Speaker Foam Replacement - Experience
Bob J
Not too long ago I posted a message here asking if there was a way to
repair my 20 year old speakers, at that time I did not even know the
term "surround" as it applied to speakers, but I soon learned it's the
foam bead that goes around the outside of the cone and suspends it in
the speaker frame.
Well, thanks to the many who responded, I ordered a Foam replacement
DIY kit from Stepp (1-800-747-3692), and here is my experience at
doing the repair job. (If you can find a pro that will do it for
$50-100 bucks it might be worth it, this take major time!)
Count on 2-3 days elapsed time to do everything, (about 4 or 5 hours
of actual nose to the grind-stone, and the rest is drying time) to
tear down the speakers, remove the drivers you plan to fix, remove the
old foam, install the foam, let the glue cure, and re-install the
driver.
Also, if you are not real patient, good with tricky things and your
hands, then forget it and take your speakers to a shop, although this
repair was not complicated it was extremely tedious.
Step 1. Tools/Preparation:
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1.a Requirements
- Need Alcohol, a sharp knife, small paint brush.
- Need Cotton Swabs(lots), tools to remove the drivers.
- Peace of stiff cardboard slightly larger then the driver.
- Foam Replacement Kit (Foam, glue, and instructions.)
- Patience, good dexterity, lots of time.
1.b Fit Test the new foam:
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Hold the new foam up to your driver cone and see if it's about the
right size, I say "about" because on the back-glued ones like mine the
inside diameter will appear too small. The bead however should be as
exact as the eye can discern, the surround Stepp supplied were an
exact match on the bead in the eye-ball measurement. If this is OK
then proceed, if not, Call Stepp - DO NOT JURY-RIG!!!
Step 2. Remove driver(s) to be repaired:
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Remove the driver from the speaker box. I have no idea how you would
approach this if you can't remove the driver, my foam glues to the
back of the cone, with front glued foam it may be possible to do this
repair with the driver still in the enclosure.
Also make sure to note and/or mark which post you pull the wires from
so you can put them back in the same place when you are done.
Step 3. Remove Old Foam from Cone:
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Remove all of the old foam, at least as much as you can without
damaging the cone, the kit gives you instructions but no tools, make
sure you have a sharp knife and take care removing any foam still
attached to the cone. DO NOT damage the thin "glue" line, this seals
the edge of the cone and prevents it from fraying.
A short bristled, small paint brush, came in real handy in removing
the stubbly foam bits left behind. Run your finger over the old foam
where it's glued to the cone (DON'T use the alcohol on the cone!),
then brush, repeat this process until no more of the old foam balls up
under your finger. Give it one final good brushing.
Step 4. Remove Old foam from driver frame:
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This was pretty easy, just take your time to make sure you get it as
clean as possible. Try to get down to the metal or painted surface and
use the alcohol to remove any old glue or other junk from the surface.
Remember NOT to use alcohol on the Cone side ever.
Step 5. Glue New Foam To Cone:
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This is by far the most difficult task, take your time and really
think about what you need to do without turning everything in to a big
mess.
You only have about 5 minutes to complete this next step, so make sure
you are all prepared. Start your timing now! Run a bead of glue around
the cone first, Stepp provides the glue and a syringe to apply it.
Now apply a similar bead to the new foam, be careful but quick, we are
in a race with the glue applied to the cone. Then go back over the
glue lightly with a cotton swab, change the swab often, I used 10 on a
15 & 3/4" driver, to keep the swab from spreading glue all over the
place and to keep the cotton from matting in to the glue. Do this on
both the cone and the surround until the glue is spread completely and
evenly. Apply more glue if necessary, you should see a nice thin even
layer all the way around the edges.
Wait for the glue to get tacky, with the Stepp's glue, they
recommended about 5 minutes, for me is was about 7. Now carefully join
the surround to the cone, in my case the foam glues to the back of the
cone so I had to carefully stretch the foam over the cone with the
tacky glue in place. (Clean anywhere glue touches where you don't want
it asap)
Adjust the foam to fit around the cone, line up the glue beads and
press the new foam to the cone. DO NOT start at one point and run your
finger all the way around, you'll end up with a bubble, use two hands
and literally pinch the seam, a finger width at a time work 1/4 of the
cone in one direction, then go the other way, NEVER RUB, open your
fingers each time you move to a new spot. This takes time, about 10
minutes for me, you will have to repeat this a couple of times, again
move carefully but quickly.
Let glue stand for at least 5 minutes, if your foam does not easily
stay where you need it you'll have to get creative, I was lucky, the
foam hugged the cone in such a way that it stayed in place by itself.
Do only one Driver at a time, I found out that I had not used enough
glue the first time and it did not stick, it was easy to do over since
nothing had really stuck. and what glue remained was still a little
tacky. I just applied new beads over the last one and re-swabbed it
smooth, then re-applied as before.
