Review and Measurements of Benchmark AHB2 Amp

[Panelhead]

I like to listen about 20 dB louder. But can only do that when no one else is home. System is in a loft area so it pressurized the whole house.

 

[Frank Dernie]

This is the power level I am interested in also. My speakers are 105 dB and are supported with an active sub. The volume at 10 mW is normal serious listening volume. 100 mW is loud.
I look at the 1 watt output noise floor, and the power supply harmonics. But a test at 10 mW would be much closer to normal operating conditions.

I have quite a few amps and one of my pairs of speakers are horns with 109dB/watt sensitivity.
I am actually more concerned by noise than distortion since it would always be a problem with super sensitive speakers and distortion is probably less from the amp than the speakers...
I have used a Devialet, which was perfectly silent and has a programmable maximum power output, a chinese Classic 16.0 push-pull valve amp (the speaker's designer favours vale amps), which had a touch of hiss but nothing I could hear from the listening position 18ft away (multi element horns are no good for near field listening or measurement) and am currently using a Job INTegrated which is silent too and has inputs for CD transport, computer and FM tuner so is perfect for the job.

 

[Panelhead]

My test for an amp is ear in the mouth of the individual horns. If I can tell if the amplifier is on or off it is culled.
Always heard good things about Devialet and JOb. Never tried one.
I want a Benchmark. Saw a used one a year ago for 1800.00 and seriously considered pulling the trigger. But have several amps that pass my noise test already. I have no doubt the AHB2 is silent.

 

[SIY]

I'm running some tests this weekend for an amp under review. Because these will be published, I can't yet name the specific amp beyond saying that it's a conventional AB amp designed according to the "Blameless" principles, but I'll post the cold and hot distortion residuals for comment.

I have run into a complication- this amp measures better than the AP residuals. I may have to borrow something else...

 

[restorer-john]

I may have to borrow something else...

 

[Panelhead]

What is the noise floor on your analyzer? I know there are many AP models.

 

[SIY]

Noise floor is fine, the problem is the 3rd and 5th harmonics at -115 dB from the fundamental.

OTOH, at that level...

The one I use is a 525 with a full complement of bells and whistles.

 

[typericey]

What delights me is that such great performance is actually accessible. I was raised (misled?) by a father who taught me that the only way to achieve sonic nirvana is with Audio Research Reference monoblocks. 3 grand is actually a fair price for what you are getting: the cleanest amp with enough power for domestic use. Can anyone cite a close contender at this price? It's a buy and forget product that will give you peace of mind (or make you worry about the inadequacy of the other components in the chain). Equally as delightful, and transparent, is John who clearly knows his stuff and takes time to engage this forum. We don't just buy products, we vote with our $ and to that I say, John, take my money! (as soon as I make it)

For me, it's out of reach for now, but nothing that some hardcore saving and gear flipping can't address. I think I found my new grail amp.

 

[GrimSurfer]

What delights me is that such great performance is actually accessible. I was raised (misled?) by a father who taught me that the only way to achieve sonic nirvana is with Audio Research Reference monoblocks. 3 grand is actually a fair price for what you are getting: the cleanest amp with enough power for domestic use. Can anyone cite a close contender at this price? It's a buy and forget product that will give you peace of mind (or make you worry about the inadequacy of the other components in the chain). Equally as delightful, and transparent, is John who clearly knows his stuff and takes time to engage this forum. We don't just buy products, we vote with our $ and to that I say, John, take my money! (as soon as I make it)

For me, it's out of reach for now, but nothing that some hardcore saving and gear flipping can't address. I think I found my new grail amp.

A Bryston B60R is a nice integrated that retails for about the same price. 60 W at 8 ohms, doubling into 4 ohms. Not quite the same noise floor but very close. Superb warranty (20 years IIRC)... and lots of stories of the company going to great lengths to stand by their products.

The B135 is the next model up. After that, it's big and powerful monoblocks.

