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October 2006
Superior Audio Equipment Review

World Premier!
Art Audio Vivo Amplifier
An organic sound with palpable dimensionality and dimension. 
Review By Ron Nagle
Click here to e-mail reviewer.



  There is a saying; if it weren't for bad luck I would have no luck at all. Well I won't say things got that bad. Let us just say I don't normally hang my hat on a star. And so that's what makes this day so extraordinary. It was a gray and rainy day in New York City I had hopped the Lexington Avenue subway over to the Manhattan Design Center building. That day there was a meeting of the Audiophile Society in the Bösendorfer Showrooms. In the midst of their demo I sat oblivious to the shuffling noises around me and had my ears locked on the sound coming from a pair of their VC7 E speakers. They were using German manufactured solid-state (best not tell you the manufacturer) electronics to power the system. I don't know if you are familiar with these Bösendorfer transducers they certainly bend the bounds of traditional speaker topology. The design is a slim tower with a narrow front panel mounted on this are two, two way front firing tweeters. Then on both sides of this very deep enclosure are four bass/midrange drivers and "Sound Boards." The specification for the 130Hz crossover point was and I am quoting, "based on the performance of the Horn Resonator."

Art Audio Vivo AmplifierThe preceding VC7 E terminology was lifted from their website I leave it too you to unravel it. In spite of the fact that I heard these speakers before at T.H.E. Show in Las Vegas while sitting there, I still couldn't figure out exactly what they were trying to say. Was hearing two separate speaker arrays in the same enclosure pretty much ignoring each other. This was going on In spite of the fact that on three sides of this stereo set up were acoustic panels placed so as to yank the room out of the musical mix. Little did I know fate was about to intervene. Enter then stage right a shuffling sound, I turned and saw three men struggling in my direction two of them hefting heavy boxes.

Knew the reputation and name of Joe Fratus for that had preceded him. Now before me was the man with two assistants each one carrying a very impressive KT 90 monoblock amplifier. When finally they had replaced the German solid-state stuff there was an occurrence of an aural epiphany. Verily It was now as if music bloomed forthrightly out into the room filling in the holes in the sonic scenery. It turns out the Bösendorfer Vc7E speakers were apparently not a product of a mad German scientist after all. Certainly due credit must go to Joe and his team for this wonderful metamorphosis. It was as if an airy envelope of music lifted the stage up and enveloped the space where resided the speakers. All at once I felt lust, blatant lust there are no other words that will suffice. Simply wanted to get my hot little audiophile paws on these gleaming mirror finished amplifiers. I fantasized being alone with them in a darkened room illuminated only by glowing rows of KT 90's tubes. Visualized my fingers lightly caressing their warm silky smooth sides as they sang a sultry song. I mustered my composure and in a voice that sounded like a kid asking Joe DiMaggio for his autograph I inquired of Mr. Fratus, "what do you call these amplifiers?"

Turns out I was orgasimating over a $16,000 per pair of Opus Ten monoblocks. These comprise 5 parallel pairs per side of KT 90 tubes powering push/pull zero feedback amplifier each pumping out 150 watts. Joe DiMaggio oops! I mean Joe Fratus unfortunately informed me that the amps were a special order and as far as I was concerned they were made out of unobtainium. Seeing my eager face hit the floor I think he took pity on me and his next words resonated in my ear as if from the Jinn in Aladdin's lamp. He granted unto me a boon an amplifier first, a world exclusive, it was to be the premier review of the new Art Audio Vivo amplifier. In my most composed professional voice I agreed and I thanked him. (The unspoken phrase, Oh goody goody gumdrops circulated in my brain)


The Vivo Art
At the first Joe, I now called him Joe, found out I had just finished reviewing Tash Goka's 3M Aveena speakers for Enjoy the Music.com and he insisted that they would be a good match for this amplifier. Unfortunately I had to wait and jog in place for a time. Joe said he was whipping up an improved transformer design and the amp wouldn't be ready for another 6 or 8 weeks. You see he went on to explain the transformers were a proprietary design custom wound just for this amplifier. As a matter of fact as you will soon learn the transformers are integral to the unique sound of this device. After this upgrade was accomplished UPS delivered it to my humble abode.

This comprised two boxes the larger containing the amplifier and a separate box holding the tubes. Just after slicing open the boxes I almost dropped my cookies trying to lift this amp out of it's packing and into the space between my speakers. Weighing 75 pounds and measuring 22 wide by 17.5 inches deep this is the largest single chassis component I have ever had to evaluate. The transformer cover and chassis are made out of gray powder coated and anodized aircraft grade aluminum. The chassis base is wrapped with a gorgeous exotic wood frame made of south East Asian Macasser Ebony. In the exact front and center of the wood trim is a round rocker style A.C. power switch. At the back or business end of the Vivo is a nice quad of gold plated speaker binding posts. There is a toggle style gain switch on the back of the amplifier near each channel between the RCA and XLR input jacks. Normally these switches are in the no gain position, actuating the switches yields an additional 6dB of gain.

