Bryston 4Be Amplifier - Rare Professional Studio Model

Free Shipping on *ALL* Electronics (Excluding Speakers, Contiguous 48 US States Only)

This Bryston amplifier is working and tested perfectly in our lab and listening room.  Some scratches on the top and on the side as shown in the photos.

The "Be" was the first of the new NRB series of amps before Bryston changed the name to NRB. The "e" in "4Be" stands for Engineering.

Note that this is a rare professional model with XLR and 1/4" TRS style connectors.  This piece came to us from Sony Studios / Sony Music Entertainment.

More from Bryston:

"Bryston's 4B stereo power amplifier consists of two amplifier modules, each with its own ±85v power supply, which can be operated independently or combined (MONO mode) to form a single 800 watt amplifier (8Ω load) in a 3 rack height chassis. Operated independently (DUAL mode) each channel can deliver 250 watts into 8Ω (or 400 watts into 4Ω).  Each of the two amplifier modules use 8 of Bryston's custom power transistors for a total of 16 output devices per 4B."

Specifications:

Frequency response:
1Hz – 100kHz, ±3 dB for 1W output

S/N Ratio:
Hum and noise, 108 dB below rated output, 90 dB IHF

Input sensitivity:
1.4V for 250Wpc into 8 ohms

Voltage gain:
30 dB

THD+noise:
20Hz – 20kHz, 0.01%

IM distortion (60Hz+7kHz, 4:1, SMPTE method):
Less than 0.01% at rated power

Damping factor:
Greater than 500 at 20Hz, at 8 ohms (equivalent to an output impedance of less than 0.016 ohms)

Input impedance:
50k ohms unbalanced, 30k ohms balanced

Polarity:
Non-inverting

Dimensions:
16-3/16" (411mm) W
7-1/8" (181mm) H
13-1/2" (343mm) D.

Weight:
40.1 lbs
(20.2kg) net.

Click here for a PDF copy of the Bryston 4Be / NRB Owner's Manual

Our Testing Process for Amplifiers (Solid State) at SkyFi:

We start with a visual inspection of all internal components to make sure there are no signs of stress or aging. Capacitors are checked for telltale sings of bulging or leaking, resistors are checked for signs of overheating or cracking, and transistors are checked for signs of stress or damage.

We then power up the unit carefully and run a simple 1k sine wave while monitoring the output on an oscilloscope for signs of distortion or noise. Finally, we run the amplifier to its full rated power into the appropriate resistive load provided by our Sencore amplifier tester. If there is an issue, it will usually be noticeable at this point. If everything reads clean, we will often test for THD (Total Harmonic Distortion) measured by our Keithley distortion meter, and compare it against the original manufacturers specifications. The amplifier then remains powered on to "burn in" on our test bench for a few hours to make sure there are no heat related issues. If there are balanced inputs available they will be also be tested.

Final testing involves pushing actual music thorough the amplifier. We've learned over time that some issues are only noticeable to a trained ear while listening to familiar source material. Our test bench has reference vintage Kef speakers that we're very familiar with which quickly reveal any discrepancies. Some amplifiers will then move into our listening room where they are tested with our in-house reference speakers of choice.

Please click here for detailed specifics regarding our specialized packing process that separates us from the rest.