Jump to content

Benchmark AHB2 power amplifier - experiences


Guest scumbag
 Share

Recommended Posts

Guest scumbag

Hi, I've been reading some reviews on the Benchmark AHB2  power amplifier  - I'm wondering if anyone's heard one and if so what are their thoughts?

 

https://www.stereophile.com/content/benchmark-media-systems-ahb2-power-amplifier'

 

The circuit topology is class AB but it supposed to have no crossover distortion. Actually distortion overall is crazy low too.

 

https://hometheaterreview.com/benchmark-ahb2-reference-stereo-amplifier-reviewed/

Link to comment
Share on other sites
9 hours ago, scumbag said:

Hi, I've been reading some reviews on the Benchmark AHB2  power amplifier  - I'm wondering if anyone's heard one and if so what are their thoughts?

 

https://www.stereophile.com/content/benchmark-media-systems-ahb2-power-amplifier'

 

The circuit topology is class AB but it supposed to have no crossover distortion. Actually distortion overall is crazy low too.

 

https://hometheaterreview.com/benchmark-ahb2-reference-stereo-amplifier-reviewed/

 

I haven't heard one but the measurements are definitely exceptional. 

 

  • Like 1
Link to comment
Share on other sites
Guest scumbag

Thanks guys. I've read a bit about the power supply and so forth. The entire design is quite unique. I was hoping for some input from someone who has heard one. The reviews are very positive and I'm wondering if anyone has any subjective impressions or points of comparison.

 

Mark

Edited by scumbag
Link to comment
Share on other sites

Quote

And, to my embarrassment, one of the speaker cables with which I routinely measure amplifiers and my test load set to 4 ohms were also introducing small amounts of nonlinearity. These problems—and here I'm talking about the difference between 0.0003% THD+noise and 0.0005%—haven't affected the measured performance of other amplifiers I've tested, but they were detectable with the AHB2's very low intrinsic distortion and noise. For this review, THX's Andrew Mason supplied me with a custom test load made with resistors using nonferrous leads and terminals, and a speaker cable terminated with a Speakon connector, both of which had guaranteed negligible nonlinearity

 

Heh.   I've lost count of the number of times I have heard about fancy terminals and connectors (vs.the humble speakon).

 

 

A very neat design.   Performance at clipping is where you're going to hear a difference between this and other 'blameless' amps.

Link to comment
Share on other sites
Guest scumbag
37 minutes ago, davewantsmoore said:

 

Heh.   I've lost count of the number of times I have heard about fancy terminals and connectors (vs.the humble speakon).

 

 

A very neat design.   Performance at clipping is where you're going to hear a difference between this and other 'blameless' amps.

Oh yes, all amplifiers sound the same unless they're under clipping or they are faulty. How silly of me to forget that. 

Edited by scumbag
Link to comment
Share on other sites
21 minutes ago, scumbag said:

Oh yes, all amplifiers sound the same unless they're under clipping or they are faulty

Not necessarily....   but it is possible (especially amplifiers with impressive performance like this one).

 

My point was that big differences will show up in clipping.   These differences are usually dramatic, and totally dominate the sound of the amplifier.

 

21 minutes ago, scumbag said:

 Of course you haven't heard it but you had to provide some input all the same.

Not this amp (Benchmark) ... but 'AAA', yes ... and other feed-forward types.

 

 

Of course, *I* think my input is quite relevant.    Clip this amplifier at your own peril (cos it will sound super-bad)

Link to comment
Share on other sites
Guest scumbag
Just now, davewantsmoore said:

Not necessarily....   but it is possible (especially amplifiers with impressive performance like this one).

 

My point was that big differences will show up in clipping.   These differences are usually dramatic, and totally dominate the sound of the amplifier.

 

Not this amp (Benchmark) ... but 'AAA', yes ... and other feed-forward types.

 

 

Of course, *I* think my input is quite relevant.    Clip this amplifier at your own peril (cos it will sound super-bad)

Dave, excuse my curtness. I see your point. The distortion rises like a cliff face after a certain point. The polar opposite of a Class-A SS or tube amplifiers. 

Link to comment
Share on other sites

8 minutes ago, scumbag said:

The distortion rises like a cliff face after a certain point.

.... THD doesn't tell the whole story (or often much of the story), as THD is usually much more benign than people figure .... it's just easy to measure, and human nature like to sort and classify things so a "THD scale" plays to that.

 

The real issue, is the 'recovery time'... once the amplifier has clipped, what happens in the future?.... and you need lots of much more complex measurement to characterise this.    High-levels of feedback control are good, until they fail.

 

 

To go off on a tangent, this is one of the reasons why THD in tube amplifiers got so confusing for people.... high levels of THD were reasonably inaudible in some, and in others put a huge fog (or worse) into the sound.   It is all about how the amp recovers after it has been pushed into clipping (which THD doesn't tell).     The way to test how audible these things are is to ensure controlled testing - modern tools are fantastic for that.   You can dial in any types of distortion you like (on their own) with a "distortion generator", and see what things sound like.

 

I heard a headphone amplifier (driving a headphone, and driving a midrange driver) reference design of AAA .... and I couldn't hear anything worth mentioning.

Link to comment
Share on other sites
Guest scumbag
4 minutes ago, Addicted to music said:

Push any amp into clipping and it will guarantee to sound Shcitt...

 

If I’m reading it right  with this amp, there is a Processor to switch off as a protective measure even if it distorts...  nifty feature for speaker protection..

