Taking apart woofer motors without damage

[cotdt]

What the title says, I want to take apart and examine some of my woofer motor structures but don't want to destroy them. They seemed to all be superglued. I want to be able to put them back together and then back into my speakers they go!

My secret motive is to modify my woofers with some of my ideas that model well in simulation programs. Such as replacing the voice coil and center pole piece with a design that lowers inductance and distortion, using thicker faraday rings, and improving the venting. I've seen examples of motor arrangements that are very DIY-friendly using off-the-shelf neodium magnets, that I have modeled and want to try out. I want to make a low-distortion midrange that is pistonic to 2kHz, but that is my secret motive, my main motive is simply to learn from the best current speaker driver designs. Got several dozen drivers that need examining, not as many drivers as Jon but enough to get me started.

I've tryed boiling my speakers in water but that didn't work. The glue doesn't want to come off! Maybe I should try freezing them at -90 Celsius. Does anyone have any ideas?

[RobP]

What color is the glue that is used and how old is the speaker?

[cotdt]

What color is the glue that is used and how old is the speaker?

To be honest I can't see the glue. I've taken apart some old vintage drivers and they were quite primitive compared to what we have today, and they seem to have been glued so I assume it's the same for modern drivers. I'm interested in taking apart Seas Excel woofers, Peerless Exclusive 7" woofers, Dayton RS180, Vifa XG18, Hi-Vi woofers, some XBL2 woofers, RSS315HF subwoofer, etc. I've got a lot of other woofers as well, and also want to examine some woofers that friends have. So I will be taking detailed pictures and taking notes of perhaps a hundred different woofers, as well as modeling them to find their strengths and weaknesses.

[ThomasW]

Modern loudspeakers are not designed to be disassembled. Doing so or attempting to do so will destory them.

You'd be better off soliciting dead drivers from others and playing with them, or spending some time at a reconing service

[RobP]

Cotdt, I have taken a couple of older speakers apart before, it takes alot of adhesive neutralizer, and can be done on the spider and surround if the matierial is porus and can allow the neutralizer to penetrate, but if the surface is not porus then it is almost impossible to remove without damage. What would be a better bet for you to do is just to order the recone kit for each woofer that you have and go that route, in the long run, it may be cheaper.

[cotdt]

Recone kits sound like a great idea, do all driver manufacterers offer these? I've already examined vintage drivers and they are very plain, have very small motors, and use none of the newer features. Still interesting, but I would like to move onto the newer stuff.

[RobP]

I cant speak for all loudspeaker companies, but most do. The trick is getting them to sell you one. Most times you have to be a authorized re-coning station approved by them to purchase.

[Dennis H]

have very small motors

Careful comparing old motors. Back in the day most of them used alnico magnets before cobalt became an endangered species. Alnico magnets are more powerful than the recent neodymium and much more powerful than the more common ferrite magnets.

[cotdt]

really? i thought the neodymium were more powerful...

[jdybnis]

Take a look at this thread. I followed capslock's instructions and was able to disassemble an RS180S completely. Nothing is damaged except I messed up the cone when I detached it from the former.

http://www.diymobileaudio.com/forum/showthread.php?t=675

My RS180S disassembled

http://www.htguide.com/forum/showthread.php4?t=19203

[cotdt]

Thanks Josh, yeah I've seen those threads but reading them again gives me new ideas to try. I hope it works for all drivers. Since most drivers seem to use epoxy, then freezing might be an alternative to capslock's method, since freezing epoxy makes them extremely brittle and applying some shock would crack the epoxy glue without damaging anything else.

[jdybnis]

What's wrong with the stove method?

[cotdt]

I'm afraid that the heat would demagnetize the magnets...

[TacoD]

I'm afraid that the heat would demagnetize the magnets...

You've a point there! Though, demagnetization of ferrite is at a higher temparature than neodym.

[RobP]

Most manufacterers use a glue called Ethyl Cyanoacrylate Ester, they do make a chemical that dissolves it, call this number 219-426-8742, its a place called WVS they supply recone glues, cone kits etc. They will have it. it will save you from freezing those speakers.

[AJINFLA]

call this number 219-426-8742, its a place called WVS they supply recone glues, cone kits etc

Do they carry diamond cones? Perhaps cotdt could do some one stop shopping there.

cheers,

AJ

[cotdt]

Thank you very much soundgravy! that is exactly what i wanted to hear...

AJ... you just wait and see!

[capslock]

Well, keep us up to date about the solvent. I tried all kind of aromates and ketones, but they did not work because they could not travel far enough into the gap between magnet and back plate.

The stove and vise method works extremely well for all kinds of drivers (but the glue in older drivers tends to be smelly). It is also possible to remove the back plate without damaging the former. The demagnetization temperature for ferrite is 450°C, and you'd really have to let it sit on the stove for very long to reach that kind of a temperature.

However, if the magnet was charged after assembly of the motor (which is the normal way to do things), you may loose 10 - 20% of the magnetization once the return circuit is removed. Some say this effect exists, others (such as Dan Wiggins) say it is not relevant. I have not seen empirical data on this, and the 2 - 3 drivers I reassembled had Bxl data in line with manufacturers specs. However, next time I do this, I will measure before and after.

Putting a motor back together when the magnet is charged and the former in place is a challenging task. I have tried this on drivers with a glass fiber/Kapton former but I am sure fatalities would be quite high with an aluminum former. Either remove the cone / former first (can be done easily with Seas drivers be letting them soak in warm water and soap for a few hours - glue will absorbe water but not dissolve) and recenter with paper slips once motor is reassembled. Or remove magnet and top plate, reassemble motor seperately and then just glue/rivet to basket, testing the centering with test tones first.

Building a demagnetizer / magnetizer would not be a bad idea, though...

[cotdt]

I got some of the solvent but like capslock, the solvent didn't penetrate deep enough to dissolve the glue. I will try freezing the motors next, and also try the capslock method of course.