Screened cable... does the voltage make a difference?

[dannyart]

I'm thinking of doing a point to point rebuild of my Valve Jr. I was looking at all the home brew amp builds and it seems that screened cable is the norm for all + connections from the jacks and pots. But what kind of screened cable do I use? Is it ordinary 12volt audio screened cable like you find in some guitars? ...do I have to consider the high voltage in an amp circuit and use high voltage screened cable accordingly?

Any help much appreciated! :AOK:

[tunghaichuan]

I'm thinking of doing a point to point rebuild of my Valve Jr. I was looking at all the home brew amp builds and it seems that screened cable is the norm for all + connections from the jacks and pots. But what kind of screened cable do I use? Is it ordinary 12volt audio screened cable like you find in some guitars? ...do I have to consider the high voltage in an amp circuit and use high voltage screened cable accordingly?

Any help much appreciated! :AOK:

Mainly, sheilded cable is used for the connections to the input of the tube which is the grid. This is the most sensitive part of the tube in regards to noise. You can use sheilded guitar cable, but it is usually too thick. Here in the States there is a type of cable called RG-174U coaxial cable, which is what I use for sheilded leads. It is about 1/8" thick (3.18mm).

Since it doesn't carry any current, and there is hardly any voltage on it, it doesn't have to be high voltage rated.

I've found that for lower gain circuits like the VJ, you don't really need it if you keep the wiring short and neat. If you do want to use it, remember to only ground one end of the shield, not both. You want to ground the end of the shield where the signal originates.

tung

[dannyart]

Thanks for that Tung. Ive found a supplier over here that sells an almost identical product to the one you mentioned so I'll use that.

I saw a layout for a 5watt amp (similar to VJr) and an 18watter that used the screened cable for all the positive connections to the pots too... is this necessary or will ordinary hookup wire do the job?