PS Audio BHK Signature 250: Minimalistic powerhouse

PS Audio BHK Signature 250 is a stereo power amplifier that bears the name of the famous engineer Bascom H. King, who developed audio equipment for many of the world's Hi-Fi brands. The device is built using a hybrid design and is housed in a massive metal case, the side panels of which are used as heat sinks.

Thanks to the powerful power supply, the PS Audio BHK Signature 250 delivers 250 W/channel into 8 ohms, 500 W/channel into 4 ohms and operates stably into a 2 ohm load, providing enough power for even the most demanding and capricious impedance speaker systems.

The amplifier's input stages are built on Gold Lion 6922 tubes, which are manually selected in pairs. These triodes operate in constant bias mode and are driven by a high anode voltage, which provides wide dynamic and frequency ranges. The preamplifier circuit does not have negative feedback to eliminate the occurrence of phase distortion. This input stage provides excellent matching with any signal source, be it an analogue pre or a modern DAC with its own volume control. The amplifier is equipped with balanced and unbalanced inputs.

The PS Audio BHK Signature 250 has a hybrid design that combines the benefits of different technologies, including a balanced differential input stage with valves, a balanced differential final stage with power MOSFET transistors and separate, isolated, analog power supplies for them.

The output stages of the PS Audio BHK Signature 250 amplifier are built on MOSFET field-effect transistors, and, unlike common circuits based on complementary pairs, it uses only N-type transistors. This eliminates distortion that can arise from mismatching the parameters of N- and P-type semiconductor devices, and makes the amplifier sound smooth and musical.

In order to maximize the effect of the hybrid amplifier design, the tube and transistor stages operate from separate power supplies. PS Audio BHK Signature 250 is equipped with two separate mains transformers that provide optimal supply voltage for both circuits. At the same time, the voltage for the tube stage is stabilized to increase sound detail. The amplifier circuit provides the shortest audio signal transmission paths and is built on the basis of audiophile-grade components – PRP resistors and Red Caps foil capacitors. To connect the acoustics, custom terminals are used, machined from copper, polished and gold-plated. There are two pairs of output terminals for each amplifier channel.

PS Audio BHK Signature 250 has the unique ability to convey even the finest nuances and details truthfully and reliably. The first impression of listening to BHK is as if a blanket had been removed from the speakers.

Characteristics of PS Audio BHK Signature 250

Number of channels 2
Gain 30.5 dB
Sensitivity 1.3 V
Noise level less than – 85 dB (100 Hz – 20 kHz)
Input impedance 50 kOhm (unbalanced), 100 kOhm (balanced)
Output impedance less than 0, 1 Ohm
Frequency range 10 Hz – 20 kHz (+/- 0.1 dB)
Harmonic distortion less than 0.01% (1 kHz)
Output power 2 x 250 W (8 Ohm), 2 x 500 W (4 Ohm)
Inputs unbalanced (RCA), balanced (XLR)
Output terminals are copper, gold-plated, 2 pairs per channel
Additional trigger input (5 – 12 V)
Dimensions (WxHxD) 434 x 220 x 350 mm
Weight 41.7 kg