![]() The dynamic range approaches 130 dB, and the frequency response extends below 0.1 Hz and beyond 200 kHz. In fact, Benchmark said, the AHB2 can perform reliably at lower impedances than 4 ohms. The black AHB2 High-Resolution Power Amplifier from Benchmark is designed to accurately reproduce high resolution audio. In any case, my speakers will be protected. Above I quoted the power output of the Benchmark AHB2 into 8ohms, Benchmark provides a series of measurements at different loads in their specifications, it is refreshing to see the complexities of such specifications acknowledged. Benchmark further assured me that this pre-condition did not represent actual conditions when playing music, so I should be fine. HiFi specifications are an interesting subset of lies, damned lies and statistics. Under these conditions, the protection mode would be asserted, which seems to be supported by the review here. In fact, the performance of this new analog amp rivals the measured performance of its world class DACs. I queried Benchmark about why they do not list specifications for bridged operation into a 4ohm load, and they replied to the effect that they do not list output specifications unless the output has been preconditioned, if memory serves me correctly, at 1/3 output for 1 hour. The new compact AHB2 however, is a new design that takes amplification to another level in terms of measured specifications. Benchmarks AHB2 power amplifier delivers musical details without introducing the masking effects of amplifier noise and distortion. ![]() I am interested in using two AHB2's in bridged mode, driving a pair of 4ohm (minimum) speakers. The AHB2 is the ideal match to the performance limits of High-Resolution-Audio (HRA) formats. The review briefly discussed this configuration and the low distortion associated with it, and continued to note that the speaker protection switched in and shut the output off. There are a few small schematic drawing errors in the power stage- ignore them, they don't translate to the actual amplifier.The efficacy of using the AHB2 in mono mode driving a speaker with a 4ohm impedance was not clear to me from this review. ![]() ![]() Schematic is attached, VAS is virtually a complete amplifier on its own. It uses a most interesting design and I wonder how it differs or is similar to other systems like the Benchmark? Perhaps you can comment on the topology and any similarities, this amplifier has always intrigued me (I have few of them) and apparently caused more than a few techs and designers to scratch their heads back in the day. That needed 150MHz fT transistors in the front end/driver and 35MHz output stages and it was made in 1983! Other feedforward/'non-nfb'/direct distortion cancelling power amplifiers from the past specified huge numbers for slew rate and not just internal. Scott, the post above simply asked whether the AHB-2 rated amplifier slew rate of 16V/uS was "sluggish".Ĭlearly, the 16V/uS quoted is surely an outer loop (overall) worst case number for the AHB-2 amplifier as a whole, wouldn't you say? Wouldn't you consider 16V/uS overall (line in to speaker out) sufficient at large outputs to reproduce content in the audible bandwidth without slew-induced distortion rearing its head?
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