Audio Research VS115 Stereo Amplifier
by Vade Forrester
||"Agile and tuneful,
even bouncy.... Its graceful, non-stressful presentation drew me into the musical experience
and make me want to stay put in my listening chair." "Bass with the VS115 had
tangible weight and power, so that the bottom octaves provided a strong foundation for the
musical structure," "but the VS115s true strength lay in the all-important
midrange." "It wasnt so much that the VS115 revealed previously unheard detail
in familiar recordings, but rather that it presented the detail as more clearly integrated
into the whole performance so that it made more sense."
||"The $6495 USD
VS115 uses the hybrid circuit currently favored by Audio Research for its non-Reference
equipment: JFET inputs followed by Sovtek 6H30 tube drivers. Output tubes are Audio
Researchs long-favored 6550Cs, specifically Winged C-brand tubes from Russia. There are
eight of them to be exact, or four matched pairs."
||"Also on the rear
panel is a series of contacts for measuring the bias setting of each pair of tubes. When you
replace tubes, which must be done in matched pairs, you can use a digital volt/ohm meter to
set the bias correctly. That sure beats opening up the amplifier and measuring the bias across
the tube pins, exposing yourself to lethal voltages."
||"The S-30 Mk III,
at roughly $3000 less than the VS115, certainly holds its own, but the Audio Research amp has
sonic capabilities that the Atma-Sphere amp can't match."
Audio Research occupies a unique position in
high-end audio -- they helped invent it. When most other manufacturers were rushing to
produce equipment with transistors, then the current fad, Audio Research moved in the
other direction and developed equipment with vacuum tubes. Fortunately, anyone who
actually listened to products (as opposed to just measuring them) like the tubed SP3
preamp could easily verify that there was a lot of life left in tubes. And Audio Research
can still repair any product made during the company's over 30 years of existence.
Sometimes, if parts are no longer available for older products, Audio Research will
develop upgrade packages to replace failing parts with new, modern counterparts. So if
your venerable SP3 is showing its age, you can have it upgraded with better parts,
improving its performance and extending its life for quite a while longer. Talk about
I have used several Audio Research products over
the years: an SP9 Mk III preamp, a D90B amplifier, and, currently, a PH5 phono stage and
an LS26 line stage. None of them ever broke down or made any untoward noise, and they all
The VS115 reviewed here is one of the latest
stereo amplifiers in Audio Researchs product line, replacing the VS110. The $6495
USD VS115 uses the hybrid circuit currently favored by Audio Research for its
non-Reference equipment: JFET inputs followed by Sovtek 6H30 tube drivers. Output tubes
are Audio Researchs long-favored 6550Cs, specifically Winged C-brand tubes from
Russia. There are eight of them to be exact, or four matched pairs.
The VS115 is rated at 120Wpc into 4 or 8 ohms.
The amplifier needs to see 1.6 volts into either its balanced or unbalanced inputs to
produce its rated power output. Input impedance is 150k ohms unbalanced, or 300k ohms
balanced. Neither figure should pose any problem for a decently designed preamp, although
the sensitivity may be low for passive preamps. The amp does not invert polarity. Noise is
extremely low: 0.2 millivolt, or 104dB below rated power. Theres a slight hum when
you first turn on the amplifier as the capacitors charge, but it goes away after about 30
The VS115 measures 17 1/2" wide by 8"
high by 19" deep and weighs in at 62 pounds. Connectors in the rear extend almost
another inch. Unless you have a huge equipment rack, plan on using a separate amp stand.
Audio Research amps have traditionally been designed with a full-height front panel and a
chassis that encloses the circuit boards, tubes and transformers, but the VS115 has a
layout that lets you see the full tube complement. Its a more traditional
tubes-in-front-and-transformers-in-back layout, and I like it. If I pay for tubes, I
doggone well want to see them! Ventilation holes between the left- and right-channel banks
of output tubes promote cooling air flow. There is a brushed-aluminum panel on top of the
chassis through which the tubes protrude. The panel reaches from the front edge back to
the transformers. This open design may expose the tubes to curious pets and children, but
it also makes replacement easy when the tubes expire.
The on/off switch is up front and squarely in the
middle of black chassis, exactly where it belongs. A soft green LED above it tells you if
the amplifier is turned on. In the rear, there are both balanced XLR and unbalanced RCA
jacks at the outer edges of the chassis. Just inside the input jacks on both sides are the
speaker terminals, with connections for 4- and 8-ohm speakers. A 20-amp IEC connector is
in the center of the back panel. It differs from the standard 15-amp connector, so your
power cords may not work without modification. Fortunately, Audio Research provides a
really hefty-looking power cord, so theres no need to rush out and buy an
after-market cord. "The 20A cord we use simply sounds better than the 15A
version" was Audio Research's reasoning here.
