BAT

VK-85 Preamplifier

Introduced simultaneously with the REX 300 power amplifier, the Balanced Audio Technology
VK-85 preamplifier blurs the lines between the finest tube and solid-state sound.
VK-85 features BAT’s trademark high-current Unistage topology with transformer-coupled outputs
that anchor the full line of Balanced Audio Technology’s preamplifiers.
VK-85’s second-generation output transformers work in conjunction with a symmetrical N-channel
Unistage gain block to provide the high-current operation that is a BAT hallmark.
A revised connection scheme for the SuperPak Quattro technology used in REX 300 offers beguiling
levels of musical finesse and textural beauty.

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.

Inputs

3 x XLR
2 x RCA

Outputs:
Main

2 x XLR

Outputs:
Tape

1 RCA

Maximum Gain: 20dB

Global Feedback: None

Volume Control Resolution: .5dB

Volume Control Number of Steps: 140

Frequency Response: 2Hz to 200kHz

Input Impedance (minimum): 100k each phase

Output Impedance: 200 ohm each phase

Noise (unweighted): -96dB

Distortion at 2V output: .01%

Maximum Output Signal: 20V

Absolute Polarity: +/- via front panel switch

Power Consumption: 250VA