PS Audio BHK Signature Preamplifier Instructions For Use Manual - page 3
Owner’s Reference
BHK Signature Preamplifier
4826 Sterling Drive, Boulder, CO 80301
Introduction
PH: 720.406.8946 service@psaudio.com www.psaudio.com
15-071-01-1
Rev A
©2016 PS Audio Inc. All rights reserved.
Introduction
®
Thank you for your purchase of the PS Audio
®
BHK Signature Preamplifier.
The PS Audio BHK Signature Preamplifier (BHK Preamplifier) is a state of-the-art instrument designed
to provide amplification, control, and interfacing tasks between a 2-channel power amplifier, or
headphones, and sources in a high end music system.
Designed by world-renowned analog circuit designer, Bascom H. King, (BHK) the BHK Preamplifier
represents the culmination of one man’s half century of design experience, as well as a lifelong
passion–an obsession really–with the art of perfect amplification. BHK has designed some of the finest
audio equipment in the world from renowned companies like Constellation Audio, Marantz, Conrad
Johnson, and Infinity. PS Audio is proud to have provided the platform and engineering resources that
allowed BHK to place his best efforts in this, his only signature preamplifier worthy of his namesake
on the front panel.
A special thank you must go to our engineering team and in particular, PS Audio Chief Engineer, Bob
Stadtherr, for his tireless efforts and work building Bascom’s dream preamplifier. A true dream team.
The BHK Signature Preamplifier features two 12AU7 dual triode vacuum tubes in the input stage that
act as a zero feedback balanced input amplification pair. A unique self biasing constant current source
and user selectable switch combination allows those who like to roll their own tube selections to place
any acceptable 6, 7 or 12 series vacuum tubes inside the preamp. The twin hand-selected vacuum
tubes that ship with the BHK are the preferred models we recommend and use in PS Audio’s Music
Room One reference system.
The BHK Signature Preamplifier features 5 identical balanced and single ended inputs. Each of the
inputs, whether single ended (RCA) or balanced (XLR) are immediately converted to a pure balanced
signal by the dual triode vacuum tube for lowest distortion, highest linearity performance. Input
switching is accomplished through hand-selected double-pole double-throw, gold plated relays that
we’ve chosen for their sonic neutrality. The signals, once selected, are passed directly to the attenuator
controlling both volume and balance.
The volume and balance control duties are handled by a combination of an input stepped attenuator,
built around the highest quality passive components for coarse volume adjustments, coupled with
controlling the actual gain of the vacuum tube for finer steps. This unique topology, which can be
controlled from either the front panel rotary controller or the remote control, provides the lowest
possible impact on music passing through–and is one of the primary reasons the BHK Signature
presents music in such a revealing, open manner.
The BHK Signature preamplifier output stage is a high-bias class A MOSFET design that is unaffected
by cable and power amplifier interface challenges. Simultaneous connections of both single ended
(RCA) and balanced (XLR) outputs have minimal impact on the delicate vacuum tube gain stage and
provide remarkable isolation between source components and the power amplifier of your system.
Thank You
Designed by
Bascom H. King
Class A MOSFET
Design
Dual 12AU7
Triodes
5 Single Ended
and Balanced
Inputs
Unique Volume
and Balance
Controls
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