Wedgehorn 8's

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Charles Jenkinson
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Wedgehorn 8's

#1 Post by Charles Jenkinson »

…time to fess up.

I’ve started a couple of Wedgehorn 8’s, for my longer term project. But, I hadn’t planned on a build thread, because: it’s been done before, I don’t have much time to make them, never mind write it up with photos - I know, we make time to do the things we want to do, …and… I’m using Malaysian hardwood ply, which has a thin veneer on both sides, and is only 11mm thick. Don’t ask why – I must have been having a senior moment. The redeeming quality is that the veneer is bloody hard, as hard as the cores, and does appear to be properly bonded to the cores; it is also 18% lighter than BB ply. Still, I’m wondering if the 18ga nails will fire into it or just bounce off – maybe duct tape will be enough to hold the joints – it’s worked before.

With the concerns about delamination, I thought best to put a link following.

http://www.ehow.com/info_7789356_causes ... ation.html

I wouldn’t say the veneers are paper thin though, so there is hopefully some mitigation against ‘separation due to handling’.

I’ll post some photos of component pieces later.

...all the great advice I have for everyone else, shattered in a moment.
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Bruce Weldy
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Re: Wedgehorn 8's

#2 Post by Bruce Weldy »

There aren't the pressures in a W8 like there is in a sub.....build 'em, enjoy 'em.

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Charles Jenkinson
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Re: Wedgehorn 8's

#3 Post by Charles Jenkinson »

...phew, that's a relief. Thanks Bruce.

Here's some pictures of the piece parts.

3 of the trickiest things so far:

Trying to jig saw 2 thicknesses of this plywood is a no no - the blade bends off due to the hardness of the wood. I managed to fettle the baffle that was on the underside of the one that was marked out, but it was very wonky to start with.

Also, routering 2-off phase plug discs or driver spacers in one go is also tricky, unless all the pieces in the stack are screwed through.

Finally, cutting the mitres on the edges of the horn mouth pieces is tricky, on a table saw, mainly for the non parallel edges. I used the angle gauge T-slide to do it.

I have very much enjoyed cutting out the pieces though - nothing as satisfying as marking a piece of wood out and ending up with something close enough to the marks as to be useable. Of course, we will see about that, yet, LOL, but it's only practice and some technique, for those who are hesitant.
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Charles Jenkinson
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Re: Wedgehorn 8's

#4 Post by Charles Jenkinson »

Got the horns assembled this evening. The first one was a little out of square. I realised that guide marks are required to set the height position up the baffle of the first two horn side pieces fixed - if they are not exactly the right height it throws out the bottom horn mouth piece, when it is abutted into place. I measured down from the baffle upper most outside edge for the second horn, put some marks at both ends of each piece, and that horn is bang on square. These height-wise positioning marks are actually essential if using a square block to help set the pieces, as per the plans.

The duct tape holds the mitres quite well on the last two pieces fitted.
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Grant Bunter
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Re: Wedgehorn 8's

#5 Post by Grant Bunter »

Looking good so far Charles!
What you have done so far is the hardest part of these cabs to do.
Other than installing the driver lol...
Built:
DR 250: x 2 melded array, 2x CD horn, March 2012 plans.
T39's: 4 x 20" KL3010LF , 2 x 28" 3012LF.
WH8: x 6 with melded array wired series/parallel.
Bunter's Audio and Lighting "like"s would be most appreciated...

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Charles Jenkinson
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Re: Wedgehorn 8's

#6 Post by Charles Jenkinson »

Thanks Grant.

I sometimes wonder if the hardest part is not being able to just bloody get on with it. It's so frustrating.

I've been thinking about grills. I'm moving towards the soft mesh pet screen like Leland sells, fitted on removable Velcro-attached frames, covering the whole front. This will be in lieu of mesh on the baffle, so it has to be decided now.

Does anyone know if there is the room to set the horn back in the outer housing by say 1/4"? The reason is that I really want a small bit of the frame to return parallel with the outer box sides, so the mesh isn't stretching round a sharp edge. Also, the sharp edges don't always cut so well on the table saw. The other way I suppose is to let the frame stick out forwards of the front of the mouth but it wouldn't look as good as flush - a chamfered edge would make it look better if it stood proud.
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Re: Wedgehorn 8's

#7 Post by Grant Bunter »

Charles Jenkinson wrote:Thanks Grant.

I sometimes wonder if the hardest part is not being able to just bloody get on with it. It's so frustrating.
Totally understood, my current build is going very slowly. I've decided to not get frustrated about that, and do what I can when I can.
Charles Jenkinson wrote:I've been thinking about grills. I'm moving towards the soft mesh pet screen like Leland sells, fitted on removable Velcro-attached frames, covering the whole front. This will be in lieu of mesh on the baffle, so it has to be decided now.
I don't like the idea myself.
Even a metal grille is only as protective as the degree to which a moment of showmanship leads the showman to think about how hard they are putting their foot through the front of the cab.
Charles Jenkinson wrote:Does anyone know if there is the room to set the horn back in the outer housing by say 1/4"? The reason is that I really want a small bit of the frame to return parallel with the outer box sides, so the mesh isn't stretching round a sharp edge. Also, the sharp edges don't always cut so well on the table saw. The other way I suppose is to let the frame stick out forwards of the front of the mouth but it wouldn't look as good as flush - a chamfered edge would make it look better if it stood proud.
Ignoring the curved front, look at Nim's WH10 build here:
http://billfitzmaurice.info/forum/viewtopic.php?t=14761

He shows you how to set back the horn...
Built:
DR 250: x 2 melded array, 2x CD horn, March 2012 plans.
T39's: 4 x 20" KL3010LF , 2 x 28" 3012LF.
WH8: x 6 with melded array wired series/parallel.
Bunter's Audio and Lighting "like"s would be most appreciated...

