Balanced Audio Technology - BAT VK-85 Preamplifier

SuperPak Quattro

The revised power supply of VK-85 incorporates the same fourth-generation SuperPak used in REX 300. In addition to providing four levels of filtration, it is connected in a new manner that dramatically lowers the preamplifier’s overall noise floor. The parts used in SuperPak Quattro include premium silver foil/oil capacitors that improve harmonic accuracy — and go far beyond the red chiclet-style caps found in most power supply bypass designs.

Unistage Design

Simplicity of design, especially in the direct signal path, remains a hallmark of Balanced Audio Technology’s purist approach to circuit topology. The signal in VK-85 is transmitted through only one gain stage — one free from the negative artifacts attributable to both extremes of modern preamplifier design: passive preamplifiers and multi-stage buffered active circuits. BAT’s trademarked Unistage circuit provides the ultimate simplicity of amplifying the incoming signal just once while using no global feedback to double-back on the integrity of that signal.

High-Current N-Channel MOSFET Circuit

The VK-85 circuit is based on N-Channel MOSFET devices. Solid-state designs customarily use complementary N- and P-Channel devices in the gain stage. Such configurations are easier to build but suffer from an important drawback: P-Channel devices are inherently inferior to their brethren because they are much slower. In VK-85, both sides of the waveform are handled by identical devices – in identical circuit configuration – assuring symmetry of the resulting signal.