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.
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:
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:
Surprisingly, there is not much degradation at higher gain levels:
This is reflected in the SNR:
I did discover some load dependency:
It is well managed though and is outside of audible band.
Intermodulation distortion is expectedly low:
Crosstalk is a hair worse which could be the different speaker wiring:
Let's run our 4 ohm power sweep at all three different gains:
You see again the impact of the speaker binding vs SpeakOn. But still excellent performance.
The dependency on wiring goes down at 8 ohm due to lower currents involved:
Changing frequencies doesn't impact the amplifier power sweep much except at 15 kHz, and even there it is well behaved:
Some of the non-linearity may again be due to binding posts.
Amplifier is stable and performant on power up:
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:
Benchmark AHB2 Reactive Power Measurements
Using my Loadbox, I tested the amplifier at different complex and resistive loads down to 2 ohm:
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):
Here is the same but in bridged mode:
As you see, it also doesn't have any issues with reactive/complex loads.
EDIT: forgot to post the pop measurements:
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.
-----------
As always, questions, comments, recommendations, etc. are welcome.
Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
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:
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:
Surprisingly, there is not much degradation at higher gain levels:
This is reflected in the SNR:
I did discover some load dependency:
It is well managed though and is outside of audible band.
Intermodulation distortion is expectedly low:
Crosstalk is a hair worse which could be the different speaker wiring:
Let's run our 4 ohm power sweep at all three different gains:
You see again the impact of the speaker binding vs SpeakOn. But still excellent performance.
The dependency on wiring goes down at 8 ohm due to lower currents involved:
Changing frequencies doesn't impact the amplifier power sweep much except at 15 kHz, and even there it is well behaved:
Some of the non-linearity may again be due to binding posts.
Amplifier is stable and performant on power up:
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:
Benchmark AHB2 Reactive Power Measurements
Using my Loadbox, I tested the amplifier at different complex and resistive loads down to 2 ohm:
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):
Here is the same but in bridged mode:
As you see, it also doesn't have any issues with reactive/complex loads.
EDIT: forgot to post the pop measurements:
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.
-----------
As always, questions, comments, recommendations, etc. are welcome.
Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
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