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Review and Measurements of Benchmark AHB2 Amp

Geert

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The Benchmark will be less affected by your speaker's impedance and will be cleaner (lower in distortion) and flatter (in frequency response).
This!

Have a look at Stereophile's measurements, John specifically mentions the high output impedance of the Octave amp: "Measured at the speaker terminals, the output impedance was fairly high, measuring 1.84 ohms at 20Hz and 1kHz, rising to 3.1 ohms at 20kHz. As a result, the variation in the V 80 SE's frequency response with our standard simulated loudspeaker was ±1.1dB (fig.1, gray trace)". It means the Octave will amplify the low end.

https://www.stereophile.com/content/octave-audio-v-80-se-integrated-amplifier-measurements
 

rdenney

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Is that really necessary though? If you don't like the sound of the amp, how is a blind test gonna change that? Get a different amplifier.
Because sometimes you have to train your ears. We are told to listen to amps that have higher distortions for hundreds of hours to “break them in” which is really intended to habituate us to the coloration those amps add. A lack of additional coloration requires habituation, too, depending on our starting point.

Rick “try a more complex recording, where more ‘meat’ often equals more mud” Denney
 

RichB

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I compared the AHB2 (sighted), level-matched to with 0.06 dB to the ATI AT522NC. There were differences and on some titles the AHB2 was noticeably cleaner, had a better stereo imaging, and attack. By Attack, the crack of a drum stick and strings was apparent where the ATI seemed to miss it. I went back and checked the voltage and the ATI was 0.02 higher.

Here is the thread: Level Matched Comparisson of the AT525NC and AHB2 | Audio Science Review (ASR) Forum

I'll see if I can get a volunteer to provide the SBT part.

The AHB2 clip indicators proved to be extremely accurate. On tracks that have near 0 dBFS peaks, -26 was 2.83 volts and the AHB2 could play at -06 without clipping. At -05.5, the clip indicators illuminated.

The AT525NC did not illuminate its peak indicators 0, that would be about 400 watts, which the ATI cannot produce cleanly (according to the specs). Between -06 and 0, sound coming from the Revel 126Bes did not seem to increase by much, perhaps the amp and/or Revels were compressing.

- Rich
 
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RobS

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I compared the AHB2 (sighted), level-matched to with 0.06 dB to the ATI AT522NC. There were differences and on some titles the AHB2 was noticeably cleaner, had a better stereo imaging, and attack. By Attack, the crack of a drum stick and strings was apparent where the ATI seemed to miss it. I went back and checked the voltage and the ATI was 0.02 higher.

Here is the thread: (1) Considering SBT amp session between AT525NC and AHB2 | Audio Science Review (ASR) Forum

I'll see if I can get a volunteer to provide the SBT part.

The AHB2 clip indicators proved to be extremely accurate. On tracks that have near 0 dBFS peaks, -26 was 2.83 volts and the AHB2 could play at -06 without clipping. At -05.5, the clip indicators illuminated.

The AT525NC did not illuminate its peak indicators 0, that would be about 400 watts, which the ATI cannot produce cleanly (according to the specs). Between -06 and 0, sound coming from the Revel 126Bes did seem to increase by much, perhaps the amp and/or Revels were compressing.

- Rich
What gain setting did you have the AHB2 on when you did the comparison?
 

RichB

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What gain setting did you have the AHB2 on when you did the comparison?

Here is the level matching and channel duplication configured in the SHD:
SHDSettings.jpg


Here are the voltages:
AHB2_AT525NC_Voltage_Level_Match.jpg

I also used -3.0 dB for outputs 1 and 2 and -8.5 for 3 & 4.
Most comparison were at -26 is 2.83 volts (1 watt), -20 (2 watts), and -16 (10 watts).
I occasionally listened at -6 dB (100 watts), which was the maximum level before the AHB2 clip indicators lit.

At this level, Feist "Metals" album remained clear and bested the ATI.
I highly recommend that AHB2 with Performa 3 Be speakers.

- Rich
 
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RobS

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No I mean the switch on the back of the amplifier. What did you have it set at? the 9.8vrms setting which is low gain?
 

RichB

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No I mean the switch on the back of the amplifier. What did you have it set at? the 9.8vrms setting which is low gain?

I used high-gain for this testing.

- Rich
 

DonH56

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Of course I will give it more time. I am also going to have my wife and son do A/B test. Quasi blind test as they don’t know anything about amplifiers.

