Not made for the UK climate, stored in a (normal for UK) damp garage for 3
years, came out making nasty "amp clipping" noise.
Now it is totally apart, small bits of aluminium oxide in the voice coil
slot were causing the distortion along with loose skirt biased to one still
retained side. 15 inch size with aluminium basket.
The voice coil is in perfect condition and no imperfections to the cone
despite 30 years old.
Prior to me getting to look the owner had removed the 3 magnet retaining
bolts and removed some perished foam filter from inside under the mesh cover
and squirted in WD40.
The white oxide formations had burst the glued skirt off , about 80 percent
of its rim, and the same for the cone rim (after removing the periphery
bolts) and nothing much holding on the remainder, easy to prize off.
At the moment intend masking off the central voice coil slot area before
abraiding back the lands to take contact adhesive to replace the skirt and
cone. Then air blast and run thick plastic around the slot to clear any
crud. The magnet does not seem to be corroded, shiney, no obvious rust
spots.
Any tips re added ptfe film, gluing sequence, positioning/algnment, what
sort of foam to add as he threw the original away? etc.

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

N Cook wrote:
Not made for the UK climate, stored in a (normal for UK) damp garage for 3
years, came out making nasty "amp clipping" noise.
Now it is totally apart, small bits of aluminium oxide in the voice coil
slot were causing the distortion along with loose skirt biased to one still
retained side. 15 inch size with aluminium basket.
The voice coil is in perfect condition and no imperfections to the cone
despite 30 years old.
Prior to me getting to look the owner had removed the 3 magnet retaining
bolts and removed some perished foam filter from inside under the mesh cover
and squirted in WD40.
The white oxide formations had burst the glued skirt off , about 80 percent
of its rim, and the same for the cone rim (after removing the periphery
bolts) and nothing much holding on the remainder, easy to prize off.
At the moment intend masking off the central voice coil slot area before
abraiding back the lands to take contact adhesive to replace the skirt and
cone. Then air blast and run thick plastic around the slot to clear any
crud. The magnet does not seem to be corroded, shiney, no obvious rust
spots.
Any tips re added ptfe film, gluing sequence, positioning/algnment, what
sort of foam to add as he threw the original away? etc.


You can probably get the whole cone out of the basket with careful use
of a hot air gun. You`ll need to remove the dust dome with a razor
knife. When it's all cleaned up refit the magnet assy to the basket,
make some shims to go down the inside of the magnetic gap from business
card or similar, and refit the cone. Glue the inner spider first, and
don't remove the shims till the glue holding the outer suspension has
dried. If you made a decent job of removing the dust dome, you can refit
it neatly with a bead of something like Bostik clear.

There`s several websites showing how to do it if you`ve never reconed a
driver before. If you cock it up, take it to Wembley Loudspeakers for a
professional repair which will be better than the original.

Good Luck

Ron(UK)

Ron(UK) wrote in message
...
N Cook wrote:
Not made for the UK climate, stored in a (normal for UK) damp garage for
3
years, came out making nasty "amp clipping" noise.
Now it is totally apart, small bits of aluminium oxide in the voice coil
slot were causing the distortion along with loose skirt biased to one
still
retained side. 15 inch size with aluminium basket.
The voice coil is in perfect condition and no imperfections to the cone
despite 30 years old.
Prior to me getting to look the owner had removed the 3 magnet retaining
bolts and removed some perished foam filter from inside under the mesh
cover
and squirted in WD40.
The white oxide formations had burst the glued skirt off , about 80
percent
of its rim, and the same for the cone rim (after removing the periphery
bolts) and nothing much holding on the remainder, easy to prize off.
At the moment intend masking off the central voice coil slot area before
abraiding back the lands to take contact adhesive to replace the skirt
and
cone. Then air blast and run thick plastic around the slot to clear any
crud. The magnet does not seem to be corroded, shiney, no obvious rust
spots.
Any tips re added ptfe film, gluing sequence, positioning/algnment, what
sort of foam to add as he threw the original away? etc.


You can probably get the whole cone out of the basket with careful use
of a hot air gun. You`ll need to remove the dust dome with a razor
knife. When it's all cleaned up refit the magnet assy to the basket,
make some shims to go down the inside of the magnetic gap from business
card or similar, and refit the cone. Glue the inner spider first, and
don't remove the shims till the glue holding the outer suspension has
dried. If you made a decent job of removing the dust dome, you can refit
it neatly with a bead of something like Bostik clear.

There`s several websites showing how to do it if you`ve never reconed a
driver before. If you cock it up, take it to Wembley Loudspeakers for a
professional repair which will be better than the original.

Good Luck

Ron(UK)

so sequence is 3 or 4 bits of shims around the outside surface of the voice
coil cylinder and into the slot.
Glue the cone to frame and when cured, remove the cards and glue back the
skirt.
I have a can of silicone spray for sewing machinists cutting out tables,
spray some of that onto the inside surface of the voice coil cylinder ?

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

N Cook wrote:

so sequence is 3 or 4 bits of shims around the outside surface of the voice
coil cylinder and into the slot.

