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
noble100's avatar
noble100
2,419 posts
 
georgelofi,

     Thank you for the further clarification.  I just tried your suggestion  with an older (non-muting) portable radio in the 500-800 khz am/band range on my amps with results being no discernible change in sound.or level.  Reassuring results.

Thanks again,
  Tim
guidocorona
4,298 posts
 

Hi all, in olden days, with the NuForce and M312, RF leaks were of some concern... My old FM tuner did pick up hash from the amplifiers if when held less than 2 feet from the power supply of the amps. 


However, newer amps like the Merrill Veritas and my current Rowland M925 do not radiate at all.... AM and FM bands are not affected at all, not even if the tuner is placed on top and is in direct contact with the amps.


Without making a broad generalization, I suspect that FM leakages might today be less common than in the past. Perhaps more of historical interest than anything else.


Worth checking out though, particularly when testing older class D amps.



Regards, G.

 on the

kijanki's avatar
kijanki
4,451 posts
 
There is about 1% of switching voltage noise on the speaker cable since filter is not perfect but, as I said before, 1/300 wavelength antenna won't radiate.  In addition, electricity in speaker cable flows in both directions canceling the most of RF (if any).  When you place radio directly on the wire you might get some capacitive coupling, but I doubt it.  Many speaker cables are twisted making it completely inefective (better than shield) for electromagnetic radiation or capacitive coupling (both ways - from cable or to cable).
cleeds
6,103 posts
 
kijanki
...  electricity in speaker cable flows in both directions canceling the most of RF (if any) ...
There's nothing inherent about an AC circuit that makes it immune to RF, so it isn't clear what your point is here.  
kijanki's avatar
kijanki
4,451 posts
 
When electricity flows in two wires in opposite direction it tends to cancel radiated EMF or capacitively coupled noise.  Same goes for receiving - the closer two speaker wires are - the less susceptible they are to pick up anything.  Twisted pair exposes both wires symmetrically to external fields making them almost immune to coupled or radiated noise.  That's why in any circuit design signal and return should always go closely together to avoid any loops.   The point of my post was that cable (two wires where electricity flows in opposite direction) is a very poor antenna for radiating and receiving.  Twisted pair is practically no antenna at all.
More to discover