Bryston 9B-THX five-channel power amplifier
By Larry Greenhill   •   September, 2000 Bright April Sunday sunshine beams through the bay window of my listening room. The light catches four loudspeakers on stands, two stacks of electronic equipment, a small video monitor, black cables strung behind furniture, and a pile of freshly opened DVDs. I sit in the center in a large, overstuffed chair covered in blue velvet, listening to an array of six loudspeakers and a TV monitor playing The Haunting's DTS soundtrack. The floor rumbles as the sounds of creaking timbers come up from below.

Now it's late June and I'm looking back on my metamorphosis. Like other middle-aged American males, I have reinvented myself. I have shed my skin and tried not to look back.

Big words, right? No, I hadn't taken up bungee jumping, hang-gliding, or racing a BMW 2001-series M3 (not that I'll turn down any offers). What had been tempting me more and more was the thought of being engulfed by the sound of a DVD-based multichannel audio/video system. Auditioning the Bryston 9B-THX—a hot new five-channel, solid-state A/V power amplifier—seemed like an easy entry to this brand-new technology. Or so I thought.

The transformation took some doing. I had to learn a new audio language, tear down my two-channel system, install new speaker cables and interconnects, run onscreen system configurations on DVD decks and A/V processors, and realize that my expensive built-in wall shelves were woefully lacking in space for gear. No more Rutter Requiem—I now use a brand-new set of DVD source material (see sidebar, "Welcome to the Real World"). Armed with a copy of Len Schneider's superb Guide to Better Hi-Fi and Home Theater and leaning on Denon's David Birch-Jones and Lexicon's Bart Lo Piccolo for A/V technology phone support, I dove in.

How did I feel? Not too bad—say, like the moment after Neo takes the red pill and is disconnected from the Matrix in the film of the same name.

But I'm getting ahead of myself. This is a review of the Bryston 9B-THX. I asked to review this product because the word on the street was that it might be the best Bryston amplifier since the 7B-ST monoblock. The 9B-THX arrived well before I completed the surround-sound installation, so it started its audition in two-channel mode. I really liked what I heard, but the best was yet to come.

Beefy Construction
The 9B-THX is a massive solid-state amplifier, much of its heavy iron coming from five large toroidal transformers and a stiff, rigid, reinforced-steel chassis that would seem to make the product reliable enough to last twice as long as its 20-year warranty. The model is designed to last in professional audio installations, where ruggedness is a main virtue.

Thermal pathways had to be carefully laid out. It's not unusual for a 9B-THX to be mounted by its front panel in a rack and transported in a truck for hours over rough dirt roads to the next gig. While removable, the plug-in channels are clamped down by capping plates to prevent anything from getting loose inside the chassis. Should a module fail, the bad channel can be repaired by simply removing the old module—transformer/circuitry/output stage/heatsink—and plugging in a replacement. The 9B-THX's 75 lbs make it the second-heaviest Bryston amplifier in production, outweighed only by the very new, 600Wpc 14B-ST.

A Roscoe S-1 Square recess screwdriver is required to loosen the 30 countersunk Robertson machine screws that fasten the 9B-THX's top panel to its chassis. These screws fit snugly into the chassis' threaded steel inserts by means of a locking thread-sealer that lowers vibration and increases structural stability.

The 9B-THX is the most densely packed Bryston product I've seen. Five large modular amplifier-channel motherboards consume all available interior space. These line up vertically, like plug-in computer cards, fitted into gold-plated edge connectors. Each channel module's large toroidal power transformer is mounted on edge just behind the front panel: except for the common AC cord, the 9B-THX is a collection of completely separate amplifiers in one chassis.

The circuit boards are very-high-quality double-sided glass epoxy with component-designator screening. Soldering is done by hand to avoid damaging the PCBs with the 800 degrees necessary for automated wave soldering. Soldered and other gas-tight mechanical connections are used for signal circuits, while power-supply circuits use high-quality push-on connectors.