Neodymium Multi-Coil Sidewinder Project

[Freekmagnet]

Having been busy elsewhere, it has been a while since I have posted on this forum. I thought I would share this current project here, just in case anyone might find it fairly interesting.

I’m looking to design a 4-string bass pickup that has a lot of punch coming out of a fairly small package. And while this prototype looks pretty deep, it measures about 1” wide. Although it’s not the most sensible design, I think it’s pretty cool.



This is the third prototype of my neodymium-powered multi-coil sidewinder project. I’ve been making refinements as I go. This round, I used some new parts I made from cast polyurethane. However, this prototype was only partially functional; I miscalculated the thickness of the bobbin flanges and the wire contacts would short out against each other. It’s an easy adjustment to fix.

The next issue is that the force of the super-strong neodymium magnets pull on the low E string enough so that as I play further up the neck, it kills the sustain and causes a vibrato effect. I have a few ideas about how to mitigate this effect, so I’ll have to try them out on the next round.

Despite not being completely functional, I will consider this stage of my experiment a success. The first big problem to solve was to design a bobbin and wind a coil that is small enough to fit in small space, durable enough to survive the assembly and encapsulation process, while being easy enough to fabricate a whole bunch of them at once. In prior attempts, I was working with paper bobbins and I soldered pigtails to the pickup wire and wrapped them with cloth tape. Because the bobbins were so small and delicate, I was having a lot of failures. The new bobbin design is much easier to manage, and I had no coil failures. In that sense, this experiment totally worked.

Previous (and completely functional) iterations have sounded promising. With the pickup in the bridge position, I’m getting some nice, thick but simultaneously bright tones. I could almost say I could support a rhythm section with a passive pickup - but the key operating term here is almost. For now, I am running it through a little two-band onboard preamp to boost the lows a teeny bit.

At this stage, I’m trying not to get too anxious about finishing this pickup. It’s tough though - I have a really nice bass I built for this pickup just waiting to be completed and played.

[LtKojak]

Man, this design is a magnetic flow nightmare... and using those relatively big Neos certainly doesn't help either, as the "strat-itis" effect you're getting attests, although if you just use smaller, N38 Neos, it would certainly mitigate the "wolftone" effect, being the bad news that you'll end up losing a fair bit of fundamental bass tone.

Unless you can somehow magnetically shield one pole from the other, I just don't see how this design would be more benefitial, tone-wise speaking, comparing it with more conventional designs. And production-wise, is very labor-intense, hence resulting in being pretty high-costing at the end, even though the cost in parts is pretty low, for what I can see.

You get a ton of brownie points for trying something unconventional, though.

Good luck, and have fun!

Yours very truly,

[Freekmagnet]

Man, this design is a magnetic flow nightmare... and using those relatively big Neos certainly doesn't help either, as the "strat-itis" effect you're getting attests, although if you just use smaller, N38 Neos, it would certainly mitigate the "wolftone" effect, being the bad news that you'll end up losing a fair bit of fundamental bass tone.

Unless you can somehow magnetically shield one pole from the other, I just don't see how this design would be more benefitial, tone-wise speaking, comparing it with more conventional designs. And production-wise, is very labor-intense, hence resulting in being pretty high-costing at the end, even though the cost in parts is pretty low, for what I can see.

You get a ton of brownie points for trying something unconventional, though.

Good luck, and have fun!

Yours very truly,

Thanks for the reply.

Yeah, this is mostly just a fun experiment. Now that I have made a few, it’s not difficult to make, but it is time-consuming. Most of my time is taken up winding and wiring up those little coils.

And yeah, aside from that wolftone, it actually sounds pretty good. It’s kind of a weird unity of opposites. Thick but bright. Focused but really broad mids. However I don’t know that “advantageous” is really much of a consideration for me. At the end of the day, it sounds like a bass pickup.

I ordered some smaller magnets. I’ll try them out. If I have to sacrifice a just little bit of bass to mitigate that weird note, I guess it won’t be the end of the world. Although I do really like the thunderous low end I’m getting out of it right now. I may be able to get away with just lowering that one pole piece.

I’ve thought about maybe building little shields out of some really thin 430 stainless I have laying around. That will bring this pickup over the top in terms of the number small parts I’ll have to make.