The second driver was a breeze, with the lessons learned on the first
one, no problems and no mistakes.
CAREFULLY INSPECT EVERY micro-inch on the glued parts, use your finger
to ensure that the foam is properly glued and can't be pulled back or
off the cone. If you find a couple of small areas where the glue did
not catch as well it is repairable without starting over. Apply a
little glue to a toothpick (wood or plastic), let it get almost tacky,
then carefully open the foam, apply and re-squeeze.
DO NOT PROCEED TO THE NEXT STEP UNTIL GLUE IS SET!!
(I gave it an hour). I used a little glue on an old piece of foam and
stuck it on some cardboard, then checked that to see the condition of
the glue.
Step 6. Glue New Foam To Driver Frame:
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The glue techniques are exactly the same as for the cone, with the
exception that now you have to pay attention to the cone alignment.
With the driver facing up on your work surface, press the cone lightly
and evenly, then release, this will center the cone. Take care not to
damage the voice coil or put a dent in the voice coil cover. (The
round bump in the center of most speakers)
Now apply glue to the cleaned frame edge and to the new foam, use your
swabs to spread the glue evenly, and let stand until it's tacky.
Again, depending on the type of speaker you have this can be pretty
easy or very difficult. I again was lucky and have a rubber seal that
mounts over the foam once installed, I used this gasket to give me an
even seal.
MAKE SURE TO RE-CENTER THE CONE AFTER THIS STEP. MAKE
SURE THAT THE VOICE COIL IS NOT DRAGGING!!!! WHEN THE
CONE MOVES. MAKE SURE YOU ARE PRESSING DEAD CENTER!
If it does, find the point on the cone where if you press there it
will move freely, this is the direction you have to pull it too. Once
determined, carefully pull the cone and surround until the cone moves
freely in the centering-test.
Once you are happy with the cone alignment, you can use the weight of
the speaker to hold things in place until the glue dries, another hour
should be good. Place a piece of cardboard over the driver frame, to
cover the whole face, slid the driver off you bench, then flip it over
and slid it back on the bench. Make sure the cardboard does not slid
in relation to the driver as you do this, if it does, flip it back and
do it again. The surround and/or gasket may move slightly and you
don't want that to happen this late in the game.
NOTE: IF THE FOAM EXTENDS PAST THE EDGE OF THE FRAME
SO AS TO MAKE IT DEFORM THE FOAM WHEN FACE DOWN ON
A FLAT SURFACE, THEN LET THE GLUE CURE WITH THE
SPEAKER FACE UP. OTHERWISE THE CENTERING MIGHT BE LOST!
At the risk of repeating myself, I can't over-emphasize this enough, I
personally had a close one on this :
MAKE ABSOLUTELY SURE THE COIL DOES NOT DRAG WHEN YOU
PUSH ON THE CENTER OF THE CONE!!!! CHECK IT A COUPLE OF
TIMES DURING THE SETTING PHASE!!!
Let all glued parts to this point sit at least another hour.
Micro-inspect your work, make sure the glue stuck, this is too much
work to screw-up it now. Use the trick noted before to fix any small
areas that may not have stuck well.
Step 7. Glue Gasket back in place:
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If you have a gasket, glue it back in place, this is not difficult or
tricky, lay out a generous bead of glue, spread as before, let stand
til tacky, put the gasket back on, use the cardboard trick once again
and the weight of the speaker to hold it together. (Again, remembering
not to deform your new foam!)
Let this sit for at least an hour. Again, inspect the gasket to frame
seal and fix if necessary. The vendor said you can re-mount the
speakers now and let them cure, but others recommended letting the
glue cure with the speaker cone-up just open, no weights. This will
ensure that the cone stay's centered during the curing process. May be
over-kill by why risk anything now.
Step 8. Let the Glue CURE 24+ HOURS:
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This is essential, everything may look usable once the glue appears
dry, but not so, give it 24 hours from when you finish the last driver
and that should do it.
Step 9. Re-Assemble your speakers:
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Re-install the drivers back in the speaker enclosure, again, take your
time, and ideally mount them in the same box and oriented the same as
when you took them out. (Make sure the leads are in the same place.)
Re-Attach the driver wires and make sure to put the wires back on the
exact same post you pulled or cut them from. If you have to re-solder
them (I didn't) make sure to sure not to de-solder the leads to the
voice coil or get the joint so hot that these wires melt.
Step 10. Crank-up your stereo and see how it sounds:
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No explanations needed for this step :)
I also want to thank those that advised me and provided the
information so I could find the parts. I know that this is a long
message, but it is my attempt to give something back for the help the
folks from this Newsgroup gave me, I hope someone finds it useful.
Thanks - Bob J.