I agree with you, however, that Benchmark makes a superb product. We're fortunate to have John's participation on the forum.

 

[etc6849]

https://www.stereophile.com/content/bryston-b-60r-integrated-amplifier-measurements

The Bryston measurements are definitely not in the same league as the Benchmark AHB2, but neither are 99.9% of amps out there. The amps I replaced had similar measurements to the B-60R for low power levels. I noticed a huge difference with the AHB2's, but my speakers are very sensitive, especially now that I drive them tri-amped with no passive XO's.

 

[Daverz]

I love my B-60, but it hums when my AC kicks in, I assume because of the temporary voltage drop. My other amps, including a Bryston 3B-SST, are not perturbed by this.

 

[maxxevv]

https://www.stereophile.com/content/bryston-b-60r-integrated-amplifier-measurements

The Bryston measurements are definitely not in the same league as the Benchmark AHB2, but neither are 99.9% of amps out there. The amps I replaced had similar measurements to the B-60R for low power levels. I noticed a huge difference with the AHB2's, but my speakers are very sensitive, especially now that I drive them tri-amped with no passive XO's.

Indeed, its not even in the same order of magnitude according to those measurements !

 

[amirm]

Indeed, its not even in the same order of magnitude according to those measurements !

Worse yet, there is high praise of THD+N versus frequency which is at 0.1%!

Granted, it is including a lot of harmonics but still, no sense in declaring that "outstanding." That leaves no room for amps like AHB2:

 

[bunkbail]

Granted, it is including a lot of harmonics but still, no sense in declaring that "outstanding."

The article was published in 1997, maybe it's an "outstanding" figure during it's time, I dunno.

 

[maxxevv]

The article was published in 1997, maybe it's an "outstanding" figure during it's time, I dunno.

Possibly. Have no clue as to what was SOTA in that era though.

I was just agreeing with @etc6849 that the Bryston wasn't anywhere near the measurement results of the Benchmark.

How it comes out in terms of music reproduction when paired with different speakers / transducers is of course not within my means to compare as I don't have either.

 

[SIY]

Worse yet, there is high praise of THD+N versus frequency which is at 0.1%!

Granted, it is including a lot of harmonics but still, no sense in declaring that "outstanding." That leaves no room for amps like AHB2:

On first glance, it looks like that distortion vs frequency graph is inconsistent with Figure 8.

 

[restorer-john]

no sense in declaring that "outstanding." That leaves no room for amps like AHB2

Well, I think you may need to create a list of superlatives and quantify the THD ranges to end all the confusion.

For example:

Without Peer 0.000005% or less
Superlative 0.00005% or less
Phenomenal 0.0005% or less
Outstanding 0.005% or less
Excellent 0.05% or less
Reasonable 0.1% or less
Below Average 0.3% or less
Poor 0.5% or less
Shocking 1% or less
Dreadful 3% or less
Putrid 5%
etc

 

[amirm]

On first glance, it looks like that distortion vs frequency graph is inconsistent with Figure 8.

THe measurement bandwidth is likely very different in each one.

 

[JohnYang1997]

Well, I think you may need to create a list of superlatives and quantify the THD ranges to end all the confusion.

For example:

Without Peer 0.000005% or less
Superlative 0.00005% or less
Phenomenal 0.0005% or less
Outstanding 0.005% or less
Excellent 0.05% or less
Reasonable 0.1% or less
Below Average 0.3% or less
Poor 0.5% or less
Shocking 1% or less
Dreadful 3% or less
Putrid 5%
etc

I believe less than 0.001% is outstanding for now. Probably needs to be less than 0.0005% to be outstanding in the near future. Also these shouldn't be taken too seriously even directly using number. thd+n at 1khz at certain level don't remotely tell the full story.

 

[restorer-john]

Also these shouldn't be taken too seriously even directly using number.

I'm just having fun. We all know absolute numbers or adjectives are only part of the story.