Tube Amps / Music Electronics
For current discussions, please visit Music Electronics Forum. New: view Recent Searches.
New: visit Schematic Hell!
The sunn still shines online!

Listen to great tunes streaming live right now!

ampage archive

Vintage threads from the first ten years

Search for:  Mode:  

applying 'ground' according to schematic

5/9/2003 6:37 PM
Mike Cornett
applying 'ground' according to schematic
I've got a schematic in front of me, and understand that it calls for a grounding of wire, but I'm not sure how to apply it in my situation...I am using a dual ganged potentiometer where the schematic is using single...They recommend grounding by soldering the ground wire to the top of the potentiometer, which I cannot do in this case.
5/10/2003 10:48 AM

can't you connect it to the ground lug on the input jack?
5/10/2003 6:15 PM
Mike Cornett

from the looks of the schematic, the volume pot has a wire that goes to the second lug on the input jack, but the tone wire has a ground that is specified to go on the opposite side of the pot.
5/11/2003 12:39 AM

Just connect the lugs that have the little arrow (ground) symbol to any ground, either the input or the output jack. Assuming the thing you use as ground is attached to a metal case and your jacks and pots have metal bodies and nuts, it'll work fine. If there's any plastic or any doubt of proper contact, simply connect everything that's supposed to be grounded to the ground lug of the output jack. You don't have to ground the pot bodies, but it would help keep things quieter if you did. The old trick of bending back a lug and soldering it to the pot body is just for convenience.
5/11/2003 5:32 PM
Mike Cornett

Thank you...My only question that stands is this...  
Would the grounding of a wire on the top (volume) potentiometer work if I sent it to the bottom of the dual ganged pot (which would technically be the bottom of the tone pot)?  
If so, would this be quieter than grounding it to the input or output jack?
5/11/2003 11:18 PM

According to the diagram, the top pot, volume, is wired:  
Pin 1 (aka counter-clockwise): black wire to ground  
Pin 2 (aka wiper): yellow wire to output  
Pin 3 (aka clockwise): red wire to input and .02 cap to tone pot wiper  
The bottom pot, tone, is wired:  
Pin 1: ground  
Pin 2: .02 cap to volume pot pin 3  
Pin 3: open  
Grounds can all be wired to the same location; this is known as star grounding. Or they can be daisy-chained together. Or you can just use whatever is convenient.  
Star grounding is the quietest, generally; but in this case it's not that important. You won't get noise from this circuit unless you leave something open that's supposed to be grounded. The original design obviously calls for one to assume that the metal case will provide a common ground for the input/output jacks and the pot bodies. The input jack is the only thing that is explicitly wired up as a "ground" wire in this diagram; the rest are apparently just left to find their ground through the case (via the pot bodies). When I wire up pedals, I tend to use the ground of the output jack as my star-grounding point. Just my preference.
   Page 1 of 1