Bryston 4B³ Cubed Stereo Power Amplifier

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Current model amplifier from legendary maker Bryston capable of delivering 300W per channel into 8 ohms and 500W into 4 ohms.

Two of these beasts (which we have available as of this writing) can be switched to mono delivering... 900W!

$7495 MSRP

Included with your purchase is a factory fresh Bryston 4B³ box to ensure safe travels to your home.

SkyFi Cosmetic Note:
Some markings on faceplate as shown in our photos.

Click below to add our recommended matching cables from Kimber Kable, all brand new as SkyFi is an official Kimber dealer.

Kimber Kable - RCA Interconnects - Better

Kimber Kable - RCA Interconnects - Best

Kimber Kable - BALANCED XLR Connectors - Better

Kimber Kable - BALANCED XLR Connectors - Best

Kimber Kable - Speaker Cables - Better

Kimber Summit Series Monocle XL Speaker Cables (PAIR) - Best

Kimber Summit Series BiFocal XL Bi-Wire Speaker Cables (PAIR) - Best If Applicable 

Kimber Kable - Power Cords - Better

More from Bryston:
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.

"A well-designed solid-state amplifier should fulfil the purest principles of music reproduction, accepting the input signal, then transparently and harmlessly delivering it to the transducers regardless of their inherent electrical demands, providing effortless and tight control of the drivers while manifesting boundless dynamic expression, detailed resolution and accurate tonality. In the 4B³, Bryston has covered all these bases covered... for at least 20 years." - Edgar Kramer, Audio Esoterica

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
• Legendary Bryston 20 Year Warranty

SPECIFICATIONS
Dimensions:
Inches:
17" W x 6.3" H x 15.5" D

Weight:
42 lbs

Frequency Response:
<1hz - 100khz: -3db

THD+N (20Hz-20kHz @ Rated Power, 8Ω):
<0.005%

Power Output (per channel):
300W @ 8Ω | 500W @ 4Ω

Noise:
RCA: -112dB
XLR: -117dB

Input Impedance:
Unbalanced 7.5kΩ
Balanced 30kΩ+ / 6kΩ-

Bryston 4B³ Cubed Stereo Power Amplifier - Owner's Manual

The SkyFi Testing Process for Solid State Amplifiers:

We start with a visual inspection of all internal components to make sure that there are no signs of heat stress or damage. Capacitors are checked for telltale signs of predictive failure including bulging, shrunken wrappers, or physical leakage. We also inspect the PCBs for discoloration from resistors or transistors that may have been running hot. On vintage units we often spot check select capacitors for value and ESR.

If the amplifier passes visual inspection, we move on to a controlled power on sequence using a Sencore safety analyzer to monitor current draw in real time. Once the amplifier is determined to be safe to operate, we connect it to full AC mains for function and power testing. We connect the speaker outputs of the amplifier to a Sencore PA81 Power Analyzer which acts as a dummy load, DC offset monitor, and oscilloscope interface. We start with a low level 1KHz test signal at the amplifier’s input and slowly increase its amplitude while monitoring the output on an oscilloscope for signs of noise, clipping, distortion, or improper channel balance. We continue increasing the signal level until the amplifier reaches clipping. At this point we take an output power measurement and compare it to the spec sheet of the amplifier to verify proper performance. If the device under test has both balanced and single ended inputs they are both tested at this time. We finish off the bench evaluation with a 1KHz square wave check and a 20Hz to 20KHz sine sweep to assess the amplifier’s frequency response characteristics. This battery of tests will usually reveal if the amplifier has any issues that need further attention.

Before the device leaves the bench, we perform a listening test with actual music using a variety of preferred test tracks. Our benches are outfitted with familiar monitor speakers which help us identify inconsistencies that will not always show up on our test gear. The main things that we are listening for are hum or noise with no signal present, proper center image, clicks, pops, or any other obvious undesirable audio characteristics.

If the unit passes all of these tests it is moved to our long term testing rig where we simulate real word operating conditions for 6-8 hours. This allows us to monitor the unit for signs of thermal runaway or intermittent issues that only crop up when the unit has fully come up to temperature.