[sdiy] Jack to PCB "flying wires"

[David Ingebretsen]

I am undertaking several modules from various SDIY designers and I have studied various builders versions as well as the designer's documentation. However, I am still confused regarding wiring audio signals from jacks to the PCB. 

I have seen/built modules where the connection is:

1. just a piece of hook-up wire from the tip to PCB and ground to PCB
2. a twisted pair of hook-up sires from the jack to the PCB
3. Co-axial cable with:
   a. shield connected at the jack
   b. shield connected at the PCB
   c. shield connected at both ends

While I understand the general idea of ground-loop interference, I am confused by the variation in connections.

Why would I do any one of these over another? 

Specifically, if I do the "one-sided" co-ax thing:

1. does it matter if I connect the shield to the jack rather than the PCB, and why?
2. does the shield really do anything if it isn't connected at both ends?
3. if the co-ax really should only be connected at one end, why then, when using hook-up wire, do people run both a tip and ground wire between the jack and the PCB?


Last question, I've noticed a "star" type grounding on some modules where the ground of some jacks are connected together then run to the PCB with a one wire. How would I decide which jacks are to be "common"? EG, Mankato filter, there are three CV inputs and a 1v/Oct CV input which are summed on the board. If using hook-up wire on these jacks, would it make sense to tie the jack grounds together and just run one ground wire to the PCB?

Really, any advice would be greatly appreciated.

David