Running Benchmark AHB2 in bridged mode and 4 Ohm Speaker
That 18 amp number was a mistake if you read further down it was clarified to be 29 amps. I am not an expert just going by what I read on benchmarks site and various reviews. Benchmark used the amp at a 2017 show to drive a pair of 4 Ohm PCM monitors in bridged mode. Reviewers have used it to drive 8 Ohm, 6 Ohm and 4 Ohm speakers in bridged mode apparently with good results. Actually I agree with you and George I don't really see why 1 amp in stereo would'nt be enough with the OP's efficent speakers that have powered subs so this amp is just driving the mids and highs I assume. But he seems to want 2 amps to try in bridged mode and from everything I have read on this amp it can do it. |
djones51 Been there, done that. https://forum.audiogon.com/posts/1647982 and here https://forum.audiogon.com/posts/1647933 But he seems to want 2 amps to try in bridged mode and from everything I have read on this amp it can do it.Not really into 2ohm which is what the amps will think their driving (bridged) and then there's the disadvantages with bridging that I and many on the net outline. If there was no disadvantages then we'd all be using and selling bridged amps. Cheers George |
George I agree with you that with efficient low impedance speakers the OP may likely be better off with a single AHB2. However it’s worth noting that unlike most power amps, the Benchmark AHB2 does not have increasing distortion into lower impedance loads. The bridged AHB2’s distortion is just as low as in stereo mode - the THX AAA circuit takes care of that - the quoted THD+N spec is the same for stereo/mono "at full rated output into any rated load". This has been corroborated by independent measurements. Note that Benchmark only provides power ratings for nominal 8 and 6 ohm loads in bridged mono. In my case the bridged AHB2 amps do sound better than a single AHB2, but my ATC speakers are very different from the OP. The ATC’s are inefficient with high power handling (ATC recommends 75-300W) and have a nominal 8ohm rating with a minimum of 5.6ohms - pretty much the ideal application for the bridged AHB2. Using the amps in mono mode also allows for much shorter speaker cables, which may also have contributed to my positive impressions vs a single stereo AHB2. Having said the above, Benchmark have demoed with bridged AHB2’s on several occasions with nominal 4ohm rated speakers. So clearly they don’t see any issue. Here is a recent positive impression: https://parttimeaudiophile.com/2018/05/21/axpona-2018-benchmark-stays-smooth-with-martin-logan/ |
In my case the bridged AHB2 amps do sound better than a single AHB2, but my ATC speakers are very different from the OP.Yes because your speakers need the extra watts, the OP’s don’t, and that’s what the discussion is all about. I would lay money on it, that if your speakers didn’t need those extra watts, you’d be saying one stereo sounds better that two bridged, regardless of the cost saving. Roger Modjeski (Ramtubes) a few posts back has also tried to say similar. Cheers George |
