Designed By Bascom H. King: Fully Balanced PS Audio BHK Signature 300 Monoblock Power Amplifier with Vaccum-Tube Input Stages Provide Consummate Realism, Musicality, Attack, Openness
It isn't often a high-end component stuns even the most dyed-in-the-wool audiophile. Yet PS Audio's head-spinning BHK Signature 300 monoblock power amplifiers are like nothing anyone has ever heard for the price. These masterful audio devices simply demand to be experienced. The end-result of legendary amplifier designer Bascom H. King's 40-year quest for optimal musical reproduction, a pair of BHK Signature 300 are twice as clear, twice as open, and exponentially more musical than their standout stereo counterpart (BHK Signature 250 Stereo) – designed to be one of the very best amps in the world. Featuring a zero-loss vacuum-tube input stage coupled to a high-bias differentially balanced MOSFET output, this American-made sonic magnum opus delivers gobsmacking levels of openness, realism, richness, precision, attack, immediacy, dynamics, and liveliness customarily associated with cost-no-object components. And did we mention power? Outputting a mind-boggling 300Wpc into 8 ohms (600Wpc into 4 ohms, 1000Wpc into 2 ohms), BHK Signature 300 monoblocks effortlessly drive, control, and power even the hungriest loudspeakers to their absolute ultimate potential.
We could employ a multitude of hyperboles to try and describe what happens to music when played through BHK Signature 300 monoblocks, but we think your ears will tell you all you need to know. Fully balanced with separate isolated analog power supplies (one for the vacuum input stage, one for the N-channel MOSFET output stage), these no-expense-spared monoblock power amps are built to leave nothing unturned with complete through-hole construction (no surface-mounted parts), separate and discrete MOSFET regulators, hand-selected passive parts, and even solid copper gold-plated binding posts. The sonic upshot of these decisions relates to the textures, nuances, transients, timing, and information you will hear – and recordings you will experience like never before. Free of signal degradation, BHK Signature 300 monoblocks transmit even the most minuscule musical cues with phenomenal clarity and truthfulness, and deposits them amidst soundstages that stretch far, deep, and wide. No other hybrid monoblock design compares. You need to hear these for yourself. 100% Music Direct Guaranteed.
“…A powerful, nimble-sounding amplifier that immediately drew me in with fast, punchy, tight bass; rich, liquid mids; and delicate, transparent highs—all effectively well integrated into a coherent whole.”
“A genuine masterpiece from an old master.”
—Anthony H. Cordesman, The Absolute Sound, Editors’ Choice Award
—Michael Fremer, Stereophile
Zero-Loss Input Stage to Preserve the Most Finite Musical Detail
The connection between preamplifier and power amplifier is critical, for it is at this junction where most essential musical details are easily lost. When it comes to preserving music’s finest nuances, nothing in a power amplifier’s design is more important than its input stage. In BHK Signature, a vacuum tube serves as the perfect interface between the preamplifier and the massive power output stage inside BHK Signature. The input stage’s seemingly impossible task of passing both delicate and powerful musical information without loss is made possible by massive numbers of free-flowing electrons traveling within BHK’s vacuum tube—electrons quantities that are not to be found in transistors. The vacuum tube is unique amongst amplification devices: It boils an abundance of free electrons in empty space while modern devices pull fixed numbers through solids. A tube’s high voltage, empty space, rich numbers of electrons, and connection through unattached fields preserve details lost in the solidity of silicon. 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. They provide the ideal 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.
“…I would be hard-pressed to identify anything wrong in the BHK 300’s sound…This kind of convincing, sophisticated performance, particularly from the midband up, is what one expects and gets from the finest cost-no-object electronics.”
- Michael Fremer, Stereophile
Best-of-Both World Hybrid Design, MOSFET Outputs for Degradation-Free Playback
The hybrid approach used in BHK Signature takes advantage of the best traits technology offers, 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. 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 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. MOSFETs handle power without the additional circuitry needed by tube power amplifiers, and sound better than tubes or their solid-state alternatives, bipolar transistors. Not all MOSFETs are the same, and their differences are characterized by their relationship with the input signal and 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. Despite this anomaly, most power amplifier designs use both types of transistor in a configuration known as complementary symmetry. BHK takes a different approach, and avoids the problem of uneven performance between N and P devices. Using only N-Channel MOSFETS in its output stage, BHK produces a near-perfect balanced waveform without the degradation inherent in a complementary design.
No-Expenses-Spared Build Quality Extends to Through-Hole Construction
Work on BHK Signature began in 2014 with the goal of building one of the top five power amplifiers in the world, regardless of price. Bascom H. King took the charge under the condition he be permitted to design and build the amplifier his way. Starting with a clean slate, he reimagined traditional transistor and tube-based amplifiers as a hybrid, with vacuum tubes on its input and transistors on its output, an idea he invented 30 years ago. In 1979, King designed the Infinity Class A, the world’s first hybrid power amplifier. J. Gordon Holt, founder of Stereophile magazine wrote: “It is the best sounding amplifier I have ever heard.” To maximize the benefits of the two amplification topologies inside the amplifier, it should be built as if it were two separate systems, each with their own power supply tailored to fit. Thus, BHK has two power transformers, one for the vacuum-tube input stage, the other for the MOSFET power output stage. Separate and discrete MOSFET regulators are used throughout to preserve details found in the music and keep noise levels to a minimum. Each passive component is hand-selected to provide the cleanest path possible. PRP resistors, film and foil Rel Caps, and the finest-sounding parts possible are hand-soldered onto BHK’s circuit boards. King insisted no surface mount parts be used in the signal path. No expense was spared. Even the output connectors are custom-machined out of copper, then polished and gold-plated for best connection.