[Freekmagnet]

Just a little follow-up. I build a fully functional version of this pickup and it sounds good. I managed to tame that wild E string by filing the pole piece down a little bit. Once I did that, I encapsulated the pickup in white polyurethane. I wasnÂ’t happy with the results, so...



I basically took a few scraps of nickel silver I had laying around and glued and then soldered a cover directly to the pickup with a soldering iron. Back in the day, I used to make structures like this every day at my day job. Back then, I used a propane torch or an oxy-acetylene torch, but this was the first time for me with a soldering iron. It didnÂ’t come out too bad! I donÂ’t know if IÂ’d do this again, but for this project it worked. Right now, IÂ’m just eager to get it into a bass and start testing it in the field.

[bbsailor]

Having been busy elsewhere, it has been a while since I have posted on this forum. I thought I would share this current project here, just in case anyone might find it fairly interesting.

I’m looking to design a 4-string bass pickup that has a lot of punch coming out of a fairly small package. And while this prototype looks pretty deep, it measures about 1” wide. Although it’s not the most sensible design, I think it’s pretty cool.



This is the third prototype of my neodymium-powered multi-coil sidewinder project. I’ve been making refinements as I go. This round, I used some new parts I made from cast polyurethane. However, this prototype was only partially functional; I miscalculated the thickness of the bobbin flanges and the wire contacts would short out against each other. It’s an easy adjustment to fix.

The next issue is that the force of the super-strong neodymium magnets pull on the low E string enough so that as I play further up the neck, it kills the sustain and causes a vibrato effect. I have a few ideas about how to mitigate this effect, so I’ll have to try them out on the next round.

Despite not being completely functional, I will consider this stage of my experiment a success. The first big problem to solve was to design a bobbin and wind a coil that is small enough to fit in small space, durable enough to survive the assembly and encapsulation process, while being easy enough to fabricate a whole bunch of them at once. In prior attempts, I was working with paper bobbins and I soldered pigtails to the pickup wire and wrapped them with cloth tape. Because the bobbins were so small and delicate, I was having a lot of failures. The new bobbin design is much easier to manage, and I had no coil failures. In that sense, this experiment totally worked.

Previous (and completely functional) iterations have sounded promising. With the pickup in the bridge position, I’m getting some nice, thick but simultaneously bright tones. I could almost say I could support a rhythm section with a passive pickup - but the key operating term here is almost. For now, I am running it through a little two-band onboard preamp to boost the lows a teeny bit.

At this stage, I’m trying not to get too anxious about finishing this pickup. It’s tough though - I have a really nice bass I built for this pickup just waiting to be completed and played.

Freekmagnet,

Tinkering is the best way to learn and also discover some unexpected things. After looking at your tinkering I had these thoughts about what else might be discovered.

1. Use two spaced magnets with the string in the center to minimize magnetic string decay loading. By varying the spacing differently with each string diameter you could find the optimal spacing between magnet pole spacing to minimally effect the strings natural decay. By measuring the decay time without the magnets and the time for the sound to decay to a specific level and the time to decay to the same level with varying spaced magnets per string diameter, you can find an optimization per string spacing and string size or diameter.

2. By using two pole pieces per string you will increase the second harmonic as the string gets near a pole on each side of a single vibration it generates a peak voltage increase and an increase in second harmonic. In this case your ear is the best measurement tool.

I hope this gets you tinkering some more.

Joseph J. Rogowski

[Freekmagnet]

Freekmagnet,

Tinkering is the best way to learn and also discover some unexpected things. After looking at your tinkering I had these thoughts about what else might be discovered.

1. Use two spaced magnets with the string in the center to minimize magnetic string decay loading. By varying the spacing differently with each string diameter you could find the optimal spacing between magnet pole spacing to minimally effect the strings natural decay. By measuring the decay time without the magnets and the time for the sound to decay to a specific level and the time to decay to the same level with varying spaced magnets per string diameter, you can find an optimization per string spacing and string size or diameter.

2. By using two pole pieces per string you will increase the second harmonic as the string gets near a pole on each side of a single vibration it generates a peak voltage increase and an increase in second harmonic. In this case your ear is the best measurement tool.

I hope this gets you tinkering some more.

Joseph J. Rogowski

That’s a really good suggestion. Thank you!
Another pickup-making friend of also suggested that developing the pole piece might be beneficial to this pickup. I’ll give a closer look; for now, I’m considering this current pickup a first-gen working prototype and I want to put it through the next phase of testing. That being said, I will be tinkering with it more in the not-so-distant future and give your idea a try. It makes perfect sense that it would help.

