I have done it experimentally but it's way too slow/tedious for production .
With my kludged/home setup I mean.
I had a sliding collar turned, think "a piece of pipe", slightly oversize (a tenth of a mm larger) so it could slide along the mandrel and former.
Its edge provides a perpendicular "wall" or "shoulder" against which flat(tened) wire can rest on edge.
Otherwise it's impossible because it's an inherently unstable position.
Same as expecting an LP or food platter to stay on edge by its own.
Even worse, being pulled hard in all directions while being wound.
I started the first turn carefully by pushing wire with my thumbnail against that edge, then each new turn against the previous one.
Very slow, it can fall against one side at any moment, a mess.
A machine can be designed to do that automatically of course, here it was only an experiment.
Round wire has none of those problems, that's why a flat wire coil can cost 10-20X what a round wire one does.
In my book, not worth it 🤷🏻
Fine for large Companies who are centered on top of the top speakers, of course, such as JBL or EV or ALTEC.
And even so ...
With my kludged/home setup I mean.
I had a sliding collar turned, think "a piece of pipe", slightly oversize (a tenth of a mm larger) so it could slide along the mandrel and former.
Its edge provides a perpendicular "wall" or "shoulder" against which flat(tened) wire can rest on edge.
Otherwise it's impossible because it's an inherently unstable position.
Same as expecting an LP or food platter to stay on edge by its own.
Even worse, being pulled hard in all directions while being wound.
I started the first turn carefully by pushing wire with my thumbnail against that edge, then each new turn against the previous one.
Very slow, it can fall against one side at any moment, a mess.
A machine can be designed to do that automatically of course, here it was only an experiment.
Round wire has none of those problems, that's why a flat wire coil can cost 10-20X what a round wire one does.
In my book, not worth it 🤷🏻
Fine for large Companies who are centered on top of the top speakers, of course, such as JBL or EV or ALTEC.
And even so ...
DIY winding sounds like a great opportunity to wind a feedback coil for motional feedback on top of the normal voice coil.
Feedback coil would need many more turns (since it needs to generate an adequate S/N voltage to feed back to the amp) but can be very fine wire (since you aren't powering the driver).
If you ask any questions about this post, it is unlikely I'll have the technical moxie to answer any, but somebody else might.
Ben
Feedback coil would need many more turns (since it needs to generate an adequate S/N voltage to feed back to the amp) but can be very fine wire (since you aren't powering the driver).
If you ask any questions about this post, it is unlikely I'll have the technical moxie to answer any, but somebody else might.
Ben
I've done a few inside/outside wound coils on that very same winder from Amazon. You just need to practice with it.
For a typical 2 layer VC, the trick is to keep the tension very even and smooth, so the final coil diameter is uniform after the first layer. The second layer isn't as critical but you still need to be consistent. I use specific diameter Alu mandrels I have turned in a lathe to exact size, which are coated with Teflon spray before the VC former is laid down first. You need to leave a separating gap in the former to account for thermal expansion. If the gap isn't there, the former will butt up at higher VC temp and go out of round on you.
There is always some reduction in final diameter when the VC is removed from the mandrel. That exact amount of reduction is what you need to achieve every time so the VC fits perfectly in the gap. You have to allow for thermal expansion, especially with Alu formers. Kapton is more forgiving.
I use a high temp epoxy to adhere the windings and apply a light final surface coating. Its then baked at 100 deg C for a few min and let cool slowly. This keeps the whole assy from deforming out of round. It also allows the former to relax and stay round after removing the mandrel.
Also, use the highest temp enamel wire and epoxy you can get. This way the VC will handle a decent amount of temp abuse. They make heat conducting epoxy to further raise power handling. You can get fancy and de-gas the finished VC before baking it in a vacuum chamber. This is what I do with larger VCs and crossover inductors.
For a typical 2 layer VC, the trick is to keep the tension very even and smooth, so the final coil diameter is uniform after the first layer. The second layer isn't as critical but you still need to be consistent. I use specific diameter Alu mandrels I have turned in a lathe to exact size, which are coated with Teflon spray before the VC former is laid down first. You need to leave a separating gap in the former to account for thermal expansion. If the gap isn't there, the former will butt up at higher VC temp and go out of round on you.
