mdf sandwich quessie

mattpman

Member
2002-01-05 6:27 pm
UK.
Hi all,

My local DIY store, being useless, doesn't have 1" MDF, so I am going to sandwich 3.75 and 0.25 to make it, but on which side do I mount the drivers? 2 out of the 3 have routing holes of 0.25, so surely I mount them on the "thin" side????

Will steel in a cabinet produce a "ring"?

Also, I saw a recomendation to paint the baffles using that "fleck spray" stuff, not as course as sand, I'm sure you all know what it is, but would it degrade the sound by not having a smooth surface????

Thanks for all your help,
Matt :confused:
 

mattpman

Member
2002-01-05 6:27 pm
UK.
excellent, thanks cyclotronguy, I only need to use a bit, because one of the braces is about 1mm too small :mad: .

For mass I'm going to use sheet lead, I heard that that was good?

Anyway, does anyone have any ideas about my first question, which way I should use the sandwich :confused: ?

thanks a lot,
Matt
 

turbo

Member
2002-03-01 2:51 am
I have the same question, only on the bonding part for the
baffle..Is it best to use something that has some damping --
say liquid nails on MDF<==>MDF bonding, or bond them such
that it is one contiguous piece?

Also curious about the metal sheeting..so would ask this question
for that concept, too.

Tom
 

mattpman

Member
2002-01-05 6:27 pm
UK.
Hi Tom, I've found a number of sites reccomending lead sheeting, heres a quick quote:

http://www.humanspeakers.com/diy/cabinets.htm#build

"Lead flashing, which comes in 12" wide, 1/8" thick rolls, and weighs about 2.5 pounds per running foot, makes a wonderful panel damping material. It is easiest to attach with construction adhesive and a few staples. It does not have to be neat or lie perfectly flat. Wear gloves when handling it and don't leave it where children or pets can play with it, since it is poisonous if ingested. It will be safe inside your speaker box."

Hope that helps :)
Still dont know about the MDF bonding though :-(
Matt

grrrrr, B&Q cut the MDF wrong AGAIN!!!!! grrrrr!!!!!
 
I am hoping to build a pair of speakers as follows:

dimensions
46" high
30" deep
8" wide

drivers:
12" Audio Concpets DV12
6" Scan Speak 18W8546
1" Scan Speak 2905-9900

The 12" will be side mounted.

Question:
for all panels but the baffle I hope to use layers of 6mm MDF with lead sheet in between layer 1 and 2 and snd between layer 2 and 3. Does this make sense?

Since the 12" is side mounted how does one mount it on a multilayer baffle (MDF-lead-MDF-sand-MDF)?

Does this mean that I would only be able to use a multilayer baffle on the sides that dont have a driver mounted in them?

Does it make better sense to use only lead sheet and not sand at all on one side (the side where the 12" is mounted)?

Another alternate is a MDF-lead-MDF-RBF-MDF sandwich. RBF means Resin Bonded Fiberglass. Using polyester resin and fiberglass rovings/mat/mesh in a mixture one can spread this across a MDF sheet and then lay the next sheet of MDF on top. Is this any good?

Lastly another idea is that I bend the MDFon the sides thereby flex it and prestrssing the cabinet walls. This can be done before th resin ins dry so that the fiberglass also dries as per the curve of the bend.