| Keith C. Perry via plug on 24 Mar 2025 14:27:47 -0700 |
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| Re: [PLUG] Ground Loops / Hum |
I read this a couple of times and while I appreciate you are running analog to all points, think you might be running into some physical realities. The first one being that shield cable isn't perfect and really just provides better noise protection than unshielded cable. In a residential house there's probably going to be enough noise to cause some sort of issue at some point. In additional to that you're locally amplifying the signal so all your speakers are powered (i.e. active speakers) which means the local environment of that speaker system is more complex that if you running to passive speakers. RCA and 2 wire systems are for very short connections. What I will offer up from my studio and live performance experience is that "house" audio is typically done with one console at the source with XLR (3 wire, balanced) connections to passive or active speakers (depending on distance). 1/4" TRS would be the next step down from that. You're most often going to find these speakers referred to as "monitors" and that because their default application in the studio / house audio need to render the cleanest and clearest audio image. These are not the same type of speakers you typically find at a club or at sports arenas as a comparison. So, how to fix? Honestly, the easiest thing would be to go "digital" but that that I mean, instance of running analog lines to your other amps, you should switch to optical or digital s/pdif connections. Optical is going to be the better of the two methods since optical is going to be the most noise immune but it is almost going to be probably be more expensive. Digital (coax) s/pdif would probably work just fine for you at a lower cost. This depends on what you need to upgrade on your computer and what might already be available on the remote amps. You're going to need a small mixer and s/pdiff capable ones usually have choices for either optical or coax connections. ***does some googling*** Actually this is going to be much simpler. There are RCA to S/PDif converters, so, it looks like you could get a couple of devices like: (note: I have no experience with this device so please do your own investigation) https://www.amazon.com/PROZOR-Digital-Converter-Optical-Toslink/dp/B00KNNSKV0/ref=sr_1_1_sspa?dib=eyJ2IjoiMSJ9.ZElU0hc0qYk0ESZhJoBsblrsxWmtNUJpxdaXjwNIyiacHq3PJh1FHLEKbIn9jrIebdxk-buEcGfnqDiXHMXkI9Zy_edsr7imZtoO0zPhUQ_KySirrd39Tk_eGmExLLdkCkcvPqLGlTZPj7RQF02IY8GH5FEHoaTj8whVuyTWgL5n1fyCqYNCKWB63_xfz7TYoEdmmLEqz-_71NFJd78bkW3CPC6i-VOyN8tz9L21mzw.IdpuMEJiAUr7klGSJQDo979RFTpDSydpcQjBFsFy-to&dib_tag=se&keywords=spdif+to+rca&qid=1742851103&sr=8-1-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&psc=1 and the s/pdif cables of your choosing and you should be good to go to replace those runs from the computer to the stereo systems. ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ Keith C. Perry, MS E.E. Managing Member, DAO Technologies LLC (O) +1.215.525.4165 x2033 (M) +1.215.432.5167 [ http://www.daotechnologies.com/ | www.daotechnologies.com ] ----- Original Message ----- From: "Philadelphia Linux User's Group Discussion List" <plug@lists.phillylinux.org> To: "Philadelphia Linux User's Group Discussion List" <PLUG@Lists.PhillyLinux.org> Sent: Monday, March 24, 2025 3:34:30 PM Subject: [PLUG] Ground Loops / Hum I've got some significant hum in my audio distribution system due to ground loops and would appreciate some electrical engineering suggestions on how to fix. My basement computer runs Music Player Daemon (MPD) and feeds the analog audio output into a distribution point that connects to multiple stereo amplifiers in various rooms of the house. I've run shielded audio cable in the walls and terminated them with standard RCA plugs at each end. Since the house was already finished, I had to run wires where it was possible, not always avoiding power lines. NOTE: I don't want to use digital audio due to variable latency in the reproduction. Right now I can walk from room-to-room, and the audio is all perfectly synchronized. Currently, I have all the signal lines tied together, and all the ground lines tied together. This, of course, is considered bad practice because it allows for ground loops. (Although I've done it previously, and never had a problem [sigh]) . So how should I kill the ground loop? I tried enhancing the earth ground connection to the shielding, but this didn't help. One thought I had was to separate all the grounds at the distribution box. Each cable run to the distribution box would be grounded only to its individual amplifier. This means the signal lines will still be shielded, but will be floating relative to ground. Is this acceptable practice? Your suggestions would be appreciated. TIA! Casey ___________________________________________________________________________ Philadelphia Linux Users Group -- http://www.phillylinux.org Announcements - http://lists.phillylinux.org/mailman/listinfo/plug-announce General Discussion -- http://lists.phillylinux.org/mailman/listinfo/plug ___________________________________________________________________________ Philadelphia Linux Users Group -- http://www.phillylinux.org Announcements - http://lists.phillylinux.org/mailman/listinfo/plug-announce General Discussion -- http://lists.phillylinux.org/mailman/listinfo/plug