Is it possible to shield single coil pickups?

[Isaac_James]

By this I mean the pickups themselves, not the cavity.

I have a Yamaha BB735A that I love playing, but the pickups are unshielded internally and produce a lot of noise from EM interference (single coil hum too, but I'm less concerned about that for now). I've shielded the control cavity and pickup cavities with grounded copper tape, which didn't make very much difference. The cavities were already sprayed with conducive paint, as it turns out, so the tape was sort of a waste of time in the end.

The bass picks up a lot of noise from background electronics, I can tell that it's not just single coil hum because it changes in volume depending on which way I'm facing. I had resigned myself to this just being an inevitable result of having single coil pickups... until I installed Wilde P46 and J45 pickups in another bass. Playing in the same room, with the same cables into the same pedals and amp, that bass is dead quiet. And all of a sudden the EM noise on the Yamaha begins to bother me again...

I've considered just getting new pickups that are properly shielded like my Wildes, but options for 5 string PJ sets are limited, and that's an expensive solution considering that I actually like the sound I get from these pickups aside from the EM noise. Which got me wondering if it's possible to shield the inside of these pickups themselves. The pickup covers come off the coil and magnets quite easily so getting inside won't be a problem.

So, is this possible? And if so, it is a worthwhile effort? Or should I just start looking into noiseless replacement sets?

 

[claudel]

I tried shielding the coils with copper tape and grounding it once, long ago, on a Stratocaster and it completely muffled the high end.

Didn't take me long to remove it.

YMMV, but I'd go with something else.

 

[Windreaper]

By this I mean the pickups themselves, not the cavity.

I have a Yamaha BB735A that I love playing, but the pickups are unshielded internally and produce a lot of noise from EM interference (single coil hum too, but I'm less concerned about that for now). I've shielded the control cavity and pickup cavities with grounded copper tape, which didn't make very much difference. The cavities were already sprayed with conducive paint, as it turns out, so the tape was sort of a waste of time in the end.

The bass picks up a lot of noise from background electronics, I can tell that it's not just single coil hum because it changes in volume depending on which way I'm facing. I had resigned myself to this just being an inevitable result of having single coil pickups... until I installed Wilde P46 and J45 pickups in another bass. Playing in the same room, with the same cables into the same pedals and amp, that bass is dead quiet. And all of a sudden the EM noise on the Yamaha begins to bother me again...

I've considered just getting new pickups that are properly shielded like my Wildes, but options for 5 string PJ sets are limited, and that's an expensive solution considering that I actually like the sound I get from these pickups aside from the EM noise. Which got me wondering if it's possible to shield the inside of these pickups themselves. The pickup covers come off the coil and magnets quite easily so getting inside won't be a problem.

So, is this possible? And if so, it is a worthwhile effort? Or should I just start looking into noiseless replacement sets?

Yes, ESP Custom Lab pickups have shielding inside the pickup cover. Said pickups were still noisier soloed than in the middle position, so the special shielding is no replacement for a humbucker.

Could try replacing the J pickup with a stacked or split-coil one. The P pickup on my BBP35 wasn't particularly noisy.

 

[Isaac_James]

Yes, ESP Custom Lab pickups have shielding inside the pickup cover. Said pickups were still noisier soloed than in the middle position, so the special shielding is no replacement for a humbucker.

Could try replacing the J pickup with a stacked or split-coil one. The P pickup on my BBP35 wasn't particularly noisy.

I'm certainly not an expert in this sort of thing so I could be way off base but I think most of the noise I'm picking up isn't 60 cycle hum. That would be a constant buzz as long as the pickup's on at the same volume, right? And I know that shielding won't do anything about that.

The noise that's bothering me gets louder or quieter depending on where I am facing, which suggests that it's interference from something external. Hence my interest in adding more shielding to the pickup coils, if such a thing would be helpful.

