RE VIE W

An Excellent Mix of Old and New

By Jeff Dorgay

The Audio Research SP-17

TONE A

uring my last discussion with Dave Gordon from Audio Research about the SP-17 that he was sending us for review, he asked me if I would like the version with the
phono section. As I had been spending a
lot of time with my vintage ARC SP-9 preamplifier (featured in the Old School section this issue), I was very excited about Audio Research returning to the good old days when a top-notch phono stage was included with a preamplifier. For those who are new to the Audio Research lineup, their preamps all used to have the SP (stereo preamplifier) designation, and there were a few legendary preamplifiers that bore that title. As LP playback started to fade into the distance and digital became more popular in the late 80s, ARC moved to the LS (line stage) designation for most of its preamplifiers. Its great to see a new SP model.
With the analog revival showing no signs of slowing down, having it all on one chassis is an excellent idea for a number of reasons. You are assured of maximum phonostage-to-line-stage compatibility, and now that interconnects and power cords have become major considerations in system building, having it all under the hood can save considerable expense; a second power cord and set of interconnects are no longer required. With low-level phono signals, it can only help signal integrity by keeping the signal path as short as possible. Last but not least, a combined preamplifier uses less rack space. A Quick Visual Tour My sample came in black anodized finish with green LEDs and the standard ARC rack handles. You dont really need the handles to move the SP-17 since as it only weighs about 20 pounds, but they look great. Although the front panel has the current ARC motif that is devoid of control knobs, featuring an LED readout to let you know the status of the inputs and volume levels, you can still see the lineage to ARC products past. Thoughtfully, all functions can be controlled by the six push buttons on the front panel and do not require the remote to operate. The standard silver ARC finish is also available. (continued)
Removing the top cover reveals a very clean layout with premium parts inside.
This is a somewhat entry-level preamplifier, priced at $3,495 with phono stage and $2,995 without, so there are no balanced inputs or outputs on the rear panel of the SP17 it is a single-ended design. The SP-17 is a hybrid preamplifier, utilizing FETs in the first stage as well as the phono preamp along with a pair of 6H30 tubes in the output stage. Removing the top cover reveals a very clean layout with premium parts inside. There are four high-level inputs, a processor pass-through along with two sets of variable outputs and a fixed record output. Those still using a tape deck or performing digital capture will appreciate this extra feature. The SP17 also features a 12-volt trigger output, should you have a power amplifier that can take advantage of this. Setup You should be able to play music in about five minutes. Remove the two tubes from their boxes, install them in their sockets and fasten the cover back in place. The phono stage has a fixed impedance of 47k and a gain of 47db, so it can be used with some of the more modest output cartridges such as the Grado and SoundSmith moving-iron models. (continued)
I did just that, using the SP-17 with the SoundSmith Voice cartridge, which has an output of.9mv but requires an input loading of 47k. Just like my PH3SE, you can physically change the loading resistors for the phono input of the SP17 and, you should have no problem adjusting the input loading accordingly to take advantage of MC cartridges with an output in the.6 -.9mv range if your system has enough overall gain, making this a very versatile preamplifier indeed.
This is truly a full-function preamplifier in the best sense of the word.
Spinning a Lot of Records The comparison between the PH3SE and the onboard phono stage was enlightening. When new, the PH3SE was a $3,000 phono stage, considered excellent by many. While the stand-alone PH3SE had more dynamics and slightly more refinement overall, the onboard phono stage of the SP-17 held its own and was more enjoyable than the add-on phono stages that Ive heard on many current preamplifiers, including a few fairly expensive preamplifiers. This is truly a full-function preamplifier in the best sense of the word, and for many users buying turntable/cartridge combinations in the $500$5,000 range, it is an excellent anchor on which to build your system. Thanks to the FET input stage, the SP-17 was very quiet, yet it had that touch of body that comes from a pair of tubes being in the circuit. The 6H30 definitely has a more-powerful, punchy sound than the 12AX7 or 6DJ8 tubes, so I suggest an audition to make sure this preamplifier is right. Where my vintage SP-9 has a more classic tube sound, the SP-17 is more modern, with more weight, more high-end extension and a lower noise floor than it all-vacuum-tube predecessor. While listening to Ali Farka Toures Niafunke, I found his plucky guitar style just hanging in midair, while the drums kept a solid line that was well separated from the vocal tracks. (continued)

