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


Hi everyone,

As most of you know, I’m a fan of Class D. I have lived with ICEPower 250AS based amps for a couple of years. Before that I lived with a pair of Parasound A21s (for HT) and now I’m listening to a Luxman 507ux.


I have some thoughts after long term listening:
  • The tropes of Class D having particularly bad, noticeable Class D qualities are all wrong and have been for years.
  • No one has ever heard my Class D amps and gone: "Oh, wow, Class D, that’s why I hate it."
  • The Luxman is a better amp than my ICEPower modules, which are already pretty old.

I found the Class D a touch warm, powerful, noise free. Blindfolded I cannot tell them apart from the Parasound A21s which are completely linear, and run a touch warm due to high Class A operation, and VERY similar in power output.


The Luxman 507 beats them both, but no amp stands out as nasty sounding or lacking in the ability to be musical and involving.


What the Luxman 507 does better is in the midrange and ends of the spectrum. It is less dark, sweeter in the midrange, and sounds more powerful, almost "louder" in the sense of having more treble and bass. It IS a better amplifier than I had before. Imaging is about the same.


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.


Please keep this in mind when evaluating.


Best,

E
erik_squires

Showing 2 responses by almarg

For an alternative possibility, see my post in this thread dated 6-20-2019.

Regards,
-- Al
 
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