Speaker foam repair on 15" woofers

Hello all!

I have a pair of Optimus 1050 (Radio Shack) 3-way home stereo speakers
that are about 20 years old. The foam ring that goes between the outer
edge of the cone and the steel frame of each 15" woofer is starting to
split/tear. The speakers still work, but I know it's not a good idea to
run them once the split goes all the way around. Looking around the
net, several places sell repair kits for this.

I have never done it before, but it seems fairly straightforward, except
for one thing: there appears to be a difference of opinion on whether
you need to remove the dust cap and stick shims in between the voice
coil former and the pole piece to center the cone or not. Some places
say you do, while others seem to prefer moving the cone by hand and
centering it before the glue on the new foam dries completely. Which
way does the group prefer?

These are not audio pile speakers. I think I paid $100-$120 each (on
sale) new, and I think I can get complete replacement woofers for $40 or
$50. The main idea here is to get working speakers for less money than
replacing the woofer or the whole speaker. The kits vary in cost and
also in what they include. Is there any US supplier that stands out?

Thanks!

Matt Roberds

 

[hrhofmann@sbcglobal.net]

I vote for shimming, it really can't hurt, and as long as you don't get dirt into the open gap, yhou should be fine.

 

On Wednesday, November 20, 2013 8:16:05 PM UTC-8, mrob...@att.net wrote:

Hello all!



I have a pair of Optimus 1050 (Radio Shack) 3-way home stereo speakers

that are about 20 years old. The foam ring that goes between the outer

edge of the cone and the steel frame of each 15" woofer is starting to

split/tear. The speakers still work, but I know it's not a good idea to

run them once the split goes all the way around. Looking around the

net, several places sell repair kits for this.



I have never done it before, but it seems fairly straightforward, except

for one thing: there appears to be a difference of opinion on whether

you need to remove the dust cap and stick shims in between the voice

coil former and the pole piece to center the cone or not. Some places

say you do, while others seem to prefer moving the cone by hand and

centering it before the glue on the new foam dries completely. Which

way does the group prefer?



These are not audio pile speakers. I think I paid $100-$120 each (on

sale) new, and I think I can get complete replacement woofers for $40 or

$50. The main idea here is to get working speakers for less money than

replacing the woofer or the whole speaker. The kits vary in cost and

also in what they include. Is there any US supplier that stands out?



Thanks!



Matt Roberds

I did 6 Advent woofers. The first kit included shims to keep the voice coil centered and had new dustcaps. I did what they said and it works fine. The later kits did not include shims and even though I had them, I did not use shims or replace the dustcaps. Those drivers also work fine.

It isn't difficult or even tedious but you do have to wait for the glues to cure.

I don't vote for shims as it requires careful removal of the dustcap to NOT damage the voice coil leads. Never disassemble more than necessary.

G˛

 

[Bob F]

mroberds@att.net wrote:

Hello all!

I have a pair of Optimus 1050 (Radio Shack) 3-way home stereo speakers
that are about 20 years old. The foam ring that goes between the
outer edge of the cone and the steel frame of each 15" woofer is
starting to split/tear. The speakers still work, but I know it's not
a good idea to run them once the split goes all the way around.
Looking around the net, several places sell repair kits for this.

I have never done it before, but it seems fairly straightforward,
except for one thing: there appears to be a difference of opinion on
whether you need to remove the dust cap and stick shims in between
the voice coil former and the pole piece to center the cone or not.
Some places say you do, while others seem to prefer moving the cone
by hand and centering it before the glue on the new foam dries
completely. Which way does the group prefer?

These are not audio pile speakers. I think I paid $100-$120 each (on
sale) new, and I think I can get complete replacement woofers for $40
or $50. The main idea here is to get working speakers for less money
than replacing the woofer or the whole speaker. The kits vary in
cost and also in what they include. Is there any US supplier that
stands out?

I did not find shimming necessary. If you carefully push the dome in and out and
there is no rubbing sound, they tend to work. You can also glue the foam to the
cone, then hold the outer edge in position and try them out. If you can sweep
though the audio range without distortion, that's the position you want to glue
them in. There are audio signal generator programs available to generate audio
tones of varying frequency. Feed that into your amp to test.

FWIW, I've done 4 pairs of speakers of various sorts. I bought a kit of foam
surrounds fairly cheaply that contained several of various sizes. I still have
most of them left. That kit, of course, only went to 12"

 

[N_Cook]

On 21/11/2013 04:16, mroberds@att.net wrote:

Hello all!

I have a pair of Optimus 1050 (Radio Shack) 3-way home stereo speakers
that are about 20 years old. The foam ring that goes between the outer
edge of the cone and the steel frame of each 15" woofer is starting to
split/tear. The speakers still work, but I know it's not a good idea to
run them once the split goes all the way around. Looking around the
net, several places sell repair kits for this.

I have never done it before, but it seems fairly straightforward, except
for one thing: there appears to be a difference of opinion on whether
you need to remove the dust cap and stick shims in between the voice
coil former and the pole piece to center the cone or not. Some places
say you do, while others seem to prefer moving the cone by hand and
centering it before the glue on the new foam dries completely. Which
way does the group prefer?

