[HooStat]

There is a very nice review in Secrets of Home Theater and High Fidelity of the 3BSST2.  It makes me want to run out and get one. 

I was struck by one thing in the review about "fully balanced".  I was just curious as to whether the author is correct (that fully balanced makes a measurable difference), or whether Bryston is correct (that just the input stage needs to be balanced).  I don't think there are any issues, of course.  I was just struck by the slight difference in results with the 14BSST2, and since this is not my area of expertise I thought others might be able to educate me on this topic.

From the review (http://www.hometheaterhifi.com/power-amplifiers/907-bryston-3b-sst2-stereo-power-amplifier.html):

"Distortion measurements were made within an 80 kHz bandwidth and into a Carver Mark IV ribbon speaker. Power output and distortion vs. frequency were made using 8 or 4 ohm power resistors.

At 1 kHz, THD+N was very low, just like the 14B. Totally within specification. The distortion was primarily 2nd order, and that is something I love to see in distortion spectra. The peaks in the 18 kHz - 21 kHz range are electrical noise in my AC lines. They are not a product of the amplifier and are below audibility. However, they do make an interesting variable to take note of in terms of noise rejection. It shows up in the 3B, but in the 14B, which is fully balanced throughout, the peaks did not show up, because of common mode rejection, which is one of the principal advantages of a balanced circuit."

Link to Bryston discussion on "differential amplifier balancing":  http://bryston.com/newsletters/31_files/vol3is1.html

[rob80b]

Hi HooStat

Bryton’s implementation for their balance inputs on the smaller amps work fairly well, the 14B is a much bigger beast with different circuit topography, so any residual noise would be amplified that much more.

As per James

“We do this on the 28B's the 7B's and the 14B's because they are 'series' designed amplfiers.  The 9B,6B,4B 3B and 2B are not series designs so we do not use independent circuit paths for them.  We use fully differential balanced inputs on all our amplifiers to reduce noise at the input if using a balanced system.

The so called fully balanced topology in the larger amps has much more to do with the 'series' design philosophy rather than any particular performance advantage.”

The 3BSST2 would be a nice replacement over the 9BST, not so much in power but in terms of finesse and naturalness of tone, especially in the upper frequencies, which your Dyns will be more than happy to demonstrate.

“It makes me want to run out and get one.”, sounds like a good idea to me."

Robert

[HooStat]

I ended up ordering a 4B SST2, just today.  Decided to opt for a little more power.  Looking forward to comparing things.

[James Tanner]

I ended up ordering a 4B SST2, just today.  Decided to opt for a little more power.  Looking forward to comparing things.

Great - looking forward to your feedback.

james