Review and Measurements of Benchmark AHB2 Amp

[ex audiophile]

If you use the ah2b to run a pair of revel 226be towers, would any of you suggest using a pair of the amps and running bridges mono? Or maybe that would be overkill. I’m just wondering how much more volume I could expect to get using a pair instead of one.

Thanks

I was running a single AHB2 in stereo mode with a pair of Revel 126be bookshelf speakers and a pair of Fathom 12 inch subs in a medium size room. When I ran ARC (STR preamp) it would set the speaker levels at +12 (max). I repeated this several times. I recently purchased a second AHB2 and running them in bridged mode the ARC program set the speakers at 0 and +2. The superficial explanation is more power from the amps but I'm sure there's more to it than that. In any case I'm delighted with the amps and the Benchmark cables are beautifully built.

 

[John_Siau]

If your speakers can take the additional power (without significant power compression), the maximum output will increase by 6 dB.

Power compression is caused by overheated voice coils. When a voice coil heats up, its resistance increases and this reduces the current through the voice coil. It is current, not voltage, that moves the voice coil.

So, if you are over driving your speakers, you will not get a full 6 dB increase in output level. Otherwise, the answer is 6 dB.

 

[maxxevv]

Today, one of the most meaningless measurements is how much an amp weighs and how big it is. I remember Peter Aczel once stating that any amp he could lift without straining his back was basically a 'flimsy' amp. And back then he had a point. How times have changed.

He probably had a really bad back then....

He'll be almost handicapped if he takes things by the same measure today though.

 

[Vasr]

@John_Siau so where does Benchmark go with this design from here? What is next to improve it?

Price?

 

[RichB]

I was running a single AHB2 in stereo mode with a pair of Revel 126be bookshelf speakers and a pair of Fathom 12 inch subs in a medium size room. When I ran ARC (STR preamp) it would set the speaker levels at +12 (max). I repeated this several times. I recently purchased a second AHB2 and running them in bridged mode the ARC program set the speakers at 0 and +2. The superficial explanation is more power from the amps but I'm sure there's more to it than that. In any case I'm delighted with the amps and the Benchmark cables are beautifully built.

I am running a single AHB2 driving Revel 126Bes with no issues. The gain is set to the middle selection to match the 4 volt output of the Oppo 205.
There are no clipping indicators driving quite loud. In theory, they should never clip with a properly encoded digital source. The Oppo max volume is set to 90 to make sure there are no overage clips.

If you are posting the STR volume levels then it may be a gain issue. Bridging adds 6 dB additional gain.
The STR preamp specs show 6.6 volts so the mid position should be best.
What gain were/are you using?

- Rich

 

[ex audiophile]

I am running a single AHB2 driving Revel 126Bes with no issues. The gain is set to the middle selection to match the 4 volt output of the Oppo 205.
There are no clipping indicators driving quite loud. In theory, they should never clip with a properly encoded digital source. The Oppo max volume is set to 90 to make sure there are no overage clips.

If you are posting the STR volume levels then it may be a gain issue. Bridging adds 6 dB additional gain.
The STR preamp specs show 6.6 volts so the mid position should be best.
What gain were/are you using?

- Rich

hi rich. i had no "problem" other than the odd levels setting chosen by the ARC program. I talked with Rory at Benchmark and he didn't think it was a concern, and the speakers sounded great. We did try all the gain settings, I had started with the middle position. The gain setting did not alter the speaker levels chosen by ARC. It just seemed to me that with subwoofers the Revels should have an easy time of it and not need the boost. ARC also set the crossover at 150hz so I'm sure the room acoustics were playing a role (there was a large drop at about 100hz). I sent the ARC file to Revel and they said it was not unusual but we'll have to take that with a grain or two of salt. It was just really interesting to me that the levels went down so much with two amps. The speakers still sound great

 

[RichB]

hi rich. i had no "problem" other than the odd levels setting chosen by the ARC program. I talked with Rory at Benchmark and he didn't think it was a concern, and the speakers sounded great. We did try all the gain settings, I had started with the middle position. The gain setting did not alter the speaker levels chosen by ARC. It just seemed to me that with subwoofers the Revels should have an easy time of it and not need the boost. ARC also set the crossover at 150hz so I'm sure the room acoustics were playing a role (there was a large drop at about 100hz). I sent the ARC file to Revel and they said it was not unusual but we'll have to take that with a grain or two of salt. It was just really interesting to me that the levels went down so much with two amps. The speakers still sound great

I don't think you needed the power, so the gain difference seemed to "stimulate" ARC.
Bridging got you -6 dB gain, the rest may attributed to the algorithms.
Algorithms are blamed for many overt actions these days.

