Benchmark Audio's claim about amplifier noise in one of their Application Notes

[Jack B]

In an announcement they say stuff like...

[td]

"Would you put a Washing Machine in your Listening Room?​

[/td]​

[td]If the answer is no, you may be surprised to discover that the distortion produced by your power amplifier may be louder than the noise produced by a major appliance." and go on to show data on several power amps claiming that several of them are very audibly noisy. I don't have the expertise to evaluate their claims, hoping someone who does (Hi, Amir!) will respond?
[/td]

 

[NTK]

It is BS. They completely ignore the existence of auditory masking, claiming a background noise of 25 dB SPL is problematic when your system is blasting at you at 105 dB SPL (S/N ratio of 80 dB) .

Post in thread 'New LaiV harmony GanM monoblocks sounds better than purifi (warning subjective information)'

Jul 22, 2025

Also, consider how much noise an amplifier generates. The norm is THD+N expressed as a percent of total output. So the louder the music the higher the distortion for the same THD+N. The music masks the distortion.
I am a Benchmark fanboi. Here is a link to a Technote they released yesterday. Along with the items mentioned above, this may be applicable to hearing a difference in amplifiers that have good measurements...

• NTK

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[MAB]

They make a similar and completely BS claims about the audibility of crossover distortion in competitors' amps.
It took some time, but John Siau finally admitted the two test samples they used for comparison both suffered from thermal stability issues with the bias circuitry.
He also admitted that even then, they needed to use a pure test tone to hear the crossover distortion. He also speculated that maybe lots of amps have unstable bias circuitry.

It's hard to make this up (from the above link):

This crossover distortion defect was present in both channels of two band new RA-500 power amplifiers. This problem could have been solved with thermally stable bias circuits, or by proper factory adjustments, or a combination of both. Clearly these two test samples were not thermally stable. For those of us who design power amplifiers, it seems incredible that these amplifiers shipped with this biasing problem. It is hard to know if this is unusual, especially in lower cost class AB power amplifiers. The RA-500 was a low-cost "studio reference" class AB power amplifier.

He got cheap amps that were known to be unstable, tested them with a sine tone compared to his amps which are among the best, and pretends the rest of the market is just as lame, and that we are all ignorant.

They make great amps. I don't like this BS marketing though.