Haha - Hopefully my next project will involve designing a pickup that is easier to build!

[Freekmagnet]

OK, I made a little update on this pickup. I basically made semi-laminated blade poles using a 1/16” bar and some pieces of thin 430 stainless steel. In this way, I was able to create a channel shape beneath the strings. (Please excuse the ugly pickup photo - this is my test rig. I transfer the coil assembly from piece to piece.)



It seems to have mitigated enough of the sustain problem I was having - enough so that I can’t notice it. I could probably attribute any other inconsistencies to the 3-year old cheap flatwounds I have on the bass.

As an added bonus, it seems to have improved the sound of the pickup somewhat. In previous iterations, the highs would “compress” when I slapped or plucked the strings really hard. This little layered blade assembly seems to have opened up the highs and made them more natural sounding.

I like how this pickup sounds. It almost has enough bottom that I could support a whole band with the pickup wired passively and placed in the bridge position. If I cranked the low end on my amp, I could probably get away with it. But, since I have a weird surrounding the use of the tone controls on my amp, I will probably use this pickup with an onboard preamp of some sort to boost the lows a little and cut the highs to taste.

[Mike Sulzer]

Man, this design is a magnetic flow nightmare... and using those relatively big Neos certainly doesn't help either, as the "strat-itis" effect you're getting attests, although if you just use smaller, N38 Neos, it would certainly mitigate the "wolftone" effect, being the bad news that you'll end up losing a fair bit of fundamental bass tone.

Unless you can somehow magnetically shield one pole from the other, I just don't see how this design would be more benefitial, tone-wise speaking, comparing it with more conventional designs. And production-wise, is very labor-intense, hence resulting in being pretty high-costing at the end, even though the cost in parts is pretty low, for what I can see.

You get a ton of brownie points for trying something unconventional, though.

Good luck, and have fun!

Yours very truly,

I do not see a magnetic flow nightmare; I see a set of single string sidewinders. (Although it certainly could be a lot more efficient using high permeability cores with very small neos if you can solve the mechanical issues.)

You would not lose fundamental relative to harmonics by using weaker magnets.

I do not see why you need to shield one pole from another. If you put just one of these single string side winders under a single string, it probably would not pickup that much from a neighboring string. Putting in the other side winders would not change this much since there appears to be nothing into the design with significant permeability.

[Freekmagnet]

I do not see a magnetic flow nightmare; I see a set of single string sidewinders. (Although it certainly could be a lot more efficient using high permeability cores with very small neos if you can solve the mechanical issues.)

You would not lose fundamental relative to harmonics by using weaker magnets.

I do not see why you need to shield one pole from another. If you put just one of these single string side winders under a single string, it probably would not pickup that much from a neighboring string. Putting in the other side winders would not change this much since there appears to be nothing into the design with significant permeability.

Thanks for weighing in on this.

You are correct - the poles do not pick up much from the neighboring strings. You can hear some of the next string, but it sounds like it's a million miles away. I don't think that is an issue. I did try shielding them with a thin piece of stainless, but it didn't really change much.

However, I did do a version with smaller magnets. They were roughly 25% smaller and there was a BIG difference in the sound - I lost a lot of low end, so I didn't really pursue that effort much further.

[Mike Sulzer]

Thanks for weighing in on this.

You are correct - the poles do not pick up much from the neighboring strings. You can hear some of the next string, but it sounds like it's a million miles away. I don't think that is an issue. I did try shielding them with a thin piece of stainless, but it didn't really change much.

However, I did do a version with smaller magnets. They were roughly 25% smaller and there was a BIG difference in the sound - I lost a lot of low end, so I didn't really pursue that effort much further.

Why would a weaker magnet give less bass with respect to higher frequencies? I do not see that in the physics.

What is the magnetization direction of your magnets?

[HaroldBrooks]

Thanks for the reply.

Yeah, this is mostly just a fun experiment. Now that I have made a few, it’s not difficult to make, but it is time-consuming. Most of my time is taken up winding and wiring up those little coils.

And yeah, aside from that wolftone, it actually sounds pretty good. It’s kind of a weird unity of opposites. Thick but bright. Focused but really broad mids. However I don’t know that “advantageous” is really much of a consideration for me. At the end of the day, it sounds like a bass pickup.