These are not audio pile speakers. I think I paid $100-$120 each (on
sale) new, and I think I can get complete replacement woofers for $40 or
$50. The main idea here is to get working speakers for less money than
replacing the woofer or the whole speaker. The kits vary in cost and
also in what they include. Is there any US supplier that stands out?

Thanks!

Matt Roberds

If you go the shimming route. I mark across the dome to cone join as a
reference , then cut a neat ring with a narrow tip scalpel. Shims 3x 2mm
wide strips of credit card. Reglue the cone with thin hotmelt string and
felt-tip/painted black glue line, easier if you ever have to remove
again. Unless the cones are on view, no cloth cover, then a more
cosmetic glue line required

 

[dave]

On 11/20/2013 08:16 PM, mroberds@att.net wrote:

Hello all!

I have a pair of Optimus 1050 (Radio Shack) 3-way home stereo speakers
that are about 20 years old. The foam ring that goes between the outer
edge of the cone and the steel frame of each 15" woofer is starting to
split/tear. The speakers still work, but I know it's not a good idea to
run them once the split goes all the way around. Looking around the
net, several places sell repair kits for this.

I have never done it before, but it seems fairly straightforward, except
for one thing: there appears to be a difference of opinion on whether
you need to remove the dust cap and stick shims in between the voice
coil former and the pole piece to center the cone or not. Some places
say you do, while others seem to prefer moving the cone by hand and
centering it before the glue on the new foam dries completely. Which
way does the group prefer?

These are not audio pile speakers. I think I paid $100-$120 each (on
sale) new, and I think I can get complete replacement woofers for $40 or
$50. The main idea here is to get working speakers for less money than
replacing the woofer or the whole speaker. The kits vary in cost and
also in what they include. Is there any US supplier that stands out?

Thanks!

Matt Roberds

Use the shims. Leave them in until the glue dries. If you are patient
and steady you will do fine. Check YouTube for vids.

 

[amdx]

On 11/20/2013 10:45 PM, hrhofmann@sbcglobal.net wrote:

I vote for shimming, it really can't hurt, and as long as you don't get dirt into the open gap, you should be fine.

As a curiosity, would applying a small voltage across the voice coil
keep the cone centered without causing other problems?
(small--1, 2, maybe 3 volts)

Mikek

 

[dave]

On 11/20/2013 10:16 PM, stratus46@yahoo.com wrote:

On Wednesday, November 20, 2013 8:16:05 PM UTC-8, mrob...@att.net wrote:

Matt Roberds

I did 6 Advent woofers. The first kit included shims to keep the voice coil centered and had new dustcaps. I did what they said and it works fine. The later kits did not include shims and even though I had them, I did not use shims or replace the dustcaps. Those drivers also work fine.

It isn't difficult or even tedious but you do have to wait for the glues to cure.

I don't vote for shims as it requires careful removal of the dustcap to NOT damage the voice coil leads. Never disassemble more than necessary.

G˛

The dust cap is usually ready to fall off by the time the foam
dissolves. Otherwise dampen the joint slightly with plain water, wait a
few, and lift it off with a hobby knife. If you are worried about
debris, use gravity and/or a well placed rag to protect the gap.

 

[dave]

On 11/21/2013 12:56 AM, N_Cook wrote:

On 21/11/2013 04:16, mroberds@att.net wrote:

Matt Roberds


If you go the shimming route. I mark across the dome to cone join as a
reference , then cut a neat ring with a narrow tip scalpel. Shims 3x 2mm
wide strips of credit card. Reglue the cone with thin hotmelt string and
felt-tip/painted black glue line, easier if you ever have to remove
again. Unless the cones are on view, no cloth cover, then a more
cosmetic glue line required

I have made shims from plastic water bottles, theatrical gels and the
old stand-by "collar stiffeners" for dress shirts. Use at lest 3 and
split the gap distance all the way around. Symmetry and full range of
unimpeded motion are the goals. Patience is THE virtue.

 

[amdx]

On 11/21/2013 8:20 AM, amdx wrote:

On 11/20/2013 10:45 PM, hrhofmann@sbcglobal.net wrote:
I vote for shimming, it really can't hurt, and as long as you don't
get dirt into the open gap, you should be fine.


As a curiosity, would applying a small voltage across the voice coil
keep the cone centered without causing other problems?
(small--1, 2, maybe 3 volts)

Mikek

I was originally thinking a DC voltage, and then had a second thought,
How about a 20khz low voltage signal, wouldn't hear it, but it may
keep things centered, or even force the fresh glue joint to move and
release any tension you/it may have caused installing the foam ring.

Mikek

 

[William Sommerwerck]

I have a pair of Optimus 1050 (Radio Shack) 3-way speakers
that are about 20 years old. The foam ring that goes between
the outer edge of the cone and the steel frame of each 15"
woofer is starting to split/tear The speakers still work, but
I know it's not a good idea to run them once the split goes
all the way around.

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Just like it's not a good idea to use your car when the tire pops off the rim.

 

mroberds@att.net wrote:

The foam ring that goes between the outer edge of the cone and the
steel frame of each 15" woofer is starting to split/tear.

Thanks for the responses! It will be a week or two before I get to
fixing these speakers; I'll post back with results.

Matt Roberds