 

[ctmullins]

You're on the right track @Isaac_James . 60-cycle hum is a completely separate thing than EMI buzz. Shielding addresses buzz, not hum. Split-coil pickups address hum, not buzz.

Shielding is relatively easy to install, and if you don't like the effect, uninstall. Just be sure to verify with a meter that it's all properly grounded.

 

[Wfrance3]

Just be sure to verify with a meter that it's all properly grounded.

When I shield a pickup cavity, I put my meter on tone and then stab around randomly inside the cavity to be sure continuity is everywhere. If I find a place where I can't get tone, I just cut out a little strip of adhesive copper foil and bridge that spot, then repeat. Once there's no daylight, I check ground wire to just a couple more random spots. Once I have that, I have it.

This is a 4 string version, but it's the best illustration I can think of off the top of my head, for a two-wire split jazz coil pickup.
Split Jazz Bass Pickups by Lindy Fralin: Noiseless Jazz Bass Pickups
Get something like that and Bob's your uncle...
I know Bartolini makes a 5 string pickup set that has a split jazz like the Fralin above, but they are a specific flavor. I like them, but in a recording situation, they can beg the question "did you bring another bass?"

 

[Isaac_James]

You're on the right track @Isaac_James . 60-cycle hum is a completely separate thing than EMI buzz. Shielding addresses buzz, not hum. Split-coil pickups address hum, not buzz.

Shielding is relatively easy to install, and if you don't like the effect, uninstall. Just be sure to verify with a meter that it's all properly grounded.

Thanks, thought I had a decent understanding of the problem, nice to hear I am correct. I knew about 60 cycle hum from my other basses and was prepared to live with it when I bought this bass, but the EM buzz is a different matter.

How do you go about doing shielding inside a pickup itself? Copper tape inside the cover? I assume I don't want it to touch the coils as that will short it out when I connect the shield to the ground. I've tried searching online but all I get is advice on how to shield the cavity, not the pickups themselves.

When I shield a pickup cavity, I put my meter on tone and then stab around randomly inside the cavity to be sure continuity is everywhere. If I find a place where I can't get tone, I just cut out a little strip of adhesive copper foil and bridge that spot, then repeat. Once there's no daylight, I check ground wire to just a couple more random spots. Once I have that, I have it.

This is a 4 string version, but it's the best illustration I can think of off the top of my head, for a two-wire split jazz coil pickup.
Split Jazz Bass Pickups by Lindy Fralin: Noiseless Jazz Bass Pickups
Get something like that and Bob's your uncle...
I know Bartolini makes a 5 string pickup set that has a split jazz like the Fralin above, but they are a specific flavor. I like them, but in a recording situation, they can beg the question "did you bring another bass?"

Bartolini specifically is not in the running for a couple of reasons, first one being that I've tried out a few basses sporting Barts and just never really liked the sound, and the second one being that they don't offer 5 string Precision pickups in the 3x2 size that my bass is routed for. There are fairly limited options there, the top contender at the moment (if I end up going with new pickups, which I may not) is Nordstrand.

I also am not especially bothered by the single coil hum in any case, as I mentioned in my response above - my issue here is EM interference.

I did make sure to test my shielding job and it's solid all the way around, so I'm confident the control and pickup cavities are shielded as well as they can be. I am assuming that the problem I have now comes from the shielding inside the pickups themselves. Right now when I take the covers off it's just a bare coil of copper wire underneath.

 

[Snert]

I'm certainly not an expert in this sort of thing so I could be way off base but I think most of the noise I'm picking up isn't 60 cycle hum.

So record the bass without it being played then have a look at the frequency response in Audacity (free) and you'll know.

 

[Isaac_James]

So record the bass without it being played then have a look at the frequency response in Audacity (free) and you'll know.

Actually not a bad idea, I have been wondering about the frequency of the midrange on this bass's preamp and I can't get an answer from Yamaha, so I can kill two birds with one stone.

