Shielding the control cavity

[max_overdrive]

Opinions differ about whether, after shielding the pickups and pickup cavities, it is diminishing returns to also shield the control cavity.

 

At 10:10 in this video Dylan of DylanTalksTone says it's counterproductive as "the wires in the control cavity are not an effective antenna and something is gonna end up touching something it shouldn't" resulting in issues.

 

Has anyone here noticed a reduction in noise from shielding the control cavity?

[neepheid]

9 hours ago, max_overdrive said:

Has anyone here noticed a reduction in noise from shielding the control cavity?

 

Yes.  Our rehearsal room is an electromagnetic hellhole.  Shielding helped a bunch.

[sandy_r]

10 hours ago, max_overdrive said:

Opinions differ about whether, after shielding the pickups and pickup cavities, it is diminishing returns to also shield the control cavity.

 At 10:10 in this video Dylan of DylanTalksTone says it's counterproductive as "the wires in the control cavity are not an effective antenna and something is gonna end up touching something it shouldn't" resulting in issues.

 Has anyone here noticed a reduction in noise from shielding the control cavity?

 

Sounds like Dylan graduated from the Star Trek School of Engineering

 

Pickup manufacturers build-in shielding, Audio Cable manufacturers likewise, Pedal and Amp makers too ...but that magic region between pickup and jack socket follows special Laws of Physics known only to Dylan and Scotty 😉

 

Shield & ground the control cavity - with continuity above and below - don't solder to pot cases (prolong their life and reduce probability of dry joints)

 

"something is gonna end up touching something it shouldn't" is not a valid excuse to ignore something important - it just means people should engage eyes and brain, and think about how to achieve shielding AND insulation - rocket science it ain't (sorry Scotty, RIP)

 

(FWIW pickups act like half a transformer - more sensitive to magnetic part of EM signals/ interference; control wiring is more sensitive to the Electric part of EMI, ie. ANY unshielded signal wire is an antenna to some frequencies - and the high impedances in the control wiring contribute to that sensitivity)

 

[TbirdnTalman]

8 hours ago, sandy_r said:

 

Sounds like Dylan graduated from the Star Trek School of Engineering

 

Pickup manufacturers build-in shielding, Audio Cable manufacturers likewise, Pedal and Amp makers too ...but that magic region between pickup and jack socket follows special Laws of Physics known only to Dylan and Scotty 😉

 

Shield & ground the control cavity - with continuity above and below - don't solder to pot cases (prolong their life and reduce probability of dry joints)

 

"something is gonna end up touching something it shouldn't" is not a valid excuse to ignore something important - it just means people should engage eyes and brain, and think about how to achieve shielding AND insulation - rocket science it ain't (sorry Scotty, RIP)

 

(FWIW pickups act like half a transformer - more sensitive to magnetic part of EM signals/ interference; control wiring is more sensitive to the Electric part of EMI, ie. ANY unshielded signal wire is an antenna to some frequencies - and the high impedances in the control wiring contribute to that sensitivity)

 

Just don't use dilithium crystals then,,,?

[sandy_r]

10 minutes ago, TbirdnTalman said:

Just don't use dilithium crystals then,,,?

 

...dilithium crystals are fine - just need to polarise them all in t'same direction

 

[Doctor J]

Not every Youtuber knows what they're taking about 🤔

[Baloney Balderdash]

Well, if you use shielded wiring for everything, including the wires from the pickups themself, that is wire where the ground wire runs as a braided shield all along the insulated hot wire, there will be no need to shield anything else than the pickup cavities, otherwise, that is using regular wire, additional shielding will have an effect.

 

Edited January 20, 2024 by Baloney Balderdash

[ezbass]

On 17/01/2024 at 00:02, max_overdrive said:

Has anyone here noticed a reduction in noise from shielding the control cavity?

Yes. I shielded my JMJ Mustang from the pickup rout, through to the control cavity (making sure it connects with the metal control plate) and it is noticeably quieter.

[Lozz196]

15 hours ago, TbirdnTalman said:

Just don't use dilithium crystals then,,,?

Ye cannae change the laws of phusics

[JPJ]

The quietest passive bass I own is the one where I shielded the pickup cavities and the control cavity with copper tape and connected all the shields together with the bridge earth and to the earth lug of the output jack. Not even a badly wired fluorescent light will affect it.

[neepheid]

14 minutes ago, JPJ said:

The quietest passive bass I own is the one where I shielded the pickup cavities and the control cavity with copper tape and connected all the shields together with the bridge earth and to the earth lug of the output jack. Not even a badly wired fluorescent light will affect it.

 

Someone on the internet will be along shortly to tell you how wrong you are...

