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Sasa built his first complicated tube amplifier in 4th grade. Today and in his head, he's mostly finalized well past 10 designs - beyond the eight already released for Trafomatic Audio (the latest one being the push/pull Experience Elegance below). "While these designs are new for us to perhaps cause surprise as to how we could roll them out in such a short period, they're not new for me. I've had them in my head for many years. With my intense focus on transformer design and manufacture, I simply never before took the time to turn those ideas into actual products. By the way, the 22 windings in the double C-core output transformer of the Experience Reference with its 8 paralleled secondaries make it a very complex affair. As big as it is, I could use it for a full 300 watts in a push-pull circuit. But for single-ended use, it's appropriate only for 15. It had to be this big to lower the DC resistance to 0.0001 ohm. Even though Trafomatic specializes in toroidal transformers, I don't like toroids for single-ended output transformers. For that critical purpose, double C-cores with silicon steel sound best to me."

Mini detour alert. As a writer, I'm tuned into how my creative process works. It moves fully cooked concepts from up there to down here. Some call that intuition. I call it constant automatic uploads of impressions and experiences. The bio computer continuously processes ordinary life data which end up in the 'subconscious' or 'higher' mind. There they percolate, get sorted and organized without conscious volition. When the time is ripe, they download as seeds which contain everything necessary. I don't know what is in them until I type things out. Then polishing trims and grooms the final results but the essence and structure came ready-made. From elsewhere, whatever you chose to call that source. Once you acknowledge -- to remain with popular computer language -- that this 'upload sphere' of ideas is freeware and openly shared by whoever taps into it, notions of ownership and credit (this is 'my' idea, dammit) become quite silly.

Without any fancy explanations necessary and limited in the first place by his halting English, Sasa confirmed that he downloads just like it. He sees complex winding geometries directly and knows without a doubt how they will work before he turns them into actual transformers. To a certain extent, he can thus perform virtual prototyping in his head. As a non-technical person myself, I very much enjoyed this confirmation of how creativity operates irrespective of whether the final expression is artistic or technical. Naturally, that distinction is quite arbitrary too. It's often said that audio transformer winding is part science, part black magic. There, Sasa disagrees. "It's all science." But to my mind, it's also art. And art communicates with the transpersonal in direct but mysterious ways. Seeing complex transformer windings in one's mind's eye and what sonics effects they'll have certainly quite transcends slide rulers and computer simulations. But back on terra firma of nuts and bolts now.

"One Serbian customer of our Experience One was shocked that we put Made in Serbia on the back. When I asked him why, he said "that must make it very hard to sell"." Racism exists in hifi as it does everywhere. China used to suffer it badly. To a lesser extent, it still does. Now Serbia makes one mean Slivovitz plum brandy but I'm not sure how the country fares in public hifi perception. I do know that Aleksandar Radisavljevic of Raal Ribbons enjoys a brilliant reputation particularly in the pro arena while NAT Audio pursues the very expensive tube audio sector. From Sasa's and Micja's accounts, I also know that the present infrastructure in Serbia demands a high degree of resourcefulness on the part of entrepreneurs. At Trafomatic Audio, that's Micja's department. Taking my review comments on Theo -- my short nick for The Experience One -- to heart, Micja had attended to improving the finish. "It's a lot better now." Based on the high-gloss black Head One and Reference loaners, definitely. Naturally, such finishes are also fierce finger print magnets but it's par for that course.

If tube amp sonics are 80% transformer-based, Trafomatic Audio enjoys quite the unfair advantage over most of its far more established competition. It's clear that Sasa breathes, thinks and dreams transformers. As is my giant Plitron step-down transformer for 120V kit, Sasa's iron is quiet and runs cool. Though it's unfortunately not common in a sector where size often equates to hum and vibration, mum is the word on the Experience Reference's substantial iron contingent. And as my passive DeVore Fidelity Nines proved, all that iron isn't just impressively silent but produces astonishing bass. "No subwoofer, right?" Sasa asked during an organ track. He grinned contentedly when I shook my head in acknowledgment.

Granted, even the best tube bass isn't as dry and damped as it will be with most quality powerful transistor amps. But that's a given. Anyone who claims differently is, in my book, not entirely honest or simply misinformed. Low output impedance for a single-ended tube amp without NFB will never exhibit a zero in front of the decimal point; nor multiple zeros beyond it before the first number hits. Which will be rather bigger than 1. That has an effect. Pretending otherwise won't change it.


The XRef however does set very high standards in bass extension, amplitude and absence of bloom (a term which in this context would just be a euphemism for lack of control). If you desire ultimate bass, run a SET on a semi-active high-sensitivity speaker such as -- to name a few I'm familiar with -- Bastanis, Rethm and Zu make; and as WLM champions with their active crossover and subwoofers. That marries transistor bass to tube everything else. If you prefer full-range SET sonics, the XRef's bass is bloody impressive and probably about as brilliant as can be wrought from 300Bs without negative feedback. Further variables there include just what 300B and 5U4G rectifier you roll. The Czech glass from EAT and EML is more dynamic, linear and damped than the Western Electrics and Shuguang's 300B-98 WE clones.


Naturally, the bass aspect of single-ended no-feedback triodes relies heavily on proper loudspeaker matching. The DeVore Fidelity Nines are ideal mates and my high-gain Supratek Cabernet Dual preamp produced very macho levels at 10:30 or sooner, depending on CD. Due to the mono's low input sensitivity of 2.5V alas, my 12dB ModWright LS/PS 36.5 hovered above 4:00 already on the more efficient Zu Presence. It was plainly under-gained for these amplifiers and thus remained on the sidelines during this assignment.

