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Review and Measurements of Benchmark AHB2 Amp

maty

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30 dB is not a randomly chosen number. For some it mark a border, in class A and AB. Class D is other world.
 

Frank Dernie

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Which ones, the bad ones or the good ones? The good ones used SpeakOn. The bad ones used banana jacks with screw terminals. Removing the terminal and going with bare wire produced 2 dB better performance. I have solid brass locking banana jacks coming to test to see if it resolves this issue.
Typical speaker connections have very poor contact area because of the difference between ideal and actual real manufacture. Spade lugs are rarely, if ever parallel and flat and are probably the worst. Banana are vey plug dependant, speakon were sensibly engineered to work properly when manufactured using normal methods.
Goldmund chose a high current coaxial connector designed for transmission stations, simply because it has very good and consistent contact area. The limit is that it only exists on Goldmund amps and speakers so when I changed to Devialet I had to go back to banana plugs.
Bare wire gives good contact until the contact pressure relieves.
 

777

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30 dB is not a randomly chosen number. For some it mark a border, in class A and AB. Class D is other world.

I know what you're talking about but all that numers are from high negative feedback probably. You can not get it with 30dB or less global feedback, only with local negative feedback. Or maybe feed-forward feedback...
 

Shadrach

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Congratulations Benchmark.:cool:
I remember reading about this amp when it first came out. I even read the Stereophile review.:eek:
Interesting thing about Stereophile is they still went on to praise some other pieces of audiophile jewelry at 100K without reference to the Benchmark.:facepalm:
It seems to me that there isn't a better buy. I agree in general with those who say it performs way past what is audible. If the amp was priced at 50K it would be an expensive excess; it isn't, it's 3K, which in audiophile terms is nothing and for a buy once to have the best for the average audio enthusiast, not much either.
If Benchmark made it five times the sized and at a weight that required and sack barrow to move it, they would probably sell more.;)
All the people I've come across using Benchmark products have had nothing but praise for the products, the service and the reliability.
If I buy another amp this will be it. There is nothing on the market that comes close.
 

MZKM

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Interesting thing about Stereophile is they still went on to praise some other pieces of audiophile jewelry at 100K without reference to the Benchmark.:facepalm:
In one of their other reviews, in comparison of the Benchmark DAC with another DAC, the reviewer said the Benchmark amp got rid of the sound of church walls in the recording...
 

svart-hvitt

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In one of their other reviews, in comparison of the Benchmark DAC with another DAC, the reviewer said the Benchmark amp got rid of the sound of church walls in the recording...

Sounds like a funny reference. Do you have a source link?
 

restorer-john

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If Benchmark made it five times the sized and at a weight that required and sack barrow to move it, they would probably sell more

Maybe Benchmark are just content to sit back and be comfortable in the fact they have produced a product which is essentially without fault, at a price which is unfathomable, in a package which suits both crazy-ass audiophiles and professionals alike, all the while without feeling the need to buy favor with HiFi magazines or their scribes.

Color me impressed.
 

josh358

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Anyone know if there is a volume discount? I just checked and I sent them an email a couple of months ago but never heard back. Earthlink wacked out their antispam scheme around then and it's still somewhat messed up, sending emails to spam even though they are on my contact list, so Benchmark may have responded but it got trashed. Figured I'd check here before pinging them again.
I don't know about volume discounts but they have had specials around show time, IIRC (and it's been two years) they did for AES a couple of years ago.
 

anmpr1

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Anyone know if there is a volume discount? I just checked and I sent them an email a couple of months ago but never heard back. Earthlink wacked out their antispam scheme around then and it's still somewhat messed up, sending emails to spam even though they are on my contact list, so Benchmark may have responded but it got trashed. Figured I'd check here before pinging them again.
When I ordered mine a couple of three weeks ago, there was an order backlog. My guess is that they build them as fast as they can, but can't match current demand. So you wait a week or two. The good news is, you get a factory fresh one when it arrives. Any other 'boutique high end' manufacturer would see this situation as an opportunity to jack the price up 20 or 30 percent. I laugh when I read about super expensive gear being touted by the high end press as 'a bargain' that 'blows away' everything else. In this case it is true. For the price, for any price, there's really nothing that touches it. And they sell it a lot cheaper than the usual high end thing.
 

josh358

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Every body is talking about this excellent amp, and it is getting quite a buzz, deservedly so.

When you find this level of performance, as others wrote, you're set for life.

To all the experts and veteran audio engineers at this forum I ask (because I haven't heard of anything similar before): Do any of you have encountered an amp with this kind of benchmark results? My guess is that indeed, there may be a few others, but they'd be multiple times costlier and heavier than this AHB2 amp.
I have never seen an amp that measures this way. I don't know that anybody has. It isn't the first amplifier to use feedforward -- indeed, John Siau points out that feedforward is actually an older technology than negative feedback -- but it's rare in doing so.

It's great to see someone breaking all the "rules" of amplifier design, because it's been in a rut for some years now, with the best designers squeezing pretty much everything that could be squeezed out of available devices using conventional topologies.

Anyone who thinks all amps sound the same will be in for a rude but happy awakening when they compare an inexpensive amp to an amp like the Benchmark.

That said, anyone who thinks that the Benchmark is a *perfect* amp because of its steady state measurements will learn that that doesn't yet exist.

