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Class D = Trash?

So, I'm on my second class D amp. The first one, a Teac AI-301DA which claimed to use an ICE module, was unlistenable trash. I burned it in for a few weeks, it just couldn't perform, so I sent it back. Following that, I tried the new Emotiva A-300 (class A/B). It was significantly better, but lacking in too many ways for my tastes. So I changed gears, got an 845 SET from China -- and it was an immediate and massive improvement.

So, before I went further down the SET road, I wanted to try a better class D product using a modern class D module. I settled on the D-Sonic M3-800S with the Pascal module and custom input stage. I read from reviews that these things like to have big cables, so I picked up an eBay 8 gauge power cable (Maze Audio, el-cheapo Oyaide copy plugs, braided 4-wire cable) to go along with it.

Mid-range GONE.
Soundstage depth CRUSHED.
Euphonics DISAPPEARED.

Yes, resolution went up. Driver control went up, allowing me to play compressed rock/pop and orchestra with the speakers being able to render it all. But enjoyment in the sound is basically gone. Using my best power cable (LessLoss Original) improved performance, but didn't fundamentally change the amp's nature. I ran back to my headphones (Focal Utopias) to detox my ear canals.

So, how long does a class D need to burn-in? I want to give it a fair shake before writing the technology off forever. 
madavid0
erik_squires
16,176 posts
 
One interesting experiment I read about I've wanted to try is to actually LISTEN to the amplifier power supply lines. The + and - supplies are, in theory, at fixed DC voltages but as the music plays, the current draw will cause the supplies to sag with each note. You can actually attach headphones (carefully, wth appropriate circuits) and hear just how much effect driving speakers has on the power supply.

This technique can be further expanded to analyze the actual frequencies that the supply is worst at isolating, and to add appropriate filtering. A fussy technique I don't know if anyone but one vendor (probably out of business) has ever done. Still, fun idea.

In stereo amps, this effect is probably one of the main reasons for increased cross-talk between channels.
h2oaudio
38 posts
 
Todd, Thank you.  But I admit my knowledge is very limited actually compared to some of the GODS of amplifier designers such as Nelson Pass, John Curl and quite a few other designers.  I am a rookie compare to these amplifier designers.  I just know enough to make the amp sounds halfway decent by lots of experimentation.

I sincerely hope I did not offend anyone with some of the statements I made.  Please remember that my opinion is just that...one opinion.  It is just happen that I am a manufacturer.  And more importantly, what I referred to as "BETTER"  is only in the context within my system and others system which I heard, and furthermore to my ears and my ears only.  I do believe lots of members on this board have been around long enough to know, that there was not, is not and will never be one absolute.  It will always depend on the system as whole and more importantly listener's preferences, type of music, room acoustic and the list goes on.  And to answer the OP's questions.  The answer is NO.  Far from trash actually.  Then again, just like what I just mentioned above.  It depend to whom are we asking?  So the correct answer I believe is YES AND NO :-).

Henry
h2oaudio
38 posts
 
Erik,

I believe Krell FPB does not have a fully regulated power supply from front to back.  The KRS series does and maybe the Krell master reference as well.  Though to my belief that power supply is one fundamental aspect of amplifier design, but it is only one of the many aspects which make the amp sounds good such as topology and devices being used, implementation to name a few. But I digress since we are talking about class D so let us switch (pun intended) back to class D channel shall we?
erik_squires
16,176 posts
 
@h2oaudio - Since I'm not that big a Krell fanboy, it is VERY likely I got the models/series wrong. :)

I only wanted to point interested parties to examples.

I am going to start another thread I think, for people who LIKE class D. :)

Best,

E
erik_squires
16,176 posts
 
Well, again, not a big deal, but this from a review on the Krell FBP:

The output stage in all FPB amplifiers employs a free-floating feedback arrangement wherein ultra-fast regulators independently monitor the output stage and respond to the smallest drop in current or voltage with regulator response that is all but instantaneous.

Bit of useless marketing/design trivia for Krell fans. :) Of course, this is only the output section, but it would be VERY weird to regulate the output but not the inputs, since the latter is much cheaper to do.

Best,

E
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