Horseshoe magnet test video

[walker]

I'm wondering if there were different mixes of steel in the shoes...

Awhile back when I had about 6 pair recharged, the guy who did the job noticed that my '68 magnets would only charge so high; I think they won't charge above 50 gauss. I notice that those horseshoes in particular appear to have a high air mix within the steel. They feel a little light and have a porous appearance. Here are pics of the 68 and 64 magnets - the '68 is the bubbly one!

[Colonel Sanders]

I'm wondering if there were different mixes of steel in the shoes, not specifically made for guitar or steel or bass, but with different ability to retain a charge, spanning the tears. I have two sets of magnetic shoes; the ones from the '62 lap steel hold a charge quite fine, whereas the set of an unknown vintage lap steel will not hold a charge very long; read not for many months.

From my experience with vintage Lowther speakers, which all have huge Alnico magnets, I would see the alloy as the reason why much more than the type of instrument.

[walker]

Listening to the video again with the balance panned to the right channel to hear the direct signal, I can hear a distinct difference with the D-G magnet upside down. The D & G strings sound a little bassier, and the E & A actually lose a little bottom end.

[johnallg]

I'm wondering if there were different mixes of steel in the shoes, not specifically made for guitar or steel or bass, but with different ability to retain a charge, spanning the tears. I have two sets of magnetic shoes; the ones from the '62 lap steel hold a charge quite fine, whereas the set of an unknown vintage lap steel will not hold a charge very long; read not for many months.

From my experience with vintage Lowther speakers, which all have huge Alnico magnets, I would see the alloy as the reason why much more than the type of instrument.

Right. I'm saying Rickenbacker had one bin for shoes. Any instrument needing shoes got the same type. But over the years, materials and manufacturers(maybe?) changed and thus the different abilities to charge and retain.

[cjj]

My guess would be that it is related to the materials used. I can't think of anything that different strings or frequencies would do to cause the magnets to lose charge, it's just that yo always hear of bass pickups going dead. Maybe it's just that the basses got really popular about the same time they made a material change and so, there are just a lot more basses out there that got the magnet material that doesn't last...

[Colonel Sanders]

Right. I'm saying Rickenbacker had one bin for shoes. Any instrument needing shoes got the same type. But over the years, materials and manufacturers(maybe?) changed and thus the different abilities to charge and retain.

Yep, I think we are saying the same thing. Alnico alloy quality/specs may have varied over years.

The pictures supplied by Mark support this.

[Seans]

Talking with a Physicist sometime back, I asked about my HS magnets as I wanted to know how to fix them, he loves talking and also educating, so I had the whole story from Iron to electrons etc etc, very very basically he said (the parts I understood),

Every magnet will loose charge and movement will be a major factor.

To re charge by magnetism, only a certain percentage can be reached, dependent too on the original charge.

To charge a magnet properly, heat as well as charge and then cooling quickly will be needed. I asked here how diy that was, eventually, ''car battery'' by now I'd lost concentration.

I could ask about Mark's reverse pole experiment, but I'm not sure I'm going to understand without some key questions to steer the lesson.

[Seans]

Listening to the video again with the balance panned to the right channel to hear the direct signal, I can hear a distinct difference with the D-G magnet upside down. The D & G strings sound a little bassier, and the E & A actually lose a little bottom end.

Mark, what I have noticed ( from my limited exp with the 60's HS pickup), with an new charged HS set, the pole heights have a very big effect on the output of each string, more so than on non HS pickups. I have spent a great deal of time with many different length screws and was amazed how just a fraction of a mm can change the output, I now have them as best I can and am pleased with the results.

[walker]

I was wondering about that, too - the space between the pole tops and the underside of the HS magnets. This would explain why the gap from pole to magnet is so tight on lap steels, but wider for basses - the space allowing for just enough room so that the string's optimum vibration range is the "sweet spot" midway between the gap.

And the vibration factor in the contribution to the magnets losing their charge sure would explain why the basses seem to drain them sooner than lap steels.

The heat & cool steps in charging a magnet (via electricity or battery?) is a new one on me. That would be interesting to learn more about. I don't suppose you recall what that temperature range was? Particularly how hot.

[walker]

Here's a theory, sort of an aside - towards 1967-68 the gaps on the HS mags was widened, apparently to accomodate the string radius of a bass - the parallel sides of the early magnets being ideal for the lap steel strings which lie flat. I wonder if ALL wide-gapped horseshoe magnets started out being the narrower type and were "re-smithed" to widen that gap. That might explain why the steel looks sort of "reworked" and may be why the material is more porous. If that's the case, it could be that all wide-gapped horseshoes will look similarly porous. (Or "porpoise" depending on where you're from.)

[Seans]

I was wondering about that, too - the space between the pole tops and the underside of the HS magnets. This would explain why the gap from pole to magnet is so tight on lap steels, but wider for basses - the space allowing for just enough room so that the string's optimum vibration range is the "sweet spot" midway between the gap.

And the vibration factor in the contribution to the magnets losing their charge sure would explain why the basses seem to drain them sooner than lap steels.

The heat & cool steps in charging a magnet (via electricity or battery?) is a new one on me. That would be interesting to learn more about. I don't suppose you recall what that temperature range was? Particularly how hot.

The heat range, as far as I could understand was similar to hardening, so very hot (certainly where chrome would be affected). Where the electrons are all facing the right way and then frozen there with a cooling plunge.
All the electrons are moving anyway and want to return to their original state and eventually will, hard for me to understand that something as hard as metal is actually not quite as solid as we would think.

[walker]

I see. So that may be how they're initially charged, but you wouldn't do this as a simple recharge if the chrome would get wrecked.

[buchrob]

Laptop 6-string horsehoe from 60's vs generic 4-string bass

Here are a few clues:
1. The lapsteel magnets measure 1.25" x 4.25" as installed. Not sure about the width of the bass.
2. Lapsteel U's are more parallel, since string gap is narrower. Pickup is very sensitive to the magnet/string/pole gap adjustment, so everything is probably of much lower charge or output compared to the bass.
3. Lapsteel pole pieces are very small, about the size of the yellow dot I show in the horseshoe gap.

Overall, the lapsteel system doesn't require a lot of current to generate pleasant sounds, so the initial charge on those magnets is probably a lot less than on the basses.

It takes a lot more energy to make a good bass sound than a guitar sound, so the components have to be beefed up.
Bass speakers and amps have to be much more powerful since it takes mucho energy to move a lot of air at those low frequencies: bigger magnets on bigger speakers and lots of wattage. There are a few good guitar practice amps putting out 5-15 watts into a smaller speaker, but no good bass amps with those specs.

[johnallg]

The shoes I took off of my '62 Electro lap steel are the widened-gap shoe type.

[walker]

Now that's interesting. Do they look porous like mine, or are they pretty dense?