THD+N Ratio 50W Bridged Mono by Jon Hancock, on Flickr Next up some frequency sweeps at different power levels. It's a very competitive $2995 mono block, given the overall performance. Let's widen the frequency range of investigation- but keep in in bridged mono. Now we're seeing a bit past 350W at the clipping point- because the two channels are being added in series, the noise floor is doubled, but we're still looking at less than 0.001% at 10W output. THD+N Ratio vs Measured Level Benchmark AHB2 Balanced Mono by Jon Hancock, on Flickr Move the SpeakOn output connector (you did get some of the Benchmark Speaker cables, didn't you?) flip a switch, and voila, a miniature bridged mono block amp. OK, that's impressive, but what about that bridged mono mode? Benchmark supports in directly with a separate SpeakOn output connector, and using the balanced inputs and stereo-mono switch. For a speaker that's 90 dB efficient, 100mW is a conversational playback level.īy 1W we're down to 0.001% THD+N, and 20W we've reached 0.0003%! Yes, three zeros in front of that 3! One of the things one ought to do to appreciate this amp is compare what it's THD+N figures look like at 100mW compared to may other "high end" amps out there- here, we're coming in at 0.003%, and I've seen many amps for 10X the money coming in at 0.02 to 0.07% at 100mW. It's possible with with more careful approach to lead dress and the test setup, I could have gotten better numbers than this, but let's leave that for the future for now. THD+N Ratio vs Measured Level Benchmark AHB2 by Jon Hancock, on Flickr. :Wįirst, we'll look at the swept sine behavior starting from a level a bit below 100mW and proceeding up to the clip point, at 1kHz. So don't expect to see as low numbers as JA published. (Keep in mind I DIDN'T use the Pro level input setting, which requires even more front end drive, and improves the SN ratio further- this middle ground setting will work fine with most good stereo preamps, say, units comfortable driving up to 4 or 5VRMS out). So, is this a "First Watt" design? optimized just for low Power? Let's take a look. and about how your preamp does or doesn't match up to that! Just think about how quiet the front end on this has to be to reach that level of performance. No, you didn't misread that at 6 watts output power, the THD+N (Total Harmonic Distortion + Noise) is just 0.00042%. something one might have not believed could exist commercially for under $10K or $20K, much less for $3K.įirstCheck_SmallWindow by Jon Hancock, on Flickr But nonetheless, when I finished connecting one of these to the AP, set the gain control switch to the mid point (adjustable between true Pro levels, a compromise level, and consumer input level- I went for the middle ground) and fired it up, and default it's showing a moderate level output signal (7VRMS with 1VRMS input), reading out the levels and THD+N, with a default FFT window, and right away, you know there's something special here. but seeing how those XLR and SpeakOn connectors fill the rear panel, you realize this is pretty itty bitty for an analog power amplifier (to be fair, it does use a very sophisticated resonant switching power supply, though).Ģ0150726132016_BenchmarkAHB2AmpFrontWeb by Jon Hancock, on FlickrĪnd I've listened to these for hours and hours since just before Thanksgiving, last November. The Benchmark AHB2 is a nicely proportioned little amp that seeing just a picture of the front may not tip you off to how diminutive it is. I've seen John Atkinson's measurements on Stereophile. You know, sometimes you know right away good things are happening.
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