Bryston 9B-SST-THX-PRO-120

The Bryston 9B SST THX is a modular, five-channel, single-chassis power amplifier that delivers 200 watts per channel into 4 ohms or 120 watts per channel into 8 ohms. 

The 9B SST employs modular construction in which each channel is completely self-contained, physically and electronically, with independent I/O connectors, toroidal transformer and power supply. The only things individual channels share is the rack enclosure and the power cord. 

Each channel is built on its own removable assembly, allowing any channel to easily be swapped out, and enabling the 9B to be configured with fewer channels if required. 

The 9B may be ordered in two to five-channel versions; the five-channel is standard. Additionally, any two of the channel modules in a 9B may be run in bridged configuration with an accessory cable.

As far as circuitry is concerned, it appears that Bryston kept the new amp essentially the same as the well-regarded original, making only minor changes to improve already excellent specs and adding a few theater/THX-related elements. 

Changes include the use of highly linear output transistors to improve already excellent high-frequency accuracy. Bryston also implemented a proprietary grounding scheme that reduces overall system noise, plus a few tweaks to receive its THX compliance.

The clean front panel features five LEDs that indicate operating status and five small recessed gain-adjustment pots; a membrane power switch is located in the bottom center of the faceplate. A rear panel toggle power switch doubles as a circuit breaker reset (no fuses). The amp features soft start power control circuitry to eliminate high inrush currents when AC power is applied. Power up of the 9B SST may be controlled by external components such as a preamp via a rear panel 12-volt input.

The rear panel is where all the action is. Each of the five modules includes an input select switch for choosing balanced input or single-ended input; a combo XLR/1/4-inch balanced input connector and an unbalanced input on RCA; a polarity switch for inverting the polarity of the input signal; a three-position input sensitivity switch selects 1 volt (THX home theatre standard for unbalanced inputs), 2 volts (for actively balanced inputs) and 4 volts (for use with high-output level preamps); and a heavy-duty three-way binding post that accommodates banana plugs, spade lugs and stripped wire up to 3 gauge.

The rackmount enclosure measures 19 inches x 5.25 inches x 19 inches and weighs a hefty 65 pounds. Maximum power consumption is 220 watts at idle and 2,295 watts at rated output into 4 or 8 ohms. 

According to the manufacturer's specs, distortion is less than 0.007 percent from 20 Hz to 20 kHz at rated output into 4 ohms. THD + Noise is less than 0.005 percent from 20 Hz to 20 kHz at rated output into 8 ohms.

Signal-to-noise ratio (measured with the input shorted; 20 Hz to 20 kHz) is greater than 110 dB at 29 dB gain and greater than 116 dB at 17 dB gain. Slew rate is greater than 60 volts per microsecond and the power bandwidth runs from less than 1 Hz to over 100 kHz.

In Use

I used the amp for a month in two environments with different objectives: multichannel mixing in a studio control room, and multichannel playback in a high-end home theater setup.

In the studio, hook up of the Bryston 9B SST THX was straightforward: two digital audio workstations (Pro Tools Mix Plus through a Digidesign 24-bit optical interface, and Steinberg Nuendo/Sonic Foundry Vegas system through a 24-bit RME 9652 interface) were already routed into a TASCAM DS-M7.1 surround controller; five XLR monitor outs were patched into the Bryston amp and out to the speakers (see review setup p. 68).

In the studio environment, I mixed several 24-bit/48-kHz multichannel music-only projects. Halfway through the evaluation, I added the Nuendo and Vegas system and was able to complete a few projects at 96 kHz, including music-only and sound design/multichannel mastering for video.

Without getting into too much audiophile adjectival mumbo, the amp performed and sounded like a Bryston: strong, clean and uncolored, and with a surprising amount of headroom for just 120 watts per channel into 8 ohms. The amp handled wide dynamic changes impeccably, and there was no perceptible crosstalk.

After a month, the amp was moved into my home theater for more, ahem, relaxed evaluation. Here, I could concentrate on the performance of the amp without distraction.

I auditioned many music-only and theatrical DVDs through the Bryston 9B SST THX. I used the multichannel outputs directly from the DVD player's surround decoders and through a Denon AVR-3300 acting as a preamp. There was a slight narrowing of the image and some added "fuzziness" or veil through the Denon's preamp, decoders and/or D/A. The moral here might be: "The fewer things between the source and the amp, the better." Or, "Time for a new preamp."

With the preamp out of line, the amp performed as above: powerful and dynamic with excellent imaging

Summary

I have always felt that playing back music through a Bryston sounds close to what was happening in the studio mix session. That is possibly because it was mixed on a Bryston; or maybe it is because it does not get any better when it comes to unfettered neutral and dynamic reproduction. 

But it does makes make me wonder why people in the audiophile market are willing to pay tens of thousands of dollars for an esoteric single-ended triode amp (because it is more soulful, musical; warm yet not limp; up front but not overly urgent...) when they can have the real deal for just a few thousand.

For both studio and home theater use, the Bryston 9B SST THX amp is worth every dollar - a true pleasure to work with professionally, or to simply sit back and enjoy.

Review Setup

Steinberg Nuendo and Sonic Foundry Vegas DAW with TC Works Powercore; Pro Tools Mix Plus DAW; SP Technology Timepiece 2.0 and Westlake LCW 8.1/4.75 monitors; Audience high-resolution speaker and audio cables; TASCAM DS-M7.1 surround controller.

BY  PROSOUNDNETWORK EDITORIAL STAFF