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Patent is modified prior art. This was posted in 2016 in diyaudio: Mark Johnson wrote:
New Bryston input stage measurable distortion < 0.001% (Audio Advisor): Just received the Audio Advisor catalog SP116 and noticed this blurb on page 5, about the Bryston 4B cubed power amp The new 4B3 power amplifier -- and all of Bryston's Cubed Series amplifiers -- features a new patented input circuit developed in conjunction with Dr. Alexandru Salomie that is precisely optimized and linear beyond any that Bryston has used before. ... The new input stage is so transparent its measurable distortion is less than 1/1000th of 1 percent! So I visited the US Patent and Trademark Office website and searched for patents that either (a) had Alaxandru Salomie as one of the named inventors; or else (b) was assigned to Bryston. I only found one: US Patent number 8,466,744 (attached below). It shows an input stage with a two complementary feedback pairs in a differential amplifier, with a current mirror load, and a third CFP used as a second stage, plus cascode. I redrew it below because the figures in the patent are crapped up with shaded overlays. For this they got a patent?
Chris Russell wrote:
I am the person at Bryston who worked with Dr. Salomie, (now sadly passed away), while he was developing the new buffer circuit. First, yes, the diagrams shown in the patent are somewhat simplified and representative. Second, much of what the patent describes has to do with the novel methods of maintaining stability in the circuit, as well as its ability to reject PS and CM noise. Bryston amps are well-known for linearity, focus, depth of field. The new Cubed Series is an evolutionary improvement on all the above, especially in 'difficult' environs. I hope that helps, at least a little.
Bryston seems to be all about specs and warranty. I was not a fan of my hefty 7BSST2 monoblocks and after trying to make them sound "musical" with various preamps - and tube rolling the tube preamps, I eventually gave up after a couple months. That's not to say they are bad amps, just not what I like to hear in amplification. Too lean clean clinical analytical and dry for my taste. Nice tight bass though. December 2017 My 7BSST2: - with ARC LS25mkII preamp
 December 2017 My 7BSST2: - tube rolling Aesthetix preamp
 P.S. The EL34 based Manleys spec rather poorly relative to the Brystons, but they sound incredible IMHO. EL34's are known to sound "glorious" but I've had several solid-state amps as well that I preferred over the Brystons.
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