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-   -   Magneplanar SMGs repair/ rebuild (http://www.diyaudio.com/forums/planars-exotics/92986-magneplanar-smgs-repair-rebuild.html)

alexmoose 28th December 2006 05:11 AM

Magneplanar SMGs repair/ rebuild
 
Hello!

I am generally a Tube forum poster, but now I have run across a rather down and out pair of Maggie SMGs.

The two speakers physically work, they sound nice except for the lack of bass, I have two 12-inch subs which are passive that I can use to help the Maggies with bass. as well, one of the speakers rattles when the music gets a little loud.

The back of the speaker is covered in wire (I really know very little about how ESLs work, except for the basic theory). The wire is rusting away, and gone in some places, I figure that this should be/ needs to be replaced, but I have no clue where to start.

Does anybody know how to fix this rattle? is it a common problem with ESLs?

please give me some help! I don't know where to start on Restoring these Maggies. I got an amazing deal on these, so I am willing to pour money into them in repairs!

I was thinking of building one of SY's Red Light District EL84 pp amplifiers to drive these Speakers, will it produce enough power to get a decent volume level out of the Maggies? I don't know what the power out on a RLD is


-Moose

amt 28th December 2006 05:29 AM

Well Maggies are actually magnetic planars and not ESLs since they are passive and use magnets rather than electrostatic means to drive them.

The SMGs are an very musical little speaker and are fairly easy to repair, although it is time consuming. You may want to check out the Planar forum at AA. Lots of repair info there.

http://www.audioasylum.com/forums/MUG/bbs.html

In a nutshell, the aluminum wire that is glued to the back of the mylar diapham will need regluing or replacing. Its tedious but not too difficult. Its just a mess and time consuming. Usually, the bass wiring comes loose but doesnt get breaks in it. The tweeter wire though just disinigrates and must be replaced. Magnepan sells a tweeter repair kit with is about $40 I believe.

amt

alexmoose 28th December 2006 07:53 AM

hey amt,

Does this aluminum wire cause the rattle? so this just keep the magnets in place?

on the SMG do I only need one kit? to rewire, or do I need a bass kit too?

-Moose

amt 28th December 2006 03:45 PM

This article will give you most of your answers. You will first need to remove all the staples and the socks (grills) to actually see what type of repairs are needed.

http://www.integracoustics.com/MUG/M...nn/repair.html

If you check the "Tweaks" and "Articles" areas of the Planar Forum, you will learn a great deal in a short time.

amt

alexmoose 29th December 2006 12:11 AM

Thanks a bunch, I am learning soo much, but there are a few things
I can't seem to figure out

1. everyone says that you can get repair kits from Magnepan.com, but I cannot find anything on their website that denotes that! could someone please send me a link? or direct me to another website. I feel kinda stupid asking this, but I can't find anything.

2. also, what does this Aluminum wire actually do? does is it really the voice coil for the speaker? because on one of the Maggies, the wire is corroded far beyond the point of electrical connection.

Thanks a lot

-Moose

mightydub 29th December 2006 03:59 PM

The aluminum wires are essentially the voice coil - they are glued to the mylar diaphragm and carry the current from the amp. Magneplanars are pretty easy to repair if the wires have fried or come loose. My experience from repairing the tweeter section in my MG-IIbs many years ago:

Disassemble the speaker. In my case this meant removing the screws that held the wood frame on the perimeter of the panel, then removing the staples at the bottom that held the fabric sock that covers the panel. Carefully remove the fabric sock.

You can then check the aluminum wires that form the high and low frequency drivers - they are (or should be) glued to the speaker diaphragm. In my case the tweeter wires had an open.

Magneplanar sent me a repair kit that included a solvent to strip the old coating, contact cement, a new coating, new wire, and solder for the aluminum wire. After stripping the old wire and coating, you paint some stripes of contact cement perpendicular to the wire path. Then stretch the new wire along the channels between the magnets. The stripes of contact cement hold the new wire in place. When done placing the wire, paint over it with the new coating to secure it to the diaphragm. Let the coating dry, solder the ends of the wire into the crossover section, re-assemble, and you're done.

I had to call Magneplanar for the kit (this was in the days before the web), they were very helpful, the kit was reasonably priced and included enough materials to do both tweeters though I only needed to do one.

Tools needed: srewdrivers, pliers (to remove the staples), soldering iron, disposable paint brushes, rags, staple gun.

All told it was pretty easy and straightforward. I still regret selling those maggies.

alexmoose 30th December 2006 04:16 PM

Thanks alot Mightydub!

