Review and Measurements of Benchmark AHB2 Amp

[Rottmannash]

Thanks for the impressions.

I've owned several amps over the years capable of differentiating between different quality sources, and seemingly pretty neutral in terms of balance. I'd be interested to hear an AHB2 to see if it brings anything new to the table subjectively that the others haven't. Will try to get a home demo as soon as it's possible.

Try a Purifi as well if possible.

 

[iwantobelieve]

Try a Purifi as well if possible.

Definitely. Ideally I’m going to try and get a side by side demo of these two. Very curious - never heard Class D before.

 

[Olli]

Weird.. Amir measured it bridged at 4ohm load (500W continuous) so that would mean in normal usage 250W in 2ohm.
Sure.. its not a doubling
in power (185W 4ohm should be around 350W in 2ohm) and protection may kick in but how many speakers are 2ohm or lower below 200Hz ?
That's where most of the needed music power goes in to.

My speakers are the ones that should cause massive issues in my setup due to the AHBs "2 Ohm problem" I guess:

Two AHBs in bridged mode, RME Adi 2 Pro FS, + 2 Rythmik F18 Subs crossed at 78 Hz. Crossover & DSP via Audiolense. What problem shoud I be experiencing in theory? Spolier: I don't in real life for almost 3 yrs now...

 

[solderdude]

You should not bridge the AHB when using such low impedance speakers.
In normal operation the amp might be fine and won't go into protection.
In normal situations one never reaches anywhere near clipping levels.
Only at near clipping levels and high continuous music power it may become an issue.

I would just contact benchmark and ask them if the speaker is suited.

 

[dlaloum]

My speakers are the ones that should cause massive issues in my setup due to the AHBs "2 Ohm problem" I guess:

Two AHBs in bridged mode, RME Adi 2 Pro FS, + 2 Rythmik F18 Subs crossed at 78 Hz. Crossover & DSP via Audiolense. What problem shoud I be experiencing in theory? Spolier: I don't in real life for almost 3 yrs now...

Yes, well my Quad 606's are fine at 2 ohm- totally stable, and sound great with a number of electrostatic speakers that have difficult (low impedance) loads...

They just don't sound their best with the Gallo's

Just because an amp can run into certain loads, doesn't means it sounds its best into those loads.

 

[aj625]

My speakers are the ones that should cause massive issues in my setup due to the AHBs "2 Ohm problem" I guess:

Two AHBs in bridged mode, RME Adi 2 Pro FS, + 2 Rythmik F18 Subs crossed at 78 Hz. Crossover & DSP via Audiolense. What problem shoud I be experiencing in theory? Spolier: I don't in real life for almost 3 yrs now...

It will also depend how much power you are using. Nobody will in theory use 100w. If you are well below you are unlikely to reach the limit. I have never experienced. 78hz is too high for a decent bookshelf speaker I guess. With 78hz lower extension you won't reach the limit anyway I guess . Remember ahb2 is the only one of few amps which is rated for full power at it's least distortion figure, not 1% or 10% thd. Though it won't allow that much clipping anyway and will stop the output. I guess people are nitpicking ahb2 just for the heck of it, without even listening it. It's one of the most competently designed audio product you would ever see. Even after 7 years or so of production nothing has superseded it in terms of overall performance. I would suggest everyone to try asap.

 

[Olli]

You should not bridge the AHB when using such low impedance speakers.
In normal operation the amp might be fine and won't go into protection.
In normal situations one never reaches anywhere near clipping levels.
Only at near clipping levels and high continuous music power it may become an issue.

I would just contact benchmark and ask them if the speaker is suited.

Not a problem according to Benchmark. And yes, I am not listening at crazy levels (mostly around 70-85 dBc at the listening position). At these levels, I am at between - 40 to -25 dB with the RME (+24 dBu, AHB2s in low gain settings accordingly) . And please note that I am using up around 12 dB headroom due to my DSP solution. So I would say that the Benchmark AHB2 "2 Ohm problem" is a very theroetical one.

 

[sq225917]

Having run the benchmark, nc400's and 4x neurochrome mod86p as bridged monoblocks all level matched my feeling was the nc400 was a little tighter in the bass but had a glare to the treble, the 86p smoother was in the treble but less extended in the bass and the benchmark somewhere in the middle.