The owner's manual states that this may be needed if you are using a no gain passive preamplifier. The amplifier comes from the manufacturer with the output transformers wired for 4-Ohm speakers. On the rear of the output transformers cover are two small flat plates these may be removed to reconfigure the transformers via wire jumpers for 8-Ohm operation. There are two versions of the VIVO amplifier the $12,500 dollar edition uses the more standard 300B out put tubes and is rated at 25 Watts per channel. The one I requested was a $13,000 dollar Hi-current version capable of 40 Watts per side. This version uses the more rugged and exotic KR 300BXLS output tubes these will set you back $525 Dollars a matched pair. That's the price I found on the Art Audio web site. The tubes are hand made in the Czech Republic with an unusually thick glass envelope able to contain a higher internal vacuum and able to withstand higher plate voltages.


Carter's Ear Candy Recipe
Now for the fiddly bit's, that's a British phrase for the smaller details in this case it's the technical details. What follows is the designer Kevin Carter's thinking about how to build a superior audio amplifier. Mr. Carter is a former associate of VAC audio. This design wouldn't have looked out of place back in 1937. It is basically a class "A" push/pull amplifier avoiding signal path capacitors and featuring internal transformer coupling. The Vivo is a three-stage design that does not use negative feedback. The amplifier has a total of ten tubes including the four KR300BXLS output tubes. There are two each 6BX7GT, 6CJ3, 6SN7GT these are stereo pairs one at each stage of the left and right channels. The first and second stages are direct coupled. The first stage uses a 6SN7GT that is fed from a phase splitting transformer in a differential configuration this splits the signal into two opposite polarity signals centered on ground. The 6SN7GT is loaded with a center-tapped choke and is direct coupled to the second stage, which is a 6BX7GT differential. Of great interest to me is the fact that the 6BX7GT is a rugged old television tube that functioned as a horizontal amplifier (wait, don't throw out that old box of tubes) and has the ability to drive difficult loads. The 6BX7GT than feeds another interstage transformer that couples it to the grids of the 300Bs.

The differential 300B output stage is than coupled to the loudspeakers through yet another transformer. The sole purpose of this last transformer is the same for all audio output transformers. It is to match the hi-output impedance of the amplifier to the much lower impendence of the speakers. All of the audio signal path transformers are high tech amorphous core Lundahl transformers. The term amorphous core refers to a core metal that has no orderly crystalline structure. Ordinary transformer cores have a tendency to remain polarized in one direction, either plus or minus and they're for not as linear. The technical term for this electromagnetic characteristic is called hysteresis. The designer believes in the superiority of tube power supplies. He uses them in this Vivo amplifier to gently soft start the tubes and prolong the life of these expensive little bottles. The main hi voltage power supply is the aforementioned Choke Input design. A choke is yet another transformer used after the rectifier section its use is once again a more expensive way to smooth out the residual A.C. ripple in the D.C. supply. Regarding the implementation of either capacitors or transformers within audio devices both types of devices have inherent limitations. However properly implemented with compatible types of tubes Kevin Carter feels that a more costly interstage transformer design can surpasses capacitors and will better drag the real out of the word reality.


Aural Aspects
I placed the amplifier on the floor between my speakers I then straightened up and donned my white cotton gloves. Guided by the diagram in the owner's manual I proceeded to install the ten vacuum tubes. First off no one told me anything about any part of this amp that would require a break in, still just to be sure I ran FM radio through it for approximately five hours. At the end of that mini burn in the amplifier did undergo one very slight sonic change. The bass tightened, it was a slight improvement not dramatic but it was there. This anomaly was part of a larger problem I had experienced in the past and now my old nemesis surfaced again. Specifically, it was a bass mode centered around 60Hz it usually happened when listening to larger speakers. In the course of the next few day's I managed to eliminate most of this interaction with my room. Yes, I have acoustic panels boxes and pipes and yes I did play with them like pieces on a chessboard. But guess what? It turns out the main culprit was floor transmitted vibration fed back to the tubes internal elements.

