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NAT Signature
Tubed PreAmp and MonoBlocks

... and it glows in the dark, too!

Finally some tubes I really like

Product: Signature Preamp, Signiture SE2 Tubed Mono Power Amps
Manufacturer: NAT - Yugoslavia
Price: Preamp $1,950, power amps $5,000 per pair, packed and ready to ship
Reviewer: Dejan V. Veselinovic
Reviewed: July, 2001

[Italian version]

[Signature PreAmp]
Signature tubed preamp

Over the years, I have somehow acquired a reputation of a tube hater. I must now deny that completely. I went into a lot of trouble to test this system, which included traveling on a Sunday to Smederevo, a city about 50 km away from Belgrade, where I live, along one not very good road.
The simple truth is that I don't like working with tubes and indeed much prefer transistors, but soundwise, as James Bongiorno put it, I really don't care how it's made, as long as it sounds good.

Anyway, I was over to audition what promised to be a very interesting system, at a very serious price. To be on the safe side, I brought along my reworked Yamaha CDX-993 CD player with my Van den Hul D102 Mk.3/Neutrik cables/plugs. But I should not have feared, as our host has a room set up especially for listening in his own house.

I was also greeted with the core of the design team, headed by Mr Dejan Nikic and his closest associate Petar, they being the heart and soul of NAT. NAT is an acronym for "Nikic Audio Team", and they are from Kragujevac, about 120 km south of Belgrade, home of the Yugo cars, some amazing firearms and hand crafted hunting double barrel shotguns, works of art in many ways (though I intensely dislike guns in general). I much prefer stunning local cheese.

Our purpose was to audition a system which Mr Nikic considers to be one of his best. In out case, it consisted of ...
Jeez, all tubes!

... their latest offering, the Signature preamp, a pair of all-tube monoblocks, delivering 100W into 8 and 4 Ohms, backed by their own power conditioner. All this was connected to a pair of Meadow Lark Blue Heron speakers (app. $6,500 worth of speakers, those), complete with their gas piezo tweeter, a patented technology.

[Inside the Pre]
Batteries ARE included

How the Signature looks you can see from the pictures. It's full of batteries and weighs 35/50 kilos net/packed (app. 80/115 lbs), the significant difference in net/gross weight being due to the fact that packing in this case means nicely finished hardwood cases, with handles. Similar packing is applied to the power amps, each weighing in at 40/54 kilos net/gross (app. 92/124 lbs).
So, your system shipping weight comes in at about 158 kilos (app. 363 lbs), meaning your sheer shipping costs will be, er, substantial. If say Scott Faller in St Louis, Missouri, USA wanted to buy them, he'd have to have about $1,100 for shipping costs alone. But if Lucio in Italy went for it, he'd pay only about $720.

The Signature uses batteries for its power supply. The arrangement works like this - actual power fed to the tubes is from the batteries, but there are two toroidal transformers making sure the batteries are always tip-top full and ready to deliver. This arrangement is reflected in the substantially increased signal to noise ratio; with standard outfits, it's typically in the 82-90 dB range (THD + noise), whereas here it's no less than -96 dB A weighted.
The overall gain is 20 dB (10:1), THD level is 0.1% or less, separation at 1 kHz is better than 95 dB, and the response is claimed to extend from 2 to 220,000 Hz at -3 dB points. There is no overall negative feedback, and there are absolutely no interstage buffers - no capacitors, no transformers, no nothing. It uses 12 PCC88 tubes. Its output impedance is a low 100 Ohms value, low enough to drive just about anything to nirvana.

The SE2 power amps use PCC88, 6SN7, 6AS7 tubes one each and two VT-4-C output tubes (per monoblock). These are from the so-called old-new stock, meaning they are original tubes produced for the US army way back before most of us were born, and cost a hell of lot of money to buy ($180-200 per tube I'm told is the usual price).
These amps deliver 100W RMS into 8 or 4 Ohms, have a response of 2-120,000 Hz, input impedance of 100 kiloohms, and a S/N ratio of -85 dB A weighted. Like the preamp, all stages are internally direct coupled, with no capacitors and no transformers, in an all triode configuration using just 8 dB (2.5:1) of negative feedback. All transformers are 100% hand wound in what Mr Nikic says is a proprietary technology.

[Signature MonoBlock]
A bit closer look


Being benevolent in general, I didn't start out trying to discover the system's weaknesses, but rather its strengths. But my nature being what it is, I couldn't help listening to the bass lines in general first, simply because my usual problem with tubes are in my view lacking bass lines. I readily agree speakers are also a very important factor here. However, for a change, I need not have worried, this system did bass just fine.

Anyway, listening to some acoustic material, such as the Weavers ("Reunion in Carnegie Hall"), human voices, male and female, came across supremely naturally, with no trace of grain or strain. Full Carnegie Hall sonic were recreated most convincingly, also due to Doug Sax's masterful rerecording work (all on tube equipment from master tapes). The number "Wimoweh" is, I believe, the best audition I ever had, so you won't be surprised to hear I had it played three times in 4 hours.

The Shadows' "Apache" sounded cool (as in downright good) and relaxed, yet lost none of the controlled energy Hank sometimes puts in his guitar. Paul Simon sounded right there in his calm and quite number "So Long, Frank Lloyd Wright", and very emotional in his "The Only Living Boy In New York".

Mark Knopfler was also with us with his "Private Investigations", it seemed like you could just about touch the band, very much present, almost tangible.


