For those with buzz/hum issues

[Bguzaldo]

I was having a lot of buzz and hum issues with some of my rack gear. Tried different cables, tried separating the audio from the power cables, tried different outlets...nothing was curing the problem.

I was in a conviniece store today and I wandered into the electrical isle and found these 2 to 3 prong converters for outlets that don't have three prong (all of mine have 3 prong just stay with me) right on the front it said "Grounding Adapters" which is what caught my eye in the first place. I'm not an electricity geek yet, but I'm assuming there is something in this adapter that grounds the third prong, before when I tried to plug in any gear as soon as the third prong touched the socket it would buzz. These concepts may be trivial but I just thought I'd share in case anyone didn't know...

 

[Lt. Bob]

I was having a lot of buzz and hum issues with some of my rack gear. Tried different cables, tried separating the audio from the power cables, tried different outlets...nothing was curing the problem.

I was in a conviniece store today and I wandered into the electrical isle and found these 2 to 3 prong converters for outlets that don't have three prong (all of mine have 3 prong just stay with me) right on the front it said "Grounding Adapters" which is what caught my eye in the first place. I'm not an electricity geek yet, but I'm assuming there is something in this adapter that grounds the third prong, before when I tried to plug in any gear as soon as the third prong touched the socket it would buzz. These concepts may be trivial but I just thought I'd share in case anyone didn't know...

no .... there's nothing in the adapter that grounds the 3rd prong.
It's an adapter in the sense that it adapts a plug that has a ground prong to fit into a socket that doesn't have a ground.
When you use one the ground is not connected to anything unless you actually ground the little metal tab yourself.
And that's what's helping your hum ..... you're 'lifting' the ground. You will often see equipment that will have a 'ground lift' and that simply means that when you lift the ground, you've disconnected it. The reason they'll put a ground lift in equipment is that often hum is caused by a ground loop which is different voltage potentials causing a volktage flow which causes the hum.
When you use those adapters you bypass the ground and that can sometimes help with a hum problem.

 

[Bguzaldo]

no .... there's nothing in the adapter that grounds the 3rd prong.
It's an adapter in the sense that it adapts a plug that has a ground prong to fit into a socket that doesn't have a ground.
When you use one the ground is not connected to anything unless you actually ground the little metal tab yourself.
And that's what's helping your hum ..... you're 'lifting' the ground. You will often see equipment that will have a 'ground lift' and that simply means that when you lift the ground, you've disconnected it. The reason they'll put a ground lift in equipment is that often hum is caused by a ground loop which is different voltage potentials causing a volktage flow which causes the hum.
When you use those adapters you bypass the ground and that can sometimes help with a hum problem.

Oh awesome, Thanks a lot for clearing that up! I knew it had something to do with that third prong!

Thanks again,
-Barrett

 

[witzendoz]

Just out of left field here, is the mains earthing on the house / studio connected correctly? The house earth may have become disconnected somewhere. This will also cause buzzing and hum. It is also very dangerous.

My 1st studio many years ago had this exact problem with a broken mains earth wire in the ceiling.


Cheers

Alan.

 

[MOFO Pro]

Whatever works is fine... But instead of lifting grounds, I prefer to assure that all connected devices share a common ground and potential.

Current seeks the path of least resistance, if you connect grounds across multiple devices that are powered across multiple outlets, you're creating a second ground path between all the devices... If one of the power outlets has a better ground potential then another... the current with less ground potential is going to utilize the additional potential of the other outlet to send a portion of it's ground through the only available path to this source, the chassis ground of your audio devices. But if you make all of your grounds equal, none of this interplay occurs. The path of least resistance in always at the correct source.

The easiest way for most home studios to achieve this is by simple plugging all gear into a power strip connect to a single outlet.

And Witzendoz brings up a very valid point... if you lose earth ground in USA there is still a backup path for current out to the poles through the neutral conductor (or any other ground path to the pole i.e.cable, phone) But I've witnessed first hand what happens when this last escape route is removed. The house goes super nova- it glows out the windows from the incandescent lights running away on the current flood... until the filaments burn out and it gets very dark... while all this is going on, there's probable a little fire kindling on the side of your house as the cable and phone wires try to handle the house ground and melt and burst into flames. Once this path is destroyed... all of your active appliances grow eerily quiet... it's amazing what destruction is wrought...