DESIGN

APPLICATION

Technology

OVERVIEW

The importance of the power amplifier in the 2-channel system chain cannot be overstated, yet it’s often overlooked. It’s the rare few music lovers that truly appreciate the power amp’s critical role in preserving music’s nuanced details, because most amplifiers fail to preserve them. Overtones from plucked instruments, subtle cues defining placement, depth, soundstage width, and transient decays are often lost in the power amplifier. Suddenly revealed are the tiniest of details that now ring clear through the BHK, perfectly preserved through its low feedback, vacuum tube and MOSFET design. When it comes to musically controlling and powering loudspeakers, the BHK Signature has few peers at any price. The stereo Signature 250 produces 250 watts/per channel into an eight-Ohm loudspeaker, 500 watts/channel into four-Ohms, and stable into 2-Ohms; enough power to satisfy even the hungriest of loads.

INPUT STAGE

A power amplifier’s input stage is a critical interface in the quest to preserve music’s essential details and vacuum tubes do it best. Hand matched pairs of Russian Gold Lion 6922s provide the perfect interface between the delicate musical transitions output by the DAC or preamplifier, transferring it without loss to the MOSFET output power stage and eventually the loudspeakers. The hybrid approach used in the BHK Signature takes advantage of the best traits technology has to offer, unavailable in traditional solid state or tube designs. While vacuum tubes are the perfect input stage, they cannot make the same claim on a power amplifier’s output. Conversely, solid state designs are correct for output stages, but suffer when used as inputs. Only a hybrid approach takes advantage of the best in both disciplines.

OUTPUT STAGE

A power amplifier connects its reservoir of energy to the loudspeaker through a type of valve (solid state or vacuum tube) controlled by the input stage. If the input stage has done a good job of preserving music’s subtle details, textures, timing and phase information, transferring it without loss to the power stage and eventually the loudspeakers is best handled by a tube-like solid state device known as a MOSFET. Not all MOSFETs are the same, their differences characterized by their relationship with the input signal and the power supply driving them: N-types for the positive going signals, P-types for negative. N-types have lower distortion and perform better than P-types but N-channel-only amplifiers are rare. Using only N Channel MOSFETS in its output stage, the BHK Signature produces a near-perfect balanced waveform without the degradation inherent in a complementary design.