Designed by Bascom H. King, PS Audio BHK Signature Preamplifier Provides Reference Sound: Vacuum-Tube Input Stage, Balanced Circuitry, Class A Output, Extraordinary Headphone Amp
"This is the best-sounding preamplifier I have ever designed or heard," states Bascom H. King about the PS Audio BHK Signature preamplifier. King, a legend with more than 50 years of high-end design experience and responsible for revered products from the likes of Marantz and Audeze, guided every aspect of this reference musical instrument's development – from the zero-loss vacuum-tube input stage to the resolution-perfect volume and balance controls. Featuring an oversized toroidal analog power supply that feeds 5 MOSFET-based discrete regulators, discrete parts and resistors, balanced circuit topology, a high-bias Class A MOSFET output stage, and a state-of-the-art headphone amplifier, the Stereophile Class A Recommended BHK Signature takes into account every individual element that impacts playback and optimizes them for extraordinary performance. Greater than the sum of its exceptional parts, this Colorado-made marvel presents music with beguiling openness, spaciousness, transparency, nuance, detail, and richness. You'll enjoy dynamic extension beyond 100kHz at the top end and far below 0.1Hz on the other extreme. Simply put, BHK Signature allows you to hear what you've been missing by revealing the information on your recordings that makes high-end audio an inimitable experience.
BHK Signature is also the rare audio showpiece that considers the needs of the user – and makes everything simple. Home-theater bypass modes for each input, custom-input naming, effortless input switching via remote or panel button, and polarity control are all at your fingertips. DC output triggers further expand your control options, and vacuum-tube standby preserves the life of the two 12AU7 dual-triode vacuum tubes while the internal solid-state circuitry remain active. In the mood to change up the tubes? BHK Signature invites tube rolling as any 6, 7, or 12 Series tubes can be placed inside the preamplifier. For your sources, five identical balanced and single-ended inputs provide the lowest-possible distortion and highest linearity. PS Audio also strove to elevate your relationship with the volume control, which is a combination of an input-stepped attenuator coupled with control of the actual gain of the vacuum tube that results in breathtaking clarity. And the near-zero-output impedance, transformer-coupled, MOSFET and discrete headphone amp – perfect for private listening pleasure – could easily be its own product. A testament to King's legacy, BHK Signature is a virtuoso preamplifier for the ages. 100% Music Direct Guaranteed.
“PS Audio’s BHK Signature preamp is one of the finest audio components I’ve had in my home. It didn’t solve my problems, but it could sure distract me from them—and, with the right recordings, even trigger catharsis or philosophical insight.”
—Jim Austin, Stereophile, Class A Recommended Component
All Inputs Converted to a Pure Balanced Signal
BHK Signature features five 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 chosen for sonic neutrality. The signals are passed directly through the multi-stage attenuator controlling both volume and balance. If the preamp is going to be part of a home-theater system controlling the main left and right channels, each input can be user-assigned as a home-theater bypass.
Hand-Selected and Matched 12AU7 Tubes Serve as Gain Stage
The heart of any preamplifier is both the gain stage that provides the amplification and the volume control that manages how loud or soft the music plays. Inside the BHK Signature, a pair of hand-selected and matched 12AU7 dual triode vacuum tubes provides the unit's gain. The tubes are fed from a discrete MOSFET-based high-voltage regulator on their plates, and a discrete MOSFET constant current source on their cathodes. The filament voltage is supplied from a separately regulated supply delivering a clean source of free flowing electrons.
Novel Volume Control for Exceptional Transparency
The second most important area of a preamplifier's performance is the mechanism used for controlling the volume. Inside BHK Signature, a combination of a stepped discrete input attenuator is combined with a novel switched-gain adjustment controlling the actual gain of the vacuum tube. This topology offers the cleanest, lowest-impact gain control in half-dB steps. The sonic transparency achieved by this unique architecture, coupled with the zero-loss vacuum tube, is largely responsible for the remarkable levels of openness and transparency. Control of the volume is handled through the front-panel haptic feedback rotary encoder or the supplied remote control.
Discrete Parts, Resistors, and Components Employed Throughout
Most modern audio products rely upon surface-mount components to pass audio signals. PS Audio also uses sophisticated surface mount parts in our digital products because they have advantages unavailable with through-hole technology. The same cannot always be said for high-end analog electronics, like those inside the BHK Signature preamplifier. When compromise is not an option, analog audio products benefit from incorporating through-hole discrete parts in the signal path. Hand-selected through-hole PRP resistors, high-grade audiophile capacitors, and the finest discrete parts are used throughout BHK Signature. Even the solder has been auditioned for best sound.
Vacuum-Tube Standby Control Preserves Longevity
It is important for any high-end audio product to remain active for best sound quality. Using the front-panel PS logo button, the preamplifier can easily be placed in standby mode or activated to play music. When in standby mode, all the internal solid state circuitry such as the headphone amplifier, voltage regulators, and high current output stage remain active while the input vacuum tubes are turned off, preserving their life.