I ordered some smaller magnets. I’ll try them out. If I have to sacrifice a just little bit of bass to mitigate that weird note, I guess it won’t be the end of the world. Although I do really like the thunderous low end I’m getting out of it right now. I may be able to get away with just lowering that one pole piece.

I’ve thought about maybe building little shields out of some really thin 430 stainless I have laying around. That will bring this pickup over the top in terms of the number small parts I’ll have to make.

I think what you are doing is very cool, and essential, to find out what might or might not work through controlled (or semi controlled) experimentation.

You formed a hypothesis about what you think may happen, and then you record the results. Even failures to get what you want teach yourself and everyone else something in the process. I was taught that years ago by a Stat professor who was quite accomplished in his field.

Audio and musical instrument signals in particular are judged primarily through qualitative assessments, and there is no better way that I know other than experimenting to see what sounds pleasing and what doesn't. The times I thought my amp tone and mods could be whittled down to sheer maths or just my current understanding, caused me to fail most every time, so I believe you have to get out there and experiment, even if your invention is based just on a hunch, IMHO. If it works, later you can figure out controls on how to replicate it, or make things better.

So far in my tenure as a guitarist and equipment hoarder, it seems some of the weakest pickups are more to my liking, in terms of tone and dynamics. But that's just my personal preference and opinion, and it might change in a nanosecond if someone were to show me something that I felt worked better. I'm waiting to change my mind, but some of the most powerful pickups used in shredder guitars leave me cold... So far that is.

So I say, Thanks for the work you are doing, and Carry on !

[Freekmagnet]

Why would a weaker magnet give less bass with respect to higher frequencies? I do not see that in the physics.

What is the magnetization direction of your magnets?

I dunno. My brain isn't big enough to give a satisfactory answer as to why the pickup sounded less bassy. I can only report my results. The smaller magnets just didn't sound as full as the pickup with the larger magnets, so I went back to the larger magnets. Same poles, same coils, same everything. The difference was pretty drastic.

I can tell you how the magnets are oriented - the structure goes like this:

n|n s|s n|n s|s

The north coils are wired in series and the south coils are wired in series and then the those two circuits are wired in series to make one big humbucker.

I think what you are doing is very cool, and essential, to find out what might or might not work through controlled (or semi controlled) experimentation.

You formed a hypothesis about what you think may happen, and then you record the results. Even failures to get what you want teach yourself and everyone else something in the process. I was taught that years ago by a Stat professor who was quite accomplished in his field.

Audio and musical instrument signals in particular are judged primarily through qualitative assessments, and there is no better way that I know other than experimenting to see what sounds pleasing and what doesn't. The times I thought my amp tone and mods could be whittled down to sheer maths or just my current understanding, caused me to fail most every time, so I believe you have to get out there and experiment, even if your invention is based just on a hunch, IMHO. If it works, later you can figure out controls on how to replicate it, or make things better.

So far in my tenure as a guitarist and equipment hoarder, it seems some of the weakest pickups are more to my liking, in terms of tone and dynamics. But that's just my personal preference and opinion, and it might change in a nanosecond if someone were to show me something that I felt worked better. I'm waiting to change my mind, but some of the most powerful pickups used in shredder guitars leave me cold... So far that is.

So I say, Thanks for the work you are doing, and Carry on !

Thanks, that means a lot!

It makes sense to me that you would like a weaker guitar pickup. At the end of the day, what makes a pickup sound good to you is entirely subjective. You can hypothesize as much as you want, but in the end, you gotta put it in a guitar, plug it in and play it.

I don't know as much about science and engineering as I'd like. I work in advertising and winding pickups is more fun for me than making web sites. I started designing pickups and building guitars about five years ago and I'm trying to digest as much as I can. If I knew a little more about the more scientific theory behind designing inductors, I'm sure it would make the process easier. I have some neighbors down the street from me who build guitars, so I get a lot of advice froim them.

Ultimately test my pickup designs playing with a live band. I play in a 7-piece band and we play funk, r&b, latin, reggae, oldies and some rock & roll, so every box has to be checked. We play every weekend, so it makes it easy for me to audition a pickup, make adjustments and come back with another test subject. Usually, if nobody (including me) notices that I'm actually conducting an experiment in addition to holding down the rhythm section, then I consider that pickup a success.