 

[max_overdrive]

45 minutes ago, JPJ said:

The quietest passive bass I own is the one where I shielded the pickup cavities and the control cavity with copper tape and connected all the shields together with the bridge earth and to the earth lug of the output jack. Not even a badly wired fluorescent light will affect it.

 

Yup, that's what I'll do. Thanks everyone 🙏

[tauzero]

On 17/01/2024 at 20:28, sandy_r said:

 

...dilithium crystals are fine - just need to polarise them all in t'same direction

 

 

Don't reverse the polarity of the neutron flow.

[Obrienp]

Not sure whether the question was specifically regarding passive or active electronics but from experience, you really do need to shield the control cavity with active. All the Ibby basses I have owned with active electronics have picked up mobile phones near them. Shielding the cavity stopped this.

 

I always shield my passive basses as well. It has never caused a problem and they have become quieter as a result, so I am assuming the cavity shielding contributed. Where the cavity is really tight, I put a bit of insulating tape over any areas of shielding that could possibly make contact with any live part of the electronics.

[ezbass]

31 minutes ago, Obrienp said:

Where the cavity is really tight, I put a bit of insulating tape over any areas of shielding that could possibly make contact with any live part of the electronics.

Had to do this with my most recent bass. A PITA, to be sure but, once done, shouldn’t need doing again.

[Martin E]

I've shielded a few basses with copper tape but always thought it was rather a crude way of doing things especially if you have to then have to stick insulating tape over the top.

I've started using shielding paint, its so quick and easy to apply but only takes  a few microns off the space in a crowded control cavity. You need two or three coats but it dries quickly.

A meter will confirm it's conductivity and it does work. Just take it over the lip of the cavity to contact the control plate. 👍

[neepheid]

Sorry, I'm a copper pervert.  There's something I find very satisfying about a shiny, copper lined cavity.  Mmm, shiny.

[ezbass]

2 minutes ago, neepheid said:

There's something I find very satisfying about a shiny, copper lined cavity.

Fnarr, fnarr!

[SamIAm]

1 hour ago, neepheid said:

Sorry, I'm a copper pervert.  There's something I find very satisfying about a shiny, copper lined cavity.  Mmm, shiny.

I'm no perv, but DO prefer lining with copper tape.

Sam x

[Obrienp]

1 hour ago, Martin E said:

I've shielded a few basses with copper tape but always thought it was rather a crude way of doing things especially if you have to then have to stick insulating tape over the top.

I've started using shielding paint, its so quick and easy to apply but only takes  a few microns off the space in a crowded control cavity. You need two or three coats but it dries quickly.

A meter will confirm it's conductivity and it does work. Just take it over the lip of the cavity to contact the control plate. 👍

Do you find it as effective as copper tape? I’ve had basses that had cavities painted with graphite paint from the factory and they are still noisy. Put copper tape over the paint and the noise disappears. Of course, the factory might not have put as many layers on as you do but it has made me default to copper tape as the best solution.

[max_overdrive]

3 hours ago, Obrienp said:

Where the cavity is really tight, I put a bit of insulating tape over any areas of shielding that could possibly make contact with any live part of the electronics.

 

You mean live wires and the live lugs of the pots?

[Obrienp]

36 minutes ago, max_overdrive said:

 

You mean live wires and the live lugs of the pots?

Yep, although I am hoping my work doesn’t leave too much live wire exposed but live lugs on pots, especially if there is a danger of it twisting and making contact with the shielding. I guess that even the grounded parts of a pot touching the shielding might generate a crackle but not sure about that.

[sandy_r]

 

+1 for insulating tape, where suitable - also heatshrink can give good results over soldered wire-to-wire and wire-to-lug connectiins:-

 

 

.[..apologies about image sizes - don't have the usual image editing on this device]

 

[Martin E]

Yes I think the problem with basses that come already painted with graphite paint is that they just don't use enough.

The  Player Jazz I bought last year had the cavity painted complete with an earth lug wired to the output earth.

It looked great in theory but the paint was so thin that probing with a meter showed it was only conductive in parts.

There was also a gap at the top of the cavity, if it had been taken just over the top to make contact with the control plate the earth wire would have been unnecessary.

Does it work as well as copper? I guess only a controlled side by side test would tell but I've proved to myself a decent coating really does give zero

resistance wherever you probe it so I don't see why not. 

[rmorris]

On 21/01/2024 at 16:31, neepheid said:

Sorry, I'm a copper pervert.  There's something I find very satisfying about a shiny, copper lined cavity.  Mmm, shiny.

 

Shiny Shiny Shiny Boots of...Copper 🤣