The remedy was my Arcici Airhead; the Vivo amplifier now sits atop three small inner tubes housed inside the box that is the Airhead isolation platform. As president Nixon use to say "I would like to make this perfectly clear." The problem is not the amplifier; as a matter of fact this amplifier has deep bass extension equal to anything I have had in my reference system. If that were not so I would never have run into this problem in the first place. Over the course of the following few weeks I reached a conclusion about the amp and what I was hearing. Wait, wait even as I typed that last statement it seemed ever so slightly off the mark. The thing is what I really had was only a concept a kinda audio sonic Gestalt. Before laying a bunch of stereo style sonic similes on you in an effort to explain, let me tell you of my little experiment, as they should help to put my conclusions in a clearer context.

Last year I reviewed and than purchased a highly regarded PrimaLuna Prologue 2 amplifier. Even though the PLP 2 cost's only about one ninth as much as the Vivo the similarities between the two amplifiers were compelling. Both are class "A" push/ pull tube powered 40 watts per channel amplifiers with a choke input power supply. The major difference is that the PLP 2 is more conventionally built, it is ultralinear with interstage capacitors and it uses four more common KT88 pentode output tubes. This is what I use as a benchmark of a good modern it's happening now conventional tube amplifier. It has decent speed good extension average and adequate power nice tube voicing without getting mushy and a nice larger than usual sized sonic stage. I don't want to mix too much into this story it will only obscure my conclusions. But I would like to give an honorable mention to Mike Yee's PA 3 25 watt Mosfet power amp. The voicing was very nice doing what you would expect from solid state. It was clean fast and detailed with good imaging but it is after all an apple in a description of oranges. As I wrap this up let me reiterate my review rational. I'm not going to tell you what recordings I listened to. Why? After reading thousands of audio articles I have come to the conclusion that this makes little sense. You probably won't have the exact same recordings I do and likely you listen through a radically different audio system. Instead let me zero in and isolate what is unique, and characterize how this device is different from its peers?

Ah, music, A magic beyond all we do here!
J.K. Rowling, Harry and the sorcerers stone 1997.


The Final Cut
In a comparison of tube amps I must directly address the tube loving audiophiles out there. Their criteria is even now still quite different from the solid-state contingent. What I am trying to say is that this is a tube lover's amplifier and even in that rarefied slice of audiophilia there exists an even more defined audience. This is making no mistake, a tubed work of Art no pun intended. It does all of those things modern tubed amplifiers are renowned for but with a little something extra. Those luscious little lifelike even order harmonic hints that people love cause the performers to appear as flesh, and in the Vivo they are there in abundance.

But now this is where my job gets dicey it is me trying to convey a subtle difference between tubes and tubes. You must understand even in the world of tube aficionados there are even finer gradations of taste. On one hand there is the purist triode faction believing that older 2A3 and 300B types of tubes portray a more true to life sound. Then contrasting this is a more modern class of pentode beam power tubes like the 6L6, KT88 and the widely used 6550. The pentode families of tubes are valued for their speed and frequency extension.

The Vivo is a 300B tube amplifier retaining great resolving power and portraying a tangible Organic quality more so than other conventional capacitor coupled triode class "A" tube power amplifiers. Images portrayed by the Vivo have all of the classic triode tube flavors with a tiny added drop of caramel. I'm going to give this description thing another try. If you do a direct comparison between the sound of KT88 pentodes and 6550 pentodes as I did with the PrimaLuna Amp you will know the degree of subtlety I am tying to convey. The Vivo sound is an enhancement above all things you would expect even from a SET (single-ended triode) tube amplifier. The performers are even more palpable because the performers on the stage have added dimensionality they seem to exist in more than two dimensions. I'm tempted to say the images of individual elements are more rounded but that implies unrealistic bloated ill-defined sound. That is not the case at all. The bass is awesome deep tube bass; I like it even though it gave me a problem. Lest I was formally not clear let me reiterate, the stage is wide realistic and detailed. Bottom line I like it I want it but I can't afford it. If you can afford it go for it, it is expensive but this is a connoisseur's amplifier with a unique sound and I don't think there is another like it. Listen long and prosper.


Type: Vacuum tube stereo amplifier

Frequency Response: 20Hz to 20kHz

Power: 40 watts/channel for 300BXLS

Gain: 24dB switchable to 30dB for the 300BXLS version

Tube Compliment: four 300BXLS, two 6BX7GT, two, 6SN7GT, and two 6CJ3

Dimensions: 22.5 x 17.5 x 10 (WxDxH in inches)

Weight: 75 lbs.

Price: $12,500 with standard 300B output tubes
           $13,000 with high-current KR 300BXLS output tubes


Company Information
Art Audio
34 Briarwood Road
Cranston, Rhode Island 02920

Voice: (401) 826-8286
E-mail: vze572mh@verizon.net 
Website: www.artaudio.com













































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