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
Post removed 
@atmasphere  Ralph, perhaps I can help a little with SMT question (although you may already know all this) .  Suggestion to use wave soldering for your production is nonsense.  It was replaced by reflow soldering more than decade ago.  The only all SMD done with wave soldering today are low density high production quantity boards  (wave soldering is a little faster than reflow).  Even mixed boards are today soldered with reflow ovens + selective soldering (mini solder fountain).  Limitation of wave soldering is at about 20 mil pitch, but board has to be designed for that (orientation of components) and everything else has to be perfect.  It is perhaps good for 25mil pitch only (compromised adhesion of thin solder dam between pins causes shorts).  Also, board has to be designed for wave soldering in mind since recommended component land areas are different - wider (take more space).  I would design everything for reflow.  Hand soldering prototype with 50mil pitch components is easy.  I can do 25mil pitch large chips with 3D magnifier (Mantis) and micro soldering iron, but it is time consuming.  I've seen technicians who can solder 20mils.  For discrete components 0402 is the limit (already hard to rework).  0603 is practical and easy.  Best bet for small operation soldering would be manual stencil and small 4 zone reflow oven (bigger number of zones is mostly for production speed - faster conveyer belt).  Vapor Phase (drawer style) soldering might be also a good option (more accurate).  Better yet leave it to good Assembly House.  They make prototype quantities and small batches.  They often can buy parts at lower cost.  I went thru about 10 assembly houses before I found one that is wonderful.  Location doesn't really matter since you send them zip file and they ship back boards (leave everything to them!).   Novatronix in Chicago area is the best I know.  Sure, it will cost you more in prototype quantity, not to mention set-up charges, but debugging and testing poorly made board can cost you a lot of time (and frustration, and wrong decisions).  I went thru all this.
For your size of operation Altium software is most likely optimal.

Sorry, for all these details, but it goes toward possibility of making own design class D SMT boards vs using standard off the shelf modules.  The answer is - yes it can be done, many ways.



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"