Here is excerpt from Absolute Sound Paul Seydor review of my amplifier Benchmark AHB2:
AHB2 employs different technique of correcting transistor nonlinearities. Instead of applying negative feedback to the input it utilizes two parallel amplifiers for each channel - one for the signal and another for the error (8 power transistors per channel). Correction of nonlinearities is done at the output instead of the input. This technology called AAA (Achromatic Audio Amplifier) was bought by Benchmark from THX (George Lucas). To me this amp is as smooth/liquid as it gets, with wonderful extension on both ends and serious slam.
Ralph, reducing bandwidth at the input to one that amp had before feedback was applied should prevent TIM, but requires fast and linear transistors that are expensive. Using more feedback instead is very tempting since even shallow 20dB feedback improves everything tenfold (bandwidth, output impedance, THD, IMD).
Because accuracy allied to absolutely reliable performance is the goal of all the Benchmarks, they are not products that tend to attract cults or other sorts of starry-eyed enthusiasts, wholly lacking any of the quirks, foibles, idiosyncrasies, sonic flavorings, euphonic distortions, and so on that characterize the objects of most audio cults. Professionals buy Benchmark because they know the products work and are reliable and accurate—indeed, reference caliber. Music lovers buy them because they are neutral and accurate and thus reproduce the tonal character of voices and instruments correctly (and also, I presume, because they are reasonably priced, most musicians, like most other people, being typically not wealthy). But audiophiles? Well, the longer I’m in this racket, the less I sometimes think I understand what audiophiles really want except that a lot of dallying about with components, equipment swapping, and coloration matching seems to be what amuses them. I’m not sure I can in good conscience recommend this amplifier to them as I am not sure they are in search of what it offers: a precision instrument designed to perform the precisely defined task of reproducing music and sound accurately, which it does essentially to perfection. But to anyone else, the AHB2 gets as high, enthusiastic, and confident a thumbs up as my arm is capable of reaching.
AHB2 employs different technique of correcting transistor nonlinearities. Instead of applying negative feedback to the input it utilizes two parallel amplifiers for each channel - one for the signal and another for the error (8 power transistors per channel). Correction of nonlinearities is done at the output instead of the input. This technology called AAA (Achromatic Audio Amplifier) was bought by Benchmark from THX (George Lucas). To me this amp is as smooth/liquid as it gets, with wonderful extension on both ends and serious slam.
Ralph, reducing bandwidth at the input to one that amp had before feedback was applied should prevent TIM, but requires fast and linear transistors that are expensive. Using more feedback instead is very tempting since even shallow 20dB feedback improves everything tenfold (bandwidth, output impedance, THD, IMD).
