role of a bass plate on a pickup

[black_labb]

hi guys, id just like to ask what the base plate on a pickup does for the sound of a pickup, and what they are like without them.

basically im looking to make a p90, and am not sure if i want to buy the bobbin and then do a cover myself using wood or adding some wood to the cover to match the body, or wether i should make the whole pup from scratch.

with the bassplates, do they effect the sound? how does a brass bass plate compare to nickel silver? i know they should be grounded. are they usually attached to the pole pieces? (making them grounded aswell) im thinking i might just superglue some nuts to the magnets and ground each of them, or superglue them into the wooden core. that would all be covered by a wooden cover.

could anyone share their experience with some of the different tones you got from bass plates and ones without conventional baseplates. thanks

[black_labb]

actually, i realised i got a bit mixed up with the dimensions of p90's, thought it was p90's i saw somewhere with a width of 70mm, i thought it was a bit narrow for them.

the question remains the same, as it will be the same construction, just taller and making a smaller coil.

[Zhangliqun]

I assume nickel silver would have less of a tone effect than brass since that's how it works with covers. I haven't A/B'd a P90 this way yet but I will be trying that soon so stay tuned...

[black_labb]

ive heard that aswell, but i dont understand why. nickel is magnetic, which in my oppinion, should make it effect the sound more. i dont know why it doesnt.

[David Schwab]

ive heard that aswell, but i dont understand why. nickel is magnetic, which in my oppinion, should make it effect the sound more. i dont know why it doesnt.

That's what I'm wondering too. But it's such a small amount of nickel as to make nickel silver non magnetic... you can't get a magnet to stick to it. But I would think a magnetic cover would have a detrimental effect on tone.

I've been reading up on Burns Tri-Sonic pickups, and they had steel base plates! And chrome plated brass covers.

I also wonder how much the plating on brass covers effect the tone. I'd like to try a plain brass cover and see the difference.

[black_labb]

That's what I'm wondering too. But it's such a small amount of nickel as to make nickel silver non magnetic... you can't get a magnet to stick to it. But I would think a magnetic cover would have a detrimental effect on tone.

I've been reading up on Burns Tri-Sonic pickups, and they had steel base plates! And chrome plated brass covers.

I also wonder how much the plating on brass covers effect the tone. I'd like to try a plain brass cover and see the difference.

i cant imagine it being much, but i dont know, the only difference between brass and nickel silver (white brass) is a bit of nickel, so i dont know really. maybe its something to do with the plating process, often they will use a hydrogen bath for chrome plating, but i cant see hydrogen effecting magnetic fields...

either way im making wood covers for mine, but it is interesting to think about.

[David Schwab]

The one thing I'm pretty sure about is that the reason covers alter the tone is due to eddy currents. Some early pickup designs had covers with open tops and slits on the sides to help eliminate this.

Maybe brass produces more eddies, which might be damped by the addition a magnetic material like nickel?

As to the original question, I think metal base plates were used for grounding/shielding purposes. If you think of a covered humbucker, the whole thing is enclosed in a metal shield. The base plate obviously just holds the pickup together, and there's no reason why you can't make it out of something non metallic. As an example, Fender pickups didn't have metal base plates.

I had a Gibson ES-330TD with two chrome covered P-90 dog ears. They didn't have base plates, and where just held on by the covers screwed to the wood. They were also wound less than the P-90's in the 70's SG's.

All metal parts on the pickup effect the tone one way or another.. either through inductance or with eddy currents.

Early guitar designers were obsessed with grounding/shielding.. look at a Tele. Metal plate for the controls, metal bridge plate holding the pickup, which had a grounded metal base plate, and was covered with a metal bridge cover! That should keep that noise out!

Some guitars even had metal pickguards with everything mounted on them.

I had read that some designers felt an electric guitar had to be made of metal! Just like they thought if a train went over 30MPH it would suck all the air out and every one would die!

It's all charmingly naive.

