home made silicone surrounds

Nice work!

I work a lot with silicone and various silicone based adhesives at my day-job, I'm a nutty experimenter so whenever I can duck out of the bosses view I make silly things out of it. Some thoughts resulting from my experiences:
for a good mold release compound use 'Super Slip'(it's made by Sleyter, but I don't remember how they spell their name) silicone spray, mostly used for upholstery but it makes a great release compound, Pam cooking spray works well too.
Nothing sticks to silicone other than silicone. When somebody screws up and gets silicone on something we need to glue(contact cement usually, sometimes superglue or lino cement) we have to scrape the silicone completely off the substrate. To get silicone to bond well to metal you need to rough it up a bit...it doesn't like to bond well to painted surfaces without scuffing, it'll just peel off.
instead of wax, try using layers of thin, flexible tape to keep a uniform thickness...

I'll write more in a couple hours...I have an appointment (doh, I'm late now).
sticking silicone to basket

hey cal and illusus,
thanks for your replies!
in fact i liked the look of my "artistic" surrounds quite much. ;)

the issues you mentioned are in fact a bit difficult.
i thought of the following:
next time i will prepare a ring of fabric (fiberglass, cotton, don't know yet) which will be half way covered with the "wet" silicone and on the other half could be easily glued to the basket.
another solution would be pressing down the silicone surround with a aluminium ring screwed to the basket.
i'll tell you as soon i find a good solution.



2003-05-21 2:51 pm

a very interresting idea! ;)

You could now investigate in ways to achieve desired TSPs for a given driver.

But I'm afraid the only way of making a reliable silicone surround is to mold it directly onto the chassis, directly bonding frame and cone together. Would you think this is possible? It could be done using a 'negative' plate and a 'positive' ring (e.g. split in halves in order to get it out easier afterwards).

You could even combine different positives with respective negatives, in order to set the stiffness (influencing Qms/VAS and linear vs. progressive excursion)

Sebastian. ;)

You made a comment on your page about odd humps in the impedance graph; I suggest that these might be caused by small changes in how the voice coil is centered now with the new surrounds.

I tried making surrounds a while ago out of clear silicone, with very little success (they tore into pieces very easily--I think I was using a different formulation, that's why) and I'm glad that someone else tried it too, with better results. :D
thanks for your replies!

i didn't have much time (no time at all, to be precise!) to go on with my silicone surrounds. i will, however!

stocker, if you have some time for experiments and are interested in recycling those old speakers, go for it! it's definitely fun!
i always find it sad to throw away a driver, that could be "repaired"...

sek, thanks for your ideas! i think it would be quite difficult trying to get predictable results out of such quick-and-dirty-made-surrounds. it would probabely be better to find someone who can make those parts professionally...

nappylady, yes, the centering-problem of the voice coil got even worse since the surrounds by now don't even touch the basket anymore. now the voice coil even start to rub the ploe plate... making ugly noises... ;)

I believe hot glue would be a pretty good surround material if a proper mold could be created. I myself have repaired many surrounds with a thin layer of hot glue and have made a few experimental surrounds out of hot glue, but the thickness varys by how much you put on there and it should be constant at the perfect amount. It's either an art, or you got to have the machinery!