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-   -   Frugel-Horn Mk3 (https://www.diyaudio.com/forums/full-range/172605-frugel-horn-mk3.html)

rjbond3rd 9th January 2013 02:43 PM

1 Attachment(s)
Quote:

Originally Posted by Bob Brines (https://www.diyaudio.com/forums/full-range/172605-frugel-horn-mk3-post3317831.html#post3317831)
The major issue in panel sound production is transparency. Wood is a pretty good conductor of sound. The stiffer and harder the wood, the better it conducts sound. This suggest that MDF might really be the better choice for small boxes. I am thinking of even softer materials; polystyrene bead-board or Celotex.

Or perhaps a laminate of a couple materials. Omega Loudspeakers uses an interesting (and I believe proprietary to them) combination of materials, not unlike what you previously used. (Image courtesy of a user on Omega's forum.)

Bob Brines 9th January 2013 05:43 PM

Quote:

Originally Posted by rjbond3rd (https://www.diyaudio.com/forums/full-range/172605-frugel-horn-mk3-post3317990.html#post3317990)
Or perhaps a laminate of a couple materials. Omega Loudspeakers uses an interesting (and I believe proprietary to them) combination of materials, not unlike what you previously used. (Image courtesy of a user on Omega's forum.)

Hmmm. My guess would be low density fiberboard (Celotex?) bonded with an elastic adhesive to 12mm BB. For those who don't know, I used to use 1/4" cement board (HardiBacker) glued to 3/4" MDF with Liquid Nails.

I'm going to try 1/2" bead-board sandwiched between 5mm plywood, using something like PL Premium (urethane) adhesive. Won't be soon, though.

Bob

xrk971 9th January 2013 05:51 PM

What is bead board?

Scottmoose 9th January 2013 05:56 PM

Quote:

Originally Posted by Bob Brines (https://www.diyaudio.com/forums/full-range/172605-frugel-horn-mk3-post3318223.html#post3318223)
Hmmm. My guess would be low density fiberboard (Celotex?) bonded with an elastic adhesive to 12mm BB. For those who don't know, I used to use 1/4" cement board (HardiBacker) glued to 3/4" MDF with Liquid Nails.

I'm going to try 1/2" bead-board sandwiched between 5mm plywood, using something like PL Premium (urethane) adhesive. Won't be soon, though.

Bob

Omega? I believe it's 'softwood MDF' laminated to a thin ply layer, and then their 'R compound', which is basically bitumen with some talc added.

Bob Brines 9th January 2013 06:05 PM

Quote:

Originally Posted by xrk971 (https://www.diyaudio.com/forums/full-range/172605-frugel-horn-mk3-post3318231.html#post3318231)
What is bead board?

Shop 1-in x 4-ft x 8-ft Expanded Polystyrene Insulated Sheathing at Lowes.com

chrisb 9th January 2013 06:47 PM

Quote:

Originally Posted by Bob Brines (https://www.diyaudio.com/forums/full-range/172605-frugel-horn-mk3-post3318223.html#post3318223)
Hmmm. My guess would be low density fiberboard (Celotex?) bonded with an elastic adhesive to 12mm BB. For those who don't know, I used to use 1/4" cement board (HardiBacker) glued to 3/4" MDF with Liquid Nails.

I'm going to try 1/2" bead-board sandwiched between 5mm plywood, using something like PL Premium (urethane) adhesive. Won't be soon, though.

Bob


What type of joinery and adhesives would you anticipate using with core materials of such different properties? PL for the laminating only, or joinery as well?

Bob Brines 9th January 2013 07:11 PM

Quote:

Originally Posted by chrisb (https://www.diyaudio.com/forums/full-range/172605-frugel-horn-mk3-post3318314.html#post3318314)
What type of joinery and adhesives would you anticipate using with core materials of such different properties? PL for the laminating only, or joinery as well?

I have used PL to glue up complete speakers. Advantage: Long open time. You can put the whole thing together in one pass. Disadvantage: You need at least 24hr before applying any shear to the joints.

I anticipate a solid wood frame around all panels, like a MDF skinned door. That way, all joints are wood to wood.

BTW, I use Titebond I for all of my builds. PL would be for special cases, sort of like Bondo.

Bob

xrk971 9th January 2013 07:20 PM

OK, I am new to these construction material terms. Bead board is polystyrene foam board - nice stuff! I will have to try it. What is PL?

malibujeff 9th January 2013 07:24 PM

Quote:

Originally Posted by xrk971 (https://www.diyaudio.com/forums/full-range/172605-frugel-horn-mk3-post3318344.html#post3318344)
OK, I am new to these construction material terms. Bead board is polystyrene foam board - nice stuff! I will have to try it. What is PL?

Adhesive. Here is a link:

Loctite PL Sealants, Adhesives, Construction Adhesives and Polyurethane Sealants | Loctite Adhesives

chrisb 9th January 2013 09:46 PM

Quote:

Originally Posted by Bob Brines (https://www.diyaudio.com/forums/full-range/172605-frugel-horn-mk3-post3318332.html#post3318332)
I have used PL to glue up complete speakers. Advantage: Long open time. You can put the whole thing together in one pass. Disadvantage: You need at least 24hr before applying any shear to the joints.

I anticipate a solid wood frame around all panels, like a MDF skinned door. That way, all joints are wood to wood.

sorta like airplane monocoque / beam box then?

Quote:

BTW, I use Titebond I for all of my builds. PL would be for special cases, sort of like Bondo.

Bob
Bondo = Terry Olsen's not so secret Polyester tone sauce ;)


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