Bryston 4B

Bryston 4B

250W/CH Stereo Power Amp Daily Rate: $40

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The Bryston ST Series amplifiers incorporate the use of an innovative gain stage topology which yields a substantially lower noise floor through the use of low-impedance pathways within the amplifier. This same approach also has strong advantages in reducing the overall distortion performance. Bryston's computer controlled distortion analyzers confirm Inter-modulation Distortion levels less than 10 parts per million (below 0.0009%) are typical for this new circuitry. All ST amplifiers use Bryston's proprietary Quad-Complementary output section, which improves linearity to a new standard of accuracy, while virtually eliminating aggressive higher harmonic distortion products. From input to output, all the circuitry in the ST series of amps has been optimized for the most accurate performance possible. Custom dual torodial power supplies provide precise and focused soundstaging. The dual power supplies employ multiple filter capacitors per channel, rather than single pairs of larger filter cans. This allows improved high frequency response and reduces overall losses in the supply. Standard features included both balanced and unbalanced gold plated inputs, a ground lift switch to reduce those annoying ground loops and a stereo/mono switch for bridging the outputs if higher power levels are required.


Amplifiers range in power from the 3B ST stereo unit at 120 watts per channel through the 4B ST stereo amplifier at 250 watts per channel, to the monstrous 7B ST monaural amplifier at 500 watts and the multi-channel 120 watt 8B ST. The 3B ST stereo amplifier at 120 watts per channel provides all the quality and value of our larger amplifiers but in a package which is both compact and powerful. Suitable for a wide range of audio/video systems where sonic accuracy, medium power and long term reliability is required.


A unique feature of the 7B ST is a switch allowing the output stage to operate in a parallel (current) or series (voltage) mode. This gives the 7B ST the power to drive, with breath-taking ease and clarity, speakers which have been considered "impossible" loads in the past.


Solid-state stereo power amplifier. Output power: 250W continuous into 8 ohms (24dBW), 400Wpc rms continuous into


4 ohms (23dBW); 800W continuous into 8 ohms in bridged mode (29dBW). Current delivery: 16A continuous, 48A


peak, per channel. Frequency response: 1Hz-100kHz, ±3dB for 1W output. S/N Ratio: hum and noise, 108dB below


rated output, 90dB IHF. Input sensitivity: 1.4V for 250Wpc into 8 ohms. Voltage gain: 30dB. 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 by 7 1/8" (181mm) H by 13½" (343mm) D. Weight: 40.1 lbs (20.2kg) net.


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