- Rich

 

[Vasr]

TI remember Peter Aczel once stating that any amp he could lift without straining his back was basically a 'flimsy' amp. And back then he had a point. How times have changed.

He'll be almost handicapped if he takes things by the same measure today though.

That would depend on how much he is able to lift these days, no? He could still be right.

 

[waynel]

That would depend on how much he is able to lift these days, no? He could still be right.

He's dead

 

[cjm2077]

He's dead

So you're saying less than before then?

 

[Billy Budapest]

@John_Siau so where does Benchmark go with this design from here? What is next to improve it?

This is going to sound stupid, but it is a stumbling block for some people:

Cosmetics.

Not to say the ABH2 is ugly, and not to say that it should look like a piece of audio jewelry, but it has a certain “lab gear” aesthetic that could be made more attractive—specifically, the design could be made to look more high tech and echo the cutting edge performance the product offers.

 

[anmpr1]

This is going to sound stupid, but it is a stumbling block for some people: Cosmetics.

The actual amplifier is quite solid--thick machined faceplate with etched name. I mean, some amps are simply a black box with an off/on switch.

I get what you are saying, but you are not paying Accuphase prices for them, either. To add Mac-like meters and a nice glass backlit front panel would probably add a thousand dollars to the price. I'm just guessing, but you used to be able to buy McIntosh amps sans meters--I think that the retail price differential (in adjusted dollars) was about a thousand dollars. I don't think Mac offers those anymore.

 

[Billy Budapest]

The actual amplifier is quite solid--thick machined faceplate with etched name. I mean, some amps are simply a black box with an off/on switch.

I get what you are saying, but you are not paying Accuphase prices for them, either. To add Mac-like meters and a nice glass backlit front panel would probably add a thousand dollars to the price. I'm just guessing, but you used to be able to buy McIntosh amps sans meters--I think that the retail price differential (in adjusted dollars) was about a thousand dollars. I don't think Mac offers those anymore.

Understood re McIntosh and Accuphase. That type of “audio jewelry” would not be not necessary. However, changing the ABH2’s studio gear aesthetic in small ways such as removing the prominent bolts and extending the faceplate so it conceals the heat sinks would make it look a lot sleeker. The faceplate is already nice but the proportions could be tinkered with a little bit to make it seem more at home in a hi-fi rack vs. a studio equipment rack, etc.

 

[RichB]

This is going to sound stupid, but it is a stumbling block for some people:

Cosmetics.

Not to say the ABH2 is ugly, and not to say that it should look like a piece of audio jewelry, but it has a certain “lab gear” aesthetic that could be made more attractive—specifically, the design could be made to look more high tech and echo the cutting edge performance the product offers.

They look like baby-Parasounds but better. Recently, Parasound went with gold-lettering, yuck.
I've never really had the coin for the Dagostino amps that look like they a good to 20,000 leagues.


The trick is to move from something truly utilitarian. My wife thinks they are cute comparted to the 3 AT6000s they replaced.
Need more proof? The cat approves

- Rich

 

[cistercian]

They look like baby-Parasounds but better. Recently, Parasound went with gold-lettering, yuck.
I've never really had the coin for the Dagostino amps that look like they a good to 20,000 leagues.


The trick is to move from something truly utilitarian. My wife thinks they are cute comparted to the 3 AT6000s they replaced.
Need more proof? The cat approves

View attachment 83257

- Rich

Love the cat...mine has yellow eyes. She loves warm places too.

 

[cistercian]

 

[Billy Budapest]

They look like baby-Parasounds but better. Recently, Parasound went with gold-lettering, yuck.
I've never really had the coin for the Dagostino amps that look like they a good to 20,000 leagues.


The trick is to move from something truly utilitarian. My wife thinks they are cute comparted to the 3 AT6000s they replaced.
Need more proof? The cat approves

View attachment 83257

- Rich

I approve of the Sonica DAC, too!

 

[Billy Budapest]

What about something that looked more like this? No bolts, concealed heat sinks, wider, shorter?

 

[D700]

Well I think the AHB2 is beautiful and as soon as my wife and I get the new lighting in her office purchased, the new patio with outdoor kitchen built, ceramic tile in the basement, the workout room finished and the house repainted, AHB2 purchase will be at the top of our list and labeled as "backup sump pump".

 

[SIY]