New EMIM magnets.

marknoir

Active Member
I tried to clean my old neodymium magnets, both from Gamma and Beta, and succeeded, but thay lost too much of their body mass and pull. Out of four EMIMs two are gone. Today received new neodymium magnets from China, bought on ebay, for peanuts. They fit right in, are only about .1 - .2 mm thicker and .2 - .3 mm wider. I put them on (not glued yet) to check the pull and it is very, very similar to my good undamaged half. I figured if my speakers played ok with magnets half-gone, they should play much better with these. I may put a thin paper spacer or two just even out the pull. I also plan to buy a whole bunch of these magnets for spares.
 

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Thx. I did. Marked them all up with red paint. Thinking now which glue to use...
If I were you I'd coat them when your done with a few coats of poly or epoxy for added protection so they have less chance of peeling but before you do it or even if you don't do it I would use rubbing alcohol to clean off any salt from the sweat from your fingers that might be on the magnets and cause them to erode prematurely
 
As for glue, on my HE-EMIM's it looks like they used a fast drying epoxy, I would think you would want to use something that gives you enough time to set one in place and be able to move it around if you have to but dries fast enough so that it don't move around when you try to install the next one
 
As for glue, on my HE-EMIM's it looks like they used a fast drying epoxy, I would think you would want to use something that gives you enough time to set one in place and be able to move it around if you have to but dries fast enough so that it don't move around when you try to install the next one
Yes, something like that. Or may be super-glue gel that gives a few seconds of movement? I will have to do some research. Thx.
 
If I were you I'd coat them when your done with a few coats of poly or epoxy for added protection so they have less chance of peeling but before you do it or even if you don't do it I would use rubbing alcohol to clean off any salt from the sweat from your fingers that might be on the magnets and cause them to erode prematurely

These look well plated. But may be I will coat them just in case. Question is, will poly stick to shiny plating? I don’t feel like sanding them all. I can treat them with a few seconds in acid to prepare the surface, but this may cause more bad than good... Will have to experiment a bit. Thx!
 
These look well plated. But may be I will coat them just in case. Question is, will poly stick to shiny plating? I don’t feel like sanding them all. I can treat them with a few seconds in acid to prepare the surface, but this may cause more bad than good... Will have to experiment a bit. Thx!
Every time I've used poly and it got on the lid of the can it's in it stuck really good, I wouldn't sand or use the acid on them, probably just clean them off with something to de grease them
 
Every time I've used poly and it got on the lid of the can it's in it stuck really good, I wouldn't sand or use the acid on them, probably just clean them off with something to de grease them

Got it. That’s what I’ll use then. I use lighter fluid for de-greasing.
 
Super Glue will crack if subjected to heat or vibration so I'd advise against using it. I use to use it for gluing gems to dop sticks and one method of getting the gem off the dop stick was to put a vibrating tuning fork next to it and then the glue would release. Heat and moisture also cause Super Glue to release. 60 second epoxy would probably be best. I really like Amazing Goop, but it takes a while to cure. I used denatured alcohol for cleaning. It leaves no residue.

Larry D.
 
Super Glue will crack if subjected to heat or vibration so I'd advise against using it. I use to use it for gluing gems to dop sticks and one method of getting the gem off the dop stick was to put a vibrating tuning fork next to it and then the glue would release. Heat and moisture also cause Super Glue to release. 60 second epoxy would probably be best. I really like Amazing Goop, but it takes a while to cure. I used denatured alcohol for cleaning. It leaves no residue.

Larry D.

Thank you. I love Goop ))). But it does take a while to cure. Since these magnets are very strong, they may drift while it cures. Also requires a rather thick film. I may try a white speaker glue. It does not dry hard. But 60 second epoxy is probably best.
 
Alpha cyanoacrylate ("Superglue") adhesives have poor shear strength, so keep that in mind as a plus or minus.
 
I used some magnets from China on some RS series Emins. Worked great, used epoxy and wood spacers to keep them from clicking together. They were far stronger than the originals. Did not notice any difference in sound though.
 
I used some magnets from China on some RS series Emins. Worked great, used epoxy and wood spacers to keep them from clicking together. They were far stronger than the originals. Did not notice any difference in sound though.

Thx
I saw your post ))). The RS magnets were samarium cobalt I beleive? So these new ones would be stronger. But I didn’t find them much stronger than the later neidymium. I wonder if a strong adhesive such as epoxy is nesessary? I think that originals were put together with “assembly cement”. I winder if regular super-cement would suffice?
 
May be... I have to make some wooden spacers. Also, I wonder if the plates can be painted or magnets have to go directly to metal...
 
Sooo... By pure
I used some magnets from China on some RS series Emins. Worked great, used epoxy and wood spacers to keep them from clicking together. They were far stronger than the originals. Did not notice any difference in sound though.
Hi. I did some measurements on different magnets' pull strength. Not exact, but sufficient for my purposes. I wasn't interested in absolute numbers, but only percentages. So, if we take old Infinity neodymium magnets as 100%, the figures are: new Chinese 80% strength, old samarium-cobalt Infinity magnets (as in your RS series) - 65%. So the new Chinese magnets are only about 15% stronger than your old ones, which explains why you didn't hear any difference. Which brings us to another point : their advertised on Ebay strength of N35 is not true. May be N30. They also sell N50, same dimensions. I bought some, and they seem to be a bit stronger than N35 from the same seller, but I already used the N35. They should be closer to Infinity neodymiums. Next time :)))
 

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