Back on the original point of this thread, a few things I have found out about the SB devices and power supplies.
The switching supply that comes with the SB3 is abysmal. It emits large amounts of EMI and sends copious amounts back into the AC mains. Both the emitted and AC born noise can wreak havoc with stereo systems. There is some that does make it into the SB and this can cause issues in the box, but most of what you hear is this extra junk getting into your system. Pretty much ANYTHING is better than this. The Touch has a much better switching supply. Its not perfect, it still sends a little noise back on the line and radiates a little bit, but it is WAY better than the SB3's supply. With the Touch you are in the situation that some linear supplies actually perform worse than the switcher that comes with it. A linear is not automatically dead quiet. The transformer has a built in resonance (which interestingly enough is usually at about the same frequency as a switching supply). The diodes commonly used emit pulses of noise, again at the same frequencies, which excite these resonances. It is certainly possible to use diodes that don't emit the noise, but they cost a little more, and you can damp the resonance in the transformer (it takes a resistor and capacitor, about $1.50). How many linear supplies do this? Strangely enough, not many. A properly designed linear supply can be better than the one that comes with the Touch, but unless you measure it you have no idea if it is or not. Cost has very little to do with it. There are some expensive supplies that use extremely high quality discrete regulators, but still shove noise back onto the line. If the rest of the supply is done right so high frequency noise is not being sent to the regulator a really high quality regulator is of very little use. If the rest is NOT done right, the quality regulator will prevent the noise from making its way into the Touch, but its generally a lot easier and cheaper to prevent it in the first place. So the upshot is that the filter thingy is probably pretty much useless with the Touch. The linear supply may offer a slight improvement over the Touch supply, but it may not, price is not a guarantor of that. If NOT implemented correctly it may even be worse. Personally I build my own linear supply because I know how to build one that is going to be really good, the emitted and mains noise is extremely low. It cost about $50 in parts. If you are going to buy a linear supply you might get lucky and get one that improves on the one that comes with the Touch, but you may not. I would make sure you can return it if it doesn't make any improvement. John S. -- JohnSwenson ------------------------------------------------------------------------ JohnSwenson's Profile: http://forums.slimdevices.com/member.php?userid=5974 View this thread: http://forums.slimdevices.com/showthread.php?t=81454 _______________________________________________ audiophiles mailing list [email protected] http://lists.slimdevices.com/mailman/listinfo/audiophiles
