Product Review - Bryston 9B-ST Five-Channel Power Amplifier - April, 1999
J.E. Johnson, Jr.
Bryston 9B-ST Five-Channel Power Amplifier
120 Watts RMS/Channel into 8 Ohms; 200 Watts/Channel into 4 Ohms
THD: < 0.01%
Damping Factor: 500
Size: 5 1/4"H x 19"W x 16"D
Weight: 59 Pounds
MSRP: $3,495 USA
Bryston, P.O. Box 2170, 677 Neal Drive, Peterborough, Ontario, CANADA K9J 7Y4; Phone 705-742-5325; Fax 705-742-0882; E-Mail email@example.com; Web http://www.bryston.ca.
Bryston is not only a company that has been in business for more than 20 years, but it is the only company that warranties their products for 20 years. They started out two decades ago just fixing anyone's Bryston amplifier for free, because so few of them broke down. So, when they went bigtime, they had to choose a warranty period. How about 20 years? OKAAAAAAAAY!
The Bryston 9B-ST is the five-channel power amplifier version of the 3B-ST (two channels), 5B-ST (three channels), and 8B-ST (four channels). All of these amplifiers are modular, with each module having its own complete power supply, including an 0.25 kVA (250 watts) toroidal transformer, dual 15,000 µF power supply capacitors, and ±60 Volts on the rail, providing 54 Joules per amplifier channel (that's 1,250 watts of toroid and 270 Joules of energy storage total, which is a LOT for a 120 watt/channel, five-channel power amplifier). Four bipolar output transistors per channel deliver 120 watts per channel into 8 Ohm loads and 200 watts per channel into 4 Ohms.
On the surface, it doesn't look intimidating does it, in a world filled with five channel home theater amplifiers rated at 120 watts per channel? One thing though: look at the weight . . . 59 pounds. That's pretty heavy for a multi-channel amplifier of such a modest rating. The reason? An absolute KILLER build quality. After all, this thing is supposed to be around for at least 20 years.
If you look at the main photo of the 9B (next to the specifications above), you can see some of the 28 screws that hold the cover on the chassis. Four screws attach each side, and four screws hold each of the five amplifier modules in place. There are so many, I decided just to use a stock photo of the 9B insides (photo at right). Click the video button and you will see and hear how solid the chassis is. You can see the five toroids and the upper power supply capacitors. What you can't see is the fact that each module is covered on both lateral sides (in other words, covering the transistors, resistors, etc., and also covering the underside where the solder joints are) by metal plates to seal out dust (the edges of each module are covered too), which over time, can decrease the heat dissipation of various circuit parts in uncovered amplifier boards.
The rear of the 9B has a three-prong (grounded) AC cord recepticle on the left, and then each of the modules' end panel, having an XLR balanced jack, slider switch for selecting balanced or unbalanced RCA (gold plated), and a +6 dB position for increased sensitivity in the balanced input (1 volt input produces 100 watts output into 8 Ohms instead of 2 volts input with the normal balanced switch setting).
The five-way speaker binding posts are unique and will be welcome to those of us who use spades and bare wire connections on our speaker cables. Each binding post has the usual opening in the back for a banana plug, but the front end has a slot and hole that serve as a convenient guide to slip the spade or bare wire into (see photo at left). It's very simple, very clever, and very useful.
The front panel has a push button on/off switch and five LEDs that indicate power on. They turn red at channel clipping. Massive handles let you carry the amplifier or move it around on a shelf. Actually, the handles add kind of a nice look to the front. The only handles I have are on my waistline.
We tested the Bryston 9B-ST with our reference home theater system, including the Yamaha DVD-S700 DVD Player, Yamaha DSP-A1 (used as a processor with the pre-outs going to the Bryston), Krix Speakers, and Nordost cables.
The first thing I would like to say is that the Bryston performed like a much more powerful amplifier. Undoubtedly, this is due to the massive amount of current available from the power supplies. 270 Joules is a large number for a five channel amplifier of this rating, so transients are given the large (short term) juice that they ask for. Bryston amplifiers had a reputation, some years back, of slight brightness. That has all been worked out of the design now, and the 9B sounded terrific at any volume I cared to set it to. Also, there is a tremendous amount of fine detail in this amplifier, something I only rarely hear in home theater power amplifiers. I could detect almost no hum, even though we have a very hum-inducing setup with lots of components and interconnects going all over the place.
The square wave response (10 kHz ±15 Volts) is practically straight up and down with nice tight corners, and only a small amount of overshoot. Measured bandwidth was 360 kHz (down 3 dB from 10 kHz sinewave value at ±20 Volts). This is a very wide bandwidth, which means no phase shift in the audible band. The 9B uses two voltage gain stages and four current gain stages, which give the large bandwidth.
In summary, the Bryston 9B-ST is a real wow product, with astonishing build quality and great sound. It has been designed for very high fidelity at modest power. However, I consider it to be conservatively rated, probably sneaking quite a bit more power for those high impact movies than one might imagine. It is obvious that Bryston has chosen to set standards rather than follow them.
John E. Johnson, Jr.
"You want to spend how much for that new amplifier in our home theater? Isn't the one in the receiver good enough?" Those might be the words coming from your wife when you tell her you are buying yet another box for the den. Hi-Fi equipment is expensive, at least the good stuff is. But, it's all relative. The problem is that our worlds exclude each other, even on vacations. We go golfing, and they go to the museums. We like audio equipment, and they like jewelry. Well, it's not such a problem after all. Here is a picture of a pair of tanzanite and diamond earrings I bought for my wife as an anniversary present (original design copyright Alex Samet 1998). They cost $2,500. About the same price as a Velodyne HGS-18 or M&K MX-5000 subwoofer, two of the best in the world. Now, I may be a typical male, but jewelry seems like just a bunch of shiny rocks that cost a lot of money. No inherent value, really. Bushels of uncut gemstones sit in warehouses to keep the price high. On the other hand, subwoofers, amplifiers, speakers, etc. have a whole bunch of stuff in them. Things that took a lot of work to make. Things that required parts from all over the country, maybe even all over the world.
You might wonder what a pair of earrings has to do with the Bryston 9B-ST. Well, both are handmade from the finest parts. Both give pleasure to their owners. Both are expensive, and both are worth it to the respective purchaser.
© Copyright 1999 Secrets of Home Theater & High Fidelity
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