Power amplifiers are the make-or-break component in the music reproduction chain. Everything in your system funnels into this critical component; anything lost can never be recovered.
The BHK Signature features a zero-loss vacuum tube input stage coupled to a high bias differentially balanced MOSFET output.
Bascom H. King has designed amplifiers for many companies, some selling in excess of $100,000, including: Constellation Audio, Marantz, Infinity, and Conrad Johnson. n. The BHK Signature is the first amplifier Bascom felt was good enough to lend his name to. It is his finest achievement in a lifetime of work.
The BHK Signature is a hybrid design enhancing performance benefits from multiple design techniques including:
- Balanced differential vacuum tube input
- Balanced differential MOSFET power outputs
- Separate & isolated analog power supplies feeding each
The stereo Signature 250 produces:
- 250 watts/per channel to eight-Ohm loudspeaker
- 500 watts/channel into four-Ohms
- stable into 2-Ohms.
The power amplifier technology is always present in stereo systems. Yet, despite the fact everyone uses them, few 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.
The BHK Signature power amplifiers are unique in their ability to faithfully pass even the tiniest of details.
The first listen to the BHK is like pulling a blanket off the loudspeakers. Suddenly revealed are the tiniest of details that now ring clear through the BHK, perfectly preserved through its extraordinary bandwidth, low feedback, vacuum tube and MOSFET design.
The BHK Signature input features a classic triode vacuum tube in a modern configuration.
Hand matched pairs of Russian Gold Lion 6922s are self-biased with constant current and high voltage, free of timing and phase distortion without the use of negative feedback. The tubes provide the perfect interface between the delicate musical transitions output by the DAC or preamplifier, and are electrically isolated from the BHK power output stage which is connected to the loudspeaker.
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.
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 are best handled by a tube-like solid state device known as a MOSFET.
MOSFETs handle power without the additional circuitry needed by tube power amplifiers, and they sound better than tubes or their solid state alternatives, bipolar transistors.
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. It turns out that N-types have lower distortion and perform better than P-types. Despite this anomaly most power amplifier designs use both types of transistor in a configuration known as complementary symmetry.
The BHK takes a different approach, one that avoids the problem of uneven performance between N and P devices altogether.
Using only N Channel MOSFETS in its output stage, the BHK Signature produces a near-perfect balanced waveform without the degradation inherent in a complimentary design.