Bryston 4B³: The Reference High-Fidelity Power Amplifier
The Bryston 4B³ is the sixth generation of a legendary power amplifier, with its first version launched in 1978. With over four decades of evolution and refinement, this model embodies Bryston’s expertise and philosophy in high-fidelity sound reproduction. The 4B³ continues the Canadian brand’s tradition of excellence while incorporating the latest technological advancements to deliver an exceptional listening experience.
Mastered Power for Faithful Reproduction
The 4B³ delivers an impressive power of 300 W per channel at 8 ohms, reaching up to 500 W at 4 ohms. This power reserve allows the amplifier to precisely control a wide range of speakers, even the most demanding ones. Its ability to maintain stable performance under different impedance loads demonstrates its versatility and reliability.
The amplifier particularly excels in reproducing low frequencies, offering deep, articulated, and perfectly controlled bass. This quality translates into faithful and nuanced reproduction of low-frequency instruments, providing a solid foundation for the entire sound spectrum.
Dual-Mono Design for Optimal Channel Separation
The 4B³ adopts a rigorous dual-mono architecture. Each channel benefits from its own independent power supply, including a dedicated transformer. This approach ensures total channel separation, eliminating interference and ensuring a precise and stable stereo image. The resulting soundstage is characterized by its width, depth, and ability to accurately position each instrument in space.
The Salomie Circuit: An Innovation for Sound Purity
One of the major innovations of the 4B³ is the integration of the Salomie circuit, developed in collaboration with the late Ioan Alexandru Salomie. This patented input circuit, present in all Bryston’s Cubed series amplifiers, significantly reduces noise and distortion. It also offers excellent immunity to radio-frequency interference and power supply disturbances, a crucial asset in our modern electronic environment.
Measured performances testify to the effectiveness of this technology: the total harmonic distortion (THD) does not exceed 0.005% across the entire audible bandwidth, even at full power. The signal-to-noise ratio reaches an impressive 119 dB.
Flexibility Designed for the Demanding Audiophile
The 4B³ offers a range of practical features that meet the needs of the most demanding audiophiles:
- Switchable balanced (XLR) and unbalanced (RCA) inputs
- Selectable gain (23 dB or 29 dB) to adapt to different speaker and preamplifier sensitivities
- The ability to operate in bridged mono mode, delivering up to 900 W at 8 Ω
- A microprocessor-controlled “SoftStart” progressive start-up system, avoiding current spikes at start-up
- A DC trigger input for integration into automated systems
A Robust Design Combining Aesthetics and Functionality
The 4B³ features a sleek and elegant design, typical of Bryston’s no-nonsense approach. Its fully machined and anodized aluminum chassis ensures excellent heat dissipation while giving the device a timeless aesthetic. Available in black or silver finish, with a 17 or 19-inch front panel, the 4B³ seamlessly integrates into any audiophile environment.
Natural convection cooling eliminates the need for fans, ensuring completely silent operation. This feature, combined with a standby power consumption of less than 500 mW, makes the 4B³ an environmentally friendly and energy-efficient amplifier.
Legendary Reliability Backed by an Exceptional Warranty
Bryston is renowned for the exceptional reliability of its products, and the 4B³ is no exception. Each amplifier undergoes a 100-hour factory break-in period before being subjected to a series of rigorous tests. This meticulous attention to manufacturing quality allows Bryston to offer a 20-year warranty on the 4B³, an unmatched duration in the high-end audio industry.
Documentation
Technical Specifications
Design
- Stereo or mono power amplifier
- Symmetrical design
- Dual toroidal transformer
Performance
- Stereo power:
- 2 × 300 W at 8 Ω
- 2 × 500 W at 4 Ω
- Mono power: 1 × 900 W at 8 Ω
- Total harmonic distortion plus noise (THD+N): < 0.005%
- Frequency response: from 1 Hz to 100 kHz (-3 dB)
Electrical Characteristics
- Signal-to-noise ratio RCA: -112 dB
- Signal-to-noise ratio XLR: -117 dB
- Input impedance RCA: 7.5 kΩ
- Input impedance XLR: 30 kΩ, 6 kΩ
- Adjustable gain: 29 dB or 23 dB
Connectivity
- 1 unbalanced RCA input
- 1 balanced XLR input, jack
- Dual speaker binding posts
- Trigger inputs and outputs
Physical Characteristics
- Dimensions (W × H × D): 431 mm × 152 mm × 381 mm
- Weight: 19 kg
Frequently Asked Questions
Is the Bryston 4B³ suitable for all types of speakers?
The 4B³ is designed to efficiently drive a wide range of speakers, from high-sensitivity models to the most challenging loads. Its high power and stability across different impedances make it an ideal partner for most high-fidelity speakers on the market.
What is the difference between XLR and RCA inputs?
XLR inputs offer a balanced connection that better rejects electromagnetic interference, especially over long cable distances. RCA inputs, more common, are perfectly suitable for short connections in a low-interference environment.
Is it necessary to leave the amplifier on all the time?
While the 4B³ reaches its optimal performance after about an hour of warm-up, it is not necessary to leave it on constantly. Its low standby power consumption and soft-start circuit allow it to be turned off without inconvenience between listening sessions.
How to choose between 23 dB and 29 dB gain?
The 23 dB gain is suitable for most systems. Opt for the 29 dB gain if you are using low-sensitivity speakers or if your preamplifier has a relatively low output level. Experiment with both settings to find the one that offers the best dynamics without excessive background noise.
- Eco-contribution included in the sale price.