In my view, tubes usually sound better at low than at high levels. Somehow, they never manage the punch and dynamics of good solid state, though they usually beat solid state on ambience and natural decay. This is, of course, in general terms only, and exceptions exist in both camps.

The Signature/SE2 combo did unusually well here, where "unusual" refers to absolute terms. They demonstrated the ambience and sound stage depth of the best of tubes, with a considerable slam not often found with tubes, but not unusual with good solid state.
I am sorely tempted to compare the NAT combo with Audio Research, my own reference point for tube technology; the overall experience is not dissimilar, but is not quite the same either. I would say Audio Research has slightly better imaging (possibly only different), but NAT has slightly better dynamics, subjectively appearing to be a bit faster.

Reproducing material by Hevia, which is extremely busy stuff, with many people pitching in at the same time, with much bass and much treble all going on at the same time, is no easy stuff for any audio gear. It usually trips up lesser components of any type, but the best manage to produce a believable piece of music. NAT was one such combo, and Jose Angel Hevia's music was a joy to listen to. "Busindere reel" and "Tanzilla" will have you tapping your feet in no time, guaranteed. And both have rather fast and heavy bass lines, which if missed, will leave the rest sounding clinical and bland.

Blue Man Group's "Rods And Cones", my favorite track, sounded very impressive, clean and clear, with perhaps just the nth lack of slam, but remember that I am now comparing tubes with some great solid state (most of which would also trip up here, I need to add). What is probably a very good bass capability test is their track 14, "Endless Column", where somebody slams a 2.5 meter (9 foot) drum - given good acoustics and power, this can rattle your window panes quite easily. I feel the NAT was let down here somewhat by the speakers, which I think have a tendency to soften things up, not much but just enough to loose that nth bit of energy and drive. Possibly the Goertz speaker cables also did their part. Not a question of absolute quality, rather a question of good matching - I think this was a mismatch.

Enigma did very well too, with most of the slam and punch there, but with more ambience than usual, even if I know it's electronically synthesized ambience. But playing The Notting Hillbillies' "Missing ..." CD, notable tracks 1 (Railroad Worksong) and 7 (Will You Miss Me) showed that natural instruments were reproduced with exceptional clarity, and voices were among the very best I have ever had the pleasure of hearing.


This NAT combo is, I feel the need to say this, very expensive. I'm not sure using old/new tubes is the reason for this, or is even worth the price, but then, who cares if it sounds good? And "good" is not the word, here we are dealing with some of the best electronics I have had the pleasure of meeting up with.

The overall sound still reminds me of Acoustic Research, and that in itself is a compliment in my book, because I believe they make the best tube gear around (subjective, of course, and not intended to belittle other outstanding products from companies like Conrad-Johnson, VTA, Graaf, etc). But I find most tube products have a tendency to soften the sound, round it off as it were, which while very pleasant to listen to, is getting away from the truth, and truth is what I'm interested in. And this seems to be NAT's greatest strength - they also seem to be hell bent on getting to the truth, not painting a pretty picture to impress you.

In my view, they have gone a long, very long way towards that elusive goal. I'm not sure anybody quite got there yet, but I know for a fact very few are even near, and I'm pleased to say NAT are among those very near. They skillfully combine the virtues of tubes with some impressive dynamics and speed much more common to the best of solid state gear, yet do so without any obvious vices, price excluded.

So, to sum up: what we have here is gear built like a tank, but looking much prettier, sounding like the voice of God on occasion (recordings permitting) and just angels on other occasions, with no vices, not even that of typical tube low power. I mean, 100W is very nice power, trust me on this, and your choice of speakers is hardly limited. Speaking of which, I believe that the Blue Heron speakers would do much better with solid state than tube gear - they seem very current hungry to me, but I could be wrong about this. My point is that I cannot shake free of the feeling that the speakers and/or cables were the limiting factor here, I have a distinct feeling that NAT gear was capable of yet more.

I am now tempted to compare it with my Karan KA-i180, but will decline to do so for several reasons, the most important of which is that I did not have them side by side, for a clean A/B comparison. What I can say is that KA-i180 is better in terms of sheer power, dynamics and slam, hardly surprising given that those are typical solid state virtues. Also, the speakers and speaker cables were very different here, which all by itself excludes direct comparison.

Overall, to use my car analogy, I'd say that KA-i180 would be a Ferrari, fast and powerful, for the young at heart, while this NAT combo is much more along the lines of a Rolls-Royce or Mercedes-Benz 600 series. It does not even try to act as something it is not, but does what it is supposed to with supreme finesse and style. Just as a Rolls-Royce would look like a cripple next to a Ferrari, so for comfort, style and bourgeois luxury Rolls is impossible to beat - especially by a Ferrari. Yet both are great cars in their own right.

So, if for you the name of the game is seeking the truth, and doing so in great style and luxury, do consider the NAT combo, that's what they had in mind while designing and building these units. The price is high, to be sure, but this is their least expensive tier for preamps, and will stand comparison with the very best of them, vacuum tube or solid state. I admit to being very impressed by how far down the road they've gone towards the absolute truth - live sounds by living musicians - something I don't often hear, tube or solid state. Truly top world class equipment.

Post Scriptum

June 17 was a nice, hot summer day, outside temperature 35 degrees centigrade. Inside would have been the same, but for the fact that this was tube gear, running in pure class A, so the inside temperature was such that going out to 35 degrees was a refreshment. Now tell me audio reviewing is fun, fun, fun all the way.

© Copyright 2001 Dejan Veselinovic - http://www.tnt-audio.com

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