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Is shielding required on a passive P-bass?
- Thread starter N. Kentucky Bass
- Start date
This being the case, why don't you just use it as you got it, and not trying to solve a problem that doesn't exist? You might wind up causing more problems than what you're trying to cure.
The two plates of your accidental capacitor are both at ground potential; it won't do anything to the tone of the signal.
It also likely won't cause any shielding problems, unless perhaps you are playing in a very high level RF field, like under a transmitting tower.
Assuming everything is grounded.
I’ve run into many pickup cavity shields that were just left floating.But to your point, I’ll agree with you completely. It’d only really be an issue if some foil worked loose and touched something on the hot side of the signal chain. (Not unheard of with a nin-pro shielding job btw.) Otherwise it shouldn’t matter.
Surely a rational path to use in this scenario. My P-bass is hanging on the wall, disconnected strings hanging below as I await delivery today of a soldering iron to fix that detached ground wire from the treble pickup to volume POT. A set of TJ flats arrives Saturday. I'll get her in shape and resume the project I'm doing in my home studio where there is (I believe) minimal electronic interference. Given COVID isolation, I do not foresee playing the bass in another location for the next several months at least. Plus my main interest is double bass. However, I confess I'm having a ball playing this one and re-emerging in the Slab World for a while. It has its own charms, for sure!!
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While you have it open, you might want to consider twisting the signal leads from the pickups. The twist helps reject noise pickup.
Star grounding prevents multiple paths to ground causing ground loops. It's not necessary if the items being grounded are independent of each other, but usually the most effective method. With so many short wavelength RF sources around now, a small ground loop could make a nice RF antenna.
Not required on a P-Bass, but certainly won't hurt* (done Properly)
*I curious as to thoughts about shielding vintage instruments though, and if that would dramatically affect their value. Probably a topic for another post...
2 years ago, I swapped out the EMGs in my '78 P for the Bill Lawrence. Obviously, the EMG model P was dead quiet.
The P-46 was not - in fact there was a surprising amount of buzz. Pole pieces were grounded, and i used the original brass shielding plate. So I hesitantly used copper shielding tape in that bass. It's dead quiet now. Don't recall if I made sure the leads were twisted on that one, or if it would have helped.
Last week I swapped PUs on a '74 P, that had been shielded with paint before I got it (including the back of the pickguard
, where tape clearly would be the preferred choice...
I also used the brass shielding plate and grounded the pole pieces. Afterwards, it was humming a bit more than my other Ps (which the room I was in tends to induce buzz from the dimmers). After jogging my memory, i took it apart and twisted the lead wires (including the Pole Piece ground lead), and, as an experiment, wrapped the wires (about 2") in shielding tape. That took care of the hum.
in other basses, I've used both shielding paint and tape, and had satisfactory results with both.
I'm curious too if all newer production Fenders have a layer of shielding paint in their cavities...
it appeared my 2009 CV 60s did (assume it was original), and my Tony Franklin also seems to have a modest coat of shielding paint, and shield ground.
*I curious as to thoughts about shielding vintage instruments though, and if that would dramatically affect their value. Probably a topic for another post...
2 years ago, I swapped out the EMGs in my '78 P for the Bill Lawrence. Obviously, the EMG model P was dead quiet.
The P-46 was not - in fact there was a surprising amount of buzz. Pole pieces were grounded, and i used the original brass shielding plate. So I hesitantly used copper shielding tape in that bass. It's dead quiet now. Don't recall if I made sure the leads were twisted on that one, or if it would have helped.
Last week I swapped PUs on a '74 P, that had been shielded with paint before I got it (including the back of the pickguard
, where tape clearly would be the preferred choice... I also used the brass shielding plate and grounded the pole pieces. Afterwards, it was humming a bit more than my other Ps (which the room I was in tends to induce buzz from the dimmers). After jogging my memory, i took it apart and twisted the lead wires (including the Pole Piece ground lead), and, as an experiment, wrapped the wires (about 2") in shielding tape. That took care of the hum.
in other basses, I've used both shielding paint and tape, and had satisfactory results with both.