Twelve-volt jacks let you turn the amp on and off
remotely (as if youd want to do that). Also on the rear panel is a series of
contacts for measuring the bias setting of each pair of tubes. When you replace tubes,
which must be done in matched pairs, you can use a digital volt/ohm meter to set the bias
correctly. That sure beats opening up the amplifier and measuring the bias across the tube
pins, exposing yourself to lethal voltages. On top of the chassis behind the three
transformers is a series of capacitors used in the power supply. Choosing to use several
small capacitors instead of a few large ones, Audio Research again focuses on the sound:
"We use them because we have found that large quantities of small caps usually sound
better than small quantities of large caps."
In spite of using eight output tubes, the VS115
doesnt run especially hot. That suggests the tubes are run conservatively and should
last a long time. Although 6550C tubes arent excessively expensive (a quick scan of
several online vendors showed prices for current production-tubes between $65 and $70 for
a matched pair), you need a total of eight, so the total cost would be $260 to $280. The
6H30 tubes cost about $30-$35 each on the open market. Of course, Audio Research keeps
large stocks of all the tubes it uses, and burns them in and tests them before shipping
them to customers, so there shouldnt be any unpleasant surprises if you get your
tubes from Audio Research.
Setting up the VS115
Because I had to return the aptly named Audio
Elegance amplifier stand after its review, I placed the VS115 on a slab of butcher block
that was designed to be used as a tabletop. The VS115 produces a respectable output, so it
can drive a wide range of speakers. I mostly used my Opera Audio M12 speakers for the
review, because they will handle up to 250 watts, but their 97dB sensitivity didnt
stress the VS115 much at all. I briefly borrowed a pair of the amazing Usher Be-718
minimonitors, which we reviewed in October 2007 and which I regard as one of audios
greatest values. With a measured sensitivity of 83dB/W/m, they need some real power to
The preamp was Audio Researchs LS26, which
is the logical partner to the VS115 in Audio Researchs product line. If you
dont want to spend the bucks for Audio Researchs top-of-the-line
Reference-series gear, the LS26 and VS115 are one step down and $7500 cheaper than the
Reference 3 and Reference 110. Unsurprisingly, they complemented each others sound
very well. I doubt youd hear the full capabilities of the VS115 through another
Audio Research recommends 600 hours (!) burn-in
for all of its gear, but Dave Gordon, the company's head of North American sales,
suggested that the VS115 would sound close to its best after 200 hours, so thats
when I began listening critically. However, the amp actually sounded quite good right out
of the box, with only a little time on it for our measurements. Like any tube equipment,
it needed to warm up 20-30 minutes to stabilize, and it continued to improve sonically for
another 30 minutes or so.
After trying numerous combinations of cables, I
elected to use Audience Au24 e interconnects, and speaker cables. For the Usher Be-718
speakers, I needed a biwire speaker cable, so I borrowed a massive Blue Marble Audio
biwire speaker cable, which turned out to be a splendid match.
Interconnects were all balanced. I refuse to
argue about whether balanced or unbalanced interconnects sound best, but I tend to think
that components whose internal circuitry is fully balanced sound a bit better connected
balanced. I used the stock power cord for the review, but having an Audience powerChord e
with the requisite 20-amp connector, I couldnt resist trying it. This power cord
provided a different view of the VS115s performance. With the Opera speakers, the
powerChord es bass seemed almost too prominent (I can see the bass lovers among you
thinking Ive lost it), and I preferred the bass with the stock power cord, but with
my MaxxHorn Lumination speakers, the extra weight of the powerChord e was appreciated. The
sound with the powerChord e seemed less noisy than with the stock cord, so that the sound
emerged out of a blacker background. At first, I thought the high frequencies had been
attenuated, but when I listened to CDs with extended high-frequency content, the highs
were still there -- the high-frequency noise was gone. As a result, the
powerChord e produced more vivid tonality and additional clarity.
If you look at my reference equipment,
youll see that I concentrate on low-power amplifiers and high-sensitivity speakers.
I wondered, therefore, if the VS115, with its substantial power output, would sound a bit
slow and lugubrious compared to the sound of my reference amplifiers. Ha! -- not even
close. It proved agile and tuneful, even bouncy. Some (not all) solid-state gear has a bit
of an edge and a harmonic structure that sounds slightly threadbare. The VS115, like all
Audio Research equipment Ive heard, is the antithesis of that. Its graceful,
non-stressful presentation drew me into the musical experience and made me want to stay
put in my listening chair.
