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Balanced Audio Technologies VK-55SE Amplifier


The Balanced Audio Technology VK-55SE vacuum-tube power amplifier is yet another outstanding addition to our highly-regarded Special Edition series of products. The VK-55SE retains all of the strengths that have made the VK-55 such a stellar performer – including the same world-class automatic-bias circuit found in our reference REX II Power amplifier, while maintaining the compact form factor that has made this design such a powerhouse in the industry. So how did Balanced Audio Technology improve upon an already superb, fully balanced, automatic-biasing, all-triode design?
Special Edition Upgrades
Balanced Audio Technology incorporates the 6H30 SuperTube into a completely revised first gain stage for the VK-55SE power amplifier. This 6H30 SuperTube is the same tube used in our reference REX II Power amplifier as well as Rex II preamplifier, and provides the VK-55SE with a more transparent, extended, and involving reproduction of the musical event. The VK-55SE also substitutes the same paper-in-oil capacitors used in our flagship amplifier designs for the polypropylene capacitors employed in the VK-55. As a result, the sound becomes more natural and coherent from the substitution of these premium oil-filled capacitors.
Finally, we’ve increased the power-supply energy storage of the VK-55SE to over five times that of the VK-55! Needless to say, the dynamic capability of the VK-55SE reaches a new level altogether – one worthy of its Special Edition status.
55 Watts per channel (Stereo) 110 Watts per channel (Mono)
The VK-55SE power amplifier is a high-current all-triode design that offers 55 watts per channel in the stereo version or a robust 110 watts per channel as a monoblock. The 6C33C-B triode output tube used in the VK-55SE power amplifier offers many times the current delivery of the more common 6550 tube used in many traditional tube amplifier designs. High impedance vacuum tubes like the 6550 require far more complicated output transformers than the low impedance 6C33C-B vacuum tube. Consequently, the VK-55SE power amplifier is quite comfortable driving low impedance loads. You can simply choose the stereo or monoblock version based upon your choice of speaker and room size. The high-current delivery of the VK-55SE power amplifier will give you the assurance of driving a difficult load with ease.
Vacuum-tube current sources
The VK-55SE power amplifier substantially improves its circuit topology by incorporating vacuum-tube current sources for the first gain stage of its design. The current source is an integral, albeit extremely important, part of a differential circuit. Its quality to a large degree determines the ultimate performance of a gain stage. As opposed to a more common resistive solution, the vacuum-tube current source is much closer to an ideal model. The benefits of implementing vacuum-tube current sources within the VK-55SE power amplifier are as follows:
The linearity of the gain stage improves.
The tube current source components operate at much lower stress level, thus improving reliability.
The vacuum-tube current sources installed in the VK-55SE power amplifier provide a more soulful portrayal of harmonic texture and instrumental timbre. All of your recordings will simply sound more alive while simultaneously yielding greater finesse, grace and inner detail.
Intelligent auto-bias
The advanced engineering of the VK-55SE power amplifier eliminates the traditional headache associated with most vacuum-tube power amplifiers; the constant need to set and readjust the proper bias of the output tubes. The VK-55SE power amplifier features an intelligent automatic bias design that adjusts for changing line voltage and aging tubes, with each output tube having its own dedicated bias circuit. For convenience, these individual automatic bias circuits contain LED indicators that show the status of each output tube. The BAT auto-bias circuit also ensures that your VK-55SE power amplifier sounds wonderful within the first few minutes of listening. This is indeed very different from manually biased designs that must be adjusted for their thermally warm set point – and thus sound too cold and clinical before their tubes are fully warmed up.
Intelligent power upgrade
The VK-55SE power amplifier is easily upgraded from the stereo version to monoblock configuration. Unlike competing designs, there is no need for the user to trade their amplifier in to obtain more power. With the VK-55SE power amplifier, the user will simply convert their existing VK-55SE to a monoblock, and then order a second VK-55SE monoblock to match. Technically, the stereo to monoblock conversion is accomplished by simply paralleling the inputs and outputs. This means that “the sound” only gets better as both current delivery and power output go up by a factor of two, and the monoblock noise floor drops appreciably as well.
The VK-55SE is a fitting addition to a Special Edition lineup that has made BAT one of the most respected brands in high-end audio. The VK-55SE offers more of the magic that already makes the VK-55 such a special amplifier – digging deeper still into the raw emotional power that bestows music with transcendent grace. Visit your BAT audio specialist today. All you need to do is listen!

Output per channel at 8Ω/4Ω 55W / 55W
Output in Mono Configuration 8Ω/4Ω 110W / 110W
THD at full power 3.0%
Input Impedance – mono version 108 kΩ
Tube Complement 2x6H30, 2x 6SN7, 2×6922, 4x6C33C-B
Remote Control No
Dimensions (Inches) 17″W x 8″H x 16″D
Weight 50 Lbs
Conversion to Mono? Factory or Wire Kit
Frequency Response 8Hz to 200kHz
Input Impedance – stereo version 215 kΩ
Gain (Nominal into 8Ω) 25dB
Number of Power Cords 1
Power Consumption (Idle/Full Power) 400W/800W
Dimensions (mm) 431W x 203H x 406D