John Sayers' Recording Studio Design Forum Archive

Ok, I built a studio last year to house all my stuff. I ran all new electrical service. I went to great lengths to insure I would not have any problems with electrical noise. Well I hooked up all my stuff (miles of cables) and all was well. I have a lounge area with a tv, dvd, stereo and video games. All that stuff is hooked to my vintage stereo system and sounds great. Well I have a pretty nice PA system (subs and all) and thaught Id hook the tv up to the PA. That way when watching concert dvd's I could have concert levels. Well thats when the problem happened. As soon as I ran rca cable to my mixer from the dvd, my PA and monitors started to hum. So I went out and bought monster cables. Same thing. I traced everything and could not figure out the problem. So I gave up. Well a year later (today), I decided to try again. I plugged this into that outlet, swapped cables, tried all sorts of things. So I unplugged everything and just plugged my dvd into the mixer and as soon as I plugged in a speaker, the damn thing started humming. I was getting really pissed. And then I said what havent I tried. I looked at the tv coax (my cable service) and said nah it couldnt be. I unplugged the coax and the noise went away. I can crank the PA up to 180db !!! and no hum !!!! The stinkin cable company is causing all the noise !!!

Now I have to plug in the cable to watch tv and unplug it to watch concerts. Anyone know of a cure. Does it sound like a contact cable tv and complain problem? They will say we dont trouble shoot PA noise. I know its a ground issue. Maybe if I ground the coax to an electrical ground ? Any help ?

You could try putting a Balun iin line with the cable TV coax... Radio Shack has them I believe. Let me know if this solves your hum issue.

Jon

Im gonna try a surge protector I have that has coax protection on it. If that doesnt help I will try one.

This is common with TV's and connecting to an audio system. You'll need an isolation transformer. For a cheap fix, you can go to Radio Shack. Or RDL (Radio Design Labs) makes a unit (I think TX-LM2?). Basically it's a line matching transformer.

This will fix your hum/buzz issue with the tv connected.

Thanks, I tried the surge and it helped alot. Its not all gone, so I will research the items that have been listed. Thanks for all the help. As of now I just unhook the cable tv when I watch a dvd and want it loud.

Actually it's not the TX-LM2, but AV-HK1 http://www.rdlnet.com/product.php?page=108