Also in common with the current Audio Research
gear Ive heard, bass with the VS115 had tangible weight and power, so that the
bottom octaves provided a strong foundation for the musical structure. Chris Joness
"God Moves on the Water" from his CD Automobiles and Roadhouses
(Stockfisch SFR 357.6027.2) opens with a strong figure from the bass guitar, and the VS115
reproduced it with the greatest power Ive heard from my speakers.
Loudspeakers MaxxHorn Lumination,
Opera Audio Consonance M12.
Power amplifiers Atma-Sphere
S-30 Mk III stereo amp, Art Audio PX 25 stereo amp.
Preamplifier Audio Research LS26.
Digital Meridian 508.24 CD player,
Oppo DV-970HD universal player.
Analog Linn LP12 turntable, Graham
2.2 tonearm, van den Hul Frog cartridge, Audio Research PH5 phono stage.
Interconnects Purist Audio Design
Venustas, DNM/Reson TSC, TG Audio High Purity Revised, Blue Marble Audio Blue IC, Clarity
Speaker cables Purist Audio Design
Venustas, Blue Marble Audio speaker cables, Clarity Cables Passion.
Power cords Purist Audio Design
Venustas, Blue Marble Audio Lightning, Clarity Cables Vortex.
Accessories Walker Audio
Talisman LP/CD treatment, VPI HW-16.5 record cleaner.
At the other end of the audio spectrum, the
treble was extended but totally smooth and free from peakiness. The high chimes that open
Jennifer Warnes "The Panther" on the CD The Well (Cisco SCD 2034)
tinkled forth with as much detail as Ive heard them, but they werent at all
peaky. But the VS115s true strength lay in the all-important midrange. The vocal
group A Sei Vocis sound on Allegris "Miserere" on the eponymously
titled CD (Na´ve E8909) was pure magic. Voices spread across the soundstage naturally and
were quite precisely located. The soundfield of the recording venue -- a church -- was
expansive, revealing the room to be moderately large and rather reverberant.
The VS115 didnt favor one part of the note,
such as the opening transient; rather, it portrayed the entire note -- from opening
transient to the sustained harmonic structure to the decay -- as well as Ive ever
heard it done. That means its rendering of a musical event -- i.e., a song -- was
more realistic than with any amplifier I can recall hearing in my system. Its one of
those things you dont know exists until you hear it. My reference amplifiers are all
decent-sounding, well-respected models, but the VS115 just sounded more realistic.
Some amplifiers deliver startling dynamics by
driving huge transient pulses into the room. While that may be exciting as a hi-fi
occurrence, sometimes those dynamic pulses dont really sound much like a live
musical event. The VS115 treated dynamics a bit differently. Although capable of fast
transients when the music called for them, it presented dynamics in a musically natural
fashion. I heard not only initial transients but also plenty of vocal and instrumental
detail throughout a musical climax. It wasnt so much that the VS115 revealed
previously unheard detail in familiar recordings, but rather that it presented the detail
as more clearly integrated into the whole performance so that it made more sense. The
VS115 didnt prettify the sonic picture, didnt make the sound
"musical," which is audiophile-speak for rolled-off, muddy sonics that mask
annoying parts of an inferior systems sound. Poor-quality recordings sounded poor,
but average or good recordings sounded uncannily real, which made them more fun to hear.
Driving the insensitive Usher Be-718 speakers
showed a different side of the VS115: its ability to deliver raw power. These speakers
need some serious juice to give their best sonic performance, and with the VS115 it was
readily available. In my largish listening room (23' wide by 20' deep by 12' high), the
Be-718s and VS115 produced tons of undistorted volume and a surprising amount of bass that
went far deeper and with more impact and weight than Id expect out of a
stand-mounted speaker with a 7" woofer and a tube amplifier. Through the Be-718's
beryllium-dome tweeter, the VS115 produced high frequencies that were oh, so smooth but
replete with musical detail. Tonal accuracy was particularly noteworthy; instruments
sounded unusually correct and vocals were easy to understand. Musical detail seemed to
come together at the right time and in a realistic soundstage. I suspected that the
Audience Au24 e cables, which focus on getting that aspect of sound right, made a
The MaxxHorn Lumination speakers are completely
different -- very sensitive (a claimed 103dB/W/m) horn-loaded speakers I reviewed a few
months ago and subsequently purchased. Because of their low power-handling capability,
specified at only 15 watts RMS, I was apprehensive about using them with the VS115. But
after the US distributor for the Feastrex drivers used in the Luminations told me the
speakers will handle quite a bit more power than their rating suggests, I had to give amp
and speakers a try. The result? Possibly the most gorgeous reproduced sound Ive ever
heard. The ability of the VS115 to reproduce a coherent, organized musical picture proved
a terrific complement to the MaxxHorns temporal coherence. Together, they produced
some of the most real-sounding reproduced music Ive experienced, and not in a
sterile, analytical fashion. Listening to "Miserere" was incredibly moving;
although I had meant to sample only a part of the piece, I literally could not bring
myself to move until the last note faded into silence, and then I sat there dumbfounded
that recorded music could sound so beautiful. Jennifer Warnes voice sounded as
realistic as Ive ever heard it on "The Panther." Ive heard this
recording zillions of times, but never has it portrayed such a real-sounding voice in a
real space. And so it went with recording after recording.
