a couple magnet theory questions...

[David Schwab]

However, I think the basis of my misunderstanding may be a simple lack of orientation regarding the meanings of "horizontal" and "vertical" in this context.

Think of it as vertical is from the pole to the string. Horizontal is from pole to pole. It's in relation to the top face of the pickup.

[David Schwab]

I do not understand how the viewing paper tells you about the vertical component of the field where the string is located.

That's true, it doesn't. It's a 2D view.

Something I've done is to put the pickup into a zip lock sandwich bag, and then pull that tight. Then I sprinkle some steel shavings on the bag. You can then see a 3D view of the field, albeit not all that tall.

[Magnut]

I have used a very clear plastic bottle filled with mineral oil and just a little bit of very fine metal shavings. Shake it up and as the filings settle you can get a really good look in 3D of the magnetic fields.

[FunkyKikuchiyo]

DS... I've used the viewing paper with my assembled pickups, and also with magnets arranged outside of the pickups, either just set next to each other, or glued to some wood to make them stay put. I've found that small magnets placed together will each have their own fields instead of behaving like a giant magnet. I've seen this either as I put them with poles all facing the same way to act like a giant bar magnet, or with poles stuck together.

With the long magnets, it makes me wonder what is keeping some neos from just snapping under their own magnetic pressure....

Thanks for sharing the gaussmeter data, that answers a lot of questions for me.

[David Schwab]

DS... I've used the viewing paper with my assembled pickups, and also with magnets arranged outside of the pickups, either just set next to each other, or glued to some wood to make them stay put. I've found that small magnets placed together will each have their own fields instead of behaving like a giant magnet. I've seen this either as I put them with poles all facing the same way to act like a giant bar magnet, or with poles stuck together.

That's not my experience at all.

Here's a dual rail pickup. There are two 1" long magnets between the rails. The magnets aren't even touching, there is about 1/4" between them.

You can see in the magnetic viewing paper that the field is seamless. Here's both the top and the bottom of the pickup. So the two short magnets are acting as one longer magnet. There is no gap in the field.

With the long magnets, it makes me wonder what is keeping some neos from just snapping under their own magnetic pressure....

You mean long neos with the poles on the ends? That's not the kind of magnet you would use in a pickup, the poles are closer together. But if you drop one it will reassemble itself.

[Possum]

....

I kind of look at it as the totally black area right above the poles is the hottest zone, so you see the strat magnets are dead black circles for the poles, in the P90 its like all the poles are unified as one long magnet, the flux is hottest at the pole top itself but extends out further and unifies all the poles almost in one unit. Yes, a 3D viewing liquid would be cool. I just know what I hear and always tell customers if they want the true fatness to put the strings close to the screw poles because the field isn't as strong as strat pickups and doesn't go vertically as high. I se the viewig paper mostly to see what kind of magnets, sealed pickups with no poles have inside. The most interesting being a set of NOS Flying V arrow shaped pickups I got several years ago, very unique design you can only see with the paper as they are epoxy sealed and are humbucking.

[FunkyKikuchiyo]

David - How bizarre! My own quick tests didn't have the same results. Maybe because you had a blade on each side? I'm not sure, if I come up with something I'll let you know. That does help a lot, it means that the shape of the field prior to the iron core won't affect how it distributes within said core. That is very helpful for me, anyway.

Possum, I know what you mean about the heights. I always wondered if that was part of why I've had varying results with humbuckers. For example, if you lower the whole pickup 1/16" and then raise each pole the same amount, you end up with a clearer more fundamental tone than if you raised the whole pickup. I always try to adjust the individual poles keeping an eye on the slugs and where they are in relation to the strings... the neck angles are pretty steep on new gibsons, and since the rings they use are basically generic, this can be off sometimes. I've found this to be a nice little trick to bringing a mediocre humbucker to life. Anyway, the whole coil/polepiece thing reminded me of that.

[David Schwab]

David - How bizarre! My own quick tests didn't have the same results. Maybe because you had a blade on each side? I'm not sure, if I come up with something I'll let you know. That does help a lot, it means that the shape of the field prior to the iron core won't affect how it distributes within said core. That is very helpful for me, anyway.

Did you have the magnets all facing the same way? Also were they all the same strength?

It shouldn't matter if it's blades or not. The neos I'm using are much shorter than the blades, and are positioned more towards the middle, but the field is the full strength all the way across the blades.

[FunkyKikuchiyo]

I repeated my tests. I misinterpreted my results, it makes a bit more sense now. Magnets placed side by side, that is with like poles facing the same direction, show individual flux lines in the paper. Magnets placed in the same fashion against low carbon steel do what yours do, and the flux lines all behave together as though it was one magnet. Putting air gaps between the magnets and the steel seem to do weird things, but the viewing paper isn't precise enough to really say what is happening. This could be because it is very hard to hold the magnets together side by side since they repel each other to an extent when in that position.

[Possum]

...

Its a real bitch when a bucker won't sit flat and level paralell to the strings. Height adjustment and pole adjustment are critical to ANY humbucker, and you can get loads of variety of tones by doing that. In general if your pole screws are flat with the top of the pickup you'll get the brightest tone. Raising the pole screws a bit will make the screw bobbin dominate a bit more and the tone will darken up. This seems counterintuitive but hook up your LCR meter and watch it happen.

[David Schwab]

Its a real bitch when a bucker won't sit flat and level paralell to the strings.

Amen to that! I think all humbuckers should have three screw hole mounts.

[LtKojak]

I think all humbuckers should have three screw hole mounts.

Me too! Seems like only Schaller's offering that possibility.

[FunkyKikuchiyo]

Three height screws wouldn't be necessary if the guitar builders thought it through a little bit better, I think. I'll never own a modern SG with the pickups mounted on the pickguard. They have a steep neck angle and the pickups are parallel with the guard. It doesn't matter what pickups are in those things, they all sound horrible! The rings can always be sanded to compensate for small miscalculations.

I've talked people out of replacing pickups by getting the heights correct many times. Especially for jazz players, they really like their even string balance.

[David Schwab]

Three height screws wouldn't be necessary if the guitar builders thought it through a little bit better, I think.

Yeah, but even with a Les Paul with the angled rings.. they wobble and there's no way to adjust them for tilt. LPs have a steep neck angle too.

There's the same issue with bass pickups, like the EMG soap bars. Even with shallow neck angle, they don't always sit parallel to the strings. The bass pickups with three mounting holes like Barts are much better.

I've had a few guitars with three mounting screws on the pickups, and it's so much better.

[FunkyKikuchiyo]

Maybe it is my imagination, but the 50s and 60s gibsons had much shallower neck angles. That is what I meant, not that certain models are different, but different years. Their CS stuff and the Collings stuff is all shallower too. Why make it so much more dramatic? My theory is that it allows more room for error.... if it is shallower you run the risk of being too shallow and needing a neck reset, but if you are too far back you just jack up the bridge.

Alright, you've convinced me that three screws would be a good idea. I just get bad feelings of trying to track down replacement rings. But, that is what I was talking about to begin with, if you adjust the screw poles paying attention to where the slugs are in relation to the strings, you can get better sounds. It might mean cranking them way up or burying them way down in, but it does help, at least to my ears.