Atma-Sphere Class D… Amazing

@jerryg123 

Call it Class A-G if it makes you happy but at it's core, the Benchmark was based on a switching power supply which is why it weighs 12.5 lbs. 

From S'Phile's coverage of RMAF 2013;

The Benchmark AHB2 amplifier, named in honor of the company's founder, Allen H. Burdick, who passed away just before the show, has a dynamic range claimed to approach 130dB, and outputs 100Wpc into 8 ohms, 170Wpc into 4 ohms and can be bridge to produce 340W into 8 ohms. THD+noise is said to be <–108dB relative to full output at 1kHz. John Siau explained that the THX modules are operated in a mode that gave the lowest noise and distortion rather than the maximum efficiency I wrote about in 2012. A key to the low THD is the use of 0.01%-tolerance resistors at critical points in the circuit. A switching power supply is used, Siau feeling that this was optimal because all the power-supply spuriae will be out-of-band and therefore more readily filtered. 

Ralph-would you be willing to discuss your Class D amp in terms of being true balanced (or not)? Please explain the circuit topology in terms of inputting and amplifying the input signal fully true balanced throughout. And assuming it does not, isn't this a compromise?

@nonoise

This guy is just messing you guys. He appears to hold a grudge. A cursory look at his posts (which is all I can bear to do) shows he is talking in circles and sometimes contradicts himself. He's gotten better at covering his mistakes but in the end, he's just messing with you guys, trying to show how bright he is, which I think, is his main objective.

Assuming that once again you are belittling me with unfounded, unproven, baseless accusations, I can't help but wonder exactly what sort of grudge it is I hold and against who and what proof of any of this nonsense you care to share?

You know, in darkness, it doesn't take much of a light to appear bright...

@holmz

I find the noise floor more distressing than the harmonic distortion. So the graphs could possibly add some insight.

There is a great deal of measurements that could add insight:

1. Distortion versus frequency: flat or rising?

2. Frequency response vs load: independent or dependent?

3. FFT vs frequency: level of even, odd, 2nd, 3rd, later harmonics?

4. Distortion + Noise versus power for different loads: increasing or decreasing? Level?

5. Power stage efficiency vs power at different loads: comparison between GaN and regular mosfets

With people making claims of this amp’s superiority, I see no issue with asking for some proof. When the manufacturer states that there is a lot about an amp’s subjective performance that can be gleaned from the measurements, I say please show us. I just find it hard to understand why the manufacturer makes the claim that measurements contain a great deal of information on the subjective performance yet won't publish said measurements. Especially at the price point. These are not unreasonable requests- plenty of other manufacturers publish this data. What’s the big deal? Why the angst and accusations of some nefarious ulterior motive?