Grounding problem ???

[johnnymegabyte]

Just moved into a house, and setting up all my gear in the basement, which is fully carpetted.

Yamaha 4 track (used as 6 channel mixer)
Inputs: 1=mic, 2=guitar gear, 3+4=Roland synth, 5+6=PC using a ground loop isolator
Outputs: 1. headphones, 2. Monitor Out ( to my stereo system ), 3. L+R Out --- to Line IN of PC

When first set it up, it was without PC and everything seemed OK

Then, I add PC into the loop, I noticed a hum, which sounded like a grounding problem.
I start playing with all the channel levels to see where it might be coming from. Not this

Then, I unplug the connection between Yamaha and stereo, and now it's gone.
The input on the receiver is CD. I am using my DVD player with TOSLink for playing CD's.

Now, I think that the cable input might be causing the ground related hum.
I have a VCR with the cable coming into it, connected to the TV, which feeds back to the receiver.

Soooooooooooo, is there a way to eliminate this hum ?
Can I ground the cable input in some way ?
Could it be the connection from Yamaha to PC Line IN ?

Any ideas ?

 

[maestro_dmc]

Yeah, get an electrician friend to check out your power before you fry yourself.

Really.

 

[Dani Pace]

With that many cables and connections there is a good possibility that there is a bad one in there somewhere. Cables are often the villian causing hum after connecting/reconnecting/moving/reconnecting. I'm not saying that is your problem but it is a good place to start. Checking (or having it checked) the grounding is also a good idea. The proxcimity of your gear to other pieces can cause hum too, avoid setting anything cloce to or in front of your pc monitor. Florescent lights? Impedance? Weak transistor some place, sheez the list goes on and on...

 

[altitude909]

Is everything plugged into the same wall socket? It should be

 

[karlocheech]

With that many cables and connections there is a good possibility that there is a bad one in there somewhere. Cables are often the villian causing hum after connecting/reconnecting/moving/reconnecting. I'm not saying that is your problem but it is a good place to start. Checking (or having it checked) the grounding is also a good idea. The proxcimity of your gear to other pieces can cause hum too, avoid setting anything cloce to or in front of your pc monitor. Florescent lights? Impedance? Weak transistor some place, sheez the list goes on and on...

Great Dani
Hi every one i'm not a soundman but i'm an electritian.
Sometimes,, most of the time it could be from bad dimmers no1,anything wireless close,cell phones thats why there not allowed in hospitals,home phones,intercoms even wired, x-10 products,bad or week pedals,,, start with dimmers
if all of this does not work try a PSU it could isolate you from the rest of the house most high end equipment are protected with PSU's just dont run your amp off it.....
As for ground its simple if you have a meter you can see if there is continuity
"betewn"(sorry cant spell it write) the white "neutral" wire & the ground,(on your plug that would be the wide slot & the ground hole) at the pannel they join together.... most hospitals & hitech places have a different ground plug
to solve this problem "the plug is orange with a little green tryangle"...
from a newbi hope it could be usefull
Kar low

 

[dgatwood]

Now, I think that the cable input might be causing the ground related hum.
I have a VCR with the cable coming into it, connected to the TV, which feeds back to the receiver.

Certain old, cheap cable TV amps can cause this. Follow the wire, find the (circa 1982) Radio Shack cable distribution amp in the line, and either replace it with a new amp or a plain old splitter.

 

[johnnymegabyte]

Certain old, cheap cable TV amps can cause this. Follow the wire, find the (circa 1982) Radio Shack cable distribution amp in the line, and either replace it with a new amp or a plain old splitter.

I also asked a few friends if they experienced any such problems. Eventually, I got a reply from one.
He's also a home musician with a much more elaborate setup than what I have. He's a major guitar and synth gear fanatic. The cable service was NOT grounded when installed at hsi house.
Thus, I need to contact the cable company and get them to ground the cable to something, such as, a cold water pipe.

Years ago, when I hooked up my TV to the stereo, I was recommended to not plug the TV and the stereo in the same outlet. The TV will draw power away from the amp / receiver. I experimented, and it was true. My music gear (boss pedals, synth, mixers) and PC are into two separate outlets.
Therefore, with four outlets being used, each has its own surge protection.

Ironically, when the furnace kicks in, the lights may dim slightly, but the TV, stereo, PC's don't appear to be affected.

Thanks for all your suggestions.

dgatwood --- a RS gizmo I have and used in the past, but I discontinued because they got very hot.

 

[dgatwood]

I also asked a few friends if they experienced any such problems. Eventually, I got a reply from one.
He's also a home musician with a much more elaborate setup than what I have. He's a major guitar and synth gear fanatic. The cable service was NOT grounded when installed at hsi house.
Thus, I need to contact the cable company and get them to ground the cable to something, such as, a cold water pipe.

Just buy a 3-way splitter with a grounding screw, fasten a 12 AWG wire to it, connect it to the ground pin on a power plug, and plug it into an outlet. Instant cable ground.

 

[easychair]

It doesn't need to be 12 guage, it's a signal not a safety ground. It probably won't help anyway, ground loops are rarely solved by adding another ground.

Most cable service these days has hum isolation built in, as with pay-per-view and on-demand service can drop out in the whole node if it gets messed with. Many companies will either install or sell isolators, which are about $10.

I'm with altitude, you have your stuff in multiple outlets, and so maybe different circuits. That's the most common cause of ground loops, using different circuits. Unplug your cable, see if the hum goes away.

If it doesn't, the problem isn't the cable. Plug all your stuff into one outlet, this will most likely solve your problem. Things don't "draw power" from each other, they are all free to pull as much as they want till the breaker pops. Unless you are actually plugged into different circuits, not just different outlets on the same circuit, plugging into different outlets isn't doing shit in that regard anyway.

If you actually need more than one circuit, there are a couple of ways to eliminate the loop. Use some kind of isolator, or connect the grounds of the different circuits using a variation of the "Poor Man's Distro".

http://srforums.prosoundweb.com/index.php/t/10116/0