Benchmark AHB2 Review (Updated Measurements)

[OldTimer]

Manual warns against going that low and didn't want to chance damaging it.

No wonder my Class AB amps broken. Now the Class D amp (Fosi Audio V3) take charge.

 

[Sokel]

What's really nice in this review is consistency this amp showed,something not always present as sample to sample variations are often a thing in electronics.
That shows quality components and tight QC.

Thanks Amir!

 

[ocinn]

Still one of the best amps ever made, in my eyes.

Is it absolutely bleeding edge? Sure, not really.

Does it realistically nail every single measurable metric with absolutely zero trade-offs (ex: la90 has low power, many class D have poor load dependency and linearity, etc etc etc ). Yes. Absolutely.

Also, when buying professional grade equipment (I.e people that make a living and earn their reputation using their products) from companies like benchmark you are essentially guaranteed to experience fantastic support and service. The same absolutely cannot be said for many other brands. This is reflected in the elevated price compared to their consumer competition.

Also, as a live sound professional, I’m grinning at the speak-on revelation in consumer gear.

They are fantastic connectors. Cheap, globally accessible, extremely durable and reliable, and orders of magnitude easier and faster to use than any consumer binding post arrangement (yes even banana plugs). They can also carry 2-8 conductors PER PLUG at 30-50amps of current and 250 volts PER CONDUCTOR. Do the math on how many watts one single connector can deliver. It’s shocking. And they have massive contact surfaces and spring pressure.

I hope to see them become a standard in home/consumer audio.

 

[amirm]

What's really nice in this review is consistency this amp showed,

It is actually remarkable. I was watching the dashboard and noticed neither the gain, nor the output power was changing. Totally static display. Thought AP software had hung! Then I looked on the right and SINAD was changing a tiny bit so nothing was hung. The amp has remarkable precision and stability.

 

[Matias]

While it's a nice amp alright, I would take an Apollon NCx500 amp over it, let alone for 1/3 of the price.

Apollon NCx500ST Stereo Amplifier Review

This is a review and detailed measurements of the Apollon NCx500ST stereo class D amplifier based on Hypex NCOREx NCx500 modules. It was kindly drop shipped from the member and costs 1,090.00€ (US $1,168) with standard opamp. While the case is stamped aluminum, it is a heavily customized one...

audiosciencereview.com

 

[ocinn]

It is actually remarkable. I was watching the dashboard and noticed neither the gain, nor the output power was changing. Totally static display. Thought AP software had hung! Then I looked on the right and SINAD was changing a tiny bit so nothing was hung. The amp has remarkable precision and stability.

Not trying to throw shade here, but this is what we should be expecting from a company dedicated to thorough R&D and delivering a reliable, bare bones (no risk of immediate obsolescence) piece of gear to professionals who make a living and build a reputation that is dependent on their gear performing perfectly every single day.

It’s straight up, not possible, to truly iron out any kinks, inconsistencies, reliability issues, sample variations, broader scope performance quirks, or most importantly, take the time to ensure the quality of your customer support and service network is top notch, when your company is focused on pumping out products at lighting speed to win a competitive arms-race over an inaudible 0.4SINAD advantage, when they are already at the bleeding edge to begin with.

Just my $0.02

 

[AdrianusG]

Back in 2019, I reviewed the Benchmark AHB2 Stereo Amplifier. I received a second sample from a kind member to update the measurements. Originally the AHB2 cost $3000 but now, $3,500.
View attachment 337815
As you see, it is a compact but very nice looking amplifier. I appreciate the clipping indicator which seemed accurate in testing. Back panel shows both SpeakOn and traditional binding posts:

In my original testing, I used the SpeakOn connectors as that gave better response than the binding posts. They are directly soldered to the PC Board as opposed to extra wiring. The amplifier is so low distortion and sensitive to load modulation that this makes a difference as you see below.

A very nice feature is three different gain settings. Highest saturates around 2 volts, middle 4 volts and lowest around 10 volts. I measured all three in areas that matter.

You can also bridge the amplifier into mono and get massively more power. Again, see below.

Benchmark AHB2 Amplifier Measurements
Let's start with our usual dashboard in low gain:
View attachment 337816
While this is phenomenal performance, we have gone from SINAD of 113 dB to 111 dB. This is due to third harmonic rising (inconsequentially to -120 dB). So ranking goes down a bit:
View attachment 337817
View attachment 337818

Surprisingly, there is not much degradation at higher gain levels:
View attachment 337819
View attachment 337820

This is reflected in the SNR:
View attachment 337822
View attachment 337823
View attachment 337824

I did discover some load dependency:
View attachment 337825
It is well managed though and is outside of audible band.

