So do you have anything in the bobbins to channel the flux lines through the coils? Or are they air-core?
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Magnets & Copper Wire: A Pickup Building Thread
- Thread starter Freekmagnet
- Start date
They’re air core. I had slugs in there before. The only real difference I could hear was that there was a lot less noise when I removed them. And by “noise”, I mean that when I shifted my seating position, I could hear it loud and clear. I liked the pickup better without the slugs.
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Works in progress:
I think you should put all three of them in one bass, no knobs, all three wired straight to the output jack.
Haha that would be awesome! With all that steel, the bass would probably weigh 15lbs!
I’ve had this design floating around for a while...
I just haven’t had time to make it happen.
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Thanks! Always nice to rule something out rather than adding another thing to the extremely long list of stuff that I want to try.
I will tell you one thing that this pickup and preamp does do - and keep in mind, I'm not trying to sell it on you - you asked a really good question and I'm just thinking out loud. We played the "big" outdoor gig of the year last night and I'm responding in part to the avalanche of videos posted on social media this morning.
The low end of the pickup/preamp and bass definitely sits comfortably beneath the band, yet it is clear and doesn't lose definition. There are plenty of highs coming out of the instrument - enough so that you could call it "bright". In a sense, I will consider this a success because that's what I set out to do when I voiced the instrument.
I generally boost a considerable amount of lows and some of the highs and upper mids right out of the bass. The mids are definitely there, but they're really flat - flat as in neutral. I could crank them up, but the three-band controls such a wide swath of frequencies - in a technical sense, a 4-band or swept midrange might be better. I just don't want that many knobs to fiddle with.
I got a little sidetracked with a few other projects over the last couple of weeks. I managed to assemble on of the new pickups using some of the newly designed parts.
It looks a little more like something that will work. Despite its looks, assembly was not a complete success. The parts worked and putting the pieces together was definitely easier. I first had to add a 1/32” strip of aluminum to the cast polyurethane base to keep it from flexing. More shielding, I guess. Plus, my original plan was to solder the wire terminals to a circuit board. However, I miscalculated the width of the bobbin and the opposing terminals were basically touching. Just to get this prototype working, I insulated the wires with electrical tape. That worked, but there was still no way to solder them to a circuit board. On the next iteration, I’ll have to stagger the terminals somehow.
The next big fail came when I realized that I’d wired one of the coils backwards. Since they were glued together there was no easy way for me to determine which one was bad. I figure since I have to redo these anyway, I’ll just chalk this set off as a loss.
Just to see if some of the other changes worked, I replaced the new coils with my previous set. The pickup sounded good, and in fact I think it sounded a little better. I think having that solid aluminum baseplate directly in contact with the wood may have been contributing to the overall noise from handling the instrument. The polyurethane may be dampening it a little bit.
I also realized that the strength of the magnets were pulling on the low E string when I played further up the neck. I’m probably going to have to use smaller magnets. This may be a good thing, but I’m a little worried because I really liked the amount of nicely rounded lows I was getting out of the pickup. I’ll order some smaller ones and see what happens. In the meantime, I should think about designing a shell for the finished pickup.
It looks a little more like something that will work. Despite its looks, assembly was not a complete success. The parts worked and putting the pieces together was definitely easier. I first had to add a 1/32” strip of aluminum to the cast polyurethane base to keep it from flexing. More shielding, I guess. Plus, my original plan was to solder the wire terminals to a circuit board. However, I miscalculated the width of the bobbin and the opposing terminals were basically touching. Just to get this prototype working, I insulated the wires with electrical tape. That worked, but there was still no way to solder them to a circuit board. On the next iteration, I’ll have to stagger the terminals somehow.
The next big fail came when I realized that I’d wired one of the coils backwards. Since they were glued together there was no easy way for me to determine which one was bad. I figure since I have to redo these anyway, I’ll just chalk this set off as a loss.
Just to see if some of the other changes worked, I replaced the new coils with my previous set. The pickup sounded good, and in fact I think it sounded a little better. I think having that solid aluminum baseplate directly in contact with the wood may have been contributing to the overall noise from handling the instrument. The polyurethane may be dampening it a little bit.
I also realized that the strength of the magnets were pulling on the low E string when I played further up the neck. I’m probably going to have to use smaller magnets. This may be a good thing, but I’m a little worried because I really liked the amount of nicely rounded lows I was getting out of the pickup. I’ll order some smaller ones and see what happens. In the meantime, I should think about designing a shell for the finished pickup.