More than 3, most recone kits include 10 or 12 thin shims, but as many
as you can comfortably slide into the gap without forcing it. Better to
have lots of narrow ones than a few wide ones. And they go on the inside
of the coil former, that`s why you have to take the dust dome off.


Glue the cone to frame and when cured, remove the cards and glue back the
skirt.

Don't remove the shims till the outer suspension is glued.

Assemble the voice coil and shims without adhesive, get a feel for how
the coil former will slide down into the gap with the shims in place,
you have to get it right first time.

Apply contact adhesive to the basket and rear suspension (spider)where
they mate, then slide the voice coil down into the gap with the shims in
place. the spider should adhere almost immediately.

Leave that to set, then - leaving the shims in place - glue around the
outer suspension, and stick it to the basket. let it cure then slide
out the shims, and if you did it right, there will be no scraping. Once
you resolder the pigtails you can run a low frequency sine wave through
it to check, but not too high power!

If all is well, drop the dust dome in and run a bead of bostik around it
- you can use evostik but it can get stringy, even PVA glue works.

I have a can of silicone spray for sewing machinists cutting out tables,
spray some of that onto the inside surface of the voice coil cylinder ?

Don't spray anything in the magnetic gap, it`s not necessary and could
lead to problems later, the voice coil should never come into contact
with the pole pieces.

Some horn drivers and tweeters have viscous liquid in the gap, either a
ferrofluid or some other gooey liquid, but if it wasn't there to start
with, don`t experiment...

The foam in the vent is just there to keep the dust out, and to help
prevent any chuffing at low frequencies, it`s not critical, but don't
use foam that is too dense, it relies on air passing in and out of that
vent to cool the coil.


Hth

Ron(UK)

Ron(UK) wrote in message
...
N Cook wrote:

so sequence is 3 or 4 bits of shims around the outside surface of the
voice
coil cylinder and into the slot.

More than 3, most recone kits include 10 or 12 thin shims, but as many
as you can comfortably slide into the gap without forcing it. Better to
have lots of narrow ones than a few wide ones. And they go on the inside
of the coil former, that`s why you have to take the dust dome off.


Glue the cone to frame and when cured, remove the cards and glue back
the
skirt.

Don't remove the shims till the outer suspension is glued.

Assemble the voice coil and shims without adhesive, get a feel for how
the coil former will slide down into the gap with the shims in place,
you have to get it right first time.

Apply contact adhesive to the basket and rear suspension (spider)where
they mate, then slide the voice coil down into the gap with the shims in
place. the spider should adhere almost immediately.

Leave that to set, then - leaving the shims in place - glue around the
outer suspension, and stick it to the basket. let it cure then slide
out the shims, and if you did it right, there will be no scraping. Once
you resolder the pigtails you can run a low frequency sine wave through
it to check, but not too high power!

If all is well, drop the dust dome in and run a bead of bostik around it
- you can use evostik but it can get stringy, even PVA glue works.

I have a can of silicone spray for sewing machinists cutting out tables,
spray some of that onto the inside surface of the voice coil cylinder ?

Don't spray anything in the magnetic gap, it`s not necessary and could
lead to problems later, the voice coil should never come into contact
with the pole pieces.

Some horn drivers and tweeters have viscous liquid in the gap, either a
ferrofluid or some other gooey liquid, but if it wasn't there to start
with, don`t experiment...

The foam in the vent is just there to keep the dust out, and to help
prevent any chuffing at low frequencies, it`s not critical, but don't
use foam that is too dense, it relies on air passing in and out of that
vent to cool the coil.


Hth

Ron(UK)

The 0.08mm thick aluminium dome must have been press-formed (or that very
hands-on turning type process that I forget the name of) with a cylinder
extension to the dome and the cylinder section is glued to the inside of the
VC former. So had to cut around the dome to remove and have to hope the
final gluing-back holds up against the air pumping process.
I'm thinking of some golf tees in the rim mount holes to give sliding
alignment with the holes in the periphery of the cone on re-assembly.

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

N Cook wrote:


The 0.08mm thick aluminium dome must have been press-formed (or that very
hands-on turning type process that I forget the name of) with a cylinder
extension to the dome and the cylinder section is glued to the inside of the
VC former.

Spinning perhaps?

So had to cut around the dome to remove and have to hope the
final gluing-back holds up against the air pumping process.

That`s partly why there`s a hole through the magnet, some speaker
manufacturers put a hole in the dome. If the original dome is damaged,
Wembley Loudspeakers will sell you one. If you're worried about
cosmetics, fit a larger dome to hide the remains of the old one.

I'm thinking of some golf tees in the rim mount holes to give sliding
alignment with the holes in the periphery of the cone on re-assembly.

Just line it up properly in the first place

Ron(UK)

--
Lune Valley Audio
Public Address Systems
Hire Sales Maintenance
www.lunevalleyaudio.com

Ron(UK) wrote in message
news
N Cook wrote:


The 0.08mm thick aluminium dome must have been press-formed (or that
very
hands-on turning type process that I forget the name of) with a cylinder
extension to the dome and the cylinder section is glued to the inside of
the
VC former.

Spinning perhaps?