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Charles Jenkinson
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Re: Wedgehorn 8's

#8 Post by Charles Jenkinson »

'A moment of showmanship', ...lol, that creased me up Grant, thank you.

It's funny, the kids had bedknobs and broomsticks on this morning, where Emelius Brown (David Tomlinson) was trying to woo Miss Price (Angela Lansbury) that they should 'combine her know how with his show how' - I think he was talking about a business venture. Masterful, even if nauseating.

Ok, I've read Nimrod's thread. There's a lot of know how and some show how going on - I would wager he's done a lot of Google sketch up on that, and is not actually moving the horn back in the shell at all. Of course, a curved steel mesh grill will take a showman's foot a lot better than even a flat steel mesh grill, and maybe that is the idea. But that pet mesh screen is extremely strong; polyester / glass fibre thread...? I'd be interested to hear if anyone has ever even managed to tear it by puncturing a stretched out sheet on a frame. Putting a foot through it would require someone to put all their weight on it (on an angle?) and even then I would think the frame would break first, or the means by which the mesh is secured to the frame would let go. I made the frame for the front of my XF212 out of hardwood - much stronger and stiffer in bending than plywood.

without doing Google sketch up mods and modifying major parts before sticking it all together, the way to achieve the step is either extend the shell forwards by sticking more wood on, or trim a bit of the sharp edge off the front of the horn piece. I believe there is not much room in the back of these things anyway. I'll draw up a couple of ideas of how it could be done, and muse on it.

I have contemplated metal grill, and could still do it, but the cost started to bother me, of getting the right perforated mesh pattern, then bright zinc plating it (if mild steel) and an appropriate painting method. If it isn't etch primed, the paint may not adhere properly. I liked Jools WH8 hex mesh - this is what was in mind. I feel that There's a lot of steps in the dance with metal grills if they're going to look good.
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LelandCrooks
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Re: Wedgehorn 8's

#9 Post by LelandCrooks »

It would take a concerted effort to tear pet screen, along with something sharp. I'm certain it would tear loose from the frame long before the screen would tear.
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Re: Wedgehorn 8's

#10 Post by Grant Bunter »

Charles Jenkinson wrote:and is not actually moving the horn back in the shell at all. Of course, a curved steel mesh grill will take a showman's foot a lot better than even a flat steel mesh grill

the way to achieve the step is either extend the shell forwards by sticking more wood on, or trim a bit of the sharp edge off the front of the horn piece. I believe there is not much room in the back of these things anyway.
Correct, it's not moving the horn backwards further, that's impossible, it's leaving it forward initially, and trimming, before setting it in it's final position, leading to a recess.

While it's cool to see the curved look, it was more about showing you the concept of trimming the horn...
Built:
DR 250: x 2 melded array, 2x CD horn, March 2012 plans.
T39's: 4 x 20" KL3010LF , 2 x 28" 3012LF.
WH8: x 6 with melded array wired series/parallel.
Bunter's Audio and Lighting "like"s would be most appreciated...

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Charles Jenkinson
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Re: Wedgehorn 8's

#11 Post by Charles Jenkinson »

One shell in the partial assembled.

I found the trickiest joint was the bottom to lower back mitre. It required the un-glued top-side on with all edges lined up correctly and checked for square before the bottom panel can be set right.
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Charles Jenkinson
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Re: Wedgehorn 8's

#12 Post by Charles Jenkinson »

A little bit of progress today.

New tool required for the job of fitting the horn to the shell - an electric planer - I found the oblique cut through the plywood too challenging to trim with a small hand plane.

I'd quite like to leave the horn back 5mm in the shell so that the front mesh support frame can be a slightly different shape and be Velcro-attached. There's enough room to get the driver in as long as it won't affect tuning.
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Chris_Allen
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Re: Wedgehorn 8's

#13 Post by Chris_Allen »

I've used electric planers on the end panels of cabs when they are quite square but they are very unforgiving if you kick out at right angles to the grain.

These cabs are looking great. How are you going to finish them?
Built:
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Bill Fitzmaurice
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Re: Wedgehorn 8's

#14 Post by Bill Fitzmaurice »

Chris_Allen wrote:I've used electric planers on the end panels of cabs when they are quite square but they are very unforgiving if you kick out at right angles to the grain.
That's not the tool to use. A router atop a sled is. Even a circular saw atop a sled.

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Chris_Allen
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Re: Wedgehorn 8's

#15 Post by Chris_Allen »

Bill Fitzmaurice wrote:That's not the tool to use. A router atop a sled is. Even a circular saw atop a sled.
I didn't have a router at the time and I couldn't cut square either! Fortunately, I don't have those problems now :D
Built:
6xDR200, 2xT39, 2xT48, 2xJack110, 1xOmni10.5, 1xAutotuba, 1xT18, 1xSLA Pro, 1xW8, 1xW10

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