Nice black and silver NAT Audio Symmetrical Preamp . Beautiful condidtion. This preamplifier is world class and the all tube design brings the music alive. You will be awestruck! This is the later version which sounds much better than the earlier version.
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NAT Audio introduces a tube balanced preamplifier called "Symmetrical". This new line stage is a dual mono topology with zero feedback all triode vacuum tube design.
There are twelve(12) tubes that works perfect symmetry, which is six(6) per each channel.
Design allows that the preamplifier may work perfectly in both balanced (xlr) and single ended (rca).
Also, the volume control network is executed with 28 highly reliable relays.
The "Symmetrical" will drive any known power amplifier no matter what type or internal impedance (compatible with input impedance of 600ohms). It also means that the interconnect length between pre and power amplifier may be of very long if desired.
Remote control is standard, and is made from a solid block of aluminum.s
Frequency Response 0.07 Hz to 300 kHz – 3 dB ; 20 Hz to 20 kHz ± 0.01 dB
Noise 47k ohms single ended: & 94k ohms balanced
Stereo Separation > 100 dB 1 kHz
Tube Complement 2 X OA 2, 2 X 6X4W, 6 X 6N1P-EV & 2 X 6N2P-EV
FROM STEREOPHILE REVIEW:
NAT Symmetrical line preamplifier
By Robert J. Reina • Posted: Aug 26, 2010
Sometimes, a product review in Stereophile can breed additional reviews. Shortly after I reviewed the Audio Valve Conductor line stage in the July 2009 issue (Vol.32 No.7), I was contacted by NAT's US distributor, Musical Sounds: "Hey, if you liked the Audio Valve Conductor [$13,995], you'll love the NAT Symmetrical line stage. Would you like to review it?" Aside from Michael Fremer's review of the battery-powered NAT Signature Phono stage in the July 2007 issue, I was unfamiliar with this Serbian maker of tube electronics. But "Sure," I replied; "why not?"
Dejan Nikic has designed tube electronics for NAT Audio since 1993. Their current product line consists of three tubed preamplifiers, a tubed phono stage, five tubed monoblock power amplifiers, a hybrid integrated amp, and three power cords. The visually striking Magma, a single-ended, class-A monoblock, uses a single TH450 tube and costs $45,000/pair. NAT claims that this amplifier, at 160W, is currently the most powerful single-ended amplifier ever made to use a single tube in its output stage. At $8000, the Symmetrical line stage is not the most expensive preamp in NAT's product line; that honor belongs to the dual-chassis Utopia line stage ($9000).
The Symmetrical's dual-mono, fully balanced circuit includes 12 tubes (6 per channel) operating in pure class-A triode configuration with zero loop feedback. The signal path for each channel has a 6N30P-DR and a 6N1P-VI tube, uses a 6X4WA tube as a power-supply rectifier, and an OA2 as a power-supply plasma-effect stabilizer. All tubes are military-spec new old stock (NOS) and are available from NAT and other tube retailers. The Symmetrical also includes custom-made toroidal transformers, as well as high-capacitance, audiophile-grade capacitors in the signal path and polypropylene capacitors in the high-voltage power supply. Nikic explained to me the Symmetrical has a sufficiently low output impedance to allow it to drive even a 600 ohm load, which he feels is unusual for a pure tube design. He also believes that the preamp's performance will not vary with either volume-control setting or under a wide range of power-supply voltages.
On the rear panel are five inputs, a tape monitor loop, and two outputs, with single-ended and balanced options for each input and output. All inputs and outputs have gold-plated, Teflon-insulated RCA jacks and gold-plated XLR (XLR) connectors. There's also a neat switch that gives you the option of grounding the line stage to its chassis, in case that results in less hum. In terms of tube noise and hum, I found the Symmetrical dead quiet throughout my listening sessions.