So had to cut around the dome to remove and have to hope the
final gluing-back holds up against the air pumping process.

That`s partly why there`s a hole through the magnet, some speaker
manufacturers put a hole in the dome. If the original dome is damaged,
Wembley Loudspeakers will sell you one. If you're worried about
cosmetics, fit a larger dome to hide the remains of the old one.

I'm thinking of some golf tees in the rim mount holes to give sliding
alignment with the holes in the periphery of the cone on re-assembly.

Just line it up properly in the first place

Ron(UK)

--
Lune Valley Audio
Public Address Systems
Hire Sales Maintenance
www.lunevalleyaudio.com

Yes metal spinning.

Golf tees are too small but 4 ball point pen barrels temporarily glued to
the extreme rim should be ideal as a nice sliding fit with the cone. I will
add black dyestuff to the glue to fix dome back. Dome and inner edge of cone
masked off close to the glue/cut line, with tape, should be neat enough.
I'll just have to make sure its pastey enough not to drip inside, through
the scalpel cut line.

And I won't add gooey stuff in the way of silicone film to the VC cylinder

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

N Cook wrote:
Ron(UK) wrote in message
news
N Cook wrote:

The 0.08mm thick aluminium dome must have been press-formed (or that
very
hands-on turning type process that I forget the name of) with a cylinder
extension to the dome and the cylinder section is glued to the inside of
the
VC former.
Spinning perhaps?

So had to cut around the dome to remove and have to hope the
final gluing-back holds up against the air pumping process.
That`s partly why there`s a hole through the magnet, some speaker
manufacturers put a hole in the dome. If the original dome is damaged,
Wembley Loudspeakers will sell you one. If you're worried about
cosmetics, fit a larger dome to hide the remains of the old one.

I'm thinking of some golf tees in the rim mount holes to give sliding
alignment with the holes in the periphery of the cone on re-assembly.
Just line it up properly in the first place

Ron(UK)

--
Lune Valley Audio
Public Address Systems
Hire Sales Maintenance
www.lunevalleyaudio.com

Yes metal spinning.

Golf tees are too small but 4 ball point pen barrels temporarily glued to
the extreme rim should be ideal as a nice sliding fit with the cone. I will
add black dyestuff to the glue to fix dome back. Dome and inner edge of cone
masked off close to the glue/cut line, with tape, should be neat enough.
I'll just have to make sure its pastey enough not to drip inside, through
the scalpel cut line.

No need, just run a bead of clear bostik around the dome in one
operation, and it`ll look like it`s never been apart. you`ll probably
damage either the cone or the dome pulling the masking off. And dont
worry too much about the rim holes being in perfect alignment, new
cones don't even have the holes when they are supplied. You make them
later with a scalpel. In fact, some new speakers don't have the holes in
the paper, some give you a choice of mounting holes.


Ron(UK)

Ron(UK) wrote in message
...
N Cook wrote:
Ron(UK) wrote in message
news
N Cook wrote:

The 0.08mm thick aluminium dome must have been press-formed (or that
very
hands-on turning type process that I forget the name of) with a
cylinder
extension to the dome and the cylinder section is glued to the inside
of
the
VC former.
Spinning perhaps?

So had to cut around the dome to remove and have to hope the
final gluing-back holds up against the air pumping process.
That`s partly why there`s a hole through the magnet, some speaker
manufacturers put a hole in the dome. If the original dome is damaged,
Wembley Loudspeakers will sell you one. If you're worried about
cosmetics, fit a larger dome to hide the remains of the old one.

I'm thinking of some golf tees in the rim mount holes to give sliding
alignment with the holes in the periphery of the cone on re-assembly.
Just line it up properly in the first place

Ron(UK)

--
Lune Valley Audio
Public Address Systems
Hire Sales Maintenance
www.lunevalleyaudio.com

Yes metal spinning.

Golf tees are too small but 4 ball point pen barrels temporarily glued
to
the extreme rim should be ideal as a nice sliding fit with the cone. I
will
add black dyestuff to the glue to fix dome back. Dome and inner edge of
cone
masked off close to the glue/cut line, with tape, should be neat enough.
I'll just have to make sure its pastey enough not to drip inside,
through
the scalpel cut line.

No need, just run a bead of clear bostik around the dome in one
operation, and it`ll look like it`s never been apart. you`ll probably
damage either the cone or the dome pulling the masking off. And dont
worry too much about the rim holes being in perfect alignment, new
cones don't even have the holes when they are supplied. You make them
later with a scalpel. In fact, some new speakers don't have the holes in
the paper, some give you a choice of mounting holes.


Ron(UK)

In the end I just used the pens with some clothes pegs to give a bit more
clearance gap for laying down the glue. Removed them prior to dropping the
cone in case they gave some bias.
Cone and spider glueing process complete, now a wait for a couple of hours
before removing the shims.
I'm just wondering how much the "monocoq" construction of the Ali dome plus
cylinder gives circular stiffness/precision, that my cutting it has
destroyed.

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

Well it passed low power 20Hz test driving with only pressure waves and not
undue extraneous noises. Unfortunately the owner has the cab.


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/