Application - I want to bond layers of Contiboard (white laminated 15mm sheets
of chipboard) together for the walls of loudspeakers I'm making. I have 3
layers of contiboard to bond, and my goal is dead, strong and sonically inert
panels. This is particularly important for the side panels which are the
largest. I will be pulling the layers together with 8mm bolts, exerting some
force. One requirement is a flexible lossy bond, and I've used EvoStik for this
before - I just hate using the stuff so prefer something less toxic. Don't want
anything that dries rigid or goes hard and fractures. I've tried putting
self-adhesive roofing strip (black tarry stuff) between the Contiboard, and
while this is great for sound deadening, it seeps out particulalry when warm,
so the bond isn't really inert once it's been put together. So - what kind of
glue can be put on fairly thickly to make a lossy layer, glues Contiboard, and
dries solid but rubbery and doesn't seep out of the cracks? Over to you! I have
some solvent free Gripfill - is this any good, or does it go brittle when it
dries? .

=== Andy Evans ===
Visit our Website:- http://www.artsandmedia.com
Audio, music and health pages and interesting links.

"Andy Evans" wrote in message
...
Application - I want to bond layers of Contiboard (white laminated 15mm sheets
of chipboard) together for the walls of loudspeakers I'm making. I have 3
layers of contiboard to bond, and my goal is dead, strong and sonically inert
panels. This is particularly important for the side panels which are the
largest. I will be pulling the layers together with 8mm bolts, exerting some
force. One requirement is a flexible lossy bond, and I've used EvoStik for this
before - I just hate using the stuff so prefer something less toxic. Don't want
anything that dries rigid or goes hard and fractures. I've tried putting
self-adhesive roofing strip (black tarry stuff) between the Contiboard, and
while this is great for sound deadening, it seeps out particulalry when warm,
so the bond isn't really inert once it's been put together. So - what kind of
glue can be put on fairly thickly to make a lossy layer, glues Contiboard, and
dries solid but rubbery and doesn't seep out of the cracks? Over to you! I have
some solvent free Gripfill - is this any good, or does it go brittle when it
dries? .



I think you would be better off not using contiboard and tracking down
some 50mm thick MDF instead.

then you wouldn't need to bond the panels together. problem solved.



RT

try using silicone, sticks like sh*t to a blanket!!

"mark bay" wrote in message
...
try using silicone, sticks like sh*t to a blanket!!


No it doesn't !

"Andy Evans" wrote in message
...
Application - I want to bond layers of Contiboard (white laminated 15mm
sheets
of chipboard) together for the walls of loudspeakers I'm making. I have 3
layers of contiboard to bond, and my goal is dead, strong and sonically
inert
panels.

Isn't it more normal to use sheets of ply separated by plastic bubble wrap
with bolts through the lot at random intervals to hold it all together
without standing resonances.

Don't know what your output power is but Contiboard will reflect the sound
too much and possibly degrade with the vibration.

Thanks guys so far - the Contiboard decision has been made - it's all cut out
and drilled. I found in the past that layers of material with some lossy
compound in between sounded good, so I won't be too far out. We have 45mm
thickness also with 3 layers. So - what about the adhesive/filler to go between
the panels? Silicone sounds like a very good idea - do you mean the stuff that
is used for sealing around bathtubs, or any other particular type? Also, what
about polyurethene glue?

=== Andy Evans ===
Visit our Website:- http://www.artsandmedia.com
Audio, music and health pages and interesting links.

On 07 Dec 2004 22:36:53 GMT, ohawker (Andy
Evans) wrote:

Thanks guys so far - the Contiboard decision has been made - it's all cut out
and drilled. I found in the past that layers of material with some lossy
compound in between sounded good, so I won't be too far out. We have 45mm
thickness also with 3 layers. So - what about the adhesive/filler to go between
the panels? Silicone sounds like a very good idea - do you mean the stuff that
is used for sealing around bathtubs, or any other particular type? Also, what
about polyurethene glue?

PU glue *could* work, but it would be advisable to roughen the
surfaces first, then spread a thin layer on one piece, spreading it
all over. Moisten the other piece since this glue requires moisture
to cure and it won't get any through contiboard.

You will need clamps to hold the pieces together while it cures and
make certain of supporting it over something where the drips won't
matter.

Also, do use gloves - e.g. latex ones. If you get it on your hands
it will be with you for at least a week.

Frankly, I'd use contact adhesive in a well ventilated space and with
a mask fitted with solvent filter.



=== Andy Evans ===
Visit our Website:- http://www.artsandmedia.com
Audio, music and health pages and interesting links.