[black_labb]

thanks for that, i thought that was the case but wanted to check. ive been thinking about my pups for a long time, but havent done much as i am putting them into a guitarthat hasnt been made yet

[Joe Gwinn]

The one thing I'm pretty sure about is that the reason covers alter the tone is due to eddy currents. Some early pickup designs had covers with open tops and slits on the sides to help eliminate this.

Yes, it is the eddy currents, and cuts and open areas do reduce these currents.

Maybe brass produces more eddies, which might be damped by the addition a magnetic material like nickel?

Not quite. Neither yellow brass nor nickel silver (a white brass) are magnetic. The difference is that nickel silver is far less conductive a material than yellow brass, volume for volume, so the eddy currents in nickel silver are proportionately reduced.

As to the original question, I think metal base plates were used for grounding/shielding purposes. If you think of a covered humbucker, the whole thing is enclosed in a metal shield. The base plate obviously just holds the pickup together, and there's no reason why you can't make it out of something non metallic. As an example, Fender pickups didn't have metal base plates.

I also think that shielding was the intent, plus shaping of the sound by eddy-current loading.

I had a Gibson ES-330TD with two chrome covered P-90 dog ears. They didn't have base plates, and where just held on by the covers screwed to the wood. They were also wound less than the P-90's in the 70's SG's.

All metal parts on the pickup effect the tone one way or another.. either through inductance or with eddy currents.

Yep.

Early guitar designers were obsessed with grounding/shielding.. look at a Tele. Metal plate for the controls, metal bridge plate holding the pickup, which had a grounded metal base plate, and was covered with a metal bridge cover! That should keep that noise out!

Music too?

[David Schwab]

Not quite. Neither yellow brass nor nickel silver (a white brass) are magnetic. The difference is that nickel silver is far less conductive a material than yellow brass, volume for volume, so the eddy currents in nickel silver are proportionately reduced.

Ta daa! That's what I was waiting to hear. Now we have an answer why brass doesn't sound as good as NS.

I also think that shielding was the intent, plus shaping of the sound by eddy-current loading.

I agree. I'm sure early designers tried things out, noticed the differences, and then used those ideas in future designs.

Music too?

Got to keep that damn loud rock and roll noise to a minimum!

[Ruel]

Is it possible to plate a brass plate with nickel and produce the same result as nickel silver? I know nickel plating would be more expensive but I just want to find out.

[Joe Gwinn]

Is it possible to plate a brass plate with nickel and produce the same result as nickel silver? I know nickel plating would be more expensive but I just want to find out.

No, it won't work, because the conductivity of the yellow brass under the nickel plate is unchanged. Also, pure nickel is a pretty good conductor. It's the alloy that has the low conductivity.

Said another way, if you take the components of nickel brass (copper, zinc, and nickel) and make them into a three-layer laminate, one element to a layer, the overall conductivity will be far higher than if you melt those three layers into a single layer of uniform composition and identical total thickness.

[kevinT]

Is DiMarzio is using yellow brass baseplates specifically as part of their pickup designs to get a certain tone....... or are they using them for cost-cutting reasons?...or both?....that is the question.

[David Schwab]

Is DiMarzio is using yellow brass baseplates specifically as part of their pickup designs to get a certain tone....... or are they using them for cost-cutting reasons?...or both?....that is the question.

In their patent, they only mention the base as "some non magnetic material, such as brass", so I don't think they used it other than being practical to work with.

I think also, back when DiMarzio first came out, brass parts on guitar was a big craze. Brass nuts, bridges, pickguards, knobs...

Carvin also uses brass base plates.

[Ruel]

No, it won't work, because the conductivity of the yellow brass under the nickel plate is unchanged. Also, pure nickel is a pretty good conductor. It's the alloy that has the low conductivity.

Said another way, if you take the components of nickel brass (copper, zinc, and nickel) and make them into a three-layer laminate, one element to a layer, the overall conductivity will be far higher than if you melt those three layers into a single layer of uniform composition and identical total thickness.

Just as I thought. Thank you Joe for verifying.