heart 21" scoop design

7 years 5 months ago #19771 by Reality Sound
Replied by Reality Sound on topic Re: 21" scoop design
Chamber Volume?
please tell me if I am doing this wrong :whistle:
Starting at the bottom,
(little triangle) 130 X 225 = 29250, 29250/2= 14625
(rectangle above it) 565 X 225 = 127125
(area in driver cutout- do you include this?) 490 X 36 = 17640
Total area = 159390 mm2
If 600mm internal width- 95.634 L
Correct?

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7 years 5 months ago #19775 by Dref
Replied by Dref on topic Re: 21" scoop design
Don't include the driver cutout.

But is the 171 part the narrowest part?
What if you draw a line from the rear baffle to the front part of the horn. Perpendicular to the panel of the front part?

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7 years 5 months ago #19776 by Reality Sound
Replied by Reality Sound on topic Re: 21" scoop design
So the area is 141759mm2.
600 mm wide volume = 85.0 L
610 mm = 86.4 L
620 mm = 87.8 L
630 mm = 89.3 L

"What if you draw a line from the rear baffle to the front part of the horn. Perpendicular to the panel of the front part?"
You just want that measurement?

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7 years 5 months ago #19777 by Reality Sound
Replied by Reality Sound on topic Re: 21" scoop design

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7 years 5 months ago #19778 by Dref
Replied by Dref on topic Re: 21" scoop design
Ah yes, though it looked like the narrowest point. So your horn starts at the 149 line. Everything above is the rear chamber (the volume you need to calculate).

Also now we get to the point where you should consider if the throat is too narrow for this driver.
14.9cm x 60cm = 894cm2.
I still recommend to get it at around 1200cm2 to get proper low bass response. What is the maximum inner width you can tolerate?

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7 years 5 months ago #19779 by Reality Sound
Replied by Reality Sound on topic Re: 21" scoop design
I don't mind making it wider (as long as I can get it thru a door) but to get that to 1200cm2 (keeping it at 14.9cm) it would have to be 805 mm wide (31inches)
So can I make the rear baffle shorter?
If I make the internal width 630, then I only need the horn path to start at 190mm instead of 149. Which can probably be achieved by chopping an inch off the rear baffle length.
Thoughts?

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7 years 5 months ago - 7 years 5 months ago #19780 by Dref
Replied by Dref on topic Re: 21" scoop design
Yep, my thought exactly. Make it the width you find practical and then try to adjust the rear baffle.
Keep an eye out for if the throat point changes its location.

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7 years 5 months ago - 7 years 5 months ago #19781 by bee
Replied by bee on topic Re: 21" scoop design
why not shorten the back baffle, this will give you a bigger throat......
or add length to the front baffle.....

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7 years 5 months ago #19782 by bee
Replied by bee on topic Re: 21" scoop design
by taking 10mm off the back baffle and adding 10mm to the front baffle will open up the throat a bit...

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7 years 5 months ago #19788 by Dref
Replied by Dref on topic Re: 21" scoop design
Making the rear baffle shorter was what we were talking about, but yea you are right it might also be a feasible idea to make the front baffle slightly longer. :)

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