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Here is an interesting video about gluing foam together. The winner is Glidden Gripper.

https://www.youtube.com/watch?v=rnOegaOKu38

ray

I thought I might use a cabinet file after I have all the parts completed, to turn that abrupt change into a smooth transition with a little freehand modifiction of the relevant pieces.

If I can assemble the cabinet without gluing it together, I might just leave that alone to see what happens, and only try to fix it if I have to. (True DIY Fashion!)

I do not think you have to glue the slabs together. I do think you need to seal the face (edge) that forms the horn.

We built a variety of backhorns for 8" drivers, up to 4x 8" in one horn, using that stacked plywood technique.

The speakers are super heavy mofos! Something to consider for pro applications, if you are thinking of moving these around.

Also, unless you use very high grade ply, you will end up with a rough surface on the flare thanks to voids.
MDF might be better in this respect, but then they will be even heavier!

I have a pr of these drivers if you are interested...BOSE!!! No highs, no lowzzzz...

4 x 3 inch cones per driver, shooting into a combiner/manifold with a 3x9 rectangular orifice.

These are out of high end Bose pro stuff. Look like an ideal doodad for a project like this.

https://www.ebay.com/itm/BOSE-VEE-4-MID ... rmvSB=true

Let me know if you want to check them out.

The face needs to be reflective of High frequencies, right?

No, the flare near the mouth it does not need to be reflective. It was standard practice in many horns to put linen or other absorptive material in that part of the horn that will reflect at the listener.

Check out Western Electric 15A, 22A, 16A. Stock horns will still have the linen "bib" that they used.

i believe that the purpose of this was to catch reflections from the horns mouth back toward the driver. in a snail horn such as this, reflections will bounce off of the part of the flare that you can see and re-radiate.

We used leather in a resin backhorn mouth for this purpose, which helped a lot.

On the other hand, in the high compression area of the horn, i.e. near the driver, it pays to have as smooth a surface as possible. Diffraction in this area is not a good thing.

I question the little wiggle you put in the throat in this region. Iirregularities here are potential sources of distortion and wacky irregularities in the throat impedance.

Yes, I recognise too, that in that place, if some bad behavior occurs, it's only going to be magnified by the rest of the horn.

It's one part of the design that I can only mitigate, but I can't actually get around.

Thanks! This was my backup idea, when the CNC people I talked to, (mostly at sign companies) told me a sheet of plywood was going to cost me $200???

I appreciate the offer of tools too, but I don't exactly have a shortage of tools to accomplish it myself!

Because of the intensive labor, and because it's just an experiment, I think I'm going to hold out until I can do it CNC.

I have also made several revisions to the design since the post, and I figure by the time I actually get around to cutting some wood, there will be several more changes.

Chris

I question the little wiggle you put in the throat in this region. Iirregularities here are potential sources of distortion and wacky irregularities in the throat impedance.[/quote]

I kind of figured that this was not too big of a violation, because most folded horn designs I have seen, fire directly into a right angle throat.

I was hoping a little bit of straight on throat section, with a radius turn into the horn would be a little improvement over that.

You might see if there is any software that can simulate your horn -

http://educypedia.karadimov.info/electr ... peaker.htm