How do you "shield a lead"?

[Henry89789]

I built a Tube sound fuzz from the Craig Anderton book and it sounded good but was noisy. The book says to use "shielded cable" for the input lead and a couple of other wires. I didn't use shielded cable when I built the pedal because I didn't understand what to do with the shield of each cable. I now want to go back and use shielded cables. I found info somewhere that said to solder a wire to the shield but what is done with the shield at each end?  Thanks in advance for any info on how to do this.

[Henry89789]

Thanks but no need to reply. I found a thread on this issue which explains all I need to know.

[deadastronaut]

just for others that have this issue and search it.

connect inner core from 3pdt switch to pcb in.

then connect one end of outer cable (shield) to a ground on pcb, other end of sheild is not connected to anything.

voil'a...

[joegagan]

well, maybe.

there are situations where grounding the case side ground is preferred over the PCB side. complicated subject, as the previous threads more than likely delve into.

[boogietone]

This is a complicated subject.

The main rule to keep in mind, though, is that only ONE end of the shield should be connected to ground. Otherwise you are asking for ground loops.

[Henry89789]

Thanks for the replies on this. I used shielded cable for the input and output (connecting the ground  only on one end to the ground on the jack). I also shortened some of the leads which were longer than 3". I think these modifications worked because it definitely reduced the noise, not a lot, but definitely reduced. From what I read these Tube Sound Fuzz pedals are notoriously noisy so I am going to leave well enough alone except I will try some different chips when I can get some new ones since I read that they vary significantly from one to another in regard to noise. 

[GGBB]

Along this line - can someone explain how this works when the pedal enclosure is already essentially a big shield.  I understand how/why shielding works, I just don't quite get a shield within a shield.  Is the enclosure not that effective?  Why not?  Is it because it is aluminum?  Does that mean a steel enclosure is a better shield, or a copper lined aluminum enclosure?  Or is it just the cumulative effect making the overall shielding better?

[merlinb]

Along this line - can someone explain how this works when the pedal enclosure is already essentially a big shield. 

It is to shield the input wire from electrostatic feedback taking place *inside* the pedal, i.e. parasitic feedback from output to input. But you're right, it is already shielded from external fields by the enclosure.

[GGBB]

It is to shield the input wire from electrostatic feedback taking place *inside* the pedal, i.e. parasitic feedback from output to input. But you're right, it is already shielded from external fields by the enclosure.

Thanks Merlin.  I've learned my new thing for the day and it's not even lunch time yet!

[Govmnt_Lacky]

Also, it is good practice in pedals that contain clocks and LFOs. It shields the non modulated lines from those that carry your modulated signals. This way, you can minimize ticking and LFO bleed through 

[beedoola]

well, maybe.

there are situations where grounding the case side ground is preferred over the PCB side. complicated subject, as the previous threads more than likely delve into.

what thread?

[armdnrdy]

what thread?

Enter "shield" into the search function.

[zombiwoof]

On this subject, what is a good shielded wire type and gauge to use in pedals?.  Anyone prefer a certain wire over others?.
Thanks,
Al

[deadastronaut]

^ i cut up RCA leads...does me fine...and i have lots of them.

[Govmnt_Lacky]

On this subject, what is a good shielded wire type and gauge to use in pedals?.  Anyone prefer a certain wire over others?.
Thanks,
Al

RG-174