There is always some reduction in final diameter when the VC is removed from the mandrel. That exact amount of reduction is what you need to achieve every time so the VC fits perfectly in the gap. You have to allow for thermal expansion, especially with Alu formers. Kapton is more forgiving.
I use a high temp epoxy to adhere the windings and apply a light final surface coating. Its then baked at 100 deg C for a few min and let cool slowly. This keeps the whole assy from deforming out of round. It also allows the former to relax and stay round after removing the mandrel.
Also, use the highest temp enamel wire and epoxy you can get. This way the VC will handle a decent amount of temp abuse. They make heat conducting epoxy to further raise power handling. You can get fancy and de-gas the finished VC before baking it in a vacuum chamber. This is what I do with larger VCs and crossover inductors.
Last edited:
I wind voice coils, and it will take a LOT of investment in time and patience to get good at it and be successful. It took me a solid year of research and development in materials to wind successful coils, with many failures along the way.
You can use a drill to wind some wire around a piece of paper or kapton and have it stay together sitting there on your workbench, but that does not mean it won't fly apart once installed in a speaker with power.
The cheapest cnc winder is about 600 usd, and the winding mandrels that the coils are wound on.. nobody makes those, you have to make them yourself. Not only that, you have to design them so that you can get the coil off of the mandrel without destroying it once it is wound. Luckily, I am a machinist so I just turned my own mandrels. But it took about 3 revisions to design mandrels that are efficient. Luciano makes his out of wood.
You will need to learn how to calculate the coil dimensions to fit your speaker and its impedance, a this site is a good source for that.
This guy sells former material and bonder, but he's in ukraine. lord of bass also sells bonder. Bae sells the magnet wire and nomex material for the collar.
The most important part is bonding the wire. The wire needs a bonder to hold it together, and it can either come pre-applied on the magnet wire as "bondable magnet wire", or you manually apply the bonder which is known as "wet winding". Either way, the bonders need to be heat cured, so you need a dedicated mandrel to put the coils on and then bake them in an oven to cure the bonder.
This is a good article about winding coils.
You can use a drill to wind some wire around a piece of paper or kapton and have it stay together sitting there on your workbench, but that does not mean it won't fly apart once installed in a speaker with power.
The cheapest cnc winder is about 600 usd, and the winding mandrels that the coils are wound on.. nobody makes those, you have to make them yourself. Not only that, you have to design them so that you can get the coil off of the mandrel without destroying it once it is wound. Luckily, I am a machinist so I just turned my own mandrels. But it took about 3 revisions to design mandrels that are efficient. Luciano makes his out of wood.
You will need to learn how to calculate the coil dimensions to fit your speaker and its impedance, a this site is a good source for that.
This guy sells former material and bonder, but he's in ukraine. lord of bass also sells bonder. Bae sells the magnet wire and nomex material for the collar.
The most important part is bonding the wire. The wire needs a bonder to hold it together, and it can either come pre-applied on the magnet wire as "bondable magnet wire", or you manually apply the bonder which is known as "wet winding". Either way, the bonders need to be heat cured, so you need a dedicated mandrel to put the coils on and then bake them in an oven to cure the bonder.
This is a good article about winding coils.
I've tried a little voice coil winding, but more for voice coil actuators (they're quite expensive, but used for movement with greater precision than my application, thus the desire to make them myself) rather than speakers, though speakers are on my bucket list.
I came across this page for voice coil binder, but it appears to be for heavy-duty high-temperature applications, and judging from the instructions and safety data sheet, I wouldn't want to try it unless the application absolutely needed it. Some form of "regular" epoxy should work for anything less than SPL-competition-worthy woofers. But if you insist on using it and have the proper oven etc., I see it for sale on ebay.
https://www.hernon.com/voice-coil-bonder-360-2
I came across this page for voice coil binder, but it appears to be for heavy-duty high-temperature applications, and judging from the instructions and safety data sheet, I wouldn't want to try it unless the application absolutely needed it. Some form of "regular" epoxy should work for anything less than SPL-competition-worthy woofers. But if you insist on using it and have the proper oven etc., I see it for sale on ebay.
https://www.hernon.com/voice-coil-bonder-360-2
The problem with epoxies is that they are usually not rated to a high enough temperature that a voice coil will see when it is pushed, even for small woofers and mids. They might be fine for paper former guitar speakers or 5-10 watt stuff, but anything bigger or more power will exceed any epoxy's rated temperature.
