I've had similar problems, particularly when the 2 devices are plugged into different outlets. The problem is due to slight differences in the ground potential at the 2 units, which results in ground currents flowing down the shield on the audio cable... which ends up as 60 Hz hum.
What generally works to reduce the noise is to get a good heavy piece of wire (say #12 stranded or better) and screw it to both the chassis of the myth box and the stereo reciever. This provides a lower impedance path and gets the currents off the cable shield. Steve > > From: [EMAIL PROTECTED] > To: MythTV Users List <[email protected]> > Date: Tue, 10 Jan 2006 20:22:59 -0600 > Subject: [mythtv-users] Slightly OT: receiver input buzzing/humming > > > I've got a Yamaha HTR-5550 receiver that receives input from (among > other places) my mythtv box. This is an analog input: the cord is a > male 1/8" stereo plug (PC side) that splits into two RCA connectors > (amp side). The motherboard is the Chaintech 7NIF2. > > Recently, I've noticed that when I'm not playing music or watching > TV (i.e. silence), there is a distinct buzzing/humming sound coming > from the speakers. The sound is barely noticeable at the "-40.0" > volume setting, and quite pronounced by "-30.0". > > I've tried messing with the volume levels on the PC; it does not > make a difference in the buzzing. I've tried re-seating both ends of > the cord (to no avail). > > Note that when I switch input channels on the amp, the buzzing goes > away. So I tried putting the RCA plugs into a different input---no > help. > > For what it's worth, the buzzing sound is the same as if I pull the > 1/8" plug out, and touch it to my finger---I'm sure this is a > familiar sound to many people. > > My guesses are that either the cable is bad (it's an el-cheapo, > don't know where it came from) or the input jacks on my PC are > crummy or not properly grounded. This sound is the kind of sound I > would expect when my plug isn't properly seated, but, as I said, > I've tried seating and re-seating it several times (across the > different outputs), and still have no success. > > Does anyone have any suggestions on my next steps to further debug > this problem? > > Thank you! > Matt > > -- > Matt Garman __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com _______________________________________________ mythtv-users mailing list [email protected] http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
