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


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.
http://store3.sure-electronics.com/media/catalog/product/cache/1/image/600x600/9df78eab33525d08d6e5f...
@georgehifi  
Who said production boards will be soldered by hand?  Many small companies, including one I worked for, make small quantity of very sophisticated high density boards using Assembly Houses.  We used to make them with semi-automatic stencil printer, manual pick and place and 4 zone Heller reflow oven, but using Assembly house  ended up being much cheaper and better, quality wise.  Nobody sane would hand solder production quantities - too much time consuming equals too expensive.  We made batch of about 5 boards for prototyping and then about 100-200 boards in production quantity.  Using good Assembly House opens whole new world for designer (removes constrains).  Now he can design for higher density or even for BGA chips.  
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