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THRAX AUDIO

TERES MONOBLOC AMPLIFIERS

Reviewer Edgar Kramer

The high-end audio space is rich with exotic products spanning a variety of technologies, ideologies and industrial designs. Traditionally, the

commanding players have been countries with a strong tradition in manufacturing such as the United States, the United Kingdom, Germany and, to a lesser degree but nevertheless making strong appearances, Switzerland, France and Italy. Even Australia, despite our depleted manufacturing base and relentless outsourcing, has had successes and continues to build a strong story. But as far as the high-end is concerned, a powerful new manufacturer of quality audio has emerged from a perhaps unlikely source – Bulgaria. The company is Thrax Audio.

In its relatively short life-span Thrax Audio has produced a steadily growing portfolio of beautifully-made and thoroughly engineered products that are earning worldwide critical acclaim. Authentically ‘high-end’, Thrax Audio’s offerings span the gamut of electronics and transducers, from the ever more important digital-to-analogue converter, through to a choice of innovative amplification devices and ending the chain at a speaker system that aims at the very top-end.

MUSCULAR SOUNDThe subjects of our review are the new Teres hybrid monobloc amplifiers.

The name has twin possible derivations. ‘Teres’ are a group of strong upper limb muscles – good symbolism for amplifiers. But in fact, more appropriately to Thrax Audio, these monos take their name from king Teres, a powerful warrior who unified various tribes in ancient Thrace, now modern day Bulgaria.

And indeed, the Teres amplifiers live up to that name, being Thrax Audio’s most powerful offerings. Thrax (for short) products have a distinctive and indeed very attractive styling and are superbly assembled from aluminium panels that are expertly machined in-house. In fact, Thrax’s significant metal CNC machining capabilities have resulted, I’m told, in the company providing OEM chassis for several high-profile high-end audio manufacturers.

So the Teres amplifiers feature chassis which incorporate heatsinking across three sides to accommodate a moderate level of pure Class-A operation with a subsequent transition into Class-B. While on the biasing, the scheme is rather cunning in the control circuitry for the output stage being powered opto-electrically via solar cells which regulate light intensity in order to make the required adjustments. The input stage is biased via a battery arrangement, while the amp is microprocessor controlled.

At Munich High End 2015, I caught up with the very approachable company President Rumen Artarski and he provided an insight into the Teres’ making.

“Teres are hybrid transformer-coupled no-feedback mono amplifiers designed to

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“We wanted to combine the

midrange beauty of valves with the

control and power of solid-state

designs. Teres takes our existing designs

to the extreme...” Rumen Artarski.

REAR PANEL IS SIMPLICITY ITSELF; SWITCHABLE RCA/XLR INPUTS, HIGH QUALITY BINDING POSTS AND, ON THE FAR RIGHT, THE PRO-TRUDING TOP OF THE 3Cg VALVE.

CNC MACHINING OF EXTRAORDINARY QUALITY HAS BEEN APPLIED TO THE ENTIRE CHASSIS WHILE THE SIMPLE FASCIA HOUSES A CENTRAL POWER SWITCH WITH LED ABOVE IT.

THRAX AUDIO TERES MONOBLOC AMPLIFIERSTHRAX AUDIO TERES MONOBLOC AMPLIFIERS

round out the rear panel’s simplicity. The chassis is extraordinary in its assembly quality and the design is an attractive mix of purposefulness and aesthetic beauty. The Teres amps are available in natural silver aluminium or in Henry Ford’s black. Thrax Audio packages the amps in solid wooden crates with built-in handles which – there’s superb attention to detail even here – have a rounded design that will not cut into the carrier’s hands.

Thrax specifies the Teres monos as providing 250 watts per channel into 8 ohms with power rising to 350 watts into 4 ohms. The output stage features JFET/MOSFET cascode output devices and, as mentioned previously, the amps feature a novel biasing scheme that allows adjustments while maintaining true Class-A at moderate levels (for “a few watts”) and then switches to Class-B at higher levels.

Without wanting to spray the entire amplification genre with a mono brush – there are so many tones to that palette – it is, however, widely believed that well-executed Class-A designs have an inherent ‘magic’ to their overall sound presentation. This same doctrine is expressed for valve amplification. Combine the two and the emotion quotient could potentially be very high… or alternatively, if taken too far, it could all turn into an over-sweet syrupy mess. At the outset, it must be stated that the balance provided by the Teres is, very much, an illustration of the former case. Artarski and his team have expertly “voiced” the Teres to provide outstanding resolution and frequency-wide detail far removed from the stereotypical over-warm, low-res sound of poor hybrid designs.