Thats pretty much what I thought the tweater wire did, although I do find it a little odd that they use Aluminum, as it is a pretty bad conductor.

My Maggies have no socks on them, the previous owner thought they looked better that way.

The low/mid drivers seem to be stuck pretty well to the Mylar with one exception, there is 10-15 years of gunk on the back of them (3 of those years were spent in a basement). In addition there is some brown goo (i don't know if it is old glue or what) toward the top and bottom of the bass/mid driver on both speakers. Is there a way I can clean this goo off without damaging the glue that is holding the wires on there to begin with? Or should I completly strip off all of the wires, clean the mylar, and re-glue everything?

As far as the tweater goes, one of the definatly needs to be replaced, the tweater is missing 1/3 of the wire, which causes a the tweeter to not work, and a rattle when bass is played. I am going to replace each speaker's tweater (time permiting) just for good measure. However I am not exactly sure how to do this, I have read many websites, and I understand the proceedure behind gluing, and un-gluing the wires, but I am yet to find a clear explaination of how to reshape the new wire into the shape that the tweater is supposed to be. If anybody has any idea how to do that, I would be eternally greatful.

Thanks so much mightytdub, and amt

SY 30th December 2006 04:27 PM

If you get these guys going, the RLD will work very well with them in a moderate-size room.

mightydub 30th December 2006 09:35 PM

Hard to say not having seen your speakers, but I think the "gunk" is the coating that bonds the wire to the diaphragm, if I recall correctly from my own experience. The most that it might need is a gentle cleaning with a vacuum cleaner and soft brush if the wire is still well attached.

Getting the new wire in the right place is pretty easy. If you shine a flashlight through the panels, you'll see that there are strip magnets running top to bottom, and the wire on the diaphragm is in the middle of the gap between the magnets. A crude representation of a cross section of the panel:

-------*--------*--------*-------- diaphragm with wires (*) bonded to it
[[[]]]]___[[[[]]]___[[[[]]]___[[[[]]]] strip magnets on perforated panel


Assuming the old stuff is cleaned off - lay the panel down flat in a place with good lighting. Paint 5 or so stripes of the contact cement perpendicular to the path of the wire across the entire width of the tweeter section - one at the bottom of the panel, one at the top, and a few equally spaced in between Starting from the bottom, where the wire connects to the crossover, just stick the wire down into the first stripe of contact cement so that it is centered between the strip magnets, then stretch it up towards the top of the panel. Look down along the length to make sure you keep it centered in the gap between the strip magnets, then still pulling it tight, lower it down into the stripes of cement. The cement is tacky so it will hold the wire, but you can pull it back up if necessary to correct any mistakes. When you get to the end of the panel, just make a U-turn and go back the other way. If you're a perfectionist you can use the end of a pencil or something to make a nice round turn. Just go slowly and take care to make sure you get the wire placed in the centers of the gaps between the magnets - it isn't hard at all, just requires some care. 6 passes or so up and back down the panel and you're done.

The repair kit came with pretty good instructions and much better pictures than I have made.

Good luck!

alexmoose 31st December 2006 04:03 AM

Quote:

Originally posted by SY
If you get these guys going, the RLD will work very well with them in a moderate-size room.
Sounds like a plan!, have you measured the power output on the RLD? being el84 Push-Pull pentode, it should be close to 15-20 watts.


Quote:

Originally posted by mightydub

Assuming the old stuff is cleaned off - lay the panel down flat in a place with good lighting. Paint 5 or so stripes of the contact cement perpendicular to the path of the wire across the entire width of the tweeter section - one at the bottom of the panel, one at the top, and a few equally spaced in between Starting from the bottom, where the wire connects to the crossover, just stick the wire down into the first stripe of contact cement so that it is centered between the strip magnets, then stretch it up towards the top of the panel. Look down along the length to make sure you keep it centered in the gap between the strip magnets, then still pulling it tight, lower it down into the stripes of cement. The cement is tacky so it will hold the wire, but you can pull it back up if necessary to correct any mistakes. When you get to the end of the panel, just make a U-turn and go back the other way. If you're a perfectionist you can use the end of a pencil or something to make a nice round turn. Just go slowly and take care to make sure you get the wire placed in the centers of the gaps between the magnets - it isn't hard at all, just requires some care. 6 passes or so up and back down the panel and you're done.

The repair kit came with pretty good instructions and much better pictures than I have made.

Good luck!

Many have used the 3M super 77 spray glue, have you ever used this product? or have you never had a problem with the contact cement?

-Moose


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