Grounding to pots or to a screw?

[moulie]

Hi Everyone,

I'm about to attempt my first rewire on my MIM P and I noticed a few people like to solder grounds to the back of the volume pot while others solder grounds to a screw they add during refurbishment.

Once I saw the screw technique, I'm leaning towards that. Any experts want to chime in on what has worked best for them and why?

Plus, any other sage advice for a novice bass modifier will be very helpful. I'm swinging for the fences with new pickups (lollar P) cts pots, switchcraft jack--the whole shabang. Got a new bridge too.

thanks

 

[seanm]

Hi Everyone,

I'm about to attempt my first rewire on my MIM P and I noticed a few people like to solder grounds to the back of the volume pot while others solder grounds to a screw they add during refurbishment.

Once I saw the screw technique, I'm leaning towards that. Any experts want to chime in on what has worked best for them and why?

Plus, any other sage advice for a novice bass modifier will be very helpful. I'm swinging for the fences with new pickups (lollar P) cts pots, switchcraft jack--the whole shabang. Got a new bridge too.

thanks

As long as you remember to solder a wire from the pots to the screw. The screw seems like overkill for me since you have to add extra wires but it shouldn't hurt.

 

[bassbully]

I use the pots ...but that me.

 

[punkanidea]

+1 to pots. it prevents ground loop that makes such a disturbing noise. though, i like to solder all ground wires to one pot volume. some say it's useless, but i prefer that one best/

 

[Rick Auricchio]

Grounding everything to a single point is best, though most companies don't bother. Single-point grounding (I'll abbreviate it SPG) presents a single ground point for pups, controls, and preamp (if you have one). There is only one path to ground for each component.

The hum problems from multiple ground paths are caused by minute resistance differences in the paths, which then allow small voltage differences among the components. Essentially, zero isn't zero, depending on where you try to get a ground. These tiny voltages get amplified as hum. (This situation is called a ground loop.)

Soldering to the pots does provide a ground, because the pots ground to the shielding in the bass. (This is either copper foil or conductive paint.) However, the shielding under the pot shaft "breaks" the SPG, because it allows the pot to "find" a ground via the shield.

Best way? Carefully removing a small circle of shield under each pot shaft, so the pot doesn't touch the shield. Installing a single ground screw into the shield somewhere. Running individual ground wires from pups, pot terminals, bridge, pot shells, and preamp to that screw. Nothing touching the shield.

In most cases, however, SPG is overkill, unless you've got a hum problem.

Note: Single-coil pups will pick up hum with their coils; SPG won't help but shielding will.

 

[punkanidea]

Grounding everything to a single point is best, though most companies don't bother. Single-point grounding (I'll abbreviate it SPG) presents a single ground point for pups, controls, and preamp (if you have one). There is only one path to ground for each component.

The hum problems from multiple ground paths are caused by minute resistance differences in the paths, which then allow small voltage differences among the components. Essentially, zero isn't zero, depending on where you try to get a ground. These tiny voltages get amplified as hum. (This situation is called a ground loop.)

Soldering to the pots does provide a ground, because the pots ground to the shielding in the bass. (This is either copper foil or conductive paint.) However, the shielding under the pot shaft "breaks" the SPG, because it allows the pot to "find" a ground via the shield.

Best way? Carefully removing a small circle of shield under each pot shaft, so the pot doesn't touch the shield. Installing a single ground screw into the shield somewhere. Running individual ground wires from pups, pot terminals, bridge, pot shells, and preamp to that screw. Nothing touching the shield.

In most cases, however, SPG is overkill, unless you've got a hum problem.

Note: Single-coil pups will pick up hum with their coils; SPG won't help but shielding will.

awesome explanation dude!! cool!!

 

[Jim C]

One mistake I see is how folks try to solder to the back of the pot.
This is typicaly plated steel and soldering to the plating is sloppy and not mechanicaly sound; also many use an iron that does not have the capacity (i.e. tiny little PC board low output that won't heat up this much metal in a reasonable period of time).

Sand a small spot on the pot with medium grit sandpaper, use a good sodering iron, tin the tip and the pot, use flux and good solder, do a proper job, clean flux residue when finished at all solder joints, get good grades, say your prayers at night, and eat all your vegetables and Bob's your uncle.