Authorized re-print of
AUDIO (Czech Republic)
December 2002

Bryston 4B-SST power amplifier

Marek Svejda

Today's already legendary line of Bryston power amplifiers bears the name of Mr. Stuart Taylor (ST). On the Czech market, it introduced its designer team as perfectionist, seeking the objective technical excellence. Continuing this quest for perfection, we introduce the brand new Bryston SST amplifier lineup, which brings several new design ideas. One of the most interesting members of this new line is the relatively affordable (in a high-end context) Bryston 4B-SST power amplifier.

What stayed the same

Similar to its predecessor the 4B-ST (review Audio 9/2000), the Bryston 4B-SST could be considered a product of "orthodox functionalism". The construction does not offer any unimportant features, which could be used just to lure the uninformed customer. The marketing department of the company obviously relies on the fact that the product, which completely fulfills the function it is designed for, will sell the best. In the case of an amplifier, this task means accurate amplification of the input signal - nothing more, nothing less. The circuitry is designed to most accurately approach the proverbial "wire with gain". One key design feature is the patented Quad-complementary interconnection of power transistors in the output stage. This circuit - developed by Bryston - results in excellent match of complementary characteristics of both types of transistors, which elegantly eliminates the crossover notch and other types of distortion. Another standard issue is the dual-mono construction, which minimizes channel interaction. Similarities to previous ST line could be seen in excellent execution. The robust, all-metal chassis has heavy-duty output terminals on the back. 8mm spades, banana or bare wire up to 6 mm diameter could be used for connection. The source could be connected to Balanced symmetrical or single-ended (RCA) inputs. The amplifier is available in black or silver version, 19" with handles for rack mounting or 17" standard.

What changed

From the point of sound quality, two main areas were addressed. The power supply was completely redesigned and the original output transistors were replaced by new types with better linearity and lower distortion. For them, new heatsinks were designed. The new power transistors were first used in 14B-ST and 6B-ST (now SST) power amplifiers. The power supply uses new more powerful power transformers, which have better immunity against "impurities" in the mains supply. The result is lower mechanical noise. The transformers are now stacked behind the front panel. Radical changes can be seen in the filtering and stabilization which is now located on the separate circuit boards running almost whole depth of the amplifier. These changes allowed for doubling the filtration capacitance and simultaneously for shortening the path between power supply and power transistors. As a result, the power output of the amplifier increased by 20 % and now reaches 500 watts into four-ohm load.
The changes affected also the soft-start circuitry. In the middle of the front panel is now a membrane switch (under SST logo). The main power switch is on the back and doubles as a mains fuse. The amplifier could be automatically powered-up when connected to switched outlet or by 12-volt trigger. This function helps when the amplifier is used in more elaborate multi-channel systems. New is also the possibility to set the gain for both Balanced symmetrical and single ended (RCA) inputs.

And how does it sound?

The reproduction contains all of the excellent sound quality found in the previous ST model. The sound is extremely clean and free of any colorations. It excels in extraordinary dynamics in the entire frequency band and has extremely accurate localization of sound images. In direct comparison to the predecessor, the newly dimensioned power supply shows its abilities. In the low frequency region, the reproduction is without a doubt more solid and more energized. Subjectively, the listener is less aware of a prominence in high-frequency regions. This effect is, in my opinion, the result of better linearity and, as a consequence, lower distortion of the new power transistors used.

In general, the reproduction is more neutral and everything is under even better control. The older Bryston 4B-ST has delicate, more euphonically sounding treble frequencies. Its reproduction could therefore, in some cases, sound more attractive due to emphasized depth localization. It is obvious that the sound characteristics of the Bryston 4B-SST are clearly extraordinary in its price category and to find comparable competition would be very difficult.

Summary

At the recent Top Audio exhibition in Prague, the visitors could hear the amazing sound quality of Bryston 4B-SST's driving the mighty Bowers & Wilkins Nautilus loudspeakers (system with four-way active crossover, two 4B's per channel). Everyone who had the opportunity agreed that it was an unforgettable experience.

This amplifier represents excellent performance for the price. The customer receives top-notch technology in service of music reproduction and not the expensive mixture of unnecessary design creations as with many other high-end components. Bryston is the excellent choice for sound perfectionists who want to hear what was recorded in the studio and not what the amplifier designer wanted them to hear.

We invite you to experience the Bryston SST² Series amplifiers

20 Year Warranty - A Generation of Music