I live with the neurochromes, could live with the benchmark, couldn't live with the ncores.

 

[HammerSandwich]

I am not listening at crazy levels (mostly around 70-85 dBc at the listening position). <snip> And please note that I am using up around 12 dB headroom due to my DSP solution.

Is a single AHB2 not adequate? Into ~91dB sensitivity, stereo mode should give 1M peaks of ~109dB at the 2-ohm minimum. Seems sufficient for your levels with all but the highest-DR recordings, or you sit really far away!

Hat tip to Benchmark for their incredibly comprehensive specs.

 

[Olli]

Is a single AHB2 not adequate? Into ~91dB sensitivity, stereo mode should give 1M peaks of ~109dB at the 2-ohm minimum. Seems sufficient for your levels with all but the highest-DR recordings, or you sit really far away!

Hat tip to Benchmark for their incredibly comprehensive specs.

Sure, totally adequate . I am sitting ca. 6 m away and 99% we listen to Tidal Hifi in our family room.

It‘s more that I always wanted to have 2 Monos

 

[iwantobelieve]

Having run the benchmark, nc400's and 4x neurochrome mod86p as bridged monoblocks all level matched my feeling was the nc400 was a little tighter in the bass but had a glare to the treble, the 86p smoother was in the treble but less extended in the bass and the benchmark somewhere in the middle.

I live with the neurochromes, could live with the benchmark, couldn't live with the ncores.

Have you heard a Purifi amp? Wondered if they’re any nicer in the treble than Ncore…

 

[tlin]

No word that I've heard. OTOH, I really doubt it is in the works since (1) the mch market is much smaller than the stereo market and (2) the AHB2s are so compact. I have 3 of them and, stacked together, they are still smaller and lighter than most traditional stereo power amps.

I wondered the same @Donovan and per a recent interview, the same question was asked and answered (I honestly chuckled out loud):

 

[sq225917]

Have you heard a Purifi amp? Wondered if they’re any nicer in the treble than Ncore…

I haven't heard one. I wouldn't my sighted opinion as gospel, just how it felt, level matched in my own system.

If I needed a sub amp I wouldn't look any further, the bass grip was remarkable.

 

[Rottmannash]

Have you heard a Purifi amp? Wondered if they’re any nicer in the treble than Ncore…

I believe so but not by much. The 252 is very close in the treble to the Purifi IMO but the ICEpower modules are very abrasive up top to me.

 

[iwantobelieve]

Thanks. I'm trying to organise a demo or two at the moment, now Covid restrictions are lifting in the UK. Very interested to hear anything Class D, and also the Benchmark.

 

[Deleted member 4708]

After reading this review I decided to buy the AHB2. Hard to argue with the measurements' results. Thanks, @amirm.

 

[DonH56]

AHB2 - It's tough when they aren't in alphabetical order! "ABH" seems to flow more smoothly than "AHB" but that ain't the name.

From Benchmark's description of the amp:

A.H.B.​

The letters A, H, and B allude to the unique topology of the amplifier's output stage. The AHB2 combines class-AB, and class-H topologies using a feed-forward error correction system.

But there is much more to the story -

The initials A.H.B. can be found on many of the circuit diagrams of Benchmark's early products dating back as far as 1983. These are the initials of Benchmark's founder, Allen H. Burdick. He personally designed many of Benchmark's early products.

Allen had a life-long passion for audio, and he became one of the leading innovators in the pro-audio industry. The AHB2 is named in his memory.

 

[aj625]

audiophiles hate measurements. they like bigger, heavier, more expensive, big front silver/golden plate with big knobs and meters, and running hot amps. ahb2 hasn't any of these. so this is not much popular or may be ahb2 owners are reclusive people who don't want to post anywhere about this.

 

[Andrew s]

Maybe there is nothing to say. Mine with a DAC 2 and Kef 201/2, in my treated listening room, just deliver a great musical experience. Regards Andrew

 

[Deleted member 4708]

audiophiles hate measurements. they like bigger, heavier, more expensive, big front silver/golden plate with big knobs and meters, and running hot amps. ahb2 hasn't any of these. so this is not much popular or may be ahb2 owners are reclusive people who don't want to post anywhere about this.

The voltmeters are audio porn visual candy... I'd buy a version of AHB2 with meters if the performance was identical.