Hah! That begs the question: If a robot plays Freebird on a molded plastic Strat in a smokey bar, would anybody even notice?
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Magnets & Copper Wire: A Pickup Building Thread
- Thread starter Freekmagnet
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Hah! That begs the question: If a robot plays Freebird on a molded plastic Strat in a smokey bar, would anybody even notice?
^^ Brilliant Freek. I hadn't seen that before but I'll have a go at building at least a single string version after the move.
I have the neck and most other parts for the test mule.
I have the neck and most other parts for the test mule.
Yeah, I've thought seriously about building such a device, a mechanical drop arm that could make a really consistent pluck on a string. For some serious testing of pickups and vibration of wood frames. Science. But we'd have to wear white lab coats and hold clipboards when using it.
Though it it sacrilegious to even suggest such a thing could happen in any decent universe, probably not after the tenth drink. I'd still sing along.
I’m pretty locked up with organizing my sock drawer for right now, but I expect one of you guys to have this guitar-playing robot built up by next week.
Keep fighting the good fight with those socks!
I have a really oddball idea, I'm wondering if I'm the only one that's ever thought about this. What about making a truly active pickup, in the sense of using an electromagnet instead of a fixed magnet? I'm sure there are many reasons why this would not make sense, but it's intriguing to me from the perspective of getting a fine degree of control - and variability - over the magnet. For instance, you could have a humbucker where you switched one of the magnets off to "coil split" instead of grounding one of the coils.
I have a really oddball idea, I'm wondering if I'm the only one that's ever thought about this. What about making a truly active pickup, in the sense of using an electromagnet instead of a fixed magnet? I'm sure there are many reasons why this would not make sense, but it's intriguing to me from the perspective of getting a fine degree of control - and variability - over the magnet. For instance, you could have a humbucker where you switched one of the magnets off to "coil split" instead of grounding one of the coils.
No, I've been thinking about it since I first read this thread. The problem in practice is that you need to power it inside the bass. Not so much of an issue for me as the new builds/mods are going to have my current hog of a preamp that will require an external supply.
I see too advantages. First is that you can control the strength of the magnetic field to control the sonics, and secondly if you had a humbucker, you could turn off one coil at a time so you could have a SC without the magnet of the inactive coil not having any pull on the string. And 2a, same with if you were only using one pickup out of a pair.
Sounds like a great idea if you have a large current source available. Running some extra power supply wires to a bass isn't really a big deal. You should definitely try it!
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An interesting idea for the pickup lab, but what would the purpose be in a live gig bass? If you had an adjustable magnet on stage, what would you do with it? Turn the output level up and down? Turn coils on and off? Could you actually change the sound by adjusting the electromagnet?
Or, is the purpose to create magnetic field shapes that you can't get with permanent magnets? Is that possible?
I could see it being a useful tool on the pickup lab bench. Quickly adjust the magnetic field strength to see what size and power magnetic field works best with a particular design of coil. Then use that information to help design your permanent magnet/pole piece to go with that coil.
I agree in the practical sense; as I mentioned before you'd need a hefty power supply to power it. It came to me as an idea as I've built field coil (electromagnet instead of a fixed magnet) speakers in the past and may again once I finish some other projects.
For me, it would be about deactivating an unused coil in order to split a humbucker and get a legitimate narrow aperture single coil tone. I have coil designs where I know what they sound like as a legitimate single coil, but putting two next to each other and then grounding one of them (as happens when you coil split a humbucker) gives a different result, since the "single" coil still has two coils worth of magnetic field nearby. I'd imagine switching off a second magnet would solve that, although it would probably introduce other problems since an electromagnet needs a slug of steel in it. So now you have a hunk of steel impacting the magnetic field when it's switched off.
I'm not sure I'll ever actually try this, or at least not any time soon, but it's fun to hear what people think about it.
I'm not sure I'll ever actually try this, or at least not any time soon, but it's fun to hear what people think about it.
Okay, that's something that could be useful on stage. You could even throw a switch and reverse one of the electromagnets. Combine that with a coil switch, and you could switch between full single coil and full humbucker.
Picture this:
Two rectangular iron blades, each covering two strings. Around each blade, wrap a coil of wire to be an electromagnet. Then, over top of that, wrap the sensing coil on each blade. The two magnet coils are in series and the two sensing coils are in series, but wire in a 2P4Pole switch between them. Throwing the switch reverses the direction of the second magnet coil and the second sensing coil at the same time. One position is effectively a single coil; the other is a split humbucker.
One other cool feature would be to power the magnet coils from an off-board DC power supply. Use the Volume control to vary that DC voltage to the magnet coils, eliminating that pot from the signal circuit.
Two rectangular iron blades, each covering two strings. Around each blade, wrap a coil of wire to be an electromagnet. Then, over top of that, wrap the sensing coil on each blade. The two magnet coils are in series and the two sensing coils are in series, but wire in a 2P4Pole switch between them. Throwing the switch reverses the direction of the second magnet coil and the second sensing coil at the same time. One position is effectively a single coil; the other is a split humbucker.
One other cool feature would be to power the magnet coils from an off-board DC power supply. Use the Volume control to vary that DC voltage to the magnet coils, eliminating that pot from the signal circuit.
If you're going to do that, why not use something that rapidly cycles the current for a tremolo-like effect.
I feel like this may be one of those questions that's either very thought evoking, or really stupid. But: should we expect a difference? Does "humbucking" in and of itself change the tone of a pickup?
When comparing a typical single coil to a typical humbucker (say, a tele pickup to a PAF style humbucker, or a Jazz bass pickup to a typical two-coil soapbar humbucker), my impression was that the difference in tone was more from the difference in sensing width along the string and coil shape, rather than just the fact that it's a humbucker. With that in mind, my thought for this electromagnet pickup was a typical two coil side by side arrangement where each coil senses the whole string and you could turn off one coil completely (the coil and the magnet).
I have made lots of plain old single coil Jazz pickups, and several split coil pickups that are essentially the exact same construction, just with the flatwork cut in half so you can wind two coils instead of one. This strikes me as more or less equivalent to your idea. I've never directly A/B'd them but I guess my question is, SHOULD there be a difference?
But I'm also starting to wonder if this would all be worthwhile at all or if there are better ways to get there. Besides the sensing width in terms of the magnet, I'm really starting to become more of a firm believer that the size and shape of the coil is important. I've recently built a new ukulele pickup that's a straightforward two-coil blade humbucker. I've made other uke humbuckes, typically as miniature versions of a guitar PAF humbucker, and they sound like you'd expect them to - like a Les Paul or other Gibson. Meanwhile, this new pickup is pretty different. The two coils are very thin (wrapped on 1/16" steel blades) and very tall (a hair more than 5/8") as compared to a PAF. The pickup sounds totally different, despite having the same magnet and the same number of turns as the PAF style pickups. If you close your eyes, you'd swear it was a twangy single coil telecaster pickup. It just sounds like a narrow single coil pickup despite being a humbucker. I've also recently built a Jazz pickup that's as short and fat as I could fit in the shell. Same number of turns and same magnets as other J's I've built, but it has a pretty different tone. Next up I'm going to try the opposite on a P pickup - make a skinny tall coil, and see if I can get something different than the typical P - my goal is to imitate the brighter, more balanced tone of an underwound P, but without the potential loss of output level. If that works (and I'm confident it will), I want to put two skinny tall coils in each P shell, and then set them up so it can be "coil tapped" by turning two of the four off. I figure that'll give the most versatility possible in a P format.
