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Review and Measurements of Benchmark AHB2 Amp

anmpr1

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Oh come on. High Fidelity was originally an expensive hobby for people with significant means and electronics skills. It was not for everyone.

It was democratized massively in the late 60s through mid 70s, and commoditized by the mid 80s. But, the best performing gear was always expensive, incredibly well built, and not something a minimum wage person could, or should be aspiring to.
In the '50s and early '60s, Marantz and McIntosh were expensive, but considered the top of the line. Kits made hi-fi more or less affordable. David Hafler's operation probably did more to open up hi-fi to the average guy as anyone. But there were others. Then you had men on the fringes, like Julius Futterman, shellacing his hand wound transformers in a pressure cooker, in his kitchen. You paid your dollars, waited a couple of years, and then got your OTL amp. By the mid '70s, anyone could walk into multiple outlets and buy something affordable. In the mid-sized city I lived in at the time, there were about a dozen hi-fi retail outlets. When I left, a few years ago, I don't think there were any strictly hi-fi shops. Some home theater contractors. Things have changed so much. Maybe in a place like NYC you can still find a lot of hi-fi shops.
 

svart-hvitt

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I was not picking sides, I was just providing a perspective. If anything, I'm on your side, but those less fortunate should have options.

You’re right. Poor people have less choices.
 

Kal Rubinson

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If you have the $$$ and like clean sound then Benchmark seems like a no brainer considering the performance and long-term support should anything go wrong.
I do agree with this statement and that is why I bought them. However,.....
But perfect amplifier? No. It excels in steady state measurements, but it isn't as dynamic sounding as other good amplifiers with which I've compared it. ................................................................................
..................................................... My Parasound A21, for example, is a less refined amplifier than the Benchmark, but it happens to be one of the best amps I've heard in this particular regard. There are those who say that the Benchmark robs music of excitement, and after several years of listening experience, I tend to agree. It's strength is in beauty of sound. The highs in particular are to die for, like gossamer.
I also agree, to a degree, with these comments based on comparison with the similar Parasound A31. It is no so much that the Benchmark robs the music of excitement but that the Parasound and Benchmark provide different types of excitement.
 

tpaxadpom

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I do agree with this statement and that is why I bought them. However,.....

I also agree, to a degree, with these comments based on comparison with the similar Parasound A31. It is no so much that the Benchmark robs the music of excitement but that the Parasound and Benchmark provide different types of excitement.
Oh common Kal. Please record them side by side and upload it to youtube so we can compare. I promise I will keep my eyes closed to avoid placebo effect. :)
 

restorer-john

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What about 3-ohms @John_Siau ? As there are often speakers that dip below 4 ohms for certain small ranges of frequencies.

Is it possible for @amirm to test at 3 ohms?

The bridged mono test results (>500W@4ohms) below confirm the amplifier is capable of >250W/ch@2ohms continuous. Remember in a BTL configuration, each ampliifer effectively 'sees' half the attached load impedance and Amir was using a 4 ohm load.

As noted in an earlier discussion of the internals, there is little concern about the output stages current ability with 8xTO3Ps per channel. It would come down to the PSU capability and the heatsink area at the end of the day to keep the devices safely in the SOA derating. I have amplifiers with half that number of output devices, running 70V +/- rails for 180W/ch@8 that will do 290@4, but are very marginal at 2ohms. This Benchmark is running way lower rails and has twice as much SOAR. It will only be the protection that stops it prematurely and I'd say they've done that to keep the amplifier completely linear.

1558744709919.png
 
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Jimster480

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Sure. I heard from @John_Siau that it was safe to run it at 4 ohm and indeed it was:

index.php


I updated the review with it.

Notice how exceptionally clean it is at the limit with such low THD+N. You get full transparency and lack of distortion until the amp shuts down at half a kilowatts.
This is BOMBSHELL performance.
I know what I'm buying when I finally get around to building my home speaker setup!
 

Music1969

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The bridged mono test results (>500W@4ohms) below confirm the amplifier is capable of >250W/ch@2ohms continuous. Remember in a BTL configuration, each ampliifer effectively 'sees' half the attached load impedance and Amir was using a 4 ohm load.

Nice, if that's continuous then even dynamic/transient dips down to 3 ohms should produce lots of power (> 250W) without any increase in distortion?

Would be nice to measure at 3 ohms if amir still has it and if @John_Siau allows
 

phoenixdogfan

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If I spend 5 large for the package, I'm not quibbling over the price of their speaker cable. Your suggestion reminds me of someone going to a fancy restaurant, and bringing their own bottled water to drink because it's cheaper than the Perrier. Sorry, at my age I've put away my soldering iron. Go for it, if you like.
Does not require a soldering iron, you just cut off the original terminations, strip the four wires and screw each bare wire into the terminal, and even if I had an extra mil to blow on speaker cable, there's absolutely no reason why I would tip any company an extra $150 FOR NOTHING! I pay only for value, and Benchmark cables are NOT A VALUE! Sorry you seem to find that declasse.
 
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amirm

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Does not require a soldering iron, you just cut off the original terminations, strip the four wires and screw each bare wire into the terminal, and even if I had an extra mil to blow on speaker cable, there's absolutely no reason why I would tip any company an extra $150 FOR NOTHING! I pay only for value, and Benchmark cables are NOT A VALUE! Sorry you seem to find that declasse.
There is time and effort involved in sourcing, ordering the parts in addition to building them. That's not free when I could spend that time doing something else I enjoy. There are excesses in audio but this one is not it.
 