Because the VS115 had produced powerful, tight
bass through the Opera and Usher speakers, I expected it to do the same with the
MaxxHorns. Although the sound was fast and detailed, it was also a bit lean, as though the
VS115 was overcontrolling the speaker. Ive heard several amplifiers, including the
Art Audio PX-25 and a prototype solid-state amplifier from David Belles, that produced
much weightier bass from the MaxxHorns, so I know it can be done. But aside from this one
cavil, the VS115 and the MaxxHorns were divine together. I should note that with the
MaxxHorn Luminations, I switched cabling throughout the system to Clarity Cables, for
which the MaxxHorns have shown a strong affinity.
When I reviewed the Atma-Sphere S-30 Mk III
amplifier ($3750) back in March 2007, it was designated a Reviewers Choice, which
was literally true because I purchased the review unit. Although it produces
"only" 30Wpc, thats more than enough power to drive the sensitive Opera
speakers far louder than Im interested in listening to them. Like the VS115, the
S-30 Mk III uses a fully balanced circuit, so I could eliminate a second variable in the
comparison by using the same interconnects. But the Atma-Sphere amplifiers circuit
is radically different from the VS115s, using 6AS7G triode tubes or equivalents in
the class-A output section, and even more different, an output stage thats directly
coupled to the speakers -- no output transformer. Thats quite unusual for a tube
amplifier; eliminating the bandwidth-limiting output transformer should produce more
transient detail and deeper bass. Thats the theory, anyhow.
In reality, bass was perhaps just a tad deeper,
although with less weight than with the VS115. The Atma-Sphere amp had fast leading-edge
transients, but the VS115 was not just fast. It controlled the musical event that followed
the initial transient so that the overall sound -- from the initial transient, to the
harmonic structure, to the decay of the notes -- was reproduced with unusual accuracy.
Soundstaging was excellent with both amplifiers, although the images weren't portrayed in
identical fashion. With the Atma-Sphere amp playing "Miserere," the performers
were spread more widely across the soundstage, so the room where they were recorded seemed
a little larger. These differences werent huge, but they were perceptible.
I greatly admire both of these amps. The S-30 Mk
III, at roughly $3000 less than the VS115, certainly holds its own, but the Audio Research
amp has sonic capabilities that the Atma-Sphere amp can't match.
Saving the best for last
Ive broken down the performance of the
VS115 into categories that are hopefully familiar to audiophiles. And in each of these
categories, the VS115 was simply splendid. If the review stopped here, youd probably
think the VS115 is one terrific amplifier, and youd be right. But the real strength
of the VS115 is that it doesnt fall into a single audiophile category. More than any
amplifier in my experience, the VS115 combines everything -- bass, treble, and
midrange prowess; soundstaging; dynamic agility; and transient speed -- to present a
musical big picture. The VS115 presented a holistic sonic presentation. Its lucid,
uninterrupted lines flowed from start to finish, clearly portraying the complete musical
structure. Music seemed better organized or, rather, the organization and structure of the
music seemed easier to understand. A song was not just a collection of notes or audiophile
events. This sort of thing happens so effortlessly when you listen to live music that you
dont even think about it, but when an audio component does it, its quite
special. Linn used to characterize the sound of its turntables as "playing the
tune" rather than just playing notes. The VS115 takes this a step further -- it plays
the song. Ive heard many more expensive amplifiers that dont do that.
You can buy less expensive amplifiers than the
VS115 and, I assume, better amplifiers as well. After all, Audio Research offers its
Reference amplifiers at prices starting at $9995 and going up -- way up. Other
manufacturers offer comparable units. Because I havent had the opportunity to hear
any of those amps in my system, I cant comment on their sound. But until I hear
something better, the Audio Research VS115 has the distinction of being the best amplifier
|Audio Research VS115 Stereo Amplifier
Price: $6495 USD.
Warranty: Three years parts and labor.
Audio Research Corporation
3900 Annapolis Lane North
Plymouth, Minnesota 55447
Phone: (763) 577-9700
Fax: (763) 577-0323