madbeanpedals::forum

General => Open Discussion => Topic started by: claytushaywood on November 03, 2013, 08:45:11 PM

Title: Using Shielded Cable
Post by: claytushaywood on November 03, 2013, 08:45:11 PM
I recently used some shielded cable inside a fuzz face build and I got a ground loop.  I disconnected the shield from one end on each of the two cables and it went away.  Am I still getting shielding when one end is disconnected?  or is their a proper way to use shielded cable in pedals?
Title: Re: Using Shielded Cable
Post by: derevaun on November 03, 2013, 08:52:45 PM
Conventional wisdom seems to be ground only one end. I assume the preferable end is whichever is closest to the "hub" of star grounding, which is typically the power jack?
Title: Re: Using Shielded Cable
Post by: stecykmi on November 03, 2013, 09:01:01 PM
ya, typically only 1 side should be grounded. the power jack or the input jack sleeve are commonly used because these are typically used to connect ground between different components.
Title: Re: Using Shielded Cable
Post by: davent on November 03, 2013, 09:14:29 PM
I recall seeing it suggested to ground the shield at the input end of the cable and float the other end of the shield so that's how i've always done it.

dave
Title: Re: Using Shielded Cable
Post by: juansolo on November 03, 2013, 09:17:44 PM
I tend to connect one end to the nearest available/convenient ground. The other end is left floating.
Title: Re: Using Shielded Cable
Post by: derevaun on November 03, 2013, 11:50:51 PM
Pardon the piggyback, but where are folks getting shielded wire? I've been using pieces I found in VCR teardowns, but I'm running out.
Title: Re: Using Shielded Cable
Post by: claytushaywood on November 03, 2013, 11:55:25 PM
I just got some from smallbear last time i ordered.  Ive been wondering about star grounding and its merits... is it really all that in low voltage circuits?  I recently built an Allen Amp from a kit and it used star grounding, definitely the quietest fender type amp ive ever heard
Title: Re: Using Shielded Cable
Post by: Govmnt_Lacky on November 04, 2013, 12:54:50 AM
As far as shielded wiring and only grounding one end... a little explanation...

If you ground BOTH ends of the shield... you are not only creating a possible ground loop BUT, you have also just created a rather large RF antenna. This can be VERY bad for wires that carry LFOs or Clocks.

If you use shielded wiring, just ground it on ONE end. Cap the ground on the other end  8)
Title: Re: Using Shielded Cable
Post by: davent on November 04, 2013, 01:12:12 AM
Quote from: derevaun on November 03, 2013, 11:50:51 PM
Pardon the piggyback, but where are folks getting shielded wire? I've been using pieces I found in VCR teardowns, but I'm running out.

Teflon is the only way to go, i've bought here but check Apex jr. as well.

http://stores.ebay.com/Johns-Silver-Teflon-Wire-Shop/Shielded-Wire-Coax-/_i.html?_fsub=3966787&_sid=155009&_trksid=p4634.c0.m322

dave
Title: Re: Using Shielded Cable
Post by: alanp on November 04, 2013, 05:14:09 AM
I think I bought a bunch of it from a NZ amplifier dude (The Amp Shop), and then bought some more from Small Bear.
Title: Re: Using Shielded Cable
Post by: juansolo on November 04, 2013, 08:21:26 AM
I don't build stuff that needs it that often, so all our stash has come from old VCR/HiFi strip downs.
Title: Re: Using Shielded Cable
Post by: miter53 on November 06, 2013, 05:54:22 AM
A question: I assume when you refer to shielded cable, you mean two conductors and a shield. What about using coax i.e. one conductor and a shield, with the shield going to ground and the center conductor to the tip? Is this problematic?
Title: Re: Using Shielded Cable
Post by: rullywowr on November 06, 2013, 06:01:10 AM

Quote from: miter53 on November 06, 2013, 05:54:22 AM
A question: I assume when you refer to shielded cable, you mean two conductors and a shield. What about using coax i.e. one conductor and a shield, with the shield going to ground and the center conductor to the tip? Is this problematic?

Actually, coax is what they are referring to (well at least what I use). The shield is the foil and you just ground one end. It comes in handy especially in high gain circuits.