2. amps-preamps
  3. 126837-80492

Class D Technology

So I get the obvious strengths of Class D. Efficiency, power output & running cool which allows for small form factors. I also understand the weaknesses somewhat. 1. Non-linear & lots of distortion that needs to be cleaned up with an output filter. 
So my question is, if it weren't for efficiency & power, would there be any reason to own a Class D amp? Do they beat Class A in any other categories that count for sound quality?  
seanheis1
mitch2
4,027 posts
 
"It’s like baking a cake"
Actually, it’s more like frosting a cake that someone else baked.

When I owned the Atsah’s (same Hypex Ncore modules as the Veritas, also in milled aluminum boxes) I had the opportunity to try different wiring harnesses between boards and from the boards to the binding posts. I tried high quality wire from Harmonic Technology (individually insulated multiple strands of OCC copper), Jupiter (high quality copper in cotton) and others and the differences between changing about 5 inches of wire did not even approach the difference between chocolate and vanilla frosting on the cake. I agree Cardas wire is good (I have Lundahl transformers using Cardas wire that sound very good) but I doubt it changes the basic signature of the amplifiers, and certainly no more than changing speaker cables.

One thing Merrill does that I like is they apparently (not confirmed because I know of no posted pictures of the insides of Merrill’s amps) solder the wire directly to the boards rather than use the generic plastic connectors intended for the Hypex boards. However, I would have an issue owning a component where the manufacturer is so concerned with people looking at how it is constructed that they would not allow the end-user/owner to even open the box to change the fuse.
guidocorona
4,298 posts
 

seanheis1, while most newer class D amps are incredibly quiet, -- as in having no background noise -- foreshortened decay or "ead and opaque leadden silence around the note is not the sign of any good amp, unless a track was created synthetically and not from a live recording, in which case, no amp can ;be imputed with wrong doing.


Rather, a good amp, and so much so a good class D amp, is expected to give you what is sometimes called the "sound of the living Silence", that is the natural decay of notes, and the unavoidable ambient cues characteristic of all venues, except for anecoic chambers.


Saluti, G.

     

mapman's avatar
mapman
22,322 posts
 
A better analogy,at least in teh case of newer BEl Canto amps, is souping up the engine.

With ref1000m amps, they add custom input board for better integration with tube pre-amps and a beefed up powersupply board.

Original ref1000 was just vanilla Icepower in a nice box. I would not even consider using that with a higher output impedance tube pre-amp.

Just goes to show not all Class D is equal, even newer ones so gotta be careful about generalizing there.   
guidocorona
4,298 posts
 

Adding some more info about the Bel Canto REF1000 Mk.2. John Stronczer of Bel Canto added a custom input stage which elevated the input impedance from 8K Ohms to 100K Ohms, to make the amp compatible with those tubed pres that exhibit high output impedance.... As a side benefit, the amp also became much sweeter, immune from audible intermodulation in the treble, and... Quieter to boot.


Regards,    to   

georgehifi's avatar
georgehifi
10,312 posts
 
sonicbeauty

Quite some years ago, I purchased a pair of Bel Canto REF-1000.

It ended up being my absolute worst purchase in my 30+ years in this hobby.

I understand of course that those class "D" designs have much improved since.

Still, I could not bring myself even today to even remotely give D another shot.

seanheis1 OP

Does anybody know what causes the dead silences in songs that is a characteristic of Class D? Is it the output filter or dead time? I really noticed this with my Ice Module and couldn’t figure out if the amp wasn’t allowing for the music to decay or if it was something else causing the inky blackness.


The BC 600 monoblocks we listened to were better than the Ref-1000’s when we a/b them, probably because of the 600’s multiple series up output filters.
But they still had a stripping of the harmonic structure of the upper/midrange and highs, leaving what seemed to be just the fundamental with no decay and an opaque sound with larger than usual "nothing" gaps in the music.

Like I said before the switching frequency needs to be several times higher so then these output filters can do their job properly well away from the audio band without their side effects coming down into the audio band.
A bit like those nasty "brick wall filters" used to do in the early days of CD
Cheers George

More to discover