Benchmark AHB2 Amplifier

[PGA]

All below is using the Benchmark in mono on TAD R1s. It’s been a long while since I had a pure class A amp. Last one was the NRG Control 400 watt monos. Those were fantastic amps in their time in 1990. But they were room heaters, not very practical in Miami. And the last pair of Class D I had were the Bel Canto Ref 1000. But even that was 10 plus years ago. Most recently I had the fabulous sounding Constellation Centaur mono, very classic class AB. For me the treble sounds more natural on the Benchmark, and I hear more details with the vanishing noise floor. Bass slam is fine on both amps, same for dynamics, ease playing loud, plus they both sound great playing at low volume. But each Benchmark is $3000 and each Centaur is 9x that. For me both the Benchmark and Constellation were better than many other AB amps, including Levinson, Pass, MSB, Cello and Spectral. All of those are great at some things but not at everything. But as I said above, mileage may vary!

Regarding load sensitivity, given the regulated power supply on the Benchmark and the very sophisticated protection circuit, I would say they are a rather perfect voltage source into loads down to a couple ohms. When you over drive them they turn off. It’s very hard to overdrive them in mono. But that does not mean you may like them on every speaker as some speakers may sound better with a less perfect but synergistic output stage.

The articles on the Benchmark site are great explaining how these amps work and measure. They have almost no crossover distortion, like a great class A. And they have almost no noise or harmonic or intermodulation distortion. You will surely notice the absence of noise and distortion, but that doesn’t mean that it will surely sound better to you. For some, a little harmonic distortion is a good thing. And for some speakers a higher output impedance at some frequencies may be synergistic.

Kal, thoughts?

 

[Platypus20]

I’m running 2 of the AHB2s and a LA4, bi-amping a pair of Acarian Alon IVs, love them

 

[tmallin]

The Alon IV and the bit later V are among the best sounding dynamic speakers--based on repeated dealer auditions--I never owned. Of roughly the same vintage, the Aerial 10T is another one I found to sound great at dealers but never owned. I was never so taken with later models from Alon/Nola or Aerial.

If you have not already, experiment with tri-wiring the Alons with the Benchmark AHB2 amps in mono bridged mode. You might get yet-better sound.

 

[Platypus20]

I have them set so one amp runs the 2, 12” drivers in the sealed boxes and the second bi-wire to the open baffle mids and highs.
I tried them in mono and like them better this way

 

[Hear Here]

I’m running 2 of the AHB2s and a LA4, bi-amping a pair of Acarian Alon IVs, love them

Odd isn't it - the AHB2 was the biggest disappointment in all the amps I've ever bought!

Perhaps it was because my expectations were too high after a fellow Avantgarde owner was raving about his new find after previously owning many very exotic amps. The AHB2 was then very new and no worthwhile reviews and no local dealers, so I bought unheard from a dealer in Scotland - I live on the South Coast 400+ miles away. After having used SETs for a decade or so since moving to high sensitivity speakers, the Benchmark was drearily dull. It was an amplifier I was never inclined to wind up the volume - more to provide background music!

Kiss of death as far as I'm concerned, so I went on a 12 amp purchasing and dealer-loan spree to find something that provided the excitement that my exciting speakers needed. Class A, AB and D amps from Mark Levinson, GamuT, Micromega, Sugden, Lyngdorf, Accuphase, Bakoon, NAD, Valvet and others were in my system for at least a week. I was expecting a Class A to win out, but in the end I went for the relatively modest Purifi Eigentakt-based Class D NAD M33. No regrets and it offers so much more excitement and musical enjoyment than Benchmark, despite it being an all-on-one that many people still consider a compromise.

PS - I notice that I've previously contributed to this long-running thread, so ignore this is you've read all earlier posts. Certainly the Benchmark is accurate, dead quiet and has other admirable features. It's just a pity it doesn't excite the emotions!

 

[Platypus20]

Yes, very interesting, to me the Benchmarks driving the Alon IVs, is about perfect, the amp is very quiet, delivers everything I both wished for and expected from them. The 2 AHB2, a LA4 and a DAC3 HGC, was my retirement present to myself. I replaced a Conrad-Johnson MF 2300 (240 watt SS amp) and a Conrad—Johnson PF 2L preamp, I’d used them for 25+ years.

 

[shawnf]

I’m running 2 of the AHB2s and a LA4, bi-amping a pair of Acarian Alon IVs, love them

Hi! I am an AHB2 owner and was thinking of purchasing another unit to run in bridged mono. Then I saw your post about biamping.

Can you share and advise how you managed to achieve this? Like how to set up the connections, components used, etc?

FYI I have an MSB Premier DAC and using the built-in preamp into the AHB2. I am planning to test 2 units with a Wharfedale Aura 2 which is currently on loan. I have the SpeakON to Banana plug cable from Benchmark.

Thanks!