And this leads us to the Teres amps’ character trait – the portrayal of mid frequencies with vivid presence and a lively balance. This is not to be confused with a brashly forward aspect that head-butts the listener with a wall of sound – these are intelligently-voiced amplifiers striving to recreate the live event. The clear intent here is to provide… music, not hi-fi.

Our favourite live recordings, such as Ani Di Franco’s Live in Clip, Harry Belafonte’s Live at Carnegie Hall, Thin Lizzy’s Live and Dangerous and Nils Lofgren’s Acoustic Live sounded ever so real, so present, that it revitalised desires to attend big-scale live performances. The wide spectrum across the midrange glows with clarity and musical information… this is transparency at its absolute best.

But again the team at Thrax Audio provides a measured balance; the Teres amps, as resolute as they are, never cross the line into objectionable brashness. This is not a trivial point… that inaccuracy is unfortunately achieved when

resolution, transparency and detail are attempted by lesser designs. This resolute philosophy carries through to the low frequencies where Teres punches solid. There’s superb control and detail at hand, even if monster solid-state designs – of the American persuasion in particular – present a more overt and deeper bass. Bass freaks need not

despair, however, as there’s a solid foundation on offer with good dynamics and accurate tonal qualities.

In fact dynamics overall are a strong point too. I enjoy the dynamic and transient snap of well-recorded snare and toms. Albums such as Joe Morello’s Morello Standard Time and even the masterful Graceland from sadly missed Jeff Buckley are great examples of good recording techniques when it comes to drums (quite obviously in the case of the former as Dave Brubeck’s percussionist in the original production). In both these recordings the Teres amps handled the fast attack and dynamic snap of the snare and toms in a way that was visceral and powerful.

And then, of course, the C3g does its thing in the wide tonal palette available from these amps given appropriately accurate speakers – in my view of the neutral dynamic or electrostatic types. And the Teres will drive anything, including low impedance high phase angle designs (within reason of course). Cymbal work is very satisfying too, with the amps providing a natural balance of highs given a good tweeter is provided.

The soundstaging qualities are superb in terms of stage width and height, with the depth perspective presenting a soundfield of reasonable, if not extraordinary proportions. Image specificity and focus are top notch and on par with the best amplifiers we’ve had in-house.

CONCLUSIONA high performance product can originate from anywhere in the world – Asia, the Americas, Europe. And here we discover a new source of excellence in execution and quality in design from an Eastern European manufacturer. With the Teres monoblocs, Bulgaria’s Thrax Audio presents a sol-idly engineered hybrid circuit that delivers on the promise of combining the magic of valves with the control and power of solid state. They are immacu-lately built, and their sonic performance is of a present midrange, natural highs and punchy low-end. This is amplifier design at its most proficient… Bulgaria has broken the borders and boldly pro-claims that superb sound is universal. Welcome!

SPECIFICATIONSTHRAX AUDIO TERES

TUBE COMPLEMENT: 1 x C3g

OUTPUT: 250 watts in 8 ohms, 350 watts in 4 ohms

INPUTS: 1 x unbalanced RCA, 1 x balanced XLR

POWER SUPPLY: 115 or 230 volts

POWER CONSUMPTION: Maximum 700 watts

FINISH: Black or Silver anodised aluminium

DIMENSIONS (WDH): 340 x 400 x 230mm

WEIGHT: 35kg

PRICE: $45,000

CONTACT: Telos Distributors on +61 419 830 587 www.telosaudiodistributors.com

produce a super-clean background and very low noise. It’s a totally individual concept from the ground up. We used the C3g valve in the input stage because of its good sound quality and its extraordinarily long life. We wanted to combine the midrange beauty of valves with the control and power of solid-state designs. Teres takes our existing designs to the extreme and features very sophisticated custom-screened transformers and power supply design.

“The output stage’s power JFET cascodes form a bridge that when unbalanced by the input signal via the two transformer windings restores balance by adjusting their current conduction through the load. The two output stages actually enclose the load in their control loops and correct errors reducing distortion to negligible amounts, leaving only the character of the input stage.

“As far as construction, we manufacture the chassis in-house from CNC-machined high-grade aluminium and we do our own anodising and laser engraving. The chassis is a solid exoskeleton aluminium structure with integrated heatsinks and is designed to fight vibrations and provide a stable platform for the internal circuitry.”

ALL ALUMINIUMThe Teres’ fascia is styled in the Thrax trademark angled cut culminating in a central high quality metal standby power switch below a status LED. The rear panel sports an indented section featuring switchable XLR and RCA inputs, and the top third of the black metal-covered C3g valve which pokes through to the outside world. Just below, very high quality Furutech binding posts, an IEC fused socket and the mains switch