A hundred hours were put on the SP17 before I settled down for critical listening in a system that consisted of the Harbeth 40.1 signatures and the Moscode 402au power amplifier. The Rega P9/ RB1000 combination along with the SoundSmith Voice cartridge proved to be a fantastic match for the SP-17, as did the Sumiko Blackbird that was mounted to my Technics SL-1200, which has a full complement of Sound HiFi mods. I just happened to have an ARC PH3SE phono preamplifier on hand, so it made for an excellent comparison between this and the onboard phono stage. The cables used were Furutech Reference III RCAs along with Furutechs reference speaker cable. The whole system was plugged into my Running Springs Jaco power conditioner on a dedicated 20A line after listening to the preamplifier plugged directly into the wall with the stock power cord per ARCs instruction manual.

P r o d u c t

R e v i e w
Audio Research VS115 Stereo Amplier
by Vade Forrester vade@soundstage.com November 2008
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 companys 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 customer support! I have used several Audio Research products over the years: an SP9 Mk III preamp, a D90B amplier, 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 sounded great. The VS115 reviewed here is one of the latest stereo ampliers 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 longfavored 6550Cs, specically 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 amplier 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 gure 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 rst turn on the amplier as the capacitors charge, but it goes away after about 30 seconds.

Review Summary Sound

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.

Features

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, specically 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 amplier 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 cant match. 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

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P r o d u c t R e v i e w

greatest values. With a measured sensitivity of 83dB/W/m, they need some real power to drive them. 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 preamp. Audio Research recommends 600 hours (!) burn-in for all of its gear, but Dave Gordon, the companys 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 rst, 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.

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 ow. There is a brushedaluminum 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 modication. 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 Researchs 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 amplier 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 amplier 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 briey borrowed a pair of the amazing Usher Be-718 minimonitors, which we reviewed in October 2007 and which I regard as one of audios
If you look at my reference equipment, youll see that I concentrate on low-power ampliers 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 ampliers. 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
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, specied 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 terric 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 ampliers, including the Art Audio PX-25 and a prototype solid-state amplier 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 afnity.

CD Automobiles and Roadhouses (Stocksch SFR 357.6027.2) opens with a strong gure from the bass guitar, and the VS115 reproduced it with the greatest power Ive heard from my speakers. 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 (Nave E8909) was pure magic. Voices spread across the soundstage naturally and were quite precisely located. The soundeld 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 amplier I can recall hearing in my system. Its one of those things you dont know exists until you hear it. My reference ampliers 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- 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 rolledoff, 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 amplier. Through the Be-718s 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 signicant contribution.

Comparison

When I reviewed the Atma-Sphere S-30 Mk III amplier ($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 ampliers 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 amplier; 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 ampliers, although the images werent portrayed in identical fashion. With the
You can buy less expensive ampliers than the VS115 and, I assume, better ampliers as well. After all, Audio Research offers its Reference ampliers 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 amplier Ive heard.Vade Forrester vade@soundstage.com
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 cant 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 terric amplier, and youd be right. But the real strength of the VS115 is that it doesnt fall into a single audiophile category. More than any amplier 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 owed from start to nish, 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 ampliers that dont do that.
Audio Research VS115 Stereo Amplier 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 Website: www.audioresearch.com

Company Info

ASSOCIATED EQUIPMENT
Loudspeakers Power Ampliers Preamplier Analog Digital Sources Interconnects Speaker Cables Power Cords Accessories
MaxxHorn Lumination, Opera Audio Consonance M12. Atma-Sphere S-30 Mk III stereo amp, Art Audio PX 25 stereo amp. Audio Research LS26. Linn LP12 turntable, Graham 2.2 tonearm, van den Hul Frog cartridge, Audio Research PH5 phono stage. Meridian 508.24 CD player, Oppo DV-970HD universal player. Purist Audio Design Venustas, DNM/Reson TSC, TG Audio High Purity Revised, Blue Marble Audio Blue IC, Clarity Cables Organic. Purist Audio Design Venustas, Blue Marble Audio speaker cables, Clarity Cables Passion. Purist Audio Design Venustas, Blue Marble Audio Lightning, Clarity Cables Vortex. Walker Audio Talisman LP/CD treatment, VPI HW-16.5 record cleaner.
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