I went from Class D to Luxman A/AB - And most of what you think is wrong

Erik, thanks for the post, always an interesting read:-)...

Erik, thanks for the post, always an interesting read:-)...

I second that!

If you have ever read the works of Nobel winning psychologist Daniel Kahneman, he devotes a lot of brainpower and ink to proving that people develop a process of thinking that usually makes it very difficult for them to accept change. Often, completely unbiased analytical data doesn't help with allowing someone to open their minds to the possibility that some process or product may be better. Therefore, we may be talking about the comparative aspects of Class D sound for a while.

Six years ago, I bought a Crown XLS 2000...a $500 Class D amp based on a TI chip.  It sounded darn good, solid and deep low end, big soundstage (width but with minimal depth), dynamic and decent but sibilant midrange and top end.

I replaced that amp with a Class A/AB Parasound Halo.  It was better in every respect...but still, pianos, trumpets and a few other things didn't seem quite right (and obviously, it could have been the speakers, dac, preamp, wires, etc.)

Then, two months ago I replaced the Halo with another Class D...which should elicit the question WHY a Class D of all things.  For exactly the reason that erik suggested...there isn't really a reason to be talking about amplifier classes so much anymore.

At any rate, I bought a 2Cherry from Digital Amplifier Company.  If you go to their website  https://www.cherryamp.com/dac-home   you will see that they are building Class D amplifiers unlike anyone else...bandwidth to 150kz...switching frequencies up to 2mghz...and they don't use modules from anyone else.  Their owner/engineer Tommy Obrien designs his own circuits and the builds his amplifiers from discrete components.  His stated goal is for his amplifiers to sound like nothing.  (Sounds a lot like the specs and statements from the well respected Class A and Class A/AB guys)


Tommy doesn't do paid advertising with anyone so one might assume that the professional reviews he is getting from the magazines might be a little more (skeptical, critical, harsh, etc.) less supportive...but in fact, they love his amplifiers.

Let me say this about the 2Cherry...in comparison to the Halo it replaced...What "shocks" you right away is the incredible level of transparency/clarity that seems to lift a fog that you didn’t know was there which brings the music alive. There is no sibilance, no brightness, no harshness, no artificially pumped up midrange and top end.  This amplifier brings you into a detailed, layered, powerful yet delicate soundstage with emotional involvement similar to a live performance.

I think we might all agree that the sound that moves us and the amplifier that brings us that sound is a personal preference...you prefer X and I prefer Y...and one of the beauties is that we have choices.  I'm with eric on this one; there is no longer a need to talk about Class D vs other classes...instead focus on what sounds best in your system and be open to the idea that it just might be a Class D amplifier.

I'd like to offer a correction.  I said:

I didn't say I did a test blindfolded. I said if I were blindfolded I could not tell the difference 

But actually, I kind of DID say that. Sorry.

What I meant to say was:

"I knew which amp was which, and even then I could not tell them apart."

Apologies for forgetting what I just wrote.

Best,
Erik

There was one significant operational difference, which others have confirmed. I don’t know why this is true, but the Class D amps needed 2-4 days to warm up. The Luxman needs no time at all. I have no rational, engineering explanation for this. After leaving the ICEPower amps off for a weekend, they sounded pretty low fi. Took 2 days to come back. I can come home after work and turn the Luxman on and it sounds great from the first moment.

Just a guess, but the switching times of transistors vary as a function of temperature, which may take a relatively long time to stabilize in a class D amp due to the low power consumption. And perhaps what is occurring during the 2 to 4 days is that the turn-on and turn-off times of the transistors which supply current to the output from the positive DC rail become more closely aligned with the corresponding switching times of the transistors which supply current to the output from the negative DC rail. Thereby reducing or eliminating "shoot-through" or "dead time" that may occur during those transitions, when both groups of transistors may for a brief instant be simultaneously on or simultaneously off.

On another note, Erik, as others have said thanks for yet another very interesting thread.

Best regards,
-- Al