shielded microphone cable guidance

[Princo]

im building a pair of 300b pse mono's and thinking about the signal wiring, input is at the rear and runs all the way to the front, obviously will try to keep clear of any mains/ht wiring.

i have some decent quality 2 core shielded microphone cable lying around which i am thinking of using but need some guidance:

1. just use one core connect to signal in and shield connected to earth and ignore the the other core

2. solder both cores together at each end and connect to signal, shield connected to earth.

3. or forget it and just using single core un-shielded

[John Caswell]

Hi Princo.
The way I use twin screened cable is thus - one core is signal, the other core is signal earth, so it and the screen are connected together at the "send" end then only the signal core and signal earth core connected at the "receive" end, with the screen being insulated/isolated from signal earth.

John

[Princo]

Hi John

you mean like this

[John Caswell]

Exactly like that, except earth it locally, ideally at the bottom of the grid leak resistor, to be near the grid input and then the common earth return from that valve then goes to the star earth. This avoids circulating earth currents getting into the grid circuitry.

John

[Princo]

Thanks John