--

..andy

To email, substitute .nospam with .gl

Silicone would be much too soft to deaden it, bitumen would be nearer
the mark. Put it on the inside.

To bond melamine, have had good results with contact adhesive.

You could make it all more rigid with tie bars from one side to the
other. Chip is weak stuff, and even 3 layers wont be above bending.

NT

On 07 Dec 2004 22:10:29 GMT, ohawker (Andy
Evans) wrote:

- I want to bond layers of Contiboard

Why ? It has to be one of the most rubbish speaker enclosure
materials ever. Lightweight, minimal damping and minimal stiffness to
small deflections. You'd be _much_ better off with MDF, or best of all
a cement fibre board like Viroc, Versapanel or Aquapanel (awkward to
saw though - the dust destroys machinery).

As an adhesive, then you need to put it on in a thick bead if you want
compliance. Even blu-tack will be stiff in shear if you use it in a
very thin layer. Probably the best option is a newish(?) flavour of
Sikkaflex polyurethane. They've been in the high-end boat and vehicle
panel trade for years, but now they're doing an extra-flexible version
and selling it into the construction trade. It's called something like
"EBT" and Kellaway in Bristol have it. Like all the polyurethanes
it's extremely sticky, has a poor shelf life (check tube dates when
you buy them) and goes off rapidly once opened.

You'd be _much_ better off with MDF, or best of all a cement fibre board like
Viroc, Versapanel or Aquapanel (awkward to
saw though - the dust destroys machinery).

there's a guy that recommends Tufnol - do you know about that?

#Tufnol
There are two issues of damping and stiffness here. If you make the enclosure
stiff enough to resist the drivers newtonian reaction and internal air pressure
fluctuations, you shouldn't need excessive damping. The application of
enclosure wall damping just adds another resonant mass which while lossy, I
suspect works at some frequencies with attendant hysteresis and not at others
at all. IMHO damping it won't cure enclosure resonance problems it will just
make 'em different!
I prefer going for ultra stiff constuction which doesn't obscure microdynamics
and bloat bass. Tufnol is great for this, it's a resin/paper composite, it's
about as stiff and dense as corian but much easier to use. You can machine it
with an ordinary router really well if you're careful. If you dado the joints
and bond them with epoxy/ microsphere mix you'll wind up with something far
superior to anything you can do with wood. Wilson use this stuff extensively,
it seems to have worked quite well for them!


=== Andy Evans ===
Visit our Website:- http://www.artsandmedia.com
Audio, music and health pages and interesting links.

On 08 Dec 2004 09:07:50 GMT, ohawker (Andy
Evans) wrote:

there's a guy that recommends Tufnol - do you know about that?

Hmmm..... Interesting idea.

Tufnol (a brand name) is going to be _very_ expensive, and I don't
recall ever seeing it in suitable sizes. A similar material called
Trespa might be better. It's a phenolic and fabric laminate like
Tufnol, but it has a higher content of mineral filler. Chemistry labs
use it for bench tops, which is where I get my offcuts.

I'd guess Tufnol is less well-damped than MDF, so you might see some
more resonance from it - although this can be avoided by not making
the enclosure panels rectangular, so that the panel resonance isn't so
strong and well defined.

On the whole though, I think I'd stick with MDF unless I was designing
uber-speakers and had an anechoic chamber to test their responses in.
It's certainly not worth it for a rectangular box enclosure.
--
Smert' spamionam

"Andy Dingley" wrote in message
...

On the whole though, I think I'd stick with MDF unless I was designing
uber-speakers and had an anechoic chamber to test their responses in.
It's certainly not worth it for a rectangular box enclosure.

nail/head.

I think these speakers he's building are for talking about not listening to ;-)

each to their own, I suppose.


RT

On Wed, 08 Dec 2004 13:25:47 GMT, "[news]" wrote:

I think these speakers he's building are for talking about not listening to ;-)

It's a hobby, but if you're going to get _that_ serious about
materials choice, you should be looking at non-rectangular enclosures.

--
Smert' spamionam

I think these speakers he's building are for talking about not listening to ;-)

Not at all! I need some reference speakers because I make valve amps as a
hobby. Serious stuff! In fact, the backs of the speakers are sloping so they're
not rectangular.

=== Andy Evans ===
Visit our Website:- http://www.artsandmedia.com
Audio, music and health pages and interesting links.

