[gab]

I'm going to try this circle after getting no response in the AVA one.

from Audio Basics Jan 1982 #1 page 2 (http://www.avahifi.com/images/avahifi/root/audio_basics/ab_pdf/ab1982.pdf):

5. Carefully examine the surface of the speaker that is mounted to the cabinet. Usually it is worthwhile replacing any original gasket with a thin layer of Plast-i-clay before remounting the driver, and mounting the driver firmly, but not “air wrench” tight on the cabinet surface. This will tend to slightly de-couple the driver from the cabinet, preventing remaining resonances in the driver framework from spreading to the cabinet.

Does anyone know if this advice would apply to very drivers (i.e., 12"-18" subwoofer drivers weighing 40 lbs or more)?

Or is there a better approach these days for the heavy stuff and what would you guys recommend? Parts Express Gasket Tape #260-540 or Speaker Sealing Caulk #260-400? Head gasket cork material from the local Autozone or auto parts company? Any advice appreciated.

gab

[Mark Korda]

Hi Gab,I started using the Plastine modeling clay building speakers when I subscribed to Audio Basics when it first came out 1982 from Frank VanAlStine.It works great!Before I get into it more,don't use Parts Express sealing gasket tape!Parts Express is about as good a store as they come,but I have a roll I have not used that I bought from them and it got all gooey and gunkie just lying around in a parts box.This could really make a mess in time if you had to change your woofer or tweeter.The parts box did not see any extreme temps,it has just been hanging around my apartment.Nothin hot going on lately!I made these mini monitors with a 8 inch Audex coaxial.I even lined the insides of the cabinet with it,maybe over kill,but who knows.The woofer was flush mounted on the baffle,not sitting in a routered circle.The gasket of clay I made,like a kid in kindergarden,is 1/2 inch thick.I made sure using a (squish test)that the clay,when smushed down by tightening the woofer did not seep out of play and touch the woofer basket or any thing else,experiment a little to see where or how far it moves by mounting the woofer on the hand made gasket you just molded with your hands by pressing it in place over the gasket.Push down on the woofer frame but do not screw in your screws yet.This is the test run to see how far the clay,which you can't see now,moves inside the enclosure.Take your woofer off now and if any clay was squished to far inward,use a special tool,a credit or in my case or  a debit card and remove the excess clay.Use it like a butter knife,trimming the excess clay like a baker would do to trim icing off a cake.Now put your woofer back on the gasket you just made.Put your screws back in,but,tighten them a little bit at at atime,each one,like when you change a tires lug nuts,a little there,then that one,then the other...you know.As you do this,to keep a pro looking seal and gasket,use a ruler to measure the gaskets thickness as you tighten each screw one at a time.The seal almost keeps the speaker there with out tightening the screws to much.Now,when every thing is the right thickness,uniform,mine was 1/2 inch,take your credit card and use it like a plastic putty knife and trim the excess clay on the baffle.My baffle is black,so if the clay leaves any smears or smudges,clean it off the baffle with paper towels and alchohol,try Windex or fantastic too.There is some stuff like clay that is easy to use called Mortite.It is like clay strips on a roll that is used to seal old window cracks to keep the cold air out,and it's pretty cold here in Maine right now.I use it in my apartment.Wayne,one of Frank VanAlstines employees warned me not to use it as a speaker gasket.It eventually hardens,as I can see right now in my windows,and the modeling clay does not.My last project using the clay was a Parts Express sub cabinet,with about 1/4 inch thick gasket.It holds up my 12 inch Titantic sub woofer with no screws.Of course I put the screws in,but did not need to tighten them down too much.This really helps from transfering the vibration of the woofer to the baffle,it keeps the woofer more isolated.I hope this might help...feel free to write me if you got any questions...take care...Mark Korda...P.S.Hot tip;When screwing your screws back in,use your free hand as a barrier between the woofer surround and the rim.One slip,and it's happened to me can ruin your woofer.

[Mark Korda]

Gab,one more thing.Think like a window glazier.Roll out a piece of clay,the glaziers call it a snake.When you get the clay to about the same thickness,lay it in place where you want your gasket.To get it really level with out using the tighten each screw and ruler technique,take a rolling pin from the kitchen or invent one,a pipe maybe.Once you get the thickness you want,use the credit card to trim the excess to make it look neater.Then do the process I already told you earlier.It's easy,fun,a cave man could do it....Mark

[gab]

Thanks Mark! Its thr feedback I was looking for.

I'm going to try it out with some Van Aken Modeling Clay (Plastalina Pate A Modeler) I just picked up at a Hobby Lobby. It states that it is a pigmented oil base modeling compound that is self-adhering and never hardens, permanently pliable with a melting point of 150 F.

[srb]

Holy Cow!  I just learned that there is actually a way to make a single 1000 word paragraph even less readable - eliminate any spaces between sentences!

[Mark Korda]

Hi Gab,I tried taking a few pictures but they came out terrible,will try tomorrow,Srb,just trying to help,not nit pick.....Mark

[Peter J]

Here's my dissenting opinion.

I'm assuming that this is intended to form a high integrity seal, as in non-ported design. If it were me, I'd use a compliant and resiliant gasket of some sort... either rubber or closed cell foam.  All things considered it would be ideal for the task at hand.  Caulk could accomplish same but is more permanent and difficult to remove if one should need to.

Clay can form a seal but once its compressed it has little ability to move differentially from the things it's in contact with. The window glazing analogy actually exemplifies this. Glazing compound is, to the best of my knowledge, not used in any modern high performance windows.  So you've got a wood box and a metal driver frame that will expand and contract at different rates. That's the nature of the materials and not a difficiency in them. Many types of rubber compounds can keep pace with this in a household environment, as can closed cell foam.

Another possible issue with clay is most is oil based, I believe. What happens when oil comes in contact with wood? It wicks into it kinda like a sponge. If the surface is sealed well the likelyhood is less, but I've seen oil wick under wood finishes and create an obvious stain that's impossible to fix without stripping the finish.

There's my opinion...worth price paid.

[*Scotty*]

I have always used the gray closed cell foam weather stripping tape sold at Lowes or Home Despot.
Its cheap and it works.
+1 on Peter's dissenting opinion. For the reasons he listed above, oil based clay of any kind would be not be my choice for this application. In as much as the gasket will likely be in contact with the edge of a hole that may have been routed out after the enclosure was finished, the edge will be raw wood which will definitely wick the oil out of the clay.
Scotty

[Mark Korda]

Srb,I'm sorry I got so snappy.I don't know how to type very well as I'm new to the computer,56,good gawd!I never learned to make a letter on the computer like the one I was taught in grade school,you got to teach me brother!I don't know where to make the right moves,up and down,left and right,and my spelling absolutley sucks.....I wandered out tonight and felt bad about this tonight....please accept my apoligy,and I know thats not spelled very well...Mark

[Mark Korda]

Peter J.,you are exactly right.I restore old windows with oil based glazing.The sashes must be primed with an oil primer or linseed oil,as the putty will suck the life out of the sashes wood.Any latex glazing is a quick fix and won't last long.I tried to take a picture of my speaker I built  to show the gasket,but it did not come out that good.I did poke my finger in the gasket,and after 20 years,I checked,it's 20,the clay was as pliable as the day I made them,just a little dusty...it's almost 4..I got to hit the sack........you guys are great...Mark