I got a little sidetracked with a few other projects over the last couple of weeks. I managed to assemble on of the new pickups using some of the newly designed parts.
It looks a little more like something that will work. Despite its looks, assembly was not a complete success. The parts worked and putting the pieces together was definitely easier. I first had to add a 1/32” strip of aluminum to the cast polyurethane base to keep it from flexing. More shielding, I guess. Plus, my original plan was to solder the wire terminals to a circuit board. However, I miscalculated the width of the bobbin and the opposing terminals were basically touching. Just to get this prototype working, I insulated the wires with electrical tape. That worked, but there was still no way to solder them to a circuit board. On the next iteration, I’ll have to stagger the terminals somehow.
The next big fail came when I realized that I’d wired one of the coils backwards. Since they were glued together there was no easy way for me to determine which one was bad. I figure since I have to redo these anyway, I’ll just chalk this set off as a loss.
Just to see if some of the other changes worked, I replaced the new coils with my previous set. The pickup sounded good, and in fact I think it sounded a little better. I think having that solid aluminum baseplate directly in contact with the wood may have been contributing to the overall noise from handling the instrument. The polyurethane may be dampening it a little bit.
I also realized that the strength of the magnets were pulling on the low E string when I played further up the neck. I’m probably going to have to use smaller magnets. This may be a good thing, but I’m a little worried because I really liked the amount of nicely rounded lows I was getting out of the pickup. I’ll order some smaller ones and see what happens. In the meantime, I should think about designing a shell for the finished pickup.
Looking good, getting closer to a working prototype design!
When you say that the magnets are pulling on the E string, what are you seeing actually happening? Do you mean that you are hearing that warbling, chorusing?
The common wisdom is that the warbling is caused by the magnet pulling on the string. I disagree with that. The magnet isn't changing the movement of the string. What's happening is that the string has moved down into a distorted section of the magnetic field. As the string swings back and forth, it's going through parts of the field that are going opposite directions. This creates secondary out-of-phase signals, behind the main signal.
The problem isn't that the magnet is too strong; you just have the string too close to the pole piece. Play around with the height of the pickup and find out how far the E string needs to be above the pole piece for the warbling to stop. That will give you some good information about the size and shape of the magnetic field around the pole piece.
My advise is: Don't change the magnets. If you need to even out the sound of the strings, do it by trimming or raising the height of the steel pole pieces.
Fine tuning the height of the steel poles is a good suggestion - I’ll work on that. However, allow me to point something out - when I lower the pickup, I lose whatever it is I’m losing tone-wise really quickly. In addition, with the E string, as I play up the neck, I get warbling, and as I go further I get less and less sustain until the string literally sticks to the magnet.
So I dunno, you don’t think trying a slightly smaller magnet would be a worthwhile experiment?
Well it's the same geometry problem: As you play higher on the neck, any string is closer to the pole and the more you'll drop into that zone. Also the unique magnet arrangement may be amplifying the effect by creating a really focused field.
Yeah, that's what I'm saying. This is a strange configuration pickup, and you're finding that the magnetic field is an odd shape that's really sensitive to the string height above the pole. To be effective, this pickup may need to be carefully fitted to the fingerboard radius, and the height adjustment may be very sensitive.
You may need to develop the shape of the pole pieces some more. Maybe make them T-shaped at the top?
You may need to develop the shape of the pole pieces some more. Maybe make them T-shaped at the top?
Another thing that comes to mind is that the fields on the E and G are going to be quite different in shape as viewed down the length of the string as compared to the A and D; much more assymetrical. Have you tried using additional pole pieces on the ends of the pickup?
Like a T-shaped cross section? Running the length of the pickup. A T-bar cut to height?
I was thinking about grinding a U-shape into the top - like a crescent-shaped bar so that there’s a little less magnetically charged surface directly beneath the pickup.
I’m thinking you may be right about fine tuning the pole height.
Yikes! More poles?! Haha I’m barely making with 4!
I thought about that, but the pickup doesn’t sound asymmetrical so I haven’t really gone down that road. If anything, the only thing I gotta fix is this E-string problem. It’s a bigger string, so it’s got more metal in there to get pulled into that field.
I meant a T head on the tops of the pole plates that you have. To widen out the field around the string, and make it less sensitive to string height.
