AHB2 - Lab Report - Amirm, Audio Science Review

"The AHB2 easily outperforms the DIY Hypex NC400 I had tested before which used to be the best amp I had tested."

"THD+N versus output level looks far cleaner than anything I have tested before."

"Intermodulation distortion versus power level shows the same story of clean power."

No Rise in Out-of-Band Noise

"Usually when we test switching amplifiers we see all kind of "interesting" things in their outputs above hearing range. The AHB2 is a classic configuration albeit, with a switching power supply so all is well and clean here."

Signal to Noise Ratio (22.5 kHz BW) at Max Power

• Ch1: 130.286 dB
• Ch2: 130.180 dB

Frequency Response

"Down 0.3 dB at 20 kHz. -3 dB down at 200 kHz!! Since this is not a switching amplifier, there is no filter there allowing the bandwidth to go to 200 kHz and beyond."

Stereo Power into 4 Ohms

"We have 185 watts of power at incredibly low distortion of 0.00016%, besting the company specifications."

Bridged Mono Power into 4 Ohms

"500 watts into 4 ohm! Stunning 0.00026% distortion at 500 watts!!"

Low-Power 5W THD Test

"As usual, I start with my 5 watt output test using 4 ohm load... I hope your jaw is on the floor just like mine was when I saw this picture emerge! 113 dB THD+N [at 5 W] in a power amplifier? Are you kidding me?"

"Look at the harmonic distortion. The worst case spike is below -130 dB! This is insanely good. Of course this type of SINAD (signal and noise ratio) crowns the Benchmark AHB2 as the best I have ever tested."

"Separating the noise from THD, we see that it is noise that we are measuring as THD+N, rather than distortion. Noise dominates (more benign than distortion)."

Noise Relative to 5W

• Ch1: -112.964 dB
• Ch2: -112.550 dB

THD Only (no noise) at 5W

• Ch1: -122.337 dB
• Ch2: -120.982 dB

Protection System

"There are a set of LEDs that show the status of the amplifier. They are driven by an FPGA (field programmable digital logic) that monitors all aspects of the amplifier and shuts down the unit if stressed. It did so very quickly and efficiently in my testing. Usually this is done with purely analog or maybe a small microprocessor. As such, the coverage of scenarios that could damage the amplifier is much less complete than using the approach Benchmark is using in AHB2."

"Bridged mode using same 4 ohm load ... you get 500 watts of stunningly clean power. Protection circuits shut the unit down after that, so it is quite safe to try. With a THD essentially matching the non-bridged mode, there is no reason to be afraid of trying this."

"... the FPGA protection mode kicks in and essentially shuts the amplifier down past the limit. You get absolutely distortion-less and noiseless performance until there is no more."

Stereo/Mono Switch

"There is a switch for selecting stereo or mono bridged output. The latter quadruples the amount of power available."

Power Dissipation

"In use the AHB2 stays very cool for a power amplifier when it is idling, outputting little power which was a nice surprise."

Certifications

"Being a proper company of course the AHB2 comes with full set of regulatory/safety/emissions certifications which is super important with power amplifiers given the high voltages and currents running around in them."

Conclusions

"It goes without saying that the Benchmark AHB2 breaks new ground with respect to performance of power amplifiers."

"Using it, you can be assured that any distortion that you hear is from other sources (speaker, source, content, etc.). This is what I look for in high-end audio: absolutely the best performance so no second guessing is involved. You buy once, and you are happy forever!"

"All of this comes from a company that is a model of transparency with proper and accurate measurements of their products on their site. And importantly, volunteering to have that data shown to be correct by independent sources such as us."

"Needless to say, the Benchmark AHB2 gets my strongest recommendation."

- Amir Majidimehr (@amirm), AudioScienceReview.com

Read the entire review at AudioScienceReview.com →