Jacky;593500 Wrote: > According to AKM4420 description the ideal output should be 0V, but > there could be still DC- offsets of +/- 60mV for each chanel. > > So for symmetrical reasons, the caps are implemented to ensure no DC > offset at all and not loading one chanel more than the other. > > For usual commercial amplifiers what effects could be without these > caps other than better sound? > > On the other side, most of SS-amplifiers have at all RCA input-stages > caps. > > Jacky
The problem is these are polarized electrolytic caps. They are designed to have at least a volt or two DC across them to work properly. The DC bias causes an ionic current flow which deposits oxides at the boundary. Its this very thin oxide layer which produces the large capacitance of the device. Without that DC bias the oxide layer doesn't form and the cap doesn't work the way its supposed to. In actuality the music signal (particularly loud bass) is constantly forming and unforming the oxide layer. This leads to a signal correlated capacitance change which gives rise to distortion. The lower the impedance the Touch drives the worse this effect is going to be. If the designers wanted a "safety cap" they should have used a non-polarized cap of some sort, preferably a good film type. Back to the original subject of this thread, in normal use a polarized electrolytic cap with DC bias quickly reaches an equilibrium state where the oxide layer thickness stays fairly constant. But without bias voltage this does not happen. As you play music there will be a small amount of residual oxide forming at the boundary but it may not even form a full insulating layer. The exact status of that oxide layer is going to be changing with time. There is almost certainly going to be a significant change in behavior at first which will slowly settle down over time. Whether those changes change the sound for the better or for the worse is difficult to say. John S. -- JohnSwenson ------------------------------------------------------------------------ JohnSwenson's Profile: http://forums.slimdevices.com/member.php?userid=5974 View this thread: http://forums.slimdevices.com/showthread.php?t=83714 _______________________________________________ Touch mailing list Touch@lists.slimdevices.com http://lists.slimdevices.com/mailman/listinfo/touch
