Tile adhesive for enclosure lining/stiffening

[float]

I've heard of concrete being used for enclosure building, and acoustic energy used some kind of cement mix inside their AE1 monitors, but has anyone tried flexible thickbed floor tile adhesive?
I used this stuff to lay my slate floor and given that its very sticky , slightly flexible and able to hold a good thickness, I thought it may stick to the inside of an MDF box to allow shaping of non-parallel sides and all sorts of texturing to break up internal waves.
The extra weight and stiffening could bring a reduction in cabinet colouration as well.
Has anyone tried this yet? Possible concerns are the mix coming loose over time and also adding colourations of its own?

cheers

[GordonW]

I actually did something similar- used tile mastic to glue cardboard onto the inside of a particle board enxlosure. Worked darn well. Built the speakers 14 years ago, and they're one of the ONLY contraptions I made from that time, that I can still listen to without embarassment... Cabinets are still pretty darn "dead", to this day...

Regards,
Gordon.

[float]

Glad to hear of your success Gordon.
I must confess I wasn't thinking of sticking anything to the walls, rather just using the adhesive to make non-parallel sides( i.e. spread the mix in a taper from nothing to maybe 50mm across the width of each panel.), and reaping the benefits of stiffer- and less acoustically transparent- walls at the same time. This way you can have an easy to make rectilinear box on the outside and any shape you want inside.
Just to be clear, the tile adhesive I'm thinking of sets virtually as hard as concrete, but claims to be flexible enough to cope with heat expansion and the like. My hope is that it would also withstand any movements in the speaker box and not become unattached over time.
I guess sticking another material to the inside may have extra benefits. The question then becomes do you use something lossy- like lead or cardboard(?)- or something stiff, like slate, ceramic tile or steel

[phase_accurate]

In the German Mag "Hobby Hi-Fi" they used this stuff to glue Hawaphon and felt onto the inside of a small two-way.

Regards

Charles

[RJ]

Just curious!!! I've never layed tile before, but since this is in home does it smell very bad??? Something like tar or what???
I'd like to try it on my next speaker project.

[gengis]

Correct me if I am wrong.

It is a latex / polymer modified cement, right? Or what they call outdoor tile adhesive. Very sticky, it will stick to anything, even plywood. As long as one keeps the surface moist until the stuff cured. It does not smell, it is a cement product.

Float,
Are you trying to make the sides with shapes for noise canceling?

[float]

Yes qenqis, I think we're talking about the same stuff.
The exact product I used on my floor was made by BAL, and its called PTB (pourable thick-bed) flexible tile adhesive. I used it for slate on a heated floor and it seems to withstand the regular expansion/contraction, and as you say, sticks like mad.
Because its designed for laying thick beds, it holds its shape with a minimum of slumping and can be formed into ripples, ridges or any shape you want for disrupting waves etc.
Plus, when cured its barely distinguishable from concrete, so should stiffen cabinet walls nicely.
I haven't actually tried it yet because I don't really want to make my cab volumes any smaller; if I use enough to be effective it will change the bass tuning too much. I need therefore to knock up some bigger cabs, but until I get round to doing this I can discuss and hopefully learn from others experiences

[gengis]

The latex / polymer modified cement I used to set tiles were thin set. The recomment thickness is 3/16" thick, It will even work at 1/8" (3.2mm). I used a 1/8" triangle notch trowel for the tile.
I have not done anything like that for speakers.

You can use short screws and screw them partly in and use the cement to cover the heads and the protruding part. Then the cement will denfinitely stick. Kind like using chicken wire mesh for doing a stucco wall.

So, 1/8" thick, It should not decrease your cabinet volume by much.

[float]

The BAL PTB adhesive will allow a thickness of around 2 inches
I was planning to use a good thickness to really stiffen ( and mass load) the cabinet, something that 1/8 inch wont do. I could also taper the thickness in two dimensions to spread standing waves within the box.
My boxes are about 16 litres( 0.6 cu.ft) and I think about 5 or 6 litres of mix would be needed and this would definately knacker the bass tuning.
With 22mm MDF walls, plus an average of say 20mm of this stuff, what are the chances of getting a cabinet as dead as a Wilson Watt?

[GM]

Greets!

FYI you need at least a 1:12 taper so 1/8" is only good for a 1.5" span......

GM