The Symmetrical's rugged-looking yet elegant faceplate of solid aluminum has two knobs: One controls the volume, and is also a pushbutton for the Mute function; the other is an input selector. Each knob is encircled by two rubber O-rings; handling the knobs, all I felt was the rubber—a cute feature. The knobs are flanked by two toggle switches, one for power, and one to switch between single-ended and balanced operation. The small remote control, of solid aluminum, sports only three large buttons: Volume Up and Down, and Mute (footnote 1). Two large heatsinks also serve as the sidepanels.
I used all single-ended input sources into the NAT, and a balanced output into my Audio Research Reference 110 amplifier. I found two aspects of the Symmetrical's operation to be somewhat unusual. Both the volume-control knob on the line stage and the buttons on the remote trigger a series of computer-controlled relays that set the volume level, which is displayed via a series of blue lights along the bottom of the faceplate. As changing the volume causes a series of relays to switch on and off, with no signal being passed during the relay switching process, there will be a few milliseconds of silence between each two steps of volume level. Thus there is a bit of stuttering chatter as the preamp cuts in and out while the volume is being changed, which I got used to rather quickly.
A more annoying feature was the Symmetrical's silent turn-on mode. When the preamp is turned on, it remains Muted while its tubes warm up. During this period the volume setting gradually decreases to zero from whatever the previous setting was; then the preamp comes out of Mute. Thus, every time you turn on the preamp, you need to chatter back up to find your original volume level. A much more convenient and elegant solution would have been to implement something like Audio Research uses in its VSi60 tube integrated amplifier (review to come): during warmup, the amplifier remains in Mute with the volume level constant; the user then needs to manually unMute it.
Listening to the NAT Symmetrical stimulated me to think about how much the state of the art of tubed preamps has advanced since I began listening to and comparing them nearly three decades ago. In the early 1980s, three manufacturers dominated the tube-preamp landscape: Audio Research, Conrad-Johnson, and the now-defunct Counterpoint. Each company's flagship products had a strong personality, a sonic signature that represented the designer's interpretation of tonal balance, soundstage reproduction, and rendering of transients. And each of these manufacturers had a cult following—only rarely would an AR guy consider buying a C-J product, and vice versa. I never joined any of those cults, however; I've owned multiple preamplifiers and amplifiers made by AR and C-J over the years, and at one point came close to buying a Counterpoint MC step-up preamp.
Today, as I reflect on my recent experiences in my reference system with Audio Valve's Eklipse and Conductor, Audio Research's Reference 3, and the NAT Symmetrical, as well as time spent at friends' houses and audio shows with C-J's Art 2 line stage, I realize how dramatically things have changed. I felt that each of these designs presented a chillingly realistic reproduction of the musical experience, with no meaningful flaws, and with strengths that far exceeded those of designs of a decade or more ago. I found that, as a reviewer, it was nearly impossible for me to rank these products, to the point that I've come to believe that an audiophile who likes one might well be satisfied with any of them (footnote 2). Which brings me to the task at hand: how to evaluate the NAT Symmetrical in the context of the current competition.
During my extensive listening to the Symmetrical, I heard no flaws whatsoever. Across the entire audioband and with every recording I played, I felt it was dead neutral, reproducing copious inner detail and ambience cues on a wide, deep soundstage, and transients and dynamic swings reminiscent of a live musical performance. But rather than end my review here, I'll concentrate on the three aspects of the Symmetrical's performance that far exceeded those of any other preamp I've had in my house.
First, the level of detail resolved by the NAT was such that I was able to analyze very familiar recordings in unprecedented depth. In "Man/Machine," from Minimum/Maximum (CD, EMI ASW 60611), each of Kraftwerk's four members uses a bank of synthesizers controlled by laptop computers and keyboards. With the Symmetrical I was able to individually follow each musician's synth part, noting his chosen waveforms, phasing, pitch, timbre, and rendering of transients and dynamic envelopes. I also heard each musician's contributions as coming from a distinct part of the soundstage. I had never noticed that with any other preamp I'd heard in my house, nor had I noticed it in the live performance of this tune that I heard at a concert in the tour during which this album was recorded.