Andy Evans wrote:

Application - I want to bond layers of Contiboard (white laminated 15mm sheets
of chipboard) together for the walls of loudspeakers I'm making. I have 3
layers of contiboard to bond, and my goal is dead, strong and sonically inert
panels. This is particularly important for the side panels which are the
largest. I will be pulling the layers together with 8mm bolts, exerting some
force. One requirement is a flexible lossy bond, and I've used EvoStik for this
before - I just hate using the stuff so prefer something less toxic. Don't want
anything that dries rigid or goes hard and fractures. I've tried putting
self-adhesive roofing strip (black tarry stuff) between the Contiboard, and
while this is great for sound deadening, it seeps out particulalry when warm,
so the bond isn't really inert once it's been put together. So - what kind of
glue can be put on fairly thickly to make a lossy layer, glues Contiboard, and
dries solid but rubbery and doesn't seep out of the cracks? Over to you! I have
some solvent free Gripfill - is this any good, or does it go brittle when it
dries?


Some background information from the BBC R&D labs:

http://www.bbc.co.uk/rd/pubs/reports/1977-03.pdf

If you want something rubbery between the layers of chipboard,
how about using rubber? Aren't rubber sheets available from medical
suppliers? Then you could use something like a Hylomar head-gasket
aerosol for a thin layer that will stay sticky and not ooze.

What internal volume have you chosen for those poor B110s?

--
Eiron.

Aren't rubber sheets available from medical
suppliers? Then you could use something like a Hylomar head-gasket aerosol for
a thin layer that will stay sticky and not ooze.

The Hylomar sticks rubber does it? Is that an option by itself if it comes in
tins? I do have a 6" rubber sheet from my camping days - not thick rubber but
no doubt compressable. Hadn't thuoght of that.
At the moment I'm inclining a bit towards the silicone - compressed between two
sheets it should be rubbery and not ooze when it sets - anything against
silicone?
Enclosure is 20 litres. The front panel is a 6" aluminium channel 15" high -
massive bit of extrusion. The sides then bolt onto that. I can use any 5" unit
- at the moment a Monacor SPH130AL which sounds promising. Could use a Jordan
JXs92. I think the Monacor is more detailed than the B110 - different sound,
lighter, less full.

=== Andy Evans ===
Visit our Website:- http://www.artsandmedia.com
Audio, music and health pages and interesting links.

Andy Evans wrote:

Application - I want to bond layers of Contiboard (white laminated 15mm sheets
of chipboard) together for the walls of loudspeakers I'm making. I have 3
layers of contiboard to bond, and my goal is dead, strong and sonically inert
panels. This is particularly important for the side panels which are the
largest. I will be pulling the layers together with 8mm bolts, exerting some
force. One requirement is a flexible lossy bond, and I've used EvoStik for this
before - I just hate using the stuff so prefer something less toxic. Don't want
anything that dries rigid or goes hard and fractures. I've tried putting
self-adhesive roofing strip (black tarry stuff) between the Contiboard, and
while this is great for sound deadening, it seeps out particulalry when warm,
so the bond isn't really inert once it's been put together. So - what kind of
glue can be put on fairly thickly to make a lossy layer, glues Contiboard, and
dries solid but rubbery and doesn't seep out of the cracks? Over to you! I have
some solvent free Gripfill - is this any good, or does it go brittle when it
dries? .

Epoxy or thick PVA should do the trick. We used to bond sheets of chip
with PVA in teh loudspeaker factory.


Clamp up and leave for a few days. I wouldn't use screws and bolts
really - tooloaclised - may get voids. Just pile on tos of weight all
over. Maybe lay on a flat surface, glue, laminate, and SANDBAG.

IUf you want something gap filing and rubbery, get loads of acrylic
decorators caulk. That dries to a sort of yough rubbery consistency. Its
not spposed to be an adgesive, but given teh area you have it shold work.

Another possibilitry is expanding foam glue.




=== Andy Evans ===
Visit our Website:- http://www.artsandmedia.com
Audio, music and health pages and interesting links.

In article ,
Andy Evans wrote:
Application - I want to bond layers of Contiboard (white laminated 15mm
sheets of chipboard) together for the walls of loudspeakers I'm making.
I have 3 layers of contiboard to bond, and my goal is dead, strong and
sonically inert panels.

The obvious answer is not to use Contiboard which is totally the wrong
material. Ordinary chipboard can be bonded as strong as the material
itself with PVA wood glue. Or better still, use MDF which is easier to
machine - and get a decent finish on for veneering etc afterwards.

However, for simply glueing Contiboard together if you must, use a
thixotropic contact adhesive - Evostick make one or Thixofix by Dunlop.
This allows easy positioning of the panels before clamping them to set.

--
*I don't suffer from insanity -- I'm a carrier

Dave Plowman London SW
To e-mail, change noise into sound.