3B SST Power Amplifier

The SST series of amplifiers is a not unexpected development after the introduction of the 14B (Spring 2001, Vol. 20 #2) and the 6B 3-channel amp (Spring 2002, Vol. 21 #1), both of which used new Motorola output devices of greater linearity and wider optimum operating range to minimize both distortion (particularly crossover distortion) and transient speed. The SST series also has, according to Bryston's white paper, "doubled filter capacitance for even deeper and better controlled bass; a new proprietary grounding protocol which eliminates the need for ground-lift switches and reduces system noise; and a new computer-modeled heatsink profile for cooler operation and longer component life. Modular design and separate power supplies for each channel ensure cross-talk is essentially nonexistent, and provide precise and focused soundstaging."

"All SST amplifiers use Bryston's proprietary output stage, which we call `Quad-Complementary' [which] improves linearity to a new standard of accuracy, while virtually eliminating aggressive higher harmonic distortion products. The overall harmonic distribution...closely approaches an ideal Class-A output, except that the overall distortion is much lower."

Regular readers will know what I (and any other listeners) thought of the first two SST products. These amplifiers have created a buzz that spans North America and Europe with their sheer transparency and power, but more on that below. The only amplifier that has yet to go from ST to SST is the integrated B60, but not only will that happen soon, but an integrated version of the 3B will also appear next year.

Speaking of which, one of the additional virtues of the new output devices is their higher power output, so the 3B SST is rated at 150 rms watts per channel. Our review sample, as indicated on the measurement test chart made after its 100 hours of burn-in with a 10 kHz square wave and capacitive load at full output, clips at 172 wpc, as opposed to the 151 of our reference 3B ST. Of course, double the power is available at 4 ohms, making the new SST able to produce 344 watts into 4 ohm speakers like our Energy Veritas v1.8s.

It can also be seen that noise levels are typical Bryston, which means they are at least twice as quiet as just about anything else out there, -112 dB at 100-watt output. And the highest distortion measured, at 20 kHz and 150 watts, was .00594%, with typical figures around .002%.

Inputs remain flexible, with the pro trademarks of combined 1/4" and XLR jacks, as well as unbalanced RCAs, with a pair of toggles to switch them, so you could run one balanced and the other unbalanced. There's also a handy switch pair to help match preamp output and speaker efficiency that allows 1- or 2-volt input sensitivity. The ground lift switch is gone, but channel bridging is still possible, and our sample produced a staggering 504 watts in this mode, though you wouldn't perhaps want to go for a thousand at 4 ohms when bridged. By the way, speaking of staggering output that'll blow you away, the 7B in SST form is now rated at 600 wpc, and 900 at 4 ohms; the only reason output doesn't double is the current limit of 120-volt power lines.

An improvement has been made in the previously crowded together output binding posts, these now on either side of the rear panel, making them more easily accept exotic cable connectors. An additional feature for home theatre and multi-amplifier installations is a power trigger system that can be switched on or off; able to be ganged from amplifier to amplifier, it could be useful for bi- or tri-amped audio systems.

Moving my Kimber Select 3035 and BiFocal tri-wire cables from the 3B ST to the SST, I immediately noticed less edge on strings in the Telarc Slatkin Mahler 1st LP, and this was followed by notably more effortless dynamics as the 1st movement continued. I could also hear better lateral separation of instruments and instrumental sections, the cellos in particular being better defined as a group. As well, front-to-back delineation was improved. It was a little like being at a party and suddenly discovering that you could much better hear all the conversations around you and focus in on them more precisely. As I said to Bob Oxley the other day when he was here, the 3B SST makes you more "privy to the conversation."

This transparency is the amplifier's most obvious trait, and further listening revealed its lack of any listening fatigue or, indeed, character of any kind. The very low distortion allows one to perceive the utter absence of noise. Even with LP sources, the noise floor was lower than I've ever heard it. This may also be due to the new grounding system.

However, when you get down to double 0 distortion (.00197 vs .00225%), we're really splitting hairs, and one is led to conclude that it is perhaps the character of the measurable distortion that is most important. It may also be that the equipment used today is more precise than that of a few years back. In fact, I've kept the charts for all 3 previous 3Bs that I've owned, and all had measured THD of less than .004% on average, and ranged from 139 watts output at clipping to the current 172.

And as far as noise is concerned, few amplifiers manage to provide an S/N ratio that even approaches 100 dB, while the last 3 3Bs have comfortably exceeded this value. And anyone who doubts the value of having balanced preamp out and amp ins, should have the luxury of switching between them with 25-foot shielded cables. Balanced is better.

If an amplifier is supposed to disappear and become an acoustically invisible conduit for the music, the new 3B SST does it better than any other amplifier I've heard, or as the case must be, not heard. This one's a keeper, too.

We invite you to experience the Bryston SST² Series amplifiers

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