Even normal bonded magnet wire is usually still coated with phenolic nitrile like the hernon stuff, and is tacked just waiting for crosslinking.
Even normal bonded magnet wire is usually still coated with phenolic nitrile like the hernon stuff, and is tacked just waiting for crosslinking.
@hurrication If you go on the Loctite/Henkel website, they list a few decent high temp epoxies which are thermally conducting. Also try Epoxy Superstore. They have a huge selection of epoxies and resins for all sorts of specialized applications. You'll want a formula which conducts heat, especially with 4 layer VCs on alu formers.
It's important to note you must use an epoxy which sets up reasonably hard, but not to brittle. You want some dampening in the VC to keep radial breakup under control. It becomes a more pronounced issue when using shorting rings at the gap.
If someone has a source for flat profile copper (not alu or copper clad) wire, please post it. EV, Celestion, JBL and Audax use flat wire in some of their VCs, which helps boost sensitivity by raising BL.
I've done a lot of direct measurement temp monitoring on voice coil windings, and even small coils on low power can get up to 150+c. While I'm sure there are some epoxies that are rated for that temp, the phenolic nitrile bonders that are out there are hard to beat and there's really no reason you would need to go with an epoxy over the traditional VC bonder.
For flat copper wire, Bridgeport has been my go-to. If you call them, ask for Juan as he's the one who deals with wire sales.
https://bridgeportmagnetics.com/bmg-product/magnet-and-specialty-wire/
For flat copper wire, Bridgeport has been my go-to. If you call them, ask for Juan as he's the one who deals with wire sales.
https://bridgeportmagnetics.com/bmg-product/magnet-and-specialty-wire/
That’s Luciano’s Setup.
I wish it was mine. It’s very good.
He’s got a transformer with caps there aswell. I think he powers the coil to get it up to a certain temp. He’s got a thermal camera aswell.
Cheers
Slight off topic.
Does anyone know anyone in the U.K. who makes coils.? Good ones.
I’ve got all the measurements.
1260 on the coil aswell. 1.26”. Fairly small.
They’re for B&W 601 S3.
I wish I could make them ,but I only need 2 and it would be too much lay out and time to make them right.
I’ve contacted reconingspeakers.com. US. Waiting to hear back so far. Anyone used them before.? Can’t find one in the U.K. as of yet.
Cheers
Does anyone know anyone in the U.K. who makes coils.? Good ones.
I’ve got all the measurements.
1260 on the coil aswell. 1.26”. Fairly small.
They’re for B&W 601 S3.
I wish I could make them ,but I only need 2 and it would be too much lay out and time to make them right.
I’ve contacted reconingspeakers.com. US. Waiting to hear back so far. Anyone used them before.? Can’t find one in the U.K. as of yet.
Cheers
I’m noticing that there are not many around that make coils. When your looking. You can’t see any. Just eBay etc that’s all.
I can see why you would want to make your own.
Apart from the winder itself you need to have a setup that’s accurate and adjustable. Need a fair few bits whether bought or made to have that. Any proper metal worker or engineer could make that stuff easy.
I posted those from Luciano so people can maybe get their own ideas and see what might be needed.
Take your time with it all.
Cheers
I can see why you would want to make your own.
Apart from the winder itself you need to have a setup that’s accurate and adjustable. Need a fair few bits whether bought or made to have that. Any proper metal worker or engineer could make that stuff easy.
I posted those from Luciano so people can maybe get their own ideas and see what might be needed.
Take your time with it all.
Cheers
I looked around a couple of years ago when I was trying to salvage some Bandors with damaged coils. Couldn't find anyone at that time, unfortunately.