You should have no problem picking out when the amplifiers change with such a large difference. I wouldn't bother. It comes down to which you prefer. I loved my tube amps but am fully aware they were not as accurate as my SS amps. I decided I prefer accuracy; can always tweak the EQ later but I like having a "known-good" starting point. But if you prefer the sound of the tube amp there's absolutely no issue sticking with it. I agree in spending a little time listening to a variety of sources at a variety of levels to see which you prefer. You may decide you prefer the higher accuracy of the AHB2 after all. Or end up keeping both amp "flavors". :)
 

Alec Kinnear

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What I got was absolute dead silence and the most effortless sounding music. I don't find the pair shrill at all. I think they're just so damned transparent that any harshness from the source is so much more apparent than with other preamp/amp combos

Thanks for your comparative listening notes. You have a point that poorly recorded/mastered music will tend to show its shrill/harsh qualities in a highly transparent environment. It's two ways of saying the same thing though. I'm on Class D now and objectively the DAC/amplification quality is perfect (RME ADI-2 DAC fs to dual vertically bi-amped Pro-ject Stereo Box DS2). Haven't found quite the same pleasure in the sound which I had when I enjoyed a fully working NAD C372 – more often the music would just become part of me. Enjoying music should not be a transparency test – listening to music should not be calisthenics or cold showers. There's nothing useful or productive about less pleasure from one's music unless one is mixing the music for others (at which point, transparency even with exaggerated flaws becomes very important).

Of course such views are not popular here. Real men listen to all the flaws in their recordings! No euphonics, no tone controls, no pleasure. Oh you brave Spartans!
 
D

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Thanks for your comparative listening notes. You have a point that poorly recorded/mastered music will tend to show its shrill/harsh qualities in a highly transparent environment. It's two ways of saying the same thing though. I'm on Class D now and objectively the DAC/amplification quality is perfect (RME ADI-2 DAC fs to dual vertically bi-amped Pro-ject Stereo Box DS2). Haven't found quite the same pleasure in the sound which I had when I enjoyed a fully working NAD C372 – more often the music would just become part of me. Enjoying music should not be a transparency test – listening to music should not be calisthenics or cold showers. There's nothing useful or productive about less pleasure from one's music unless one is mixing the music for others (at which point, transparency even with exaggerated flaws becomes very important).

Of course such views are not popular here. Real men listen to all the flaws in their recordings! No euphonics, no tone controls, no pleasure. Oh you brave Spartans!

I would have kept the NAD and paired it with the RME: https://www.stereophile.com/content/nad-c-372-integrated-amplifier-measurements
 

RichB

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Thanks for your comparative listening notes. You have a point that poorly recorded/mastered music will tend to show its shrill/harsh qualities in a highly transparent environment. It's two ways of saying the same thing though. I'm on Class D now and objectively the DAC/amplification quality is perfect (RME ADI-2 DAC fs to dual vertically bi-amped Pro-ject Stereo Box DS2). Haven't found quite the same pleasure in the sound which I had when I enjoyed a fully working NAD C372 – more often the music would just become part of me. Enjoying music should not be a transparency test – listening to music should not be calisthenics or cold showers. There's nothing useful or productive about less pleasure from one's music unless one is mixing the music for others (at which point, transparency even with exaggerated flaws becomes very important).

Of course such views are not popular here. Real men listen to all the flaws in their recordings! No euphonics, no tone controls, no pleasure. Oh you brave Spartans!

I understand the measurements show that there are many great performing amps but all amps do not perform the same driving speaker reactive loads.

I recently compared the ATI AT525NC and AHB2 and the ATI gets louder but not much driving the Revel M126Bes.
Levels matched and quick switching, my subjective view is the AHB2 produces sounds clearer and better defined, also less harsh. It could be heard at 1 watt, but it was easier to identify at 4 and 10 watts (power computed in using voltage measurements).

There are harsh recordings but, unless an amp is rolling off high-frequencies, adding distortion or perhaps limiting transients is not going to make, even bad recordings, sound better.

- Rich
 
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pjug

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I understand the measurements show that there are many great performing amps but all amps do not perform the same driving speaker reactive loads.

