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.


Who said production boards will be soldered by hand?I didn't

I didn't, I inferred if you design a GaN board from scratch, you'd do the whole thing SMD because the GaN semiconductors are all SMD, therefore my statement was.
" They're not stupid and know it's impossible to create a "retail product" complete Class-D board, using all smd components, and making it by hand soldering"
@kijanki Thanks for your elucidation of some of what's involved with surface mount. I think a lot of people think that since we make tube gear by hand that somehow that means we don't have an education or something- or don't keep up with the times. We're using 603 components right now- as you point out, easy to do by hand. And probably too for production- depending entirely on volume of sales! On this basis, this statement:
it's impossible to create a "retail product" complete Class-D board, using all smd components, making it by hand soldering.
You say it can be done, but that would only be a 1 off prototype and not the production version.
-is simply false. Now at some point we may go to 402s just to reduce inductances and resulting ringing and radiation. But for now the 603s have worked out alright. If 'sales' translates to 100s of shipments, then its likely we will farm out the work.
it's impossible to create a "retail product" complete Class-D board, using all smd components, and making it by hand soldering
There appears to be a sleight of hand going on here, compare the above quote above to this one that appeared earlier:
To do that you need to buy either ready made boards then do simple mod and call them your own, if not and you want to do your own GaN Technology boards, you need the knowledge to design it from scratch, and you need some serious automated wave soldering machines to do all those smd parts that are involved, you can’t do it by hand. 
When comparing these two, we see that George had to back off from the idea that 'to do all those smd parts that are involved, you can’t do it by hand'; that's morphed into you just can't create a 'retail product' by hand soldering. Both statements are false. The soldering industry has all sorts of products designed for hand soldering work- and one of my employees worked doing production smd work all by hand.
Except for maybe a prototype, good luck hand soldering for retail production a Class-D that’s all SMD components like this cheap $34 Class-D stereo.
We're not planning to build a $34.00 amplifier and to be clear a $34.00 amp isn't going to have GaN FET output devices- such an amp would be all entirely on one chip. Its realistic to discount that comment as irrelevant.

Ralph + 1 burn: Fanning the flames
OK, I've had the March Audio p252 in the system for two days (Hypex nc252mp), so I'll follow up with my thoughts in this contentious Class D thread.

I had a bit of a long strange trip comparing it to my old amp (Adcom 5802). When I first connected the March, I was sure I could hear a difference. A bit tighter in the bass, not as smooth in the highs. Was the image not as wide? The soloists seemed a little further back? A difference in Cymbal decay?

This evening I had a chance to A/B them, albeit under less than ideal conditions. Since I had to power them off before reconnecting, there was a bit of a lag between listens, and, of course, I'm getting up from the couch to do it. Just to complicate things, the March reverses the channels, so I had to be careful to connect right channel on my DAC to left channel on the March. I put in a pair of speaker cables with bananas instead of spades, to make it easier. After trying to volume equalize on the music, I started doing it on a 1k test tone (with a decibel meter). As it happens, the two amps have the same gain, so I realized I didn't have to change the volume at all. Eventually I got the switch down to less than 30 seconds.

The better I got at making the swap, the less I could hear a difference. When I started I was almost sure I could. Ninety minutes later I'm pretty sure I would fail a blind test between the two.

On the one hand, I am reasonably persuaded by the volume of tests that suggest well-designed and adequately powered amps will sound very similar. On the other hand, on very first blush I immediately started hearing some of the things detractors say about Class D. Hmm, which way do my biases run?

All in all, it was a weird experience.  But it's nice to have a cool amp here in the living room, so I can leave the A/C window unit off and hear the music. Also, with only the DAC/Streamer and the tiny p252, I could get rid of the audio rack and de-clutter....

Next I'm planning to test the Orchard Audio PecanPi DAC/streamer against my current rig (Cambridge Edge NQ).

Class D is to analytic. At the beginning, it sounds good, but after a while, you will miss something. It have no body, no personality.. you cann’t have “the” connection with the music. Our ears are analoque.
For me,still the best is Class A:pure, natural, real,more holographic.. you enjoy more. Class A/B is good for those who want more power ,those who wanna play loud...but sometimes you mis the attention  (the detail) and some tones suppressed by being too low. It does not represent a fair and real image. It is also reallly tiring for the ears, why many people have hearing problems in the long term .