When I listen to "Sins of My Father," from Tom Waits' Real Gone (CD, Anti- 86678-2), I usually like to analyze the phrasing of Marc Ribot's brilliant guitar solo. This time I focused on other things. With this spectacular recording, in which Waits' voice is given some intentional mild distortion to dirty its texture, I found myself analyzing the singer's phrasing. His pitch inflections, at times slightly off-key, and his phrasing, sometimes ahead of and at others slightly behind the beat, demonstrate a level of phrase control that suggested levels of individuality and skill comparable with Frank Sinatra's at his best. Then on to Ribot's guitar solo—but instead of analyzing the guitarist's phrasing, I focused on his sound. It was fairly easy for me to estimate which model of Fender amp Ribot was using, where his volume and tone controls were set, and how far the studio mike was from the amp's speaker.
On "Becuz," from Sonic Youth's Washing Machine (CD, Geffen DGCD-24825), guitarists Thurston Moore and Lee Ranaldo play Fender Jazzmaster guitars tuned in just intonation and played through similar distortion devices. During the ensemble instrumental passages, the two play using similar techniques in an attempt to sound like a single giant, shimmering, cacophonous guitar. Through the Symmetrical I was able to distinctly follow each player's part.
Normally when I listen to Charles Wuorinen's Ringing Changes for Percussion Ensemble (LP, Nonesuch H71263), an all-percussion work recorded during Nonesuch's golden age, I'm accustomed to hearing each instrument naturally reproduced on a wide, deep soundstage. Through the NAT, I noticed that each instrument was reproduced with a different attack envelope and decay curve that varied with the type of instrument, how and where it was struck, and how far the instrument was placed from the recording mikes.
The second thing about the Symmetrical that floored me was its rendering of low-level dynamic inflections. I've been impressed with other preamps that were able to render subtle dynamic inflections down to the ppp level in a way that was linear and organic (the latter an adjective I tend to overuse). Not only did the NAT resolve down to pppp, but with the best recordings, I could hear the linear change from pppp to ppp, from ppp to pp, and from pp to p, each shift in volume made with a sense of natural dynamic continuousness. I had never heard this effect in my system before; only in live performances, when I've been able to score the best orchestra seats at Carnegie Hall.
Listening to the recent remastering of the Beatles' Abbey Road (CD, Apple 382462 2), I focused on Ringo's drum work during the densely orchestrated chorus of "Something." Despite the complex mix of vocal harmonies, instruments, and orchestral backfill, I was able to follow every dynamic inflection of Ringo's clever snare and tom work, even though it was buried deep in the mix. And with Robert Silverman's reading of Beethoven's Piano Sonata 1, from his complete set of the sonatas (CD, OrpheumMasters KSP-830), I was able to analyze every movement of Silverman's stylized technique in a piece I have played many times in the past.
Jazz horn solos best illustrated the Symmetrical's subtle dynamic strengths. I cued up Jerome Harris's arrangement of Duke Ellington's "The Mooche," from Rendezvous (CD, Stereophile STPH013-2), and analyzed the solos of trombonist Arthur Baron and alto saxophonist Marty Ehrlich. Baron's solo was blatty, silky, and bloomy; at times, he and Ehrlich felt as if they were joining me in the room—I was worried about getting some spit on me (footnote 3).
The third aspect of the NAT that impressed me was its rendering of high-level dynamic slam. This was problematic for me—I found it difficult to compare several dozen recordings without constantly changing the volume setting, lest I incur the wrath of an annoyed wife or risk scaring small animals. I turned up Helmut Rilling's recording of Penderecki's Credo (CD, Hänssler 98.311) high enough that I could enjoy bass Thomas Quasthoff's solo in the first movement. Through the NAT, this meant that the loud choral and percussive crash of the climax preceding the solo came through at ffff, which startled my two sleeping shelties—who had just slept through Sonic Youth at 98dB—and made them jump. My wife gave me a look that read, "Tell me John Atkinson's wife puts up with this!" (footnote 4).
