VK-90t Tube Power Amplifier

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.