Benchmark AHB2 Review (Updated Measurements)

[Julf]

Sorry, but I don't find your question particularly funny and I can't take it entirely seriously either.
A timbre describes the overtone spectrum of a tone and the time course of the occurrence of
the overtones.
The timbre of a violin note changes as the bow is bowed closer to the bridge
or the bow pressure changes. A clarinet has many more overtones in the low register than in the high register.
A cymbal sounds different in piano than in forte.
When an amplifier adds distortion to the signal it may be that certain overtones are more obscured or, in the case of phase problems, the transient process
no longer corresponds to the natural transient process. Then it can occour, that those subtle changes in timbre can no longer be perceived (masking effect).
I'm a bit surprised that I have to explain something like this here.
By less timbres of the Mc, I meant that the AHB2 dissolves such subtile changes of a recorded sound, for example from nasal to dark, more finely. As professional klassical musican I think, that I am able to hear this.
Getting tired: Recognizing of a Instrument with its specific overtone spectrum is a mental achievement.
Known overtone spectra are compared with what is heard and the brain tries an assignment to a well-known voice/instrument. In addition,
the transient process is analyzed over time.
The less distortion an amplifier has, the easier it is to do this and the longer you can listen without getting tired. This is simply science:
Perceptual psychology and physics. You can also say stressed instead of tired. Did you never listen to a bad measuring amp for a longer time and making such a experience?
But my point isn't about any timbres, I just wanted to point out that the AHB2 in my experience simply works wonderfully even with a load of 0.6 to 1.2 ohms.
I wonder a little bit why you didn't address that at all.

I have no idea who you are responding to, but yes, the AHB2 deals just fine with low impedance loads - already concluded.

As to the "tired" - what you wrote was "Compared to the AHB2, the Mc [...] tires more quickly", implying that it is the amp that gets tired, not the listener.

What level of distortion do you think is audible?

 

[cornoalto]

I have no idea who you are responding to, but yes, the AHB2 deals just fine with low impedance loads - already concluded.

Julf, I dont know anybody here who made experiences which such low loads like 0,6 Ohms. Even the engeneering department of benchmark named this a unique situation.
Some speakers may reach at several frequencies about 1,5 Ohms. But look at the impedance-plot of my speaker. Because of this I would not say that this is already concluded and I think this might be of interest to someone else too.
Tired: sorry of my bad english: of course I spoke of the listener. What else?
Your question for audibility: look at here and calculate:

THD+N Audibility Calculator

Calculate the sound pressure level (SPL) of the amplifier THD+N at your listening position. This will help to determine the audibility of the THD+N. If it is below, 0 dB SPL, it will not be audible. If it is above 0 dB SPL, it may be masked by the music or it may be audible if the THD+N is well...

benchmarkmedia.com

What level of distortion do you think is audible?

Make this experiment from benchmark by yourself and give me the answer:

Power Amplifiers - A "First Watt" ABX Test

In Benchmark's listening room we recently demonstrated the importance of the first watt using two 100 watt stereo power amplifiers. One amplifier was a traditional class-AB amplifier, the other was Benchmark's AHB2 power amplifier with feed-forward error correction. Using a double-blind ABX...

benchmarkmedia.com

 

[SuicideSquid]

Julf, I dont know anybody here who made experiences which such low loads like 0,6 Ohms. Even the engeneering department of benchmark named this a unique situation.
Some speakers may reach at several frequencies about 1,5 Ohms. But look at the impedance-plot of my speaker. Because of this I would not say that this is already concluded and I think this might be of interest to someone else too.
Tired: sorry of my bad english: of course I spoke of the listener. What else?
Your question for audibility: look at here and calculate:

THD+N Audibility Calculator

Calculate the sound pressure level (SPL) of the amplifier THD+N at your listening position. This will help to determine the audibility of the THD+N. If it is below, 0 dB SPL, it will not be audible. If it is above 0 dB SPL, it may be masked by the music or it may be audible if the THD+N is well...

benchmarkmedia.com

Make this experiment from benchmark by yourself and give me the answer:

Power Amplifiers - A "First Watt" ABX Test

In Benchmark's listening room we recently demonstrated the importance of the first watt using two 100 watt stereo power amplifiers. One amplifier was a traditional class-AB amplifier, the other was Benchmark's AHB2 power amplifier with feed-forward error correction. Using a double-blind ABX...

benchmarkmedia.com

You may wish to keep in mind that these are published by a marketing departing whose job is to sell amplifiers, not by disinterested/neutral parties.

 

[Head_Unit]

It’s built to last decades and maybe could be passed down to your children

Who will ask, what the heck IS this thing, daddy?!?

 

[Head_Unit]

Power Amplifiers - A "First Watt" ABX Test

In Benchmark's listening room we recently demonstrated the importance of the first watt using two 100 watt stereo power amplifiers. One amplifier was a traditional class-AB amplifier, the other was Benchmark's AHB2 power amplifier with feed-forward error correction. Using a double-blind ABX...

benchmarkmedia.com

Well now that is a very interesting white paper which actually makes sense. Hooray!

 

[sandeep_s300]

Is the AHB2 more a neutral sounding power amp like the hypex ncx500 ?

 

[Chester]

 

[gfinlays]

Is the AHB2 more a neutral sounding power amp like the hypex ncx500 ?

The AHB2 is about as close to a "wire with gain" as it's possible to achieve. It's free of colouration, audible noise and distortion and any other euphonic nonsense. You won't hear a difference between the AHB2 and a Hypex unless you run both amps to their limits.

