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-   -   Alpair 7 with loose magnet... (http://www.diyaudio.com/forums/markaudio/188519-alpair-7-loose-magnet.html)

pauldune 6th May 2011 02:33 PM

Alpair 7 with loose magnet...
 
1 Attachment(s)
Today I received my new ordered alpair 7's from Europe Audio.

When I opened the box I saw that one of the speakers had a loose 2nd magnet.

My question:
Can I glue the magnet back on myself, (what type of glue?) or do I have to return them?

greetings, Paul

Cal Weldon 6th May 2011 02:40 PM

Yes you can reglue it but it's a little tricky. I would use epoxy and a vice. Remember you have to have the magnet with opposing polarity so it's likely to be a two person job. If the magnet came off it probably took quite a jolt so you might want to make sure everything else is ok and that the original glue job was a weak link. Also look into surface prep before you attempt to glue.

pauldune 6th May 2011 02:50 PM

Hey Cal,
Its not opposing polarity; it snaps right into place if I put it back on. I'm sure thats how it's supposed to be, because the cap is still glued to the second magnet.
Also, I'm not so shure about placing a driver made out of plastic in a vice..

greetings, Paul

markaudio 6th May 2011 03:23 PM

Hi Paul,
My apologies for this problem. Cal is wrong, there's a quick simple fix.

1 - Use a wire brush to roughen both contact surfaces. You only need to brush for a minute or so. Wipe clean with a soft dry cloth.
2 - Apply a good quality epoxy glue to both surfaces and gently press together. The magnetic tension will do the rest (Don't use a vice as Cal suggests).

This method will make the fix and the driver will perform normally.

Thanks

Mark.

Cal Weldon 6th May 2011 03:35 PM

Sorry Mark, not trying to interfere here but I am confused. It's not a bucking magnet? If that's the case, I apologize, the vice is for bucking magnets and should be used with the driver mounted to a temporary baffle and of course protection on the rear. Hence the two persons.

markaudio 6th May 2011 03:45 PM

Quote:

Originally Posted by Cal Weldon (Post 2563660)
Sorry Mark, not trying to interfere here but I am confused. It's not a bucking magnet? If that's the case, I apologize, the vice is for bucking magnets and should be used with the driver mounted to a temporary baffle.

Hi Cal, no worries,

The Alps have attracting magnet systems so its an easy fix (no vice needed). I am contemplating using no glue on this section, giving the guys the choice of non-sheilding or partial shielding. The potential advantage of the non-shield is a slight increase in SPL as the drive-train electrical damping changes; And there's less mass behind the cone inside the box.

The new batch of Alpair 7's have retaining guide lugs built-in to the back of the frame mount so this method is easily possible. More on this when I announce the latest Alp7 in the next week or so.

I'm already running a prototype unit with this option. I'd need to do more testing on this to make sure other performance factors remain stable.

Cheers

Mark.

Scottmoose 6th May 2011 03:49 PM

Useful to know. Cheers Mark.

Cal Weldon 6th May 2011 07:26 PM

Yes, thanks Mark.

jimbro 6th May 2011 08:04 PM

You might to cover the cone with something while brushing and gluing to protect it from what I call "Jims".

pauldune 6th May 2011 08:17 PM

Mark, thanks for the method. I will fix it myself then, no need to send it back.
As to other damage: I can see none. Wonder why it came loose....

Greetings, Paul

Ps. Diyaudio is a amazing place! Where else can you get advice from the man who designed and created the speaker?


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