Lewguitar
New member
SWD: We talked about the addition of adjustable poles pieces; would that change the sound any, the magnetic field-disbursed through the bobbin?
Seth Lover: On the humbucker the adjustable pole piece extends out the bottom. If you had a magnet that was quite weak you could absorb some of the energy, depends on how far through that screw was, because it’s going to absorb some of the energy there. But as a rule, with a good magnet there wasn’t too much.
SWD: How did the mounting ring come about? In the drawing in your patent...
Seth Lover: I used the old ES-125 (dog-ear cover) as a start because we didn’t have any mounting ring for this. So this was not acceptable as a mounting ring I felt. Because you notice this there was a slight slope to it--slightly different here and here (neck angle). I designed two different mounting rings. One near the bridge and one near the fingerboard. One near the fingerboard is quite shallow at the front edge; and, I tried to set that so the thing would have the slope of the strings when you were fretted at the last fret. And then the one that was back near the bridge, it had to be held up a little higher so I wanted to bring the pickups up close to the string. Because the closer you can keep the pickup to the string the more output you are going to have. It doesn’t do any good to bring--to put the pickup down and bring the screws up to compensate because you’ve lost--you’ve got to get the pickup as close as you can to the strings.
SWD: Because you're losing your magnetic field?
Seth Lover: That’s right, the magnetic field comes up to the stings there and magnetizes the strings. That’s one of the things that most people don’t understand. They figure that string is waving there and cutting the magnetic lines of force. Nuts. That isn’t it. The magnet, all it does is magnetize the string. Now you’ve got a waving magnetic field. And we have a fixed coil with a waving magnetic field to induce voltage. If you want to, take the magnet out. One you’ve magnetized your strings, it will play until the string loses it. Players think the string, the magnetic field from the magnet comes up to the string and by twisting the magnetic flux back and forth that’s what induces the voltage. That’s not what happens. There’s a certain amount of that, but that’s minor. What is happening is you have a magnetic field that is moving back and forth across the coil. And when you move a magnetic field back and forth across the coil you induce voltage. If you move the field up and down it wouldn’t induce any voltage. It’s the motion back and forth across the pickup that does it.
SWD: How did you come about using alnico magnets?
Seth Lover: If I’m not mistaken I think the Oscar Moore pickup had tungsten carbide magnets or some such name as that. In other words what ever as the best magnet available-pre WW II (World War II) Well after WW II alnico magnets became quite popular. They started using it for the magnets in speakers and things like that. And finally electrodynamics died out and we had the alnico magnets. And of course everybody was selling speakers, selling alnico magnets and we found that we could get alnico magnets fairly reasonable, small in size for the amount of strength and the only thing that you run into with alnico’s was they were cast which means if you wanted to keep a dimension you had to pay the price for grinding the edges. And if you wanted an assembly to fit exactly between those pole pieces, you had to make sure that your dimensions didn’t vary too much. As cast, they ask as much as plus or minus .030” thousands. That means as much as 16th of an inch variation. We didn’t care about the thickness varying that much because one would be a little bit stronger and another a little weaker. You could live that. But the distance across the width had to have ground surfaces. They were ground to dimensions. We tried to hold within plus or minus .005” which is pretty tight.
SWD: What is the material and purpose of the bottom plate?
Seth Lover: The bottom plate is a non-magnetic material so that you did not detract from the magnet. You wanted the magnet to go through the pole pieces and the pole screw to the strings. That’s the path you wanted the magnetism to follow. That’s why on most of those you’ll find brass screws in the bottom. I didn’t want to detract any from the magnet into those brass screws.
SWD: Some pickup manufacturers use steel screw to secure the bobbins to the bottom plate.
Seth Lover: If they are willing to accept that loss, well fine. When I designed it, I wanted brass in there. I didn’t want to take away any of the magnetic strength in a useless point.
Seth Lover: On the humbucker the adjustable pole piece extends out the bottom. If you had a magnet that was quite weak you could absorb some of the energy, depends on how far through that screw was, because it’s going to absorb some of the energy there. But as a rule, with a good magnet there wasn’t too much.
SWD: How did the mounting ring come about? In the drawing in your patent...
Seth Lover: I used the old ES-125 (dog-ear cover) as a start because we didn’t have any mounting ring for this. So this was not acceptable as a mounting ring I felt. Because you notice this there was a slight slope to it--slightly different here and here (neck angle). I designed two different mounting rings. One near the bridge and one near the fingerboard. One near the fingerboard is quite shallow at the front edge; and, I tried to set that so the thing would have the slope of the strings when you were fretted at the last fret. And then the one that was back near the bridge, it had to be held up a little higher so I wanted to bring the pickups up close to the string. Because the closer you can keep the pickup to the string the more output you are going to have. It doesn’t do any good to bring--to put the pickup down and bring the screws up to compensate because you’ve lost--you’ve got to get the pickup as close as you can to the strings.
SWD: Because you're losing your magnetic field?
Seth Lover: That’s right, the magnetic field comes up to the stings there and magnetizes the strings. That’s one of the things that most people don’t understand. They figure that string is waving there and cutting the magnetic lines of force. Nuts. That isn’t it. The magnet, all it does is magnetize the string. Now you’ve got a waving magnetic field. And we have a fixed coil with a waving magnetic field to induce voltage. If you want to, take the magnet out. One you’ve magnetized your strings, it will play until the string loses it. Players think the string, the magnetic field from the magnet comes up to the string and by twisting the magnetic flux back and forth that’s what induces the voltage. That’s not what happens. There’s a certain amount of that, but that’s minor. What is happening is you have a magnetic field that is moving back and forth across the coil. And when you move a magnetic field back and forth across the coil you induce voltage. If you move the field up and down it wouldn’t induce any voltage. It’s the motion back and forth across the pickup that does it.
SWD: How did you come about using alnico magnets?
Seth Lover: If I’m not mistaken I think the Oscar Moore pickup had tungsten carbide magnets or some such name as that. In other words what ever as the best magnet available-pre WW II (World War II) Well after WW II alnico magnets became quite popular. They started using it for the magnets in speakers and things like that. And finally electrodynamics died out and we had the alnico magnets. And of course everybody was selling speakers, selling alnico magnets and we found that we could get alnico magnets fairly reasonable, small in size for the amount of strength and the only thing that you run into with alnico’s was they were cast which means if you wanted to keep a dimension you had to pay the price for grinding the edges. And if you wanted an assembly to fit exactly between those pole pieces, you had to make sure that your dimensions didn’t vary too much. As cast, they ask as much as plus or minus .030” thousands. That means as much as 16th of an inch variation. We didn’t care about the thickness varying that much because one would be a little bit stronger and another a little weaker. You could live that. But the distance across the width had to have ground surfaces. They were ground to dimensions. We tried to hold within plus or minus .005” which is pretty tight.
SWD: What is the material and purpose of the bottom plate?
Seth Lover: The bottom plate is a non-magnetic material so that you did not detract from the magnet. You wanted the magnet to go through the pole pieces and the pole screw to the strings. That’s the path you wanted the magnetism to follow. That’s why on most of those you’ll find brass screws in the bottom. I didn’t want to detract any from the magnet into those brass screws.
SWD: Some pickup manufacturers use steel screw to secure the bobbins to the bottom plate.
Seth Lover: If they are willing to accept that loss, well fine. When I designed it, I wanted brass in there. I didn’t want to take away any of the magnetic strength in a useless point.
