Messing With Pickups In My Strat - Advice Needed:

[Von Herndon]

I'd expect some difference between a low carbon steel and an aluminum keeper, because:

1) A steel keeper directs the magnetic flux of the permanent magnet to the pole screws, increasing the sensitivity of the screw coil. An aluminum keeper is magnetically non-existent
2) As aluminum is a much better conductor than steel, it will increase Eddy current losses and lower treble response.
3) Steel slightly increases the inductance of the PU , while aluminum doesn't.

I'm aware aluminum is not "proper" in this application, as neither are stainless steel pole pieces for the same reasons you have outlined.

I am not advocating that others use non-ferrous keeper bars. Just sharing.

I've pulled pickups apart that had plastic keeper bars in them (Gibson DSC) and that made me think maybe magnetically conductive material is not always necessary???

You can get machined keeper bars in different materials, including brass, copper and stainless, all of which are basically "invisible."

I've made some from aluminum and they seem to work just fine. The biggest difference I notice is they give a much mellower attack on the unwound strings.

Some old Gibson PAF's I have opened up (to replace the lead cable) had a wood keeper bar covered with thin copper sheet and held in place with tiny nails. Not sure of the origin of this as I've never seen it since.

I had a nice Gibson 498T pickup that had (6) stripped pole screws, so I replaced all the screws with stainless steel ones. That pickup worked really well, despite the SS screws could not conduct magnetic energy.

How does a steel keeper bar affect the inductance???

[Helmholtz]

...stainless steel pole pieces for the same reasons you have outlined.

There are magnetic and non-magetic stainless steels.

Some old Gibson PAF's I have opened up (to replace the lead cable) had a wood keeper bar covered with thin copper sheet and held in place with tiny nails. Not sure of the origin of this as I've never seen it since.

Certainly not original.

How does a steel keeper bar affect the inductance?

The high permeability of low carbon steel increases inductance. The influence of the keeper is relatively weak as it is outside the coil. The permeability of the pole screws has a strong influence on inductance.

[Von Herndon]

There are magnetic and non-magetic stainless steels.




Certainly not original.




The high permeability of low carbon steel increases inductance. The influence of the keeper is relatively weak as it is outside the coil. The permeability of the pole screws has a strong influence on inductance.

Thank you for that explanation.

After a great deal of trial and error, this pickup is just absolutely incredible. I took it to the studio where I work today and we recorded with it and everyone has commented favorably on how good it sounds.

My next project is to remove the 3 ceramic magnets from a Gibson Dirty Fingers and replace them with a single A4 or A5 and wood spacers.

It's a 9.5k with twin rows of screws....