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amirm

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No SNR results?
Sorry, missed that somehow. Here it is:

index.php


This is incredible. If you play at peak of 120 dBSPL, your noise floor will be at -10 dBSPL. In other words, total silence despite such massive peak.

The AHB2 continues to amaze....
 

Xulonn

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I was not picking sides, I was just providing a perspective. If anything, I'm on your side, but those less fortunate should have options.

If I had the means - as in the past - I would be very very tempted to purchase the Benchmark amp. By all indications, it is a fantastic product for a fair price and excellent customer support. It pushes all of my buttons as being a classic American company that reminds me of my younger days when Marantz, McIntosh, Scott, Fisher, Sherwood and other excellent audio companies were the mid to high-end audio manufacturers.

(I wonder why Benchmark - or Emotiva - are not listed on the AmericanMadeAudio.com website?)

As a retiree who blew his investments and is now living in Panama on my {decent} SS pension, I am one of those who is forced to look at less expensive options. I am currently using a Topping PA3 amp, and although I think it is an excellent cheap amp, I am "upgrading" and waiting for my ICEpower modules to put in the Chinese Ghent amplifier case that has already arrived. Total cost for an excellent pair of balanced connection components - a "DIY assembly" 100 WPC ICEpower amp, and a Topping DX7s DAC with volume control and a remote - will cost under $400. That is $2,500 less than the superb Benchmark AHB2, but even $400 stretches my budget.

With respect to cheap Chinese audio electronics, Topping and SMSL - as verified by Amir's testing - are prominent among the exceptions to the mountain of cheap Chinese audio garbage currently being sold around the world. This website and Amir's comprehensive testing are a godsend for those of us considering and buying truly inexpensive audio gear. However, the testing here has also exposed flaws and sub-par performance even with supposedly respected - and expensive - audio hardware, so whether we buy less or more expensive components, if they have been tested, we can use those results to make informed buying decisions.

(One route I will not take is commodity-level components from "re-branders" like Douk, Nobsound Monoprice. I want to know who actually makes the components that I buy - even with Chinese brands.)
 

RayDunzl

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If you play at peak of 120 dBSPL, your noise floor will be at -10 dBSPL. In other words, total silence despite such massive peak.

Try to explain that to the Police at 2am.

"I'M TRYING TO HEAR MY NOISE FLOOR DAMMIT!"

"Sir, you don't need to shout. You'll just have to turn it down a bit."

"WHAT?"

---

Real life version (1967):


.
 
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restorer-john

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Sorry, missed that somehow. Here it is:

You say 'max power'. Did you measure the S/N with respect to Benchmark's rated power in stereo (2 ch) or bridged mono (1ch) and at what load? Alternatively is it one of your measured powers and if so, which one?

130.286dB with respect to Benchmark's rated 100W@8ohms equates to 8.65uV noise.
130.286dB with respect to your measured 185W@4ohms equates to 8.26uV noise.
130.286dB with respect to your measured 500W@4ohms equates to 13.68uV noise.

Whatever way you look at it, the amplifier is pretty silent noise wise, incredible for a power amp, especially one with an SMPS. Maybe they have a VW style defeat device that shuts down the entire output stage in the absence of signal...kidding. I hope. :)

PS 'Max Power' sounds like a superhero, or a pornstar.

 

jazzendapus

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I do agree with this statement and that is why I bought them. However,.....

I also agree, to a degree, with these comments based on comparison with the similar Parasound A31. It is no so much that the Benchmark robs the music of excitement but that the Parasound and Benchmark provide different types of excitement.

:facepalm:
And I thought this forum would be free from stereophilisms...
 

Cortes

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Fantastic product by Benchmark, and they don't demand a ridiculous price for top-level engineering.

However, I see this like state-of-the-art turnables. I speculaate that new generations of audiophiles will only be interested in active speakers, and there will be no place for amps. This might happen when Gennis, Neumann, etc, begin to release Kii level of performance at pro, no audiophile, prices.
 

trl

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Yes they are both audibly transparent.

Why? Our very best transducers have H2 or H3 that is 60dB down (0.1% THD)
See:
https://hificompass.com/en/speakers/measurements/accuton/accuton-s280-6-283n

Or:
https://www.innerfidelity.com/images/SennheiserHD650.pdf

Maybe 70dB for an outstanding unobtainium driver, or a narrow frequency range.

See:

https://www.innerfidelity.com/images/FocalClearsnA1BRQE000007.pdf

But I’ve never seen a transducer, headphone driver or loudspeaker driver, whose H2 or H3 was 80dB down (0.01% THD)
And you don’t want to see what happens with IMD in a speaker...

So of course whatever problem in the amplifier is masked by the transducer.

We’re living in an era where the distortion of amplifiers and DACs are below noise of our audio sanctuary.

Really interesting post, thanks for sharing. I guess you're referring to "Near field HD spectrum (20 mm distance)" from https://hificompass.com/en/speakers/measurements/accuton/accuton-s280-6-283n. I should probably give it a try myself too, but @RayDunzl is the man for such measurement, in case he haven't done it already. It would be nice to check H2...H5 for 90dB at 2-3 meters in front of speakers (listening point), of course...sinewaves (-1dBFS maybe).

Thank you!
 

Kal Rubinson

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:facepalm:
And I thought this forum would be free from stereophilisms...
Too bad. There is an audible difference which is easy to hear and for which I cannot account logically. I have confirmed it, so far, with three different loudspeaker systems. To deny it would be dishonest on my part. Drop in some time, I will demonstrate it to you.

(Frankly, I was not going to bring it up here for obvious reasons but, when josh358 raised the issue, I felt it necessary to concur.)
 
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