4B3 Cubed Amplifier

The Bryston 4B³ is a dual channel (stereo) amplifier internationally acclaimed as being suited for the finest and most sophisticated sound systems. It is Bryston's most popular Cubed Series model winning SoundStage Network's 2017 Products of the Year Award.

A rarified few components in audiophile lore have become so ubiquitous that nearly every music lover once had, lusted after, or if they're really lucky, currently owns one. One such legend is the Bryston 4B. This product has been manufactured continuously (though often refined) since 1978. Currently this venerated amplifier is on its 6th generation, and it's never been better. Now rated at 300 watts per channel into 8 ohms, (and upwards of 500 into 4 ohms), this true dual-mono amplifier is powerful enough for practically any speaker, yet it's priced to remain within reach. The degree of clarity, power, nuance, and outright truthfulness of this amp is stunning. If you've always wanted one, maybe now is just the right time.

"The 4B³ is a control freak in terms of grabbing hold of your speakers' drivers and maintaining bass control, depth and power."

Edgar Kramar, Audio Esoterica

"These dig right to the heart of the music and result in one of the best all-round power amplifiers I have encountered at this price."

Adam Smith, Hi-Fi News & Record Review

Inputs

• Inputs: 2x Balanced Inputs (XLR or TRS), 2x Single Ended Inputs (RCA)

Power Capabilities

• 300W into 8Ω
• 500W into 4Ω
• 900W into 8Ω (Bridged Mono)

Features

• Balanced XLR and Single ended RCA input
• 2 Channels each with fully independent power supplies including transformers
• 300W into 8 ohms (and up to 500 into 4 ohms) per channel
• The patented Salomie circuit found in all Cubed Series amplifiers
• Switchable gain (23dB or 29dB)
• Fully convection cooled means no noisy fans
• Machined and anodized aluminum enclosure and dress panel
• Less than 500mW standby power consumption
• SoftStart microprocessor controlled startup sequence won't trip circuit breakers
• DC trigger for automated turn on and turn off
• Active extremely low distortion input buffer
• Balanced and Single Ended audio inputs
• Selectable gain at 23 or 29dB
• Regulated power supplies to all voltage gain stages
• Independent power supplies for each channel
• Convection cooled and housed in a fully aluminum chassis.
• No fans or other moving parts
• Bridging switch configures amplifier into a single 900W Channel
• Legendary Bryston 20 Year Warranty

Options

• Available with Silver or Black faceplate
• 17” or 19” faceplate (non-rack mountable) 19" comes with front mounted handles
• PRO version includes 19" rack mount dress panel in black plus rear panel channel trim pots (-14 to 0dB)

First to Last Watt Philosphy

A significant part of the design criteria for the new Cubed series was to develop amplifiers that would maintain an ideal power curve from the first watt to the last. Most amplifiers exhibit a power curve where the best noise floor, drive capability and distortion are acheived from about 1/3 power and up. The new Bryston Cubed series amplifiers maintain their ideal power curve starting right from the first watt.

Achieving this starts with a number of design approaches:

1. Complete freedom from low-level crossover, zero-crossing, artifacts

   Most class-AB amplifierrs have sufficient bias to prevent primary crossover distortion, but secondary crossover distortion is caused by insufficient speed in the driver transistors. The Cubed Series uses very fast drivers to help prevent this, as well as proprietary technology. Bryston's Quad Complementary Output design vastly reduces the capacitance seen by the driver transistors, virtually eliminating storage delay in the output stage that could contribute to nonlinearities in the zero-crossing region.

2. Continuing efforts to reduce low-level noise. The clarity of level noise

   The clarity of Bryston's designs is enhanced at low listening levels by pushing the noise floor far below the signal level, improving the silence between the notes and enhancing the clarity of the music at low power levels.

3. Concentration on reducing distortion at all levels, especially high frequencies

   Bryston amplifiers are perhaps the only designs to concentrate so much effort at reducing HF distortion artifacts, and the results are remarkably flat THD-with-frequency curves, sho frequency curves, sho frequency curves, showing almost no tendency to wing almost no tendency to increase distortion as frequency rises. This has the effect of reducing overall haze, helping to pull the quietest passages out of the background.

Additionally, the new Cubed Series employs highly effective RF employs highly effective RF rejection in the power supplies, which traps and eliminates radio-frequency hash from either interfering with or emanating from the amplifier via the power cable or signal cables.

Press and Reviews

Bryston Magazine

Guides & Advice
by Moon Audio

Bryston 4B Cubed

by SOUNDREBELS
June 2022

Best Amps 2022

by Part Time Audiophile
Nov. 2021

Audiophile

by Marc Phillips
Mar. 2021

Hifi Advice

by Christiaan Punter
Dec. 2017