Compression horn for DR250 question

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Grant Bunter
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Compression horn for DR250 question

#1 Post by Grant Bunter » Tue Jan 08, 2019 2:04 am

In the middle of a new build.
Just installed the diffraction rod holder in the middle of module 1 (prior to adding module sheaths) and it sits back, say, the front edge of the 5/8" hole is 1/2" to 3/4" from the leading edge of the module.

Sketchup shows me it should sit flush with the leading edge of the module.

It's got me baffled as all the measurements are all spot on otherwise, in line with the plans and sketchup as well.

I assume the diffraction rod being further back decreases horizontal dispersion and that's an issue.

Do I need to fix it?

TIA
Built:
DR 250: x 2 (melded array) with March 2012 plans. 2 more under way with CD horn
T39's: 4 x 20" BP102 , 2 x 28" 3012lf.
WH8: x 3 with melded array.
Bunter's Audio and Lighting "like"s would be most appreciated...

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Chris_Allen
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Location: Huddersfield, UK

Re: Compression horn for DR250 question

#2 Post by Chris_Allen » Tue Jan 08, 2019 2:58 am

I've not built the new module in the DR's, mine are the old design. Could you send a picture to highlight what you are describing?
Built:
6xDR200, 2xT39, 2xT48, 2xJack110, 1xOmni10.5, 1xAutotuba, 1xT18, 1xSLA Pro, 1xW8, 1xW10

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Bill Fitzmaurice
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Re: Compression horn for DR250 question

#3 Post by Bill Fitzmaurice » Tue Jan 08, 2019 8:01 am

The rod should be flush, or very close to flush, with the leading edge of the horn.

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J_Dunavin
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Re: Compression horn for DR250 question

#4 Post by J_Dunavin » Tue Jan 08, 2019 11:51 am

When I built them for the 200s I did this last summer, I had to cut them a little oversized then sand to fit.
1/2 inch back sounds like way too much.
I know you said your measurements are spot on, but is the angle of the two front pieces correct? I could foresee if they were too wide how that might cause this issue.
6 - DR200
2 - DR250
9 - T24
6 - T45
1 - Auto Tuba

Grant Bunter
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Joined: Mon Nov 28, 2011 11:12 am
Location: Ilfracombe Queensland Australia
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Re: Compression horn for DR250 question

#5 Post by Grant Bunter » Tue Jan 08, 2019 3:13 pm

J_Dunavin wrote:
Tue Jan 08, 2019 11:51 am
...but is the angle of the two front pieces correct?
Thanks all.

Now the module is cured and I could remove it to inspect;
Turns out one of the 2 front pieces has been bowed in construction.
Consequently the diffraction rod holder is also out of kilter. My bad.
It's not as bad as I first thought, but needs addressing.

Next step, see if I can rescue that half of the module, or start over on that half...
Built:
DR 250: x 2 (melded array) with March 2012 plans. 2 more under way with CD horn
T39's: 4 x 20" BP102 , 2 x 28" 3012lf.
WH8: x 3 with melded array.
Bunter's Audio and Lighting "like"s would be most appreciated...

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J_Dunavin
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Joined: Sun Jul 09, 2006 3:13 pm
Location: Appleton WI

Re: Compression horn for DR250 question

#6 Post by J_Dunavin » Tue Jan 08, 2019 3:35 pm

Well, at least you know what the culprit is.
6 - DR200
2 - DR250
9 - T24
6 - T45
1 - Auto Tuba

Grant Bunter
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Joined: Mon Nov 28, 2011 11:12 am
Location: Ilfracombe Queensland Australia
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Re: Compression horn for DR250 question

#7 Post by Grant Bunter » Wed Jan 09, 2019 3:06 am

J_Dunavin wrote:
Tue Jan 08, 2019 3:35 pm
Well, at least you know what the culprit is.
Sure do!

Cheers J
Built:
DR 250: x 2 (melded array) with March 2012 plans. 2 more under way with CD horn
T39's: 4 x 20" BP102 , 2 x 28" 3012lf.
WH8: x 3 with melded array.
Bunter's Audio and Lighting "like"s would be most appreciated...

CoronaOperator
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Joined: Wed Mar 25, 2009 7:07 pm
Location: Medicine Hat, Alberta, Canada

Re: Compression horn for DR250 question

#8 Post by CoronaOperator » Wed Jan 09, 2019 3:31 am

Grant Bunter wrote:
Tue Jan 08, 2019 3:13 pm

Turns out one of the 2 front pieces has been bowed in construction.
Had that happen to me on my build too, I cut them a smidgen too long and when I put them in place they bowed in on me.

Do you have an oscillating saw? They'll un PL anything you already PL'd without making a mess.
Built:
17" width 10" driver Autotuba
2 x 29" width dual Lab12 Tuba60
6 x DR250 2510/asd1001
In progress:
2 x DR250 2510/asd1001
For best results, point the loud end of the array towards the audience

Grant Bunter
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Joined: Mon Nov 28, 2011 11:12 am
Location: Ilfracombe Queensland Australia
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Re: Compression horn for DR250 question

#9 Post by Grant Bunter » Wed Jan 09, 2019 3:01 pm

CoronaOperator wrote:
Wed Jan 09, 2019 3:31 am
Grant Bunter wrote:
Tue Jan 08, 2019 3:13 pm

Turns out one of the 2 front pieces has been bowed in construction.
Had that happen to me on my build too, I cut them a smidgen too long and when I put them in place they bowed in on me.

Do you have an oscillating saw? They'll un PL anything you already PL'd without making a mess.
Certainly do have an oscillating saw CO. Magic they be for such situations :)
Hopefully onto the repair today...
Built:
DR 250: x 2 (melded array) with March 2012 plans. 2 more under way with CD horn
T39's: 4 x 20" BP102 , 2 x 28" 3012lf.
WH8: x 3 with melded array.
Bunter's Audio and Lighting "like"s would be most appreciated...

Grant Bunter
Posts: 5964
Joined: Mon Nov 28, 2011 11:12 am
Location: Ilfracombe Queensland Australia
Contact:

Re: Compression horn for DR250 question

#10 Post by Grant Bunter » Fri Jan 11, 2019 2:34 am

A few cuts with the oscillating saw, a bit of shoving and pushing, a bigger hammer, some :cussing: re PL'ed and it's all sorted.

It still fits back into the cab again as well!
I'm amazed.

Thanks everyone :)
Built:
DR 250: x 2 (melded array) with March 2012 plans. 2 more under way with CD horn
T39's: 4 x 20" BP102 , 2 x 28" 3012lf.
WH8: x 3 with melded array.
Bunter's Audio and Lighting "like"s would be most appreciated...

ACUA
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Joined: Sun Sep 25, 2016 6:21 pm

Re: Compression horn for DR250 question

#11 Post by ACUA » Fri Jan 11, 2019 5:25 pm

Them diffraction horns are about the hardest thing I have ever fabricated with the limited tooling I have!!!
Advanced concepts underground audio

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Tom Smit
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Location: Sarnia, Ont. Canada

Re: Compression horn for DR250 question

#12 Post by Tom Smit » Sat Jan 12, 2019 12:36 am

That means that you are getting more "pro"! Yeehaw, haha! :clap:
TomS

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