BALANCED AUDIO VK-255SE
"The fully balanced VK-255SE exhibits a 'pace' that is in fact more balanced and 'accurate', more carefully prepared. It purposely does not create the illusion of communing with the artist, 'here and now', by promoting a strong foreground or near-field experience : Instead, this amp is 'Honest' and gives credence to its name - it is "Balanced".
Warmth of tubes, dynamics of solid state
The VK-255SE power amplifier represents Balanced Audio Technology’s hallmark out-of-the box approach to audio circuit design. Unlike most solid-state amplifiers that feature four or more gain stages in a high-feedback push-pull configuration, the VK-255SE features only two gain blocks in a high-power, zero feedback, and purely symmetrical design. Available as either a stereo or monoblock unit, the VK-255SE has the warmth and texture typically associated with the finest vacuum-tube designs combined with the dynamic capability of the best solid-state offerings.
A robust 300WPC plus supreme audio symmetry
The VK-255SE’s elegant signal path follows Balanced Audio Technology’s purist approach of using zero negative feedback to achieve the design goals of wide bandwidth and circuit linearity. The whole amplifier circuit consists of just two gain blocks and is based entirely on N-Channel MOSFET devices. Assuring ultimate symmetry of the resulting signal, both sides of the waveform are handled by identical devices in identical circuit configuration. The VK-255SE offers a robust 300 watts per channel into a four-ohm load; the monoblock version doubles the current delivery of the stereo edition.
Revised power supply equals enhanced musical refinement
To complement the inherent simplicity of the VK-255SE’s fully balanced design, only the highest-grade parts are used throughout. The revised power supply incorporates second-generation oil-filled capacitors. They increase the high-quality filtering capacity, dramatically lower the noise floor, and present a grain-free, more refined portrayal of musical harmonics. Coupling speed and grace with an exquisite fidelity to the timbre and texture of instruments and voices, the VK-255SE markedly closes the performance gap between vacuum-tube and solid-state amplification. It will serve as the anchor of any world-class system.
Output per channel at 8Ω/4Ω
150W / 300W
Conversion to Mono ?
Output in Mono at 8Ω/4Ω
200W / 400W
2Hz to 240kHz
THD at full power
Input Impedance - stereo version
Input Impedance - mono version
Gain - nominal into 8 ohm
12V trigger Input & Output
Power Consumption idle-full power
225W / 1400W
19" x 6.5" x 16"
VK-255SE MONOBLOCK PAIR
What they say ...
Aron Garrecht May 18, 2018
"The smooth-talking VK-255SE proved masterful at reproducing dynamic inflections, was fully capable of producing mesmeric levels of bottom-end fortitude and control, and its midrange was purer than that of almost any other solid-state power amplifier I’ve heard ... if tube-like warmth, buttery textures, and arresting dynamics are what you find most inviting, then this amplifier deserves to be on your audition list".
[ English Translation ]
BAT VK-255SE - BAT-PAK capacitors
"In the BAT-PAK version, ten more "second generation" oil capacitors are added to the power supply. The critical aspect of Victor Khomenko's designs are precisely the capacitors ... and they are usually included in the his most expensive circuits. In this case, the "second generation" capacitors in the BAT VK-255SE amplifier come from the very expensive, two-element flagship REX preamplifier.
There are four capacitors per polarity, with a capacity of 10,000 µF each. This means a total of over 80,000 µF per channel.
As in the Mark Levinson and Pass amplifiers, here we have four amplifiers in one housing - two amplifiers per channel, each amplifying one half of the signal.
Khomenko is a Tube Fanatic
When Viktor creates his transistor derivatives, his goal is to make their sound as similar to a tube as possible, hence his choice of very special, and not other transistors - only MOSFETs with an N channel work in BAT devices.
This in turn means that the output stage works in a pseudo-balanced circuit. Unlike other common designs, BAT's first stage also works with high currents. One of the characteristics of BAT's semiconductor amplifiers are only two gain levels - the same as in Pass amplifiers. Expensive Caddock and Dale resistors were used in every step.
The practical advantages of a balanced design have been known for a long time and are used primarily in studio devices, where we deal with long connections and many different sources of interference.
Without going through a lengthy analysis of the balanced topology, one can nonetheless isolate the phenomenon of its sound -- It is "softness". Not warmth, not tube-like, but softness. No doubt, Viktor wanted the sound to be shaped in such a way that it resembled as much as possible what we get from his tube amplifiers.
However, I will start out with what seem like a a "slight" contradiction to this softness. The BAT sounds completely communicative without falling into mannerisms and mischief. It is characterized by a high resolution of the midrange range. The midrange is not as warm as in the Pass, and it is clearer and a bit brighter than in the Levinson.
The vocalists June Christy from "Something Cool", or Laurie Anderson from "Homeland", had a distinct and differentiated timbre. They were shown a bit behind the loudspeaker line, and were not as close as in other listening sessions. Phantom sources are not small, but real. The depth of the stage is clearly shown. Both in monophonic and stereo recordings, you had the impression of breathing and a lot of space behind the speakers. In recordings in which these elements play a large role -- "Magnetic Fields" by Jean Michel Jarre and "The Friends Of Mr Cairo" by the John & Vangelis duo -- the BAT created the "right mood", and presented events in the right proportions.
In no way should one assume or conclude that the BAT VK-255SE is really, and primarily, only a "mid-range" virtuoso. This amp definitely conjures up good tonal proportions no matter what music genre it is restituting ... and this, without underlining or withdrawing anything.
The attack of the sound may be somewhat restrained, especially the impetus of the treble, but this because this is what this amp is all about.
Comparing the behavior of our three test amplifiers, the Levinson "neutralizes" the top, the Pass warms it up, and the BAT "softens" it. The VK-255SE's highs are however quite strong, but never aggressive. Not surprisingly, and in keeping with the BAT Sound, the bass was also a bit "soft", but as with the treble, it was
notably also perfectly differentiated.
When we listened to the sound of the double bass and to male vocals (Freddie Cole and Mills Brothers), we were a bit surprised to note that the BAT expressed something extra, something that was not present with the competition :
Although the attack is slowed down, the decay was quick and short. This was perfectly evident with the Anderson recordings, where the extremely low, saturated bass, coming in for a moment, did not cover or smear the vocals.
In direct comparison with more expensive solid state amplifiers, the BAT may come across as being less dynamic. This results from the aforementioned "drawing of the scene from a more distant perspective" ...
... everything develops a little bit more slowly, but this "pace" is in fact more balanced and "accurate", more carefully prepared.
This BAT amplifier does not create the illusion of 'communing' with the artist in a "here and now" manner by promoting an omnipresent foreground scene or a near-field experience :
Instead, this amp is "Honest" and gives credence to its name - it is "Balanced".