Getting on just famously with my WLM Grand Viola monitors, Zu Presence loaners and DeVores, it were the Rethm Saadhanas with Western Electrics which hit the mondo jackpot. The sounds became completely and utterly disconnected from the speakers and the amount of micro detail which the amps managed to resolve was sublime.


The active bass system relieved the WEs from exhibiting their relative limitations in the nether regions as compared to the bigger beefier Czech bottles. Their micro-detail refinement meanwhile truly catered to the 98dB Lowthers.


In this idealized context, the XRef amps are the antithesis of deep triode tricks which quickly turn one-trick pony. Instead, these monos pay tribute to the 300B triode reputation as one of the most linear amplification devices extant - if and when used within their window of linearity.

Detractors of paralleled SETs point at current hogging whereby tube mismatches cause one tube to carry most -- rather than equally share -- the load.


Sasa shook his head. For current hogging to be possible, the power triodes would have to be tied together. His aren't. "It's not an issue. At all."


I have long since suspected that the reason I prefer single-ended to push/pull amplifiers in tubes has to do with matching and bias offsets.


Multiple output devices per channel combine non-identical behavior between these devices and average at the outputs.


On matching, single-ended has the advantage. Paralleling might seem to negate it. After all, ultra resolution isn't about averaging. It's about ultra specifics.
Just how specific is most apparent at low amplitudes, micro detail and on vocals. There our survival reflexes help us recognize realism the easiest. In conjunction with the superb reflexes of the Lowthers in this range, I could not point at any artifacts which, compared to my non-paralleled Yamamoto A-09S and Woo Audio Model 5 amps, suggested averaging, obscuring or dulling. That crisp freshness on well-recorded vocals which causes the cherished "here in the room" reaction was in full evidence. In fact, it was more acute than over the denser 6SN7-driven Woo. The Yamamoto meanwhile is a bit fluffier versus the Trafomatic's more articulated grip.

The Saadhanas' adjustable low pass for its isobarically loaded twin 6ers is a very useful feature not only to adjust the relative midbass balance to room and listener preferences. During reviews where the room variable remains fixed, the subjective need for how high or low to set the turnover frequency tells much about the driving amplifier. In this speaker, the heavily modified DX-55 runs wide open. It begins its roll-off around 70Hz. Many low-power tube amps want the woofer crossover set to 100Hz or higher. This then fleshes out the vital power region through deliberate overlap with the hidden woofers.
With the XRefs, 75Hz was perfect. It showed that these amps are very linear and produce proper weight. I also had to back off the Level Control for the same reason. While I can't give you hard
figures that would be relevant outside my own room and system, I can tell you in no uncertain terms that the sub 300Hz performance of these Serbian amps is plainly superior to what I'm used to from quality examples of this breed.

Coming off 45s, 300Bs usually are thicker, more endowed in the midbass, not as open on top, not as quick nor quite as articulated all around but with deeper tone colors. Trafomatic's Experience Reference narrows this gap significantly while 'supercharging' the minuscule 2-watt output power of single-ended 45s to a rather more useful 15 watts. Not as lit up as 45s, not nearly as padded as the usual 300Bs, the XRef takes the middle ground here, then adds serious gravitas down low. The outcome is precious little sonic semblance with popular expectations for 300Bs such as one finds them expressed in the forums by worried yet tantalized would-be owners.

Like the Nelson Pass FirstWatt F5, the XRef has a very sublimated personality. What little character remains needs direct comparisons to become relevant. With the added variables of EAT, JJ and WE 300Bs and NOS vs. EML 5U4G rectifiers, a detailed conclusion will take more time. What's patently clear early on is that these amps truly live up to their 'Reference' moniker. Those who discriminate based on country of origin and whatever they imagine that implies here naturally could care less. Those for whom merit is utterly separate from where something is made; and who have eyed a pair of award-winning Wyetech Labs Sapphires - such folks will be pleased to learn of very strong alternate contenders. These amps implement the 300B as a very linear and highly refined output device. They successfully strip off the fuzz, subliminal soft focus, languor and midbass-for-bass trade one often hears in lesser implementations.


The ECC99 driver, twin rectification, stout inductive loading, discrete power tube feeds and monster OT combination shows the 300B to be a leaner, faster, more agile performer. Consequently, that vocal eroticism as a function of significant harmonic distortion, midrange emphasis and deliberate contouring is quite toned down. Or perhaps the IT is largely responsible for eliminating capacitor coagulate (to coin a new audiophile obsession like Mosfet mist)? Especially noticeable on struck and plucked strings, the XRef monos convey all the energy and glitter on the attack rather like the transistor F5 - as though the interstage transformer eliminated a common energetic filter or deccelerator.

Or as Sasa put it: "Signal path capacitors in amplifiers kill the sound." Be that as it may, his ingredients together certainly make the 300B valve a far more even-handed all rounder and one unexpectedly suitable for raunchier driven fare - an equal opportunity employer. Declaring their amps "made in Serbia" is obviously right and necessary. But in this instance and after meeting these very funny, utterly unpretentious gents, one also imagines a subversive delight of going against the grain. Plus, it's national pride and identity for team Trafomatic. Does it prove to the rest of the world that Serbian hifi can compete on the global market? Svakako. Certainly. At least to those who pay attention. For those who don't, right away, Sasa is working on the matching Reference Preamplifier. It'll have input and output transformers and my favorite preamp tube. The OT for that will be another terribly complicated affair. "Micja has to build us a small special machine so we can wind certain parts of it." Trafomatic Audio is most aptly named indeed. Conclusion in due time...
Trafomatic Audio website