The Devialet have an interesting way of dealing with clipping. They actually reduce power via DSP. If you have a look at the power output graphs on these amps you see the power get up to the point of clipping then power  actually reduces as the volume control is increased.

113Devifig05.jpg

Edited by scumbag
Link to comment
Share on other sites
3 minutes ago, Addicted to music said:

Push any amp into clipping and it will guarantee to sound Shcitt...

Dramatic over-simplification.... of something which is very important to overall amplifier sound.     Different amplifier designs behave very(!!!!) different when distorting .... and very(!!!!!) similar when operating in a a band of "acceptable" performance.

  • Like 1
Link to comment
Share on other sites

3 minutes ago, scumbag said:

The Devialet have an interesting way of dealing with clipping. They actually reduce power via DSP. If you have a look at the power output graphs on these amps you see the power get up to the point of clipping then power  actually reduces as the volume control is increased.

113Devifig05.jpg

I like it...  Because going into distortion and even clipping is not doing your  hearing any good,  and it tells the listener that this is the limit which also safeguard speakers.

Link to comment
Share on other sites
5 minutes ago, davewantsmoore said:

Dramatic over-simplification.... of something which is very important to overall amplifier sound.     Different amplifier designs behave very(!!!!) different when distorting .... and very(!!!!!) similar when operating in a a band of "acceptable" performance.

Yes they all do due to different design and implementation.   Every amp I have had in the rig sounds different.  Drive difficult loads puts the flee power amps on notice.

Link to comment
Share on other sites
Guest scumbag
1 minute ago, Addicted to music said:

Yes they all do due to different design and implementation.   Every amp I have had in the rig sounds different.  Drive difficult loads puts the flee power amps on notice.

Just about every amplifier I have owned has sounded different to my ears (some more than others), in my system. And that's well inside the envelope of clipping. 

For example, the NAD M2 is a radically different sounding amplifier to ANYthing I've heard. I can't imagine that someone would listen to one of the M2's at 10watts RMS and then switch to a Rega Brio at the same volume (as a random example) and not perceive a marked difference. If not, clean out your ear canals and/or get different speakers.......

Link to comment
Share on other sites
9 minutes ago, Addicted to music said:

Because going into distortion and even clipping is not doing your  hearing any good

Why?

 

(Aside from "bad sounding sound" is generally offensive to people who like good sound).

 

9 minutes ago, Addicted to music said:

safeguard speakers

I'm not sure I understand.

 

Clipping doesn't damage speakers (even though you see it stated confidently frequently everywhere) ....  too much power damages speakers.

 

Of course, if you had an amp which clipped at 100w amp, and speakers which would damage at 100w.... then clipping 'protection' would keep you away from damaging your speaker ..... but this is a rare situation where the amp clipping and speaker damage levels are the same.

Link to comment
Share on other sites

Guest scumbag
2 minutes ago, davewantsmoore said:

Why?

 

(Aside from "bad sounding sound" is generally offensive to people who like good sound).

 

I'm not sure I understand.

 

Clipping doesn't damage speakers (even though you see it stated confidently frequently everywhere) ....  too much power damages speakers.

 

Of course, if you had an amp which clipped at 100w amp, and speakers which would damage at 100w.... then clipping 'protection' would keep you away from damaging your speaker ..... but this is a rare situation where the amp clipping and speaker damage levels are the same.

Well a clipped amp' doesn't put out DC but a sustained high voltage square wave is not going to do wonders for your speakers.

Link to comment
Share on other sites
2 minutes ago, davewantsmoore said:

Why?

 

(Aside from "bad sounding sound" is generally offensive to people who like good sound).

 

I'm not sure I understand.

 

Clipping doesn't damage speakers (even though you see it stated confidently frequently everywhere) ....  too much power damages speakers.

 

Of course, if you had an amp which clipped at 100w amp, and speakers which would damage at 100w.... then clipping 'protection' would keep you away from damaging your speaker ..... but this is a rare situation where the amp clipping and speaker damage levels are the same.

I’ve had 500W @8ohms  Perreaux driving a set of Kans....  never did seem to take out any drivers of the Kans....

ive had a 40w Yammie AV receiver take out the tweeters of the Kans....

 

it just goes to show that diving speakers into clipping pushes what looks what looks like a square wave into the tweeters.    It’s the DC component of the clipping that overheats coils.

Link to comment
Share on other sites
  • Volunteer
33 minutes ago, davewantsmoore said:

The real issue, is the 'recovery time'... once the amplifier has clipped, what happens in the future?.... and you need lots of much more complex measurement to characterise this.    High-levels of feedback control are good, until they fail.

My theory (well Roger Sanders theory which I like) is that the vast majority of the difference in amp sounds is due to the differences in the way that amps clip.

His view is that most amps are underpowered and will clip into most "normal" speakers. The clipping may be very brief and possibly inaudible in itself but the way the amp recovers will make it sound different from other amps.

So when we say amp A sounds different to amp B we are really saying that the effect of clipping is different between the amps

Link to comment
Share on other sites
Guest scumbag
7 minutes ago, davewantsmoore said:

As before, it's the high voltage ... not the square wave. 

Yeah sure, so has anyone heard the Benchmark-ahb2 power amp?

Link to comment
Share on other sites
 Share

  • Recently Browsing   0 members

    • No registered users viewing this page.




×
×
  • Create New...
To Top