I recently compared the ATI AT525NC and AHB2 and the ATI gets louder but not much driving the Revel M126Bes.
Levels matched and quick switching, my subjective view is the AHB2 produces sounds clearer and better defined, also less harsh. It could be heard at 1 watt, but it was easier to identify at 4 and 10 watts (power computed in using voltage measurements).

There are harsh recordings but, unless an amp is rolling off high-frequencies, adding distortion or perhaps limiting transients is not going to make, even bad recordings, recordings sound better.

- Rich
Are you able to record the voltage at the speaker with an scope to see if there is really a noticeable difference (other than the ultrasonic residuals)?
 

toddverrone

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Thanks for your comparative listening notes. You have a point that poorly recorded/mastered music will tend to show its shrill/harsh qualities in a highly transparent environment. It's two ways of saying the same thing though. I'm on Class D now and objectively the DAC/amplification quality is perfect (RME ADI-2 DAC fs to dual vertically bi-amped Pro-ject Stereo Box DS2). Haven't found quite the same pleasure in the sound which I had when I enjoyed a fully working NAD C372 – more often the music would just become part of me. Enjoying music should not be a transparency test – listening to music should not be calisthenics or cold showers. There's nothing useful or productive about less pleasure from one's music unless one is mixing the music for others (at which point, transparency even with exaggerated flaws becomes very important).

Of course such views are not popular here. Real men listen to all the flaws in their recordings! No euphonics, no tone controls, no pleasure. Oh you brave Spartans!

I just joined here. I'm not as hard core as some, my final verdict on any change to my stereo is whether I like the change or not.

I like the benchmark stack because I've found the clarity it brings has made all my music more enjoyable to listen to. I have noticed less issues with distortion or artifacts which had previously distracted me from being fully immersed in the music. I guess I'd described the sound as effortless as opposed to clinical, if that makes sense
 

RichB

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Are you able to record the voltage at the speaker with an scope to see if there is really a noticeable difference (other than the ultrasonic residuals)?

Not really. The best I can do is level match using the Fluke 87V.
The Fluke has the ability to measure peak voltage with resolution up to 4kHz. It samples, so over time, would catch higher frequencies but I might give that a try.

- Rich
 

Andysu

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£3 grand for this and how well does it stand up to using (matched LCR behind a projection screen) with Star Trek VI the undiscovered country on the opening titles to the planet exploding and the amp only offers less than 200w stereo or 500w bridge for £3 grand, please, £3 grand. daylight robbery and they stick the THX letters on the back rather than on the front with a proper THX badge, and doesn't have rack ears for rack mounting, please £3 grand.
 

Jukka

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It looks like this is the only amplifier that powers speakers in Benchmark catalogue. My next speakers are going to be fully active, I would love something smaller and multichannel enabled for them. Less than 100 W continuous is required for high efficiency horn + compression driver. Also space will be a factor for 6 amplifier channels.
 

toddverrone

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£3 grand for this and how well does it stand up to using (matched LCR behind a projection screen) with Star Trek VI the undiscovered country on the opening titles to the planet exploding and the amp only offers less than 200w stereo or 500w bridge for £3 grand, please, £3 grand. daylight robbery and they stick the THX letters on the back rather than on the front with a proper THX badge, and doesn't have rack ears for rack mounting, please £3 grand.

You're obviously welcome to your opinion. I had class D monoblocks before this with 500w to each speaker. This little amp plays just as loud. My room can't take any more volume and still it doesn't clip. It's so much cleaner and effortless. It's that it delivers all it's power with no distortion.

Don't judge this thing before you've tried it
 

Andysu

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Still doesn't have THX on the front for £3k. Say what get me 30 of these for £1k off the back end of lorry and we have a deal. Otherwise £3k I keep my Behringer and Crown amps. I know find out what makes it so good and take those parts and I can stick them in the Behringer and Crown amps.
 

toddverrone

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Still doesn't have THX on the front for £3k. Say what get me 30 of these for £1k off the back end of lorry and we have a deal. Otherwise £3k I keep my Behringer and Crown amps. I know find out what makes it so good and take those parts and I can stick them in the Behringer and Crown amps.

I actually had a crown XLS. The ICEpower monoblocks sounded a bit better than the Crown. The benchmark beats the pants off the Class D and the Crown.

It's funny how a bunch of you are all of a sudden throwing shade all over this amp. I mean, there's nothing wrong being happy with what you have, but why bother wasting your time attacking another product that gets universal praise?

Attacking scam products I understand, but this is just silly.
 
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