throat filler question

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didjital
Posts: 21
Joined: Thu Jun 23, 2016 2:48 pm

throat filler question

#1 Post by didjital »

Im about half way through building a pair of dr280s and have a question.

I've had a lot of experience with foam over the years as an avid rc plane builder/pilot. Specifically with the type of foam that the throat filler is supposed to be made of. 5he whole idea of cutting and sanding the foam and then leaving it bare has me a little concerned. In my experience, over time, that type of foam dries out and gets crumbly. Because of my fear of this, I ordered "molded" fillers from a supplier. I expected these "molded" parts to have a melted foam "skin" on the outer surface like most molded foam parts do. When the parts arrived I was disappointed to find that they were just laminated building foam cut and sanded as per the plans, not molded in the usual expanded-polystyrene-in-a-steamed-mold technique.

Anyway, I'm wondering if I should treat them in some way to curtail the deterioration process. I have foam-safe clear spray, as well as tons of acrylic paint and an airbrush. Do the fillers need to be absorbent to work? I've also thought of making them out of expanded polypropylene foam, but it's closed cell type foam (not absorbent). Could I make them from wood? The ones I bought are already the right shape and size, so I'd rather go the surface treatment route if possible. Any thoughts?

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Tom Smit
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Joined: Sat Jan 05, 2008 1:24 pm
Location: Sarnia, Ont. Canada

Re: throat filler question

#2 Post by Tom Smit »

I used the pink insulation of which I had found during someone's renovation. I looked online and found a DIY hot-wire cutter method and it turned out pretty good!
If you want, you may build it out of wood.
TomS

CoronaOperator
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Location: Medicine Hat, Alberta, Canada

Re: throat filler question

#3 Post by CoronaOperator »

didjital wrote:Im about half way through building a pair of dr280s and have a question.
That is a mirage that you see, the halfway point is on the other side of the horizon.

Image

I used the pink insulation as well. If you are worried about it you can easily slap a coat of latex paint on the fillers. Do that after you do the rub test with the test tones. I had to sand down as least 6 of mine to get the rubbing to go away. There won't be any uv rays inside the cabinet so I don't think the foam will break down like on a RC wing.
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

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LelandCrooks
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Re: throat filler question

#4 Post by LelandCrooks »

I'm sorry you were disappointed. My website pretty clearly shows they're the blue foam, does not say molded. My molded supplier quit at least 5 years ago. Then the plans were modified so only the DR's use these, making the creation of new molds and finding a new supplier cost prohibitive for the number of fillers sold.
Feel free to return them for a full refund.
If it's too loud, you're even older than me! Like me.
http://www.speakerhardware.com

didjital
Posts: 21
Joined: Thu Jun 23, 2016 2:48 pm

Re: throat filler question

#5 Post by didjital »

I was not upset leland...that's why I did not mention the place I bought them. It's my fault for thinking they were still molded....

I'm going to keep them for sure as I would still have to make them, probably the same way you did anyway:)

Do you reckon I need to do the test tones to see if they rub the 3012hos? Or are you confident that they are sized properly. If I do test them, how do I know if they are hitting the driver? What will it sound like?

didjital
Posts: 21
Joined: Thu Jun 23, 2016 2:48 pm

Re: throat filler question

#6 Post by didjital »

Corona operator:
I'm at that exact stage in my build. Not the halfway point? :(

CoronaOperator
Posts: 1648
Joined: Wed Mar 25, 2009 7:07 pm
Location: Medicine Hat, Alberta, Canada

Re: throat filler question

#7 Post by CoronaOperator »

didjital wrote:Do you reckon I need to do the test tones to see if they rub the 3012hos? Or are you confident that they are sized properly. If I do test them, how do I know if they are hitting the driver? What will it sound like?
If you don't mount the driver and test them now, then mounting the driver, removing it to sand and repeating the process is extremely difficult once the sides go on. 6/8 of mine required sanding, some I had to remove the driver, sand, remount the driver, test and remove the driver and sand more than once. All mine were sized to the plans but thickness of glue and lining them up properly, centering the driver, how far the gasket compresses on the driver, etc all play a part to whether or not they will rub, do the test as per the plans.

You will hear a very distinct ratt-a-tat-tat if they rub. It will go away if you lower the volume level.
didjital wrote:I'm at that exact stage in my build. Not the halfway point? :(
That depends on what your idea of halfway is. You could very well be halfway to the halfway of the halfway point, hard to tell :D. They're worth it.
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

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LelandCrooks
Posts: 7244
Joined: Thu May 04, 2006 9:36 am
Location: Midwest/Kansas/Speaker Nirvana
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Re: throat filler question

#8 Post by LelandCrooks »

Pretty confident. Test them anyway.
If it's too loud, you're even older than me! Like me.
http://www.speakerhardware.com

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