However, I don't think I need to do this to confirm my suspicions, I can identify both 60 cycle hum and the EM noise when I listen through headphones. One changes in volume when I love around and one doesn't.

 

[micguy]

The bass picks up a lot of noise from background electronics, I can tell that it's not just single coil hum because it changes in volume depending on which way I'm facing.

That is precisely what you expect from single coil hum - your observation doesn't absolve it from being single coil hum, it pretty much proves it is.

Pickups have 3 kinds of interference:

1) Magnetic hum - the thing pickups up magnetic fields, and you hear them. The only way to practically get rid of this is hum cancelling pickups - all the electrostatic shielding in the world won't do a darn thing to this source of interference.

2) Electrostatic hum - the thing picks up electrostatic fields. These can be shielded by placing the pickup inn a Faraday cage - surrounding it with conductive stuff, like copper or aluminum.

2) RF interference - this is a special case of the above kinds of interference, but the wavelengths are often tiny enough that you really need to work harder to keep it out of things.Often, RF mitigation is done in the circuitry that the thing drives, but good shielding can't hurt.

 

[jeff62]

I had to shield a pickup recently as it was just slightly noisy. Wrapped black electrical tape around the coils and it did the trick.

 

[Isaac_James]

I had to shield a pickup recently as it was just slightly noisy. Wrapped black electrical tape around the coils and it did the trick.

I don't see how ordinary electrical tape would do anything to shield electronics, it's an insulator but there's nothing in it that interrupts magnetic fields as far as I know.

 

[micguy]

I had to shield a pickup recently as it was just slightly noisy. Wrapped black electrical tape around the coils and it did the trick.

If putting electrical tape on a pickup made it quieter, then a happy accident happened while you were doing that.

 

[slowburnaz]

I don't see how ordinary electrical tape would do anything to shield electronics, it's an insulator but there's nothing in it that interrupts magnetic fields as far as I know.

Yeah, that’s definitely weird.

But, if you wanna shield the single coil pickup, you can wrap the coil with electrical tape (I like Kapton tape, myself), then on top of that, wrap it with copper tape. To avoid killing a lot of high end, you should leave a small gap so the copper tape doesn’t make a complete loop. Then connect the copper tape to ground.

 

[sikamikanico]

Is it still noisy if you solo the neck pickup?

 

[kevrex]

are all of the cavities connected? is it noisy in both active and passive modes?

 

[Isaac_James]

Yeah, that’s definitely weird.

But, if you wanna shield the single coil pickup, you can wrap the coil with electrical tape (I like Kapton tape, myself), then on top of that, wrap it with copper tape. To avoid killing a lot of high end, you should leave a small gap so the copper tape doesn’t make a complete loop. Then connect the copper tape to ground.

That makes a lot more sense, but how does leaving a small gap avoid killing the top end?

Is it still noisy if you solo the neck pickup?

Less so, but still yes.

are all of the cavities connected? is it noisy in both active and passive modes?

Yes, and yes, though active mode seems a little noisier (this is with all EQ knobs flat).

Turning down the treble in active mode, or rolling down the tone in passive, reduces the noise significantly. But I don't like the muffled sound that produces either.

 

[slowburnaz]

That makes a lot more sense, but how does leaving a small gap avoid killing the top end?

Mod Garage: How to Shield Single-Coil Pickups

From the article:
“The real reason for the high-end loss are eddy currents in the metal film, which act like a shading coil in a transformer. The gap breaks the eddy currents and the loss of high end is minimal—and in most cases, not even audible.”

 

[rutabaga bob]

Nice article! Thanks!

 

[Isaac_James]

Mod Garage: How to Shield Single-Coil Pickups

From the article:
“The real reason for the high-end loss are eddy currents in the metal film, which act like a shading coil in a transformer. The gap breaks the eddy currents and the loss of high end is minimal—and in most cases, not even audible.”

Awesome, thank you! This looks cheap and easy, certainly worth giving a shot.