Предусилители — PS Audio BHK Signature Preamplifier

The BHK Signature Preamplifier is a fully balanced hybrid line preamplifier from PS Audio, designed by Bascom H. King and fitted with a built-in headphone amplifier. It combines vacuum tubes in the gain section with a solid-state output stage. The regular list price was USD 6,999, and PS Audio ended new production in 2024. It was offered in black and silver.

Key specs that matter

Connections comprise five balanced XLR inputs with a minimum impedance of 66 kohm and five single-ended RCA inputs with a minimum impedance of 33 kohm. Output impedance is 100 ohm and output level is 4.0 V RMS. Response across 20 Hz to 20 kHz is held within 0.1 dB, and the -3 dB bandwidth stretches from 0.1 Hz to 200 kHz. THD plus IM at 1 kHz stays below 0.03 percent, while noise sits more than 90 dB below signal. The chassis is 430 mm wide, 100 mm tall and 360 mm deep, and power consumption is 60 W from a 100, 120 or 230 V supply at 50 or 60 Hz.

Engineering and use context

Two hand-selected, matched 12AU7 dual triodes form a zero-feedback balanced input amplification pair. Level is set by combining GainCell control of the tube gain with a stepped attenuator built from passive parts, giving half-dB increments. The output stage is a high-bias Class A MOSFET design, which PS Audio states is unaffected by the interface with cables and amplifiers. Every input is converted to a balanced signal, and the circuit stays fully balanced from there on. Construction uses through-hole discrete parts, PRP resistors and selected capacitors. A dedicated standby button lets the valves rest while the unit stays ready, and on switching to operate a 30 second countdown runs while the tubes come up before the outputs go live. The tubes are accessible for owners who want to swap them, and there are no user-serviceable fuses inside.

Pairing

Outputs on XLR and RCA, usable at the same time, can drive a power amplifier of either input type, and two 12 V DC triggers can switch other components on with the preamplifier. The MOSFET headphone stage, also designed by King, delivers 200 mW into 300 ohm and 4.0 W into 16 ohm with an output impedance below 0.5 ohm, so it covers both high-impedance and low-impedance headphones. Plugging in headphones disconnects the preamplifier outputs. An OLED display shows input, level and balance, each input can be given a custom name, and any of the five can be assigned as a home theatre bypass that holds a fixed level regardless of the volume knob. The supplied remote covers mute, balance, input choice and a dim function that blanks the display.

Alternatives

For a solid-state option, PS Audio also makes the StellarGold Preamplifier, a fully balanced line-level design.