I've owned an AHB2 for several years now, and it's the cleanest amplifier I've ever heard. I was listening to it last night and I can only describe the sound as ravishing. Like silk. Or like Class A without the absurd size, weight, and heat. (If you've ever heard crossover notch distortion you know why Class A amps sound better than A/B ones, it's incredibly audible and annoying in small amounts.) And the low weight, tiny form factor, and efficiency of the AHB are really welcome. It's a save-the-planet kind of amplifier, without the sonic compromises of Class D.

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. Again, this isn't a question of steady state measurements or amplifier power -- I'm not clipping it. But listen to a piano on the Benchmark and another good amp and you'll hear what I mean: it rounds off the attack.

Amplifiers actually differ surprisingly in the degree to which they do that. 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.

Another issue is, paradoxically, lack of distortion masking. Lower order harmonic distortion is known to render higher order harmonic distortion euphonic. This is because of the mechanism by which we detect the timbre of sounds. And higher order distortion is unfortunately quite common on poorly made recordings and badly-designed equipment. What this means in practice is that the AHB2 will sound great on clean recordings, but will pass the harshness through on more distorted ones, while some more colored amplifiers with lower order harmonics will tend to mask that harshness.

So the Benchmark isn't a perfect amplifier, but anyone who has never heard a really good amplifier or thinks that all amps sound the same is going to be blown away by the sound. It's a bargain, too, by the standards of high end amplifiers, and with its sophisticated protection circuitry, quite bulletproof!
 

Snafu

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Better than ASR Emitter that i have been eyeballing as my endgame amp...

Thanks for saving +10k for me :eek:
 

josh358

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I know what you're talking about but all that numers are from high negative feedback probably. You can not get it with 30dB or less global feedback, only with local negative feedback. Or maybe feed-forward feedback...
Yep, the AHB2 is a feedforward design. This has a number of benefits including the fact that they can use a relatively low bias while maintaining Class A performance throughout the power range.
 

Purité Audio

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Better than ASR Emitter that i have been eyeballing as my endgame amp...

Thanks for saving +10k for me :eek:
I had an ASR emitter, three boxes and huge silver connecting cables, like an octopus, Benchmark is certainly smaller and lighter and less expensive.
Keith
 

pjug

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Color me impressed.

The DAC3 looks to be exactly what I would want for a preamplifier as well, with its hybrid volume control. I could easily go all in on Benchmark if I could just find a spare $5K. Maybe I should have a few beers tonight which might make me a little loose with the credit card.
 

tktran303

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Also nice to see a currently available reasonably priced product that puts paid to the hype, surrounding Hypex. "Ncore® is the first Class-D amplifier not just to nudge the best linear amplifiers, but to surpass them in every aspect relevant to sound quality."

With all due respect Hypex nCore is an old product. I’ve owned a Hypex nCore amplifier since 2012, and still recall conversations with Bruno from 2011 strategising the way forward for his new product.

I told him not to release the nCore400 to the DIY market, because I felt the Ucd products were good enough for mainstream use (and it still is imho)

My view was that it was best to beat the high end at their own game by releasing his own high end product, with a excellent build and luxurious finish, exceptional customer support and outstanding warranty. And a big price tag to match. After all, nCore was scalable all the way up to 2000W into 2 ohms.

Of course, Bruno decided not to do that, and released a unit to the DIY market (the best (IMO) nCore400, with a discrete input buffer & 200/400/600Watts into 8/4/2ohms)
and more powerful ones to OEMs, without an input buffer, so manufacturers could tailor the sound to their liking eg. nCore1200, nCore2K.

The hyperbole was an attempt to get the high-end buyers AND manufacturers of big-iron amplifier to pay attention. Remember that in the early 2000s, naysayers were poo-pooing class D. “Class A IS still the best” , “Class D is ok for subwoofers but that’s about it”

And rightly so, because if you see measurements of virtually all other class D amps (at that time, it was full of artifacts and problems IN the audio-band.

Bruno was the first to crack the code with his UcD, and refine it in the nCore. In 2011, here was a class-D that was not just excellent for the money or weight class, but at any price.
It was equal or better than the very best class A or A/B.

Eventually it was adopted by many of the bigger names.
Theta Digital
Bel Canto Black
NAD
ATI

Sure, naysayers will still say that there are artifacts beyond 35Khz... but somehow not seems to complain ultrasonic problems with SACD/DSD.

Like the AHB2, the Purifi eigentakt is another low gain amplifier that is set to rewrite the rules on class D, and show what Bruno can do:
THD+N <0.00017% (~116dB) @ 100W, 4Ω, 20-20kHz.

https://www.purifi-audio.com/eigentakt/
 
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Purité Audio

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I have both Ncore’s here and Benchmark and I can’t hear any difference with the passive speakers I have here, they are both excellent , quiet compact, efficient.
Keith
 

Snafu

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I had an ASR emitter, three boxes and huge silver connecting cables, like an octopus, Benchmark is certainly smaller and lighter and less expensive.
Keith

Half joking there since i have heard Emitter at the store a few times (and it is outstanding to my ears).

How did you like ASR as over all, sound and user experience ?
Thanks
 

jazzendapus

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Neat! Can't wait for Chinese to steal this design and start selling those amps at 1/5 the price :p
 
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