Intermodulation distortion is expectedly low:
View attachment 337826
View attachment 337827

Crosstalk is a hair worse which could be the different speaker wiring:
View attachment 337828

Let's run our 4 ohm power sweep at all three different gains:
View attachment 337829
You see again the impact of the speaker binding vs SpeakOn. But still excellent performance.
View attachment 337830
The dependency on wiring goes down at 8 ohm due to lower currents involved:
View attachment 337831

Changing frequencies doesn't impact the amplifier power sweep much except at 15 kHz, and even there it is well behaved:
View attachment 337837
Some of the non-linearity may again be due to binding posts.

Amplifier is stable and performant on power up:
View attachment 337832

Benchmark AHB2 Bridge Mode Power Measurements
The amplifier goes into differential mode which in theory quadruples the power. It is however only rated above 6 ohm. I tested it at 8:
View attachment 337833

Benchmark AHB2 Reactive Power Measurements
Using my Loadbox, I tested the amplifier at different complex and resistive loads down to 2 ohm:
View attachment 337834

There is a bit of voltage droop as we go down from 8 ohm but still respectable when you consider how much power is being pumped out (approximately):
View attachment 337835

Here is the same but in bridged mode:
View attachment 337836
As you see, it also doesn't have any issues with reactive/complex loads.

Conclusions
Using standard binding posts reduces performance just a bit but certainly nothing to worry about. What we have is still state of the art and one of best ever consumer stereo amplifiers produced.

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As always, questions, comments, recommendations, etc. are welcome.

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Hi Amirm,

This being a Power Amp, how am i going to connect this to my Pre Amp?,
i see no RCA nor balanced inputs.

 

[dogmamann]

In a world where LA90 exists, these are not worth it. Topping is clear as fresh glass. This is glass with small specks of dust. But these are way better than amps like Roksan which are dusty as f.

 

[McFly]

Max power at 20hz shows 153w? you have 108w written?

 

[Matt_Holland]

Hi Amirm,

This being a Power Amp, how am i going to connect this to my Pre Amp?,
i see no RCA nor balanced inputs.

 

[Matt_Holland]

How? This is all inaudible.

The interesting thing is that there’s a difference. And for those interested in the SOTA, it’s a downside to the anp, even if it can’t be heard. Can we explain it?

Hopefully the binding posts aren’t “cheesy steel parts” lol!

 

[AdrianusG]

View attachment 337852

Ah, okay, the picture is quite dark so i didn't see.
these look like Balanced though, so i still would need some adapters, my Pre is RCA out only.

 

[AdrianusG]

Ah, okay, the picture is quite dark so i didn't see.
these look like Balanced though, so i still would need some adapters, my Pre is RCA out only.

Or is there also an Benchmark version with RCA's in?

 

[AdrianusG]

The interesting thing is that there’s a difference. And for those interested in the SOTA, it’s a downside to the anp, even if it can’t be heard. Can we explain it?

Hopefully the binding posts aren’t “cheesy steel parts” lol!

Oh, and 1 more thing, which ones are "Speakon" connectors then?

 

[sweetchaos]

I get that this was state-of-the-art since being announced in 2014 (ie 9 years ago).
But recent advancements in class D amps, from Purifi and Hypex, have pushed the boundaries of technology and now are considered state-of-the-art.

Ignoring the price, what makes this a better buy than the current state-of-the-art options of today?

 

[pogo]

But recent advancements in class D amps, from Purifi and Hypex, have pushed the boundaries of technology and now are considered state-of-the-art.

Especially in load independence, see NAD M23 as example.

 

[Koeitje]

Oh, and 1 more thing, which ones are "Speakon" connectors then?

The ones between the XLR input.

 

[Chester]

I get that this was state-of-the-art since being announced in 2014 (ie 9 years ago).
But recent advancements in class D amps, from Purifi and Hypex, have pushed the boundaries of technology and now are considered state-of-the-art.

Ignoring the price, what makes this a better buy than the current state-of-the-art options of today?

I suppose better protection, higher build quality, proven longevity. Well, those are the reasons I bought it anyway.

 

[amirm]

Max power at 20hz shows 153w? you have 108w written?

Oops. Will correct tomorrow.

 

[Matt_Holland]

You can find answers to your questions by visiting the Benchmark website.