STATUS - AVAILABLE
Click here for more pictures

Description :
The Bryston 4B-ST is a quite attractive in its own modest way and not a room-filling equipment by any means. Sporting nicely beveled handles and two 45-degree chamfers running the width of the amp, it has nice business-like cosmetics that should not intrude on any decor. The front panel consists of a power switch with two green LEDs above it, nestled in the top groove. These LEDs are said to be three-color units to warn of clipping or its onset. Rated at 250Wpc (8 ohms) and up to 800 watts bridged (also 8 ohms), the Bryston 4B-ST never seem to run out of steam even at extreme levels. The stereo amplifier consists of two amplifier modules, each with its own +/- 85V power supply. Each of the two amplifier modules uses eight of Bryston's custom power transistors for a total of 16 output devices. The channels may be operated independently, or combined to form a single 800W monaural amplifier into 8 ohms. Other features include a stereo/mono switch, gold-plated input/output connectors, and switchable balanced XLR and RCA single-ended inputs.

The Bryston 4B-ST provides consistent, quiet power, and is responsive to dynamic recordings. Its high-current delivery and damping factor ameliorate to a good extent the upper-bass looseness. It delivers tight, and surprisingly good ambient retrieval well into the deepest bass. The mid/treble performance, specifically tonal voicing, delivers undiluted signals. It has some whitening of overtones in the upper midrange, accompanied by a slight drying of ambiance in the treble region. On some pop material, there seems to be a little lift in the treble response, nothing noxious but perceptible. The Bryston 4B-ST exhibits immense control of the speakers in the dynamic peaks of recordings. It addresses detail resolution through the near elimination of linear/non-linear distortions. It is quite capable in the area of imaging. The image bloom, or rather the sense of the recorded venue encompassing the listener, is actually improved, probably due to the lack of bass smearing in the stiff power supply, much like the way a bass trap affects the room acoustic, in that it unmasks previously hidden low-level information. The depth presentation is the Bryston 4B-ST’s only major shortcoming. When compared to some other heavy hitters, depth seems to be mildly foreshortened. But, at the rear of the soundstage that expands into the corners improves noticeably.

Specifications :
Type................................................Solid-state stereo power amplifier
Output Power...................................250W continuous into 8 ohms (24dBW)
                   ....................................400W per channel RMS continuous into 4 ohms (23dBW)
                   ....................................800W continuous into 8 ohms in bridged mode (29dBW)
Power Bandwidth..............................<1Hz to over 100kHz
Slew Rate........................................>60 Volts per microsecond
               ........................................>120 Volts per microsecond, bridged
Total Harmonic Distortion..................<0.007%, 20Hz - 20kHz @ 250 Watts
Intermodulation Distortion..................<0.007%, 20Hz - 20kHz @ 250 Watts
Noise...............................................>106dB below full output
Input Sensitivity................................1.4 Volts unbalanced
                       ................................2.8 Volts balanced
Input Impedance...............................50k ohms unbalanced, 20k ohms balanced
Damping Factor................................Greater than 500 at 20Hz, 8 ohms
Current Delivery................................16A continuous, 48A peak, per channel
Frequency Response........................1Hz to 100kHz, +/- 3dB for 1 Watt output
Signal-to-Noise Ratio........................Hum and noise, 108dB below rated output, 90dB IHF
Voltage Gain....................................30dB
Polarity............................................Non-inverting
Dimensions(w x d x h)......................48.5 x 41 x 15 cm
Weight............................................19kg

Miscellaneous :
XLR Input.........................................Yes
Made In...........................................Canada
Condition.........................................8/10 (Decent condition)

Product Information :
http://bryston.com/PDF/Manuals/3B-8BST_MANUAL.pdf (Manual)
http://bryston.com/PDF/Schematics/3B-8BST_SCHEMATICS.pdf (Schematics)
http://www.dnaelectronics.ca/specs/bryston_4b_st.html (Specifications)

Reviews :
http://www.soundstage.com/revequip/bryston_4b_st.htm
http://www.audioreview.com/cat/amplification/amplifiers/bryston/4b-st/prd_115643_1583crx.aspx
http://forum.audiogon.com/cgi-bin/frr.pl?ramps&1032915845&&&/Bryston-4B-ST-Amplifier
http://www.audioasylum.com/reviews/Amplifier-SS/Bryston/4BST/general/13943.html
http://www.stereophile.com/solidpoweramps/592bryston/index.html (Bryston 4B NBR)