Crack input wiring

[sl-15]

Hi, I would like to experiment with different input wiring on my newly built Crack. I am thinking about using the shielded Belden wire that was also used in the Foreplay 3. I found an old post from Paul Birkeland that says to attache the drain wire from the shield to an additional ground solder lug drilled into the chassis near the volume pot (near the load).
What is the benefit of having the drain grounded at the load end? (And also could the drain wire be connected to terminal 3 instead of drilling an extra hole near the volume pot?)
When I make interconnect cables with shielded wire I usually attach the drain wire to the source end of the cable and leave it off at the other end. That seems to be the opposite layout to what is suggested in Pauls post and I am curious which might be better.
Also when just using different wire instead of a shielded input cable would it be beneficial to have braided separate runs for the left and right input instead of sharing the negative for both channels. Thanks for any input.
Best, Stefan

 

[Paul Birkeland]

Oof, that's a lot of questions.

You can connect the drain wire to the anti-rotation nib that sticks out of the volume pot.  That's probably easier than drilling an extra hole.  Terminal 3 is fine as well, but that's a long way to run a bare drain wire, and it's already a crowded place in the build.

I cannot remember why I earth the load end rather than the source end.  You are certainly welcome to try it both ways and let us know what you end up liking!  So much of the academic material that would delve into this revolves more around long runs of CAT5 or long runs between components.  This isn't really what we are after inside a chassis!

For using different wire, you could do a twisted pair for each channel.  That gets to be really tough with the Crack and the wire we provide, as those extra ground wires get tough to fit into the pot lugs, so we just used one for both channels.

If your aim is RF reduction, you could drill a small hole between the RCA jacks, install a solder tab, then put in a small Z5U cap between each jack's shell and the chassis.

 

[sl-15]

Paul, Thank you so much for the detailed answer. Using the volume pot anti-rotation nib is a genius idea!