Question on mounting Geddes' Waveguides. - diyAudio
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Old 18th February 2009, 03:06 PM   #1
JoshK is offline JoshK  Canada
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Default Question on mounting Geddes' Waveguides.

I bought a pair of 12" waveguides from Dr. Geddes. I did not buy the kit as this was prior to the release of the abbey kit. I was wondering if any others had bought just the waveguides.

If so, are your also fiberglass and cut square at the mouth? I ask because I am building my baffles and realizing that flush mounting these waveguides is a non-trivial task. A friend suggested one idea that just might work but I was hoping to gather more ideas on how to mount them.

I need to find pictures I took of the waveguides, as a picture is worth a thousand words. Essentially the difficulty arises, compared to a driver, in that there is no rim to mount to the baffle. There is a flat portion to glue to, but it is only in the corners of the square and there is nothing beyond the contour where the square tangents the mouth.

This is not an impossible task, but it isn't trivial either. I am looking to do a good job and would like to learn others' ideas to consider.
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Old 18th February 2009, 03:38 PM   #2
JoshK is offline JoshK  Canada
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Found the picture.
Attached Images
File Type: jpg waveguides_small.jpg (99.1 KB, 579 views)
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Old 18th February 2009, 09:53 PM   #3
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I got a pair of the 15" waveguides of that type that were made some time ago. Here's how I implemented them:

Side shot of a 'guide:

Click the image to open in full size.

Foam plug (top wasn't rounded at this point)

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The first thing I did was trim them down to a circle (~17" if I remember right)

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Then I routed a lip into the box and attached the wavguides via liquid nails

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Then I made a mounting plate for the compression driver's mounting plate to attach to (yours already have this):

Click the image to open in full size.

Then I reinforced the back of the waveguide with fiberglass (resin + matte + mdf ribs) and glassed on the mounting plate:

Click the image to open in full size.

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Then I sealed up around the mounting plate using bondo glass:

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Then on the front I plastered bondo on the area where the waveguide meets the baffle and sanded:

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Click the image to open in full size.

I then bondoed and sanded the throat area (maybe not relevant to your question but included for completeness)

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Click the image to open in full size.

After assembling the rest of the box I covered it with spray-on bedliner. The transition at the mouth is seamless.

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Finally, I rounded and attached the foam plugs with spray adhesive:

Click the image to open in full size.

On the whole the process was pretty straightforward- but a lot of that has to do with the coarse bedliner hiding some imperfections. If you were painting them you might have to be more careful about matching the hardness of the filler, glass, and wood and you'd definately have to sand it finer and do passes through with filler (and then primer).
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Old 18th February 2009, 10:39 PM   #4
JoshK is offline JoshK  Canada
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Thanks!
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Old 19th February 2009, 12:28 AM   #5
JoshK is offline JoshK  Canada
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What did you use to cut the WG?
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Old 19th February 2009, 12:41 AM   #6
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I used a bandsaw... not the best for the blade. I would normally use a jigsaw- either way the edge is pretty rough.
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Old 19th February 2009, 12:51 AM   #7
JoshK is offline JoshK  Canada
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Another net friend of mine suggested a "cartridge roll".

like these
http://www.sa-motorsports.com/cat/p1...#cartridgeroll

Reminds me of a bits I have for my dremel. I could cut some of the bulk off before hand to save lots of grinding.

The only gotcha I see is that, unlike your where you had excess "flat part" beyond the contour all the way around, I do not. In a couple places I am in the negative, as in if I place the guide face down on a flat surface there are places that are near 1/8" off the surface. I imagine I am going to have to fake it with bondo.

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Old 19th February 2009, 12:54 AM   #8
fb is offline fb  Australia
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I wonder if it's possible for Earl to update his waveguides to make them re/mountable like drivers are. The prices are a bit steep for something I can only use in one cabinet.
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Old 19th February 2009, 03:39 AM   #9
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Just a note: these are the older fiberglass versions. The new ones may be more reusable- I don't know. I bought mine secondhand for a lot less than what Earl charges now, but they needed a lot more work.

I pulled off a fiberglass negative in case I want to make some for use in another cabinet later:

Click the image to open in full size.
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Old 19th February 2009, 02:33 PM   #10
JoshK is offline JoshK  Canada
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One idea I thought of, but probably won't end up trying, is to build a rim for the waveguide so it can be remounted. Using plywood or mdf, build a circular rim, like a frame. Before permanently gluing the WG to the frame, mount bolts through the frame extruding out the back. These bolts can then be secured to the baffle from the inside. Ends up being too much work. I want results sooner.

The only real reason why I'd want to reuse the WG's is to try out OB versus a closed box. Guess I'll have to use my DDS WG's for that.
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