Balanced Audio Technology VK-90T Power Amplifier

A fully symmetrical circuit with high-current, all-triode, zero-feedback, and a fully balanced topology. Can be run stereo or bridged to mono

The Balanced Audio Technology VK-90t power amplifier features a fuse-less protection circuit, active current sources for its two gain stages, intelligent auto-bias circuit with LED indicators, and high-current, all-triode, zero-feedback, fully balanced topology.

Its 25th anniversary industrial design is complemented by new, silver-gold oil capacitors and ultra-transparent internal wiring in the signal path. With VK-90t, BAT realizes that serious listeners want unique technology, user-friendly experiences, and faithful-to-the-source sonics in high-end equipment. The equivalent of having two single-ended amplifiers per channel, VK-90t meets these demands and more—and sounds mesmerizing minutes after being turned on. VK-90t also means there are no tubes to bias; no fuses to replace; no pentodes imitating triodes, and no direct current at the tube output stage.

Active Dual-Stage Current Sources for Improved Linearity and Accuracy

VK-90t extends the advantages of active current sources by including these in both the first and second gain stages of the circuit design. There are multiple benefits to implementing active current sources (solid-state as well as tube) for the first two stages. Specifically, the linearity of the gain stages improves; the adjustments for the first and second gain stages become independent and more easily optimized; and the active source components operate at lower stress level, improving reliability. The final result is an impressive improvement in the linearity, yielding a more accurate representation of the output signal to the original input signal. And that, in essence, is the measure of any amplifier.

Fully Symmetrical, All-Triode Circuit Banishes Conventional Drawbacks

In a world of cookie-cutter pentode/tetrode designs and frail single-ended counterparts, VK-90t stands apart. Its design is fully symmetrical from beginning to end. You can think of it as having two single-ended amplifiers per channel, with their waveforms summed at the output transformer. Since no direct current flows through the output transformer, the latter is a true wide bandwidth design that also reduces low-frequency distortion. When you combine VK-90t’s fully symmetrical circuit with its high-current, all-triode, zero-feedback, fully balanced topology, all of the drawbacks of push-pull and single-ended amplifiers are banished.

Features

• Symmetrical single-ended bridge design
• All triode signal path from input to output

• Second generation silver gold oil capacitors
• Second generation ultra-transparent internal interconnect
• Intelligent automatic bias combined with fuseless protection circuit
• Zero global feedback
• All aluminum 25th anniversary design
• Available as either a stereo or monoblock from the factory
• Stereo amplifier is easily converted to monoblock

Specifications

Output Per Channel (Stereo, Mono): 70 W, 150 W

Gain: 26 dB

Tube Complement: 4 x 6C33C-B, 6 x 6SN7, 4 x 6H30

Input Impedance (Stereo, Mono): 200 kΩ, 100 kΩ

Power Consumption (Idle, Full Power): 500 VA, 1,000 VA

Dimensions: 17″ x 8″ x 24″

Weight: 88 lb