12/23/2023 0 Comments Benchmark ahb2 review stereophile![]() ![]() You can't appeal to authority - I'm a musician so I am right - plenty of musicians and composers own tube amps and hate SS amps. Otherwise they'd all own the same system. Magazines hire reviewers and it's not like reviewers agree with each other. "The Benchmark AHB2 gets my strongest recommendation.Hi-Fi Critic is run by Martin Colloms who has written books on Loudspeakers, was the technical editor for Stereophile, is a recording Engineer, formed Monitor Audio Loudspeakers, came up with the often coined term PRaT (Pace, Rhythm and Timing).īut it is not the magazine. "The Benchmark AHB2 breaks new ground with respect to performance of power amplifiers." KellenVancouver, Forum Member Comments from Amir's AHB2 Test Report: "So far the only thing to displace a Benchmark product has been newer upgraded Benchmark products." ![]() "Been using Benchmark since the DAC1 came out." Rubinson, Forum Member, Stereophile Reviewer "I bought the AHB2s because I liked the sound from the get-go and the excellent measured performance was a great confirmation. "We know they are top of the heap in terms of measured performance, outdoing plenty of the competition in terms of typical distortion measurements." "I'm asking because clearly Benchmark is a highly regarded company here, and plenty of ASR members own Benchmark amplification/DACs." It is truly a high-resolution amplifier." Not only does its performance lie at the limits of what is possible for me to reliably test, it packs high power into a very small package, especially when used in bridged-mono mode. "Benchmark Media Systems' AHB2 is an extraordinary amplifier. (Note the expanded vertical scale in this graph.) The second and third harmonics lie at –128dB (0.00004%) and –124dB (0.00006%) with respect to what would have been the level of the fundamental both are close to the residual distortion in the Audio Precision's signal generator (fig.11)." ![]() To make the distortion harmonics stand out as much as possible from the level of random noise, I averaged 32 captures (footnote 1) to produce the graph shown in fig.10. "I performed a spectral analysis on the signal with the fundamental tone notched out, so that the full resolution of the Audio Precision's analyzer could be brought to bear on the distortion and noise with the AHB2 driving a 1kHz tone at 50Wpc into 8 ohms. The S/N ratio did increase by around 3dB in the lowest-gain condition, implying that the specified ratio was measured in that mode." Referenced to the AHB2's clipping power of 100W, this is equivalent to a dynamic range of 128.5dB, which is close to the specified 132dB. Reducing the measurement bandwidth to 22Hz–22kHz increased the ratio to 106dB, while switching an A-weighting filter into circuit increased it further, to 108.5dB. 1W into 8 ohms, was very high, at 89.3dB. "The Benchmark amplifier has a claimed S/N ratio "approaching 130dB," which, at 6.02dB per bit, is equivalent to more than 21-bit resolution. The wideband S/N ratio, measured in the high-gain, stereo condition with the input shorted to ground and ref. the clipping point is now 410W, this also a little higher than Benchmark's specification." "The AHB2 clipped at 108W into 8 ohms and 210W into 4 ohms, both powers slighter greater than those specified by Benchmark. In bridged-mono mode into 8 ohms. "The AHB2's channel separation was superb at >110dB in both directions below 2kHz, and still 90dB at 20kHz." "The amplifier offers a flat audioband response into 8 ohms, with then a –3dB point close to a high 200kHz, which correlates with the superbly square waveform of a 10kHz squarewave into this load, with short risetimes and no overshoot or ringing." These problems-and here I'm talking about the difference between 0.0003% THD+noise and 0.0005%-haven't affected the measured performance of other amplifiers I've tested, but they were detectable with the AHB2's very low intrinsic distortion and noise." Correctly characterizing the AHB2's measured performance would therefore present a challenge. And, to my embarrassment, one of the speaker cables with which I routinely measure amplifiers and my test load set to 4 ohms were also introducing small amounts of nonlinearity. "However, the Benchmark amplifier's specifications are close to those of my Audio Precision system, both regarding the purity of its signal generator and the dynamic range of its analyzer. "Conventionally, it is assumed that the measurement system used to test a product is much better than the device under test." at the Limits of What is Possible for Me to Reliably Test" ![]()
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