Wires touching each other

[NielsR]

Hey good people,

just a quick question regarding the wiring in general. How important is it that the wires attached to the top of the pots doesn't touch each other? In the video guides you're told to check if the wires touch - might lead to hum etc.

My thought is that if they are all soldered to the same point then they are already effectively “touching” and therefore it's not very crucial.


Any experiences or advice on this?


Best

Niels

[Brendan]

Niels - my understanding is that you are not wanting to form separate loops with the wires. So long as they all meet somewhere and there is no full loop (i.e., pot A - pot B - pot C - pot A), you should be right.

[Rabbitz]

Niels - my understanding is that you are not wanting to form separate loops with the wires. So long as they all meet somewhere and there is no full loop (i.e., pot A - pot B - pot C - pot A), you should be right.

I struggle to understand why people say this.

It is all about voltage (potential) differences. The hum from so-called ground loops occurs when two ground (or earth - same thing in this context) have a difference in their potential. This causes current to flow between the ground points and this in turn can create hum.

A guitar has a single earth reference voltage i.e. the shield on the guitar lead. The wiring looms are so short as to have negligible voltage drop, thus cannot create potential differences.

If all the grounds are joined to this single earth reference I struggle to see where a difference in potential can occur to cause the current flow. I am happy to be educated on this.

We then put all this copper tape in and join it all up - creating the very loops that are so feared. Yet it is imperiative to have this type of earth (Yes I get it is a Faraday shield and is to filter out RF but it still creates loops).

Ground loop hum is an issue on P.A.'s as there is a likelyhood that the various parts of the system can be at different potentials - the most likely scenario is having the mixer and amp rack on different house circuits. This happens simply because one is at the back of the room and the other is at the front of the room so are fed from different circuits. Therefore if you loop the grounds then noise can be induced.