier
Price: $8000 USD.
Warranty: Three years parts and labor; 90 days, tubes.
Audio Research Corporation
3900 Annapolis Lane N.
Plymouth, MN 55447-5447
Phone: (763) 577-9700