chill;345383 Wrote: > First let me say that I categorically do NOT believe that wired sounds > any different from wireless in an SB2 or SB3. > > However, I should point out my own experience in re-housing an SB2 in a > chassis that contains my DIY pre-amp. Being in the same chassis, the > SB2 [...] > quiet fizzing static sound corresponding to the SB2 buffer refilling > over the wifi link. > [...] > I hesitated to make this post, as it might give ammunition to a point > of view I don't agree with. My own DIY configuration was definitely > not a normal setup, and it should perhaps serve more as a warning to > DIY builders than to users of the conventional off-the-shelf units.
Don't hesitate ;-) You could have experienced direct RFI from the SB to your pre-amp but more often this noise is transferred via a shared power-supply or any cabling or ground-connection between the two (even though moving items around makes a change indicating direct RF...) Read http://en.wikipedia.org/wiki/Radio_frequency_interference to find out how misleading RFI can be. Both situations can be resolved but you need to determine where the problem is first. Easiest is to connect SB to it's own PSU. If that helps you need to filter the DC. If there's no change, disconnect audio-link between SB and pre-amp (if that helps you need a choke in that cable) If it's really direct RF, you need to do some RF shielding. If it's RF via power-supply, you need to block it using a ferrite-bead-coil and some capacitors. This filter is very easy to do as what you want to pass is DC and what you want to block is RF which is miles apart. I can give specifics on how to build that; parts only cost a couple of bucks. If it's direct RF you need to create two compartments within the housing. Separation plus housing itself needs to be metal or cover the inside with spray-glue & aluminum-foil or better, a conducting paint that's available in DIY spray cans. Read this: http://en.wikipedia.org/wiki/RF_shielding In my own RF designs I put a small ceramic capacitor (1 nF) across Vcc and ground pins of every IC/chip as close to the chip as possible on the PCB. Many of those might not be needed but some are and they are cheap enough to do this for home-build projects. A couple of those added across the power-supply pins of your op-amps (assuming you use op-amps) can be all the cure you need. Cut the leads as short as possible and solder it across the pins directly on the underside of the PCB. If you make your own PCB's, make sure that more than 50% of copper surface after etching is ground and decouple DC for RF at every IC. good luck, Nick. -- DeVerm ------------------------------------------------------------------------ DeVerm's Profile: http://forums.slimdevices.com/member.php?userid=18104 View this thread: http://forums.slimdevices.com/showthread.php?t=53207 _______________________________________________ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
