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FYI: How I fixed my Mal-X 21's

post #1 of 20
Thread Starter 
As you can see, the flux ring is no longer vibrating. (YAY)



Step 1:
VERY very very carefully remove the cone and spider with a small flathead screwdriver without damaging them; this takes about 2-3 hours... takes patience borderlining on insanity, no less.

Step 2:
Then use the wood handle of a painters fan brush (any non-magnetic substance really) to confirm the loosest side of the ring.

Step 3:
Grab your superglue and a toothpick.

Step 4:
Insert the toothpick into the top of the ring on an angle and drop drips of superglue into the crevasse via the toothpick.

Be VERY very very careful not to get any excess glue on the gap walls, you only have 0.25mm or so of motor clearance. (Or the toothpick stuck)

Step 5:
Reattach cone and spider with more glue, make sure it is centered to the n-th degree +-0.5mm

Your done.

These things are far too good at generating infrasound to just throw them away; not only that, but they are almost at expensive as LMS-18's!!!

Without the repair they make nasty super-annoying metallic noise, similar to that of bottoming or rub; but it's niether, it's actually Lenz's Law of EMF backforce vibrating the loose ring around, made worse by coil heat, over time.

I'm just happy with the thought of getting all 17 of my subwoofers back up and running again... this is gonna take years, ohhh......

Right now I'm only running 5 subwoofers, by summer I should have 9 going (maybe); I've changed my mind on box designs, multiple singular sealed scattered throughout the room is the way to go.
post #2 of 20
Glad to see someone actually trying to fix these bad batch subs!

I'm ignorant to the materials you used for the fix but just curious as to how well the glue will hold up once the sub is heated up really good? How high is the glue rated for and do you have any idea how hot the sub will get in a small/medium sealed enclosure? Which brings the next question.

How are you going to be using the sub/subs? Sealed, vented, etc...?

How many bad subs do you have?

Good luck with the fix as I truly love these subs and hate thinking about all that were wasted and ultimately led to the end of their production.
post #3 of 20
Thread Starter 
Were talkin micro-liters of glue here, barely enough to fit under your fingernail.
No idea what it's rated for, but it seems to be holding so far.

The rest of the glue is far enough away from heat source that it doesn't really matter.

I have 4 Dayton Pro's, 2 SDX-15's, 8 Mal-X's, 2 Mal-X 21's and 1 LMS-18

Dayton's are in a 15x19x19, SDX in a 20x20x21, LMS in 23x23x24.5

I haven't tried IB or Horn configs yet, maybe one day I will, but for now I think I'm going to keep it simple and go sealed for all of them.

The Mal's will all be 23x23x24.5 as well.

My system has 30 to 200hz well covered already, so I was thinking of making them mostly infrasonic generators at no higher than 35hz...
put all that surface area to use where it is needed most, and avoid being obnoxious to the health of my eardrums or drowning out the rest of the music with excessively bloated bass. Or at least, that's the idea we'll see...
post #4 of 20
Can you post a picture of where you accessed the area you worked on on the driver?
post #5 of 20
Hey thanks for posting this i got a vegas 21 i want to use IB which may need this work some day......
post #6 of 20
I've got two bad ones sitting on my garage shelf that I just couldn't bring myself to throw away. Sounds tedious but worth a shot. The more info and pictures you can provide the better. Thanks.
post #7 of 20
my hat's off to you for figuring out how to do this. If I were you though, for the rest of them I'd consider using some higher end type of adhesive. Maybe the CA will work fine but for all the trouble you are going through to get these apart and back together, seems like using some $20 glue instead of $1.99 glue might be worthwhile. That being said, I don't have enough knowledge of adhesives to recommend a specific alternative.
post #8 of 20
NICE!!!

But like Vitaminbass said, CA might not be the best...For all that work, A good high temp epoxy would be best.


Steve
post #9 of 20
I'm sure Loctite makes something suitable, i.e. a high temp low viscosity, and that contacting their tech support would advise accordingly.
post #10 of 20
Thread Starter 
Quote:
Originally Posted by LINEARX View Post

Can you post a picture of where you accessed the area you worked on on the driver?