As for electronic dance music, I compared the aforementioned Kraftwerk tune with "Bad Romance," from Lady Gaga's The Fame Monster (CD, Streamline B001353-72). Although the Gaga track is very well recorded (as opposed to most of the sonically horrendous electronic stuff on Top 40 rock radio), it was noticeably compressed compared with the thundering Kraftwerk tune. Finally, the horn tuttis in "Bluesville," from Count Basie's 88 Basie Street (LP, Pablo/Acoustic Sounds 2310-901), punched me in the face.
The Symmetrical's capabilities in terms of high-level dynamic slam went hand in hand with its seemingly bottomless, fast, and uncolored reproduction of the bottom three octaves. I cranked up Attention Screen bassist Chris Jones' solo track, "Midnight Sun," recorded under the name Overcast Radio (45rpm single, Surface Tension STNSN002). The opening, rapid-fire bass-synth ostinato made me write "Slamming!!!" in my notes. On the more delicate side, I compared drummer Mark Flynn's technique on bass drum and Korean Puk drum on Attention Screen's Live at Merkin Hall (CD, Stereophile STPH018-2). The timbres and dynamic envelopes of the two instruments were clearly distinct. Finally, when bassist Peter Freeman forcefully enters in the opening passage of "Aurora," from Jon Hassell's Last Night the Moon Came Dropping Its Clothes in the Street (CD, ECM 2077), it woke the dogs again.
The NAT's clean, extended, undistorted high frequencies made me want to listen to well-recorded guitars. I equally enjoyed listening to Kevin Barry's Stratocaster on the title track of Mighty Sam McClain's Give It Up to Love (CD, JVC JVCXR-0012-2) and Taylor Swift's pristine and silky Taylor (don't you think she should marry a guitarist named Martin?) flattop acoustic on "White Horse," from Fearless (CD, Big Machine BMRATS0200). In addition to the NAT's flawless midrange reproduction of the aforementioned jazz horns and piano, and its silky and forceful rendition of George Harrison's voice on "Something" caused me to draw parallels between Harrison's vocal and guitar phrasing.
I used several recordings to compare the NAT Symmetrical with my Audio Valve Eklipse (now $5700; see my review in August 2007), but spent much of my time with Attention Screen's Live at Merkin Hall. As both line stages were detailed, dynamic, and uncolored performers, I felt at times as if I were splitting hairs. However, there were several areas where the NAT's performance exceeded the Eklipse's, and none in which it fell short.
First, their sonic perspectives were a bit different—I felt the NAT presented the music as if from mid-hall, whereas the Audio Valve was a bit more forward, especially in the midrange. The stages reproduced transients equally well, although instruments were a touch more clearly defined through the NAT, with a bit more separation and sense of openness. Pianos sounded somewhat more clean, crisp, and rich through the Symmetrical, and with a touch more decay and air. It sounded as if the NAT's noise floor was lower; that is, although both preamps were dead quiet, it seemed that as notes decayed, the transition from mid-volume to the softest passage took longer with the NAT before the music dropped off into silence. The preamps' rich, silky, natural reproductions of voices were nearly identical. Finally, I felt that the Eklipse added a subtle electronic haze to the music that the Symmetrical did not.
Among today's expensive tube preamps, so many are so nearly flawless that it's difficult for a relative newcomer to come up with a creative and cost-competitive design that will cause audiophiles to take notice—but NAT Audio has done so with the remarkable Symmetrical. Anyone who can afford to spend $8000 on a new line stage should give this baby a listen. Every minute I spent playing music through this gem was a revealing and enjoyable experience. In the Symmetrical, NAT has a real winner.