HiFi Test Magazine

Unfortunately the manufacturing of an audiophile high-end pre and power amplifier combination is not quite as simple as described above. Many years of experience, comprehensive know-how, and foremost a proper amount of musical "feeling" are necessary in order to build an unsurpassed top class HiFi product. Bryston has recourse to these virtues, because HiFi Products of extremely high standard have been developed and manufactured by the amplifier specialists from Ontario (Canada) for over 20 years. A quick look info the long list of professional Bryston customers reveals the best-known sound studios of the world and a long list of radio and TV stations, all of whom rely on the indestructible construction and excellent sound quality of the Bryston products. What other manufacturer, besides Bryston provides a 20 year warranty for their products? HIFI TEST evaluated the combination consisting of the BP 25 preamplifier, with MC phono stage, and the 4B-ST Power Amplifier for you.

Behind the almost unassuming name, 4B-ST, hides a true power amplifier meteor. Already the robust housing of massive metal in flawless workmanship arouses astonishment. The inside of the 4B-ST is dominated by two gigantic transformers which together with large quantities of electrolytic capacitors. provide completely separate power supplies for both output stages. The actual output stage circuit boards for the completely independent monaural sections are mounted directly on the massive heatsinks which provide adequate cooling for the eight output transistors of each channel. Besides the truly impressive dimensions of the subassemblies and the clearly visible conscientiousness of manufacture the 4B-ST "power house" offers a small technical subtlety which is unique in amplifier technology Bryston's chief developer Stuart Taylor, (from whence the ST) does not, as is usually done, utilize N and P transistors respectively for amplifying the positive and negative half-waves music signals, but instead lets both the N and P types operate simultaneously. By use of this unconventional but extremely effective, circuit design, small asymmetries between the N and P transistor types are cancelled out. The result is almost ideal behavior especially during the amplification of small signals.

For the technical layperson the simpler apparent high1ights of the 4B-ST are its immense output, the impressive laboratory data, and the distortion-free balanced XLR inputs. With 2x 396 watts and a 4 ohm load, a distortion factor of two zeros after the decimal point, and a damping factor of over 300 (over 100 would already be remarkable) the 4B-ST amplifier is totally beyond the norm. And those, who want even more, can operate the 4B-ST in bridged mode and enjoy 780 watts at 8 ohms. Additionally it is astonishing that even the region of 100 kHz is amplified without glitches, proof of the enormous "speed" and "clean" (circuit) design of the 4B-ST.

BP 25 Preamplifier with Phono Stage
The matching BP 25 preamplifier with its extensive components provides competition for many a power amplifier. Constructed no less expensively than the 4B-ST, the BP 25 boasts 5 unbalanced RCA, 2 balanced XLR, and one MM/MC phono input, as well as two (unbalanced)RCA and one (balanced) XLR outputs. The switchable phono section consists of an elaborate, discretely built MM section and two high-grade (and immensely expensive) mumetal encapsulated MC transformers. In order to keep interfering electrical fields away from the sensitive subassemblies of the preamplifier, the power supply of the BP 25 is built into a separate housing. An encapsulated rotary switch, located directly behind the inputs, is used for switching input sources. Especially interesting for sound perfectionists is the "phase switch" on the front of the unit, which by simply inverting the musical signal produces to some extent with certain CD's (for example "Graceland", Paul Simon) amazing changes in spatial reproduction. Furthermore the remote control, which controls volume and phase, is up to par because it is made of massive metal and fits comfortably in one's hand.

Listening Test
We connected the BP 25 phono preamplifier, the 4B-ST power amplifier, and a Proceed "CDP 1" CD player with balanced cables from Sun Audio, and allowed a three-day warm-up period for the entire combination. For the test we used a pair of JBL L90 and two Celestion Kingston loudspeakers in our listening room. The first listening attempt was carried out with the JBL dynamic monitors and. the Quincy Jones production of "Handel's Messiah." The massive, abysmal drum beats right at the beginning of the "Overture" were reproduced powerfully and. at &e same time extremely precisely and controlled by the Bryston combination. The percussive , dynamic upper tonal sections of these drums were reproduced so naturally and glass clearly that one could believe that one were sitting directly next to this drum. The enormous effort that is simultaneously required in the bass region, the Bryston combination achieved without batting an eyelash Where other amplifiers become "bloated" and ' harsh " at high volume levels &e Bryston combination really came into its own. At the same time the 4B-ST did not act simply as a power house. the "Kingston" speakers from Celestion, beloved for their true tonal and spatial reproduction revealed further strengths of the Bryston combination Loose, airy and lively without acting nervous or hyper active, the preamplifier and power amplifier always stayed with the matter at hand and reproduced "Keb Mo's" acoustic guitar true to life in the listening room. The strong impressive voice of the black blues singer radiated with every V percussive attack of his percussive of his guitar resounded almost explosively Even intensive lower notes were cleanly reproduced with extreme precision despite the rather compact "Kingston" speakers - thanks to the 4B-ST.

Conclusion
It's not a surprise that sound studios depend on Bryston amplifiers The almost unlimited dynamics, the nimbleness and speed of the Bryston combination imbue all types of music with not simply more apparent pressure but and musicality to the light day -that is genuine reference qualities In light of this high sound standard and the imposing manufacturing quality we can unconditionally recommend this combination for about 9,000 g marks!