JohnSwenson;158072 Wrote: > I have had some experience with the little wall wart that comes with the > SB3. As many of you know I have modified my SB3 to take its "I2S" (which > is really left justified) data signals into my DAC and feed the DAC's > clock into the SB3. The other day I had it out on the bench trying out > some changes to the output stage and was seeing all kinds of RF on the > output stage. > > After a lot of debugging it turned out to be the wall wart that came > with the SB3. I didn't bother to take the linear supply out to the > garrage so just used the wall-wart. It was radiating large amounts of > RF every where. Even with the SB3 disconnected from the DAC It still > had the same amount of RF in the DAC. It also stayed the same with the > SB3 disconnected from the supply. With the wall-wart unplugged the RF > goes away. With the SB3 connected to the linear supply there is a very > tiny amount of RF in the DAC but WAY less. I think this is coming from > the unshielded SB3. > > As far as I can tell that supply is just spraying RF all over the > place. Its a bit interesting because it comes in bursts. It looks like > the RF is happening when the supply is conducting from the wall voltage > so we get tone bursts. Under load the bursts get longer (the supply is > conducting over a longer period of the AC cycle) but the intensity of > the RF is the same. > > So there is a pretty high probability that this RF is getting picked up > by other components in a system whach may be causing significant > differences in sound. > > This can also help explain to some degree why ome peoples systems have > a larger change when changing supplies than others. It would depend > very much on how the components and wiring respond to RF. Some will do > a better job of rejecting the RF than others. > > When I first got an SB3 I had to switch to shielded interconects, it > was unlistenable with the unshielded ones I had been using. At the time > I thought it was the SB3 itself that was radiating the RF, now I realize > it was the wall-wart that was doing the damage. > > One good thing that the experience produced is that I "hardened" my DAC > significantly to outside RF, even with the wall-wart the amount of RF in > the DAC is a lot less than it used to be. Just doing that has > significantly improved the sound of my system. > > John S.
VERY important and interesting information. Thanks JohnSwenson! What steps did you take to harden your DAC from RF? Also, is this issue with RF a common one with switching power supplies, or is it just this particular make of supply that is especially troublesome? -- NewBuyer ------------------------------------------------------------------------ NewBuyer's Profile: http://forums.slimdevices.com/member.php?userid=7862 View this thread: http://forums.slimdevices.com/showthread.php?t=29633 _______________________________________________ audiophiles mailing list [email protected] http://lists.slimdevices.com/lists/listinfo/audiophiles
