Unwanted machine noise

[BertKoor]

Sorry to repeat myself, but would disconecting the ground be the same as setting up in the US, say?

I 've never been in the US, so I wouldn't know... All I can say is: if 2-pins works for you, then do it. And brag to all your friends you run the risk of electrocution when making music, which makes it so exitable and make you feel alive, your tracks have improved by this with 200%

[ghost666]

... And with the laptop case being made of plastic there's no danger for you to get electrocuted.

My lappy is magnesium alloy... I assume that means that there is a danger for me in this situation?

[jupiter8]

... And with the laptop case being made of plastic there's no danger for you to get electrocuted.

My lappy is magnesium alloy... I assume that means that there is a danger for me in this situation?

A laptop only gets like 9 volts from the charger so no danger of electrocution there,ever. Regardless of plastic or metal case.

[Lunch Money]

Without giving too detailed an explanation (I frankly don't understand all the science behind it) the odds of you getting shocked are slim. Surge protection is to protect your equipment, not you. You're almost never at risk of being shocked even without surge protection. Your equipment will just explode.

If YOU are grounded, you're more at risk of having the current pass through you if it comes to that, anyhow. You want to be isolated from ground, not connected to it.

As far as surge protectors go, it's completely irrelevant whether the equipment attached to them is 2- or 3-pronged. If the surge protection kicks in, it's breaking the connection between the surge protector and the outlet, not between the surge protector and your equipment. It just shuts it off wholesale so that more current doesn't flow from the outlet into whatever you happen to have connected to it.

Greg

[Bunnyboy]

The easiest way to get rid of the nosie is to use DI box with a ground lift switch - works wonderfully

[nix808]

OK, thanks, I've had a bit of a look at DI boxes. They're a good option to have in this situation. Would a ground lift eliminate all ground and machine noise? The isolator I'm using at the moment cuts out all but the barely audible. I'm still kicking around the idea of using 2 pin. So basically I'm simply not protected from shorts, is this right?
Cheers folks, nix

[BertKoor]

Nix: the ground isolator you currently have on your audio line operates the same as a DI box with ground lift. Identical technology in the box, but with a different label on it.

What needs to be protected from shorts, you or your equipment?? Firstly there's a 10A or 16A main fuse installed somewhere in your house which is designed for that: if too much power is used (typical for a short-circuit scenario) then it blows. So there's ALWAYS a protection against shorts.

I think you need some background info about electrical systems.
http://en.wikipedia.org/wiki/Domestic_A ... nd_sockets

There are at least two wires to provide you with power: a "live" and a "neutral" wire (brown/blue or red/black). This is the same all over the globe.

If these two get directly in contact with each other, then there's a short-circquit situation and the main fuse will blow. Some electrical devices have a fuse of their own that will blow before the main one does. In any case the device needs to be repaired, or else the replaced fuse will blow again. Since all devices are isolated, there's no direct contact between the casing and either of the power wires, so you are never at risk yourself.

Then there's the third (optional) green/yellow "ground" wire. Now this one IS connected with the casing. If either the "live" or "neutral" wire is put in contact with the ground, then your health is at risk. Unless your domestic installation has a "ground fault circuit interruptor" or "residual current device" to protect you from this situation.
http://en.wikipedia.org/wiki/Residual-current_device

Your laptop computer is not connected directly to the main power. There's an AC adaptor inbetween that converts the 250V main power to around 12V. This voltage level is not dangerous to you at all. You may feel a tiny shock, but that's all. So everything is taken care of, your safety is not at risk.


Now about ground loops... Suppose all your equipment is grounded. That means that all the casings are interconnected by means of the yellow/green wire of the power cables. And by itself that's fine.

But audio signals also have a ground connection. So if you draw a diagram of the whole system there's a possible loop: from device A to B through mains ground, and back through audio ground. And this is where problems may arise.

Now this loop has to be broken somewhere. Either with a DI box or isolator as you have on the audio line, or by using a 2-prong power connection. One fix is sufficient to break the loop. Now which fix is better, that depends.

I hope the explanation is now sufficient.

[nix808]

Thanks so much for your time, Bert. Those links were informative. I've now installed DI boxes and I think they are cutting all gound noise out from my lappy. It's hard to tell though because I've found that some noise is being created by the PC. Should I expect some line noise when plugging so many devices through each other? It would be sweet to have a noise free setup, eh. Can a desktop also create ground loop hum? I tried fitting the isolator to the line between my soundcards, but this stopped the signal. Any help with this would be much appreciated.
Cheers, nix
Edit: I tried the isolator again on the line between soundcards and it worked! I now have a noise free system to record. It's sounding great and I can plug my FX in in whatever order I like. Thanks heaps for helping me suss my problem kind people .
Cheers, nix