OB Dampening.....more newb questions

lord_glum · « **on:** 17 Oct 2008, 08:27 pm »

So I orderd the full set of hawthornes...15" SI and Augies. I have my test baffle planes worked out. I am using 3/4" birch and 1/2" MDF. Hoping the different densities help with resonance. I have 3 quesitons....

1. I am doing the regular l_ shaped baffle. My run a bit of wood on the sides for bracing. I am looking for experience on what people are using. I have seen fancy rouneded braces to shelf bracket. Looking for some examples.

2. I have seen various levels of sound damping material....all over the back of the baffle to none. I am going to start out at none and go from there, but I am looking for some reference.

3. Looking for ideas for places to put the augie amp...

Thanks,
Jvo

hurdy_gurdyman · « **Reply #1 on:** 17 Oct 2008, 10:03 pm »

There are a lot of examples in the Hawthorne Audio Gallery. http://www.hawthorneaudio.com/photos/

Dave

Bob in St. Louis · « **Reply #2 on:** 17 Oct 2008, 10:06 pm »

#1 If you run wood down the sides for bracing, don't make "wings" around the SI's. It'll muck up the sound (IMO). As far as the shelf brackets are concerned, those are only used as an inexpensive way to make 'feet' to keep the baffle upright, seldom are they used as tone controls. If the feet are straddling the Augie you can use them as tone controls (wings), but not very nessesary (IMO, again).
Since you're doing two layers of dissimilar material, one interesting idea is to use GreenGlue (GG) as the adhesive between the layers. If you do this, do not make any physical/mechanical contact between the two layers (nails, screws etc...) as it will defeat the purpose of the GG.

#2 "Backing" material for the baffle: Some folks use felt, some use the spongy kitchen cabinet shelf liner (also sold in woodworking stores as "the third hand" for woodbenches.

#3 Amp location: I put mine in the equipment rack. No reason to bring 110volts near your speakers.

Hope that helps J

Bob

Bob in St. Louis · « **Reply #3 on:** 17 Oct 2008, 10:21 pm »

Green Glue:

lord_glum · « **Reply #4 on:** 17 Oct 2008, 11:34 pm »

I browesed the hawthorne gallery for a bit last night and got some ideas. I know the basic layouts, now my questions are a bit more into the details.

Yeah i was planning on just using glue. I was just planning on using titebond, but I can change that I guess.

So people just line the back of the baffle with felt? I was talking more along the lines of blackhole 5 or something similar.

Also,
has anybody used damar on the cone of the midrange?

Thanks,
Jvo

Bob in St. Louis · « **Reply #5 on:** 18 Oct 2008, 02:15 pm »

Not once have I heard of anyone using Damar on the cones, I know of one fella that's been wanting to try it, but hasn't yet. Maybe he'll chime in here.

Felt, yup, just plain felt. I do think there's a few fellas using Blackhole or something similar, but not too many that I know of.
The backs of mine are coated with "Great Stuff" expanding foam. After it was finished expanding and completely dried, I used a belt sander to shape it, and knock off the hard "shell". What remains is spongy to the touch and very porous. A light mist of aerosol textured paint gave it a very interesting look and that "softness" for the back of the baffle we're talking about.

For general baffle building tips, it's generally thought to be a good idea to have rounded edges as opposed to having two 90 degree sharp turns from the front to the sides, then to the back edges. Places where the front and rear waves meet should be smooth.

Bob