grounding an audio system

leftwinger57

I know this has been covered before but it never really affected me until now in a minor way. Both my former and present turntables had no ground wire so I did never ground then to the pre/amps or anything else. Now again no ground but I'm picking up a slight hum maybe more pronounced because the Dynaco pre/amp is more sensitive. Get this, I have no cold water ground pipe or anything remotely close to get to and running wire used to be my profession. Also get this, my apt is so old the electric cable is not Romex but aluminum wire w/ some old type of jacket that resembles horse hair that has been hardened in such a way. What it really is I have no idea. I do have a hot water pipe by my rack because my heat is forced hot water and believe it or not I don't even have a thermostat I have a graduated valve that goes from 0-10. When on it works great but that's how old my complex is. The only thing that is close and might work if a ground is needed is opening the nearest outlet and taking the ground off of that. Problem being this aluminum wire is so brittle I'm afraid to mess w/ it. Any ideas or leave it alone. Again the only hum is when I go to I-net radio or t.v. and is slight and it's never happened before.

Speedskater

Before we get into troubleshooting.
Do you have a 2 pin AC receptacle?
If it's 3 pin have you checked it with one of those dumb 3 LED power testers?
Cable TV or cable internet often cause problems.

pitdogg2

I hope you have good renters insurance that sounds like a fire waiting to happen.

leftwinger57

2nd that on renter's w/ my car insurance which I have and by the way is cheaper than my cable bill, go figure that one. Now I just found out it's not the 2 chll. at all that has the hum. I'm playing my Yamaha avr w/ my Klipsch smalls only now watching the game and the hum is there. It's not the long run from computer to avr because it 's happening on regular t.v. Not noticeable w/ the i-pod at all. All my receptacles are 3 prong so I will check cable box next. I do not use the HDMI cable for audio I use RCAs out of the cable box because I like to watch t.v. and listen to tunes at the same time for the most part like Nascar. Thanks for the hint and thank G-D it has nothing to do w/ the Dynaco pre or any part of the 2chll rig. Maybe I upset the apple cart yesterday and need to check my cables again.

tonyb

Sounds like a ground loop hum to me. Too many grounds in one spot. A good power conditioner might help some if you don't have one already. Especially given the amount of gear you have on hand.

You can also try the old school way. Simply take a piece of wire and connect it by a rear case screw to another piece you know has no hum. Sometimes it works, sometimes not, cheap to find out though.

westmassguy

tonyb wrote: »

Sounds like a ground loop hum to me. Too many grounds in one spot. A good power conditioner might help some if you don't have one already. Especially given the amount of gear you have on hand.

You can also try the old school way. Simply take a piece of wire and connect it by a rear case screw to another piece you know has no hum. Sometimes it works, sometimes not, cheap to find out though.

Agreed. Sometimes it does the trick, sometime it does nothing, and sometimes it makes it worse. You may also have a Ground Plane Differential, which the jumper wire should solve. Long cable runs with poorly shielded cable can also introduce hum into the chain.

leftwinger57

Guys it's resolved. It was the Dynaco after all. I ran a wire through my closet near the rack where some other wires were run and opened the closest outlet and attached it to the ground screw and the hum is all gone on every thing. For some reason I thought it was the Yamaha because I do run all my sources through that then into the Dynaco tuner input and I get them all and even though I thought it was for only a tt for the Dynaco you must ground the pre as told to me by the guy I bought it from and he was right. The stars are aligned once again. Sorry for the panic.