I'm curious too if all newer production Fenders have a layer of shielding paint in their cavities...
it appeared my 2009 CV 60s did (assume it was original), and my Tony Franklin also seems to have a modest coat of shielding paint, and shield ground.
Twist the pickup leads around each other. It acts as a poor man's substitute for shielded cable.
Huh. I subbed in a set of P46s into a MIM P. I don’t recall using a brass shield, didn’t shield the cavity and it was dead quiet.Not required on a P-Bass, but certainly won't hurt* (done Properly)
*I curious as to thoughts about shielding vintage instruments though, and if that would dramatically affect their value. Probably a topic for another post...
2 years ago, I swapped out the EMGs in my '78 P for the Bill Lawrence. Obviously, the EMG model P was dead quiet.
The P-46 was not - in fact there was a surprising amount of buzz. Pole pieces were grounded, and i used the original brass shielding plate. So I hesitantly used copper shielding tape in that bass. It's dead quiet now. Don't recall if I made sure the leads were twisted on that one, or if it would have helped.
Last week I swapped PUs on a '74 P, that had been shielded with paint before I got it (including the back of the pickguard
I also used the brass shielding plate and grounded the pole pieces. Afterwards, it was humming a bit more than my other Ps (which the room I was in tends to induce buzz from the dimmers). After jogging my memory, i took it apart and twisted the lead wires (including the Pole Piece ground lead), and, as an experiment, wrapped the wires (about 2") in shielding tape. That took care of the hum.
in other basses, I've used both shielding paint and tape, and had satisfactory results with both.
I'm curious too if all newer production Fenders have a layer of shielding paint in their cavities...
it appeared my 2009 CV 60s did (assume it was original), and my Tony Franklin also seems to have a modest coat of shielding paint, and shield ground.
When I was a tech, we called this stuff “weird s*** from space.”
Overkill. For the voltages present in a passive bass, star grounding is totally unnecessary because it won’t make a difference. About all it will accomplish is to add additional lengths of wire into the control cavity and possibly act as an antenna. Using the least amount of wiring consistent with getting a good and reliable ground connection is sufficient.
The difference in lead length between terminating ground at the jack vs. the volume pot is minimal.
Does the termination point ON the volume pot make a difference? Or will anyplace on the underside do?
It doesn't matter. Connect the grounds wherever it's convenient. There's no need to get caught up in overthinking this. As long as everything that is supposed to be grounded has a good connection to something that is ultimately connected to the ground lug at the jack, you'll be 100% totally fine.
Theoretically ground is ground. The entire pot shell should be grounded. Any point will work. I find as a practical matter terminating at the jack is a more sure connection.
I recently worked on a bandmate’s strat. I fixed a wicked bad hum problem by running new ground wires and terminating at the jack. But the previous wiring was poor. I just fixed it the best and fastest way I could.
Exactly! In this application, terms like "star ground" and "paths to ground" are meaningless IMO. As long as shielding is connected to ground at the jack, the shielding IS the ground, not a path to it. As is everything connected to it.
Nevertheless, star grounding is completely unnecessary for a passive bass or guitar.
And if you’re actually doing star grounding, that would include using separate ground leads from the pickup and control cavity shielding plus any pickup shields, along with separate ground leads from the bridge along with separate grounds for every pot and switch. The whole point of star grounding is that every grounded component has one (and only one) ground connection wired straight to a single main ground, which would be the jack ground lug. And if we’re talking a JB for example, there’s 3 pots, 1 bridge pickup cavity, 1 combo neck pickup/control cavity, and the bridge ground wire. So I’m counting 6 separate leads minimum to the jack’s ground lug if you’re using a star layout.
That’s a lot of unnecessary wire IMO.
But that’s me. If you’re more comfortable with a star layout that’s ok too. Bottom line: as long as everything is properly grounded it’s all good. I just try to do what’s necessary and keep things as simple as possible. I come from a family of mechanical and electrical engineers. And they dunned into my head from an early age that the more elaborate your design, the greater the number of PPFs - or potential points of failure.
It doesn't act as a shield; it causes phase cancellation of the noise due to the changing orientation of the conductors with respect to the magnetic field.
