2. amps-preamps
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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
noble100's avatar
noble100
2,419 posts
 

     I also leave my two stereo and one pair of mono-block class D amps on 24/7 and they do sound considerably better when fully warmed up than from a cold startup from being off for awhile.


Tim
audiofun
799 posts
 
It’s not the class D (ICE in this case) that’s the issue. It’s the sucky SMPS’s that are the problem. I have a pair of (when available) $25k Acoustic Reality Thaumaturges, it is one of the finest amps I’ve yet to hear and own and that is a very long list. I also had a pair of the Acoustic Reality Ones (if I recall the model correctly), they were about $6k per pair and had some custom mods performed by the manufacturer to take them even higher than stock. The One’s used a SMPS and like all SMPS’s I have ever experienced, the moment they are plugged in anywhere near my system, the whole system TANKS AND SUCKS!

I sold the One’s, they were HORRID! I’ve owned the Thaumaturges with their linear power supply for nearly 10 years now. The only amps I’ve preferred to them are my Graaf GM 200’s and my Graaf Modena, maybe my former Tube Research Labs GT 200’s but not sure about that, been a long time since I owned the very impressive TRL’s.

Class D can be wonderful but in my experienced opinion, if it has a SMPS just forget it! Even my Mac Mini music server SMPS killed the sound, it now has a linear supply.

Even my router LOL!
erik_squires OP
16,021 posts
 
It’s not the class D (ICE in this case) that’s the issue. It’s the sucky SMPS’s that are the problem.


Well, that certainly was not my experience.

audiofun
799 posts
 
erik_squires:

Not sure if you are intimating that it is the ICE tech that is an issue (to you) or if the SMPS is not a problem to you.

If the former, I am certainly not stating that all ICE implementations are the same or that they would all be good if not but for SMPS’s.

I’m saying SMPS’s ruin everything I’ve ever heard including the Studer A820, which is one of the reasons I passed on that deck when looking for a tape deck (it has multiple SMPS’s). It’s also one of the main reasons I sold my Technics SL 1200 GAE.

If you are saying you can live with SMPS’s well then we just differ in how we hear which is ok.

kijanki's avatar
kijanki
4,428 posts
 
Class D can be wonderful but in my experienced opinion, if it has a SMPS just forget it! Even my Mac Mini music server SMPS killed the sound, it now has a linear supply.
All highly rated Rowland class D amps have SMPS. When done properly SMPS is much quieter than linear power supply, not to mention line and load regulated while linear supply is not.
Rowland uses SMPS even in preamps, where efficiency is not important, just because they can be so quiet. Another example is Benchmark. Their products, known to be extremely quiet, contain SMPS. They were able to lower noise by 10dB in their DACs just by switching from linear supply to SMPS. AHB2, an extremely quiet power amp uses SMPS.

"Linear Power Supply", in fact, is a very primitive unregulated switcher operating at 120Hz and switching at max voltage, charging output capacitors with narrow current spikes of very high amplitude. It produces 120Hz ripple as well as very narrow switching spikes, both very difficult to filter out. Also, many believe that transformer has to be heavy to deliver a lot of current. It is all matter of frequency. Small 1" ferrite transformer operating at 100kHz can deliver as much power as huge transformer operating at 60Hz.

Yes, SMPS can be very bad, especially when in cheap/crude computer power supplies but can also be wonderful when done right. It is funny that anybody can think, that SMPS is not good enough for class D, while class D is modulated SMPS.

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