I didn't take any photo's, but you can watch the video in 1080p mode @ 50 seconds in you can clearly see the flux ring.

If you count the number of slugs from the top of the basket, the flux ring is attached to the inside of the second black metal slug (the one directly above the pair of ferrite slugs), it is a 3" metal ring inside the gap.
You can't miss it, it's the only thing not painted black or made of ferrite.


It shouldn't need more than a hairline amount of glue, just enough to fix it in place, and not decrease the gap width.
post #11 of 20
should have used epoxy. keep in mind these were already glued, and the heat caused it to loosen up due to expansion and other factors.
post #12 of 20
Quote:
Originally Posted by notnyt View Post

should have used epoxy. keep in mind these were already glued, and the heat caused it to loosen up due to expansion and other factors.

Then wouldn't a lot more eventually fail?

I thought it was a mfg defect on only particular units, like too little was used
post #13 of 20
I was told lack of glue, but a very small amount of crazy glue is not gonna compare to a proper amount of epoxy.
post #14 of 20
Thanks for reminding me about these. I had one chilling in the garage from the latest vegas sub offering. Since motor heat and glue failure was the culprit I opted to use it IB with about 225W.

Lets see how long it lasts in a setup like mine.......
post #15 of 20
Quote:
Originally Posted by notnyt View Post

should have used epoxy. keep in mind these were already glued, and the heat caused it to loosen up due to expansion and other factors.

Yeah that was my thinking once I saw how a fix "could" possibly be done. Either that or a good thin, slow curing (30min or more), medium hardness/density resin would work well as it would have enough time to settle in all the voids before it hardens. I was just under the impression that they were pretty much paper weights if they went bad, but now that I see the speaker it could work. Still a chance that will have to do multiple fixes before getting it to the point where all the voids are fixed though. For those that dont want to spend money or cant its def worth it!
post #16 of 20
waiting to see how this goes back together.
post #17 of 20
Thread Starter 
Quote:
Originally Posted by notnyt View Post

waiting to see how this goes back together.

The hardest part was actually not puncturing the surround with whatever sharp object your using to deattach it with.

The second hardest part was recentering the coil without rub, that takes pure wizard-like skills, I'd hate to have to work it a woofer factory doing this all day they must have a lot of throwaways; you have to be damn sure it's good, no margin for error.

I didn't capture the reassembly, just take your time... measure 5 times and glue once

I've fed the thing every watt the EP4000 has got and the glue is still holding after all this time. She hasn't popped yet. I don't think she's gonna.


Obviously the LMS is the star of the show
post #18 of 20
Quote:
Originally Posted by BassThatHz View Post

The second hardest part was recentering the coil without rub, that takes pure wizard-like skills, I'd hate to have to work it a woofer factory doing this all day they must have a lot of throwaways; you have to be damn sure it's good, no margin for error.

I wonder if you're doing it the right way; the various recone kits at least make it sound like it's not a big deal; I believe you just center the VC with shims.
post #19 of 20
Thread Starter 
Quote:
Originally Posted by noah katz View Post

I wonder if you're doing it the right way; the various recone kits at least make it sound like it's not a big deal; I believe you just center the VC with shims.

I couldn't see how shims would help here because at some point you have to pull them out without moving the spider that overlays on top of it, before gluing it down and that would probably make things worse because of the increased likelyhood of accidental movement.
post #20 of 20
Quote:
Originally Posted by noah katz View Post

I wonder if you're doing it the right way; the various recone kits at least make it sound like it's not a big deal; I believe you just center the VC with shims.

A typical "tight" gap is ~0.5mm all around. As you get into high excursion "loose" designs, you'll see gaps in the .8-1.5mm range.

Like you said, no margin for error.

The issue you had was that the dustcap was already attached. If it wasn't you'd simply uses a centering jig to fits like a sleeve over the center pole. It sets the correct VC position and centers it. Once the spider and edge glue joints dry, you just pull it out and slap on the dustcap.

Here is a picture I found on google images that shows the jig in the center.
http://www.soundadviceblog.com/wp-co...8/finished.jpg

The recone kits will ship with shims or bendable delrin or something you slide inside of the coil. It will wrap around the pole and center it quite easily, even with a very tight gap.
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