Eric Carroll;173867 Wrote: > I just finished recommissioning my old Rotel system as the world's > largest distributed alarm clock in the bedroom. 180Wpc ought to wake me > up! > > My alarm clock configuration is SB3 -> Rotel RB-890 -> B&W Matrix 805 > bookshelf speakers. Note that the SB3 is about 6.5 dB hot on line > levels for the RB890 (1V input sensivity). I *do not* have proper > analog attenuators installed yet (still looking for an easily orderable > Canadian source), so the noise floor is definately double the volume it > should be. I have the Preamp Volume Control set to -6.5 dB to keep me > from being blown out of bed in the morning by accident. > > > Since the RB890 has no trigger I leave the amp on even when the SB3 is > in powered off mode (not really off...). The SB3 is set not to turn off > audio when "powered off". > > I have noticed that on the right channel only, with no music playing, > there is a perceptible high frequency tone. It is very low volume, > right in the noise floor. Because the room is so small and quiet, I do > hear it even a few feet away. My hearing has always been very sensitive > to very high audio frequencies (although this is definately falling off > as I age). > > I have tried the following steps to debug this: > 1. I swapped the R/L channels at the SB3. The tone follows the channel > (i.e. when I swapped L for R the tone moved to the L speaker). > 2. I flipped the SB3->RB890 RCA cable R/L on both sides. Problem > remained on the R channel. > 3. I tried a second SB3 I have on hand, same results. > 4. I moved the wall wart switcher PSU from right beside the amp to > around a corner, far away from the amp. > 5. I have changed the brightness levels. > > (1) implies the problem is either the SB3->RB890 interconnect cable or > the SB3 itself (problem moved channels, so it is not the amp or > interference on the speaker cables) > (2) eliminates one side of the cable as the problem (if it was the > cable problem should have moved to L channel). > > (4) requires more explaination because it is the only change that > impacts the tone I have made so far. > > The SB3 has 5 brightness levels (0 - off, 1-4 from dimmest to > brightest). > > On display brightness 0, 4, and 1 there is no tone that I can pick out. > Brightness 3 has the loudest tone. 2 is much less noticable. > > The pitch of the tone is related to how much text is displayed on the > SB3 screen (the tone changes between lots of text and a little text are > not large). > > If I had to guess i would say the R channel in the SB3 is picking up > some RFI from the computing cycles. > > This rates as a "nit" not a big problem, because I do not hear this > tone when playing music (usually at volume 40-50 right now). Its just > an issue when not playing music because I leave the amp powered up and > the tone is somewhat evident. Also I did *not* notice this in the > previous room that I had the SB3/RB890 in (now replaced by > Transporter/Bryston) - it was a much larger room and I was much further > away from the speakers. > > Has anyone else experienced this? > > Will this go away with proper attenuation? > > Are there any other suggestions to resolve this?
Suggestion for attenuation. Have noe expirence with it my self, but i have read some pro audio/home studio use it or an other m - patch version. http://www.smproaudio.com/index.php?option=com_content&task=view&id=24&Itemid=68 -- eiret ------------------------------------------------------------------------ eiret's Profile: http://forums.slimdevices.com/member.php?userid=11521 View this thread: http://forums.slimdevices.com/showthread.php?t=32045 _______________________________________________ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
