Casting papier-mache as speaker enclosures

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
diyAudio Member
Joined 2007
Yes I have searched
But unable to find answers to this question, ANYWHERE!!

I am asking this question as a result of my last patching job.
Background
I had a biggish hole that needed filling and being a tight*** wanted to use what I had on my shelf.
We shred a lot of paper here for privacy reasons so I had lots of shredded paper, I always have lots of PVA adhesive and I found an old bag of Plaster of Paris.
I mixed the shreddd paper with PVA until it wa sticky and properly wet and added enough dry plaster to make a thick paste.
OK I filled the hole and waited for it to dry ( 48 hours + ) and I'm now trying to sand it flush.
I have to say the mix is tough, very tough and doesn't sand as smooth as plain plaster, this is due I am sure to the plasticising effect of the PVA.
Now for the question Any thoughts on the suitability of this mix for speaker enclosures??
How would I mould it if I go ahead, it needs to be repeatable.
no point in making a "one-off" mould
More questions follow if any-one is interested enough to comment

Thanks
Ted
 
There is some information somewhere on the net about paper mache horns. I think they were built up over a wire mold on a lazy susan type turntable. I cannot remember the source. I am at work now but I think I have a copy of the article at home. Will let you know later this evening.
jamikl
 
I used to make paper mache and plaster sculptures, and the thought had crossed my mind to use it for speaker cabinets. I haven't yet, there are a few thoughts that deter me.

First, the structure will take several tries to make it both strong, light and acoustically dead enough. Neither medium (mache or plaster) are particularly robust, and break or deform easily. Similarly, giving them a nice finish would be hard. They tend to end up lumpy, and it would take a good eye/hand and a lot of work to make them not look like a high-school art project. Here in the States, I used to use something called Scupley, and my wife used Chavant brand modeling clay. Envirotex, an epoxy resin (I think), is what I might try to harden and finish the surface (its the sort of stuff used to finish surf boards).

The other problem is the flat mounting needed for a driver. I haven't been impressed with diy attempts at mounting flat drivers onto curved surfaces. You invariably end up with sharp corners close to the drivers or larger distances between drivers..

That brings us to the final problem - what are the advantages? More rounded corners? Looking different? Using a sculptable medium will add tons of work, especially prototyping, for not much gain, as far as I can see.

But don't let me discourage you. I actually think its a great idea, and going beyond a wood box has a lot of potential. Its just going to take a lot more work. I'm currently building only open baffle speakers, so I'm just fine with a sheet of wood. :clown:
 
Administrator
Joined 2004
Paid Member
I did a pair of paper horns about a year ago. Used very heavy Arches watercolor paper. It was hard to work with, being so heavy and stiff - but the results were pretty darn good. Weat paste was the only binder.

Very stiff, very neutral, no real sound of their own. Cheap, too.
But labor intensive - OMG!
 
diyAudio Member
Joined 2007
Thats why I am trying to think of a casting method.
I have to tell everyone that the mix of shredded waste paper PVA and plaster has some great properties, although it is quite difficult to sand but I have not yet tested for fragility.

A friend uses a similar mix inside wooden boxes for damping resonances so I know the medium itself works well
 
I haven't tried using your particular mix to make a speaker.
I have worked extensively with those and other similar materials used in the stage prop and visual arts, to make free form structures.
Very low tech DIY stuff.
The last spherical speaker I made was cast from a 8" sphere, using reinforced Tarlatan for the basic sphere. This removed from the form was reinforced with plaster bandage, that was covered with fiber reinforced polyester auto body filler.
The resulting multi layered shell is very inert.
I would agree: These sort of materials/methods are cheap, and labor intensive, but allows for non-rectilinear structures.
 
Casting is great, but it only as good as your mold. Creating the mold is the pain. Unless you use something preexisting. A while back, I used a large 'yoga' ball as a mold, and made 2' semispheres with plaster and cotton rag. Solid, heavy, and fragile. They were supposed to diffuse sound down to 500hz, but they didn't really work in practice, I think.
 
diyAudio Member
Joined 2007
I have found a local suplier of the styrofoam forms used by florists, MIY artcrafts, in Glenhuntly Melbourne, lots of scope there, balls, eggs and cones, so shapes are appearing in my head.
Balls are relatively cheap too
Casting may be out for the time being but as soon as current projects are finished I may start some free-form shapes.

I can see big advantages to using foam cores, easy to put mounting points and terminals in place first etc
 
I have all this waste paper around the house that arrived in the post, as well as a mess of old bills that need to be retired in some way. It would be no less than poetic justice to cut them up in strips and soak them in diluted PVA glue, in order to lay them up into some sort of righteous free-form speaker cabinet. more details when I think of what to do. The paper mache` horn I saw in this context looked righteous, but may be too ambitious for the likes of me.
 
Hi Moondog!

I would start with a blown up baloon. Layer it with paper and glue to set the shape. Paper and cardboard are great for damping. Once set you just put a pin through the paper to burst the ballon. You need good quality ballons.

Next wrap it in fine wire mesh and add a layer of acoustic concrete. see http://www.diyaudio.com/forums/construction-tips/152459-guide-using-acoustic-concrete.html Then add a layer of body filler. Cut a hole for the driver and well you get the idea.

Could be a fun way to soak up some time and paper.

Terry
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.