 

[gfinlays]

Please correct me if I'm wrong, but I think something should be said against driving a trend for the use of SpeakOn connectors in the possibly wrong-minded impression that this will give better performance in all cases.



Not sure if I missed it in the 24 pages of discussion but I think it should be emphasised that the performance difference is likely due to the direct board connection rather than the type of connector. As such, it should be made clear that the following conclusion is specific to the AHB2 implementation:



In general, it shouldn't be assumed that SpeakOn connectors will automatically give better performance than speaker binding posts.

For example, those who are ordering other class D amps (not AHB2) won't necessarily get better performance by opting for SpeakOn rather than binding posts. As mentioned above, it will be implementation dependent and will likely depend on factors such as the length and path of wiring that runs to the connectors, and its proximity to sources of noise within the case.

I know it's quite a while since your post. To me, the benefits of SpeakON are that they have a positive, locking connection which won't shift if you move your anplifier. They're fully insulated, so no chance of short-circuiting, have a low contact resistance and a ridiculously high current carrying capacity. Some are weatherproof too.

This is why they're de rigeur in pro stage applications. Go to a festival with those multi-kilowatt stacks providing sound to a 100,000 crowd and look at the speaker connections. 100% Neutrik SpeakON.

Electrically, they're as good as it gets. Mechanically, they're Abrams Tank level.

 

[sandeep_s300]

I got the AB2 running as mono with my Revel f228BE .. very neutral sounding amps, a bit too flat in compare to my Apollon hypex ncx500 with sonic imagery 990 opamp stereo. The Hypex seems to have better bass detail and airy top end. The little difference in sound and 4 times the price difference, have decided to sell off the AHB2s and also the Apollon hypex amp. Will get buckeye to build 2 hypex ncx500 monos , as I have also recently ordered hypex ncx500 3 channel amp for HT use. It will be a perfect match on the plus side.

 

[tmtomh]

I ran a pair of Infinity Kappa 9s with a Purifi-based amp for a while. I mostly ran the Kappas in "Normal" mode, which raises their ridiculously low bass impedance a bit. But I did try them out in "Extended" mode which makes them become a 0.8 ohm load down around 30Hz. And I believe they also dip down below 1 ohm around 10kHz (which is of course independent of the bass-mode setting). The amp didn't break a sweat, and I can't imagine the Benchmark AHB2 is any less robust given what we know about it.

So that's the question again?

 

[HappyCow]

Do like my bridged AHB2s but managed to get ahold of one Mark Levinson 5302 (mint demo ex) at the same price as the two AHB2s, so now I have 3 amps at home for my stereo setup.

Not sure how to do quick (within seconds) A/B without adding a lot of extra equipment, so will run a comparison for a few months and then settle for one configuration.

I must say that on first impressions the ML 5302 does sound very good with my setup.

I have Revel Studio2s with a Topping D70 Pro Octo DAC and miniDSP SHD studio for pre-amp and room correction duties (primarily Dirac).

 

[SuicideSquid]

I got the AB2 running as mono with my Revel f228BE .. very neutral sounding amps, a bit too flat in compare to my Apollon hypex ncx500 with sonic imagery 990 opamp stereo. The Hypex seems to have better bass detail and airy top end. The little difference in sound and 4 times the price difference, have decided to sell off the AHB2s and also the Apollon hypex amp. Will get buckeye to build 2 hypex ncx500 monos , as I have also recently ordered hypex ncx500 3 channel amp for HT use. It will be a perfect match on the plus side.

Was this a controlled and blinded test?

 

[Pearljam5000]

 

[etc6849]

There's also another video they did a while back that focuses more on the DAC3. I watched it too as they are both really informative.

 

[new2hifi]

I see that many people have found AHB2 as flat, less emotional, less engaging amplifier (when it measures perfect). Could it be due to some, phase/time smear happening at different frequencies, which they are more sensitive too? After reading many posts across many threads, I feel as if AHB2 is performing like perfect CD sound of early 80’s; which was measuring perfect compared to LPs but with anecdotal observations of being flat, less emotional, less engaging. Later, it was blamed on filters, jitter, impulse response, oversampling… all that stuff that was either not measured at that time or not thought to be important to the sound quality.

In the video, at time 10:01, as I understand, using low pass and high pass filters, AHB2 uses feedback at lower frequencies and feedforward at higher frequencies

.
All filters have consequences. Is there something happening to phase across audio band? Nonlinear phase response? Group delay? Does the low pass and high pass filters are doing something which is not being measured but some people are picking up as flat sound or less engaging?

Group delay is measured for loudspeakers, why it is not part of standard set of amplifier measurements?

 

[SIY]

see that many people have found AHB2 as flat, less emotional, less engaging amplifier (when it measures perfect). Could it be due to some, phase/time smear happening at different frequencies, which they are more sensitive too?

No. This would take great effort to engineer in and would be blatantly obvious in measurements.

All filters have consequences. Is there something happening to phase across audio band? Nonlinear phase response? Group delay? Does the low pass and high pass filters are doing something which is not being measured but some people are picking up as flat sound or less engaging?

No.

The actual answer is that NONE of those anecdotes were as a result of ears-only listening with basic controls.

 

[DonH56]

At best, the AHB2 is ruthlessly exposing the limitations of the source material. Some people can't handle the truth.

 

[HappyCow]

Has anyone tried it with a tube pre-amp which is supposedly giving a warmer sound?

 

[kyuu]

Has anyone tried it with a tube pre-amp which is supposedly giving a warmer sound?

Why in the world would you pay a lot of money for an amp that's this transparent just to trash it with a tube pre-amp? Just buy a much cheaper tube amp to color your sound. Or any old amp and use some EQ to get the colored sound you're after.