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Multi-Way Conventional loudspeakers with crossovers

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Old 13th September 2019, 10:06 PM   #201
mabat is offline mabat  Czech Republic
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Sure. When made large enough in a large enough free space, a gated impulse response will make the baffle look virtually infinite. That should work. The good thing is that you don't need to get very much down low in frequency, so you don't need a long time window.

Looking forward to your results!
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Old 18th September 2019, 12:37 PM   #202
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For anyone's interest, this is the radius of curvature of the OS profile for the first 100 mm - for 1" and 2" throats, 90 deg coverage.

Code:
# Gnuplot code

set terminal pngcairo size 1200,1000 font "Helvetica,12"
set output "oswg.png"

rt = 25
alpha = 45

set angles degrees
k = rt*rt
q = tan(alpha)
q = q*q
pow3(x) = x*x*x

wg(x) = sqrt(k + q*x*x)		                # OS profile
wg1(x) = atan(q*x / (sqrt(k + q*x*x)))          # first derivative
wg2(x) = q*k / sqrt(pow3(k + q*x*x))            # second derivative
rk(x) = sqrt(pow3(k + (q + q*q)*x*x)) / (q*k)   # radius of curvature

set title sprintf("OSWG radius of curvature: dt=%g mm, alpha=%g deg", 2.0*rt, alpha)
set xrange [0:100]
set xtics 10
set xlabel "x [mm]"
set logscale y
set ylabel "R [mm]
set grid

plot rk(x) lw 2 not
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File Type: png oswg1.png (41.5 KB, 346 views)
File Type: png oswg2.png (40.8 KB, 367 views)
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Old 18th September 2019, 01:11 PM   #203
mabat is offline mabat  Czech Republic
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First and second derivative. Waveguide with a smaller throat approaches a cone a bit faster, i.e. it is less prone to curvature mismatch at the joint (as talked about eariler).
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File Type: png oswg-d1.png (58.8 KB, 366 views)
File Type: png oswg-d2.png (59.1 KB, 369 views)

Last edited by mabat; 18th September 2019 at 01:13 PM.
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Old 18th September 2019, 03:11 PM   #204
mabat is offline mabat  Czech Republic
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Finally, radius of curvature for the three common throat sizes in comparison, and wall slopes.
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File Type: png oswg.png (65.4 KB, 337 views)
File Type: png oswg_slopes.png (63.6 KB, 46 views)

Last edited by mabat; 18th September 2019 at 03:20 PM.
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Old 18th September 2019, 03:47 PM   #205
mabat is offline mabat  Czech Republic
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Corresponding actual profiles
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Old 18th September 2019, 04:30 PM   #206
mabat is offline mabat  Czech Republic
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This is for a throat entry angle of 25 deg (wall to wall) - some drivers do have exit angle this large. I still wonder whether it helps in shaping a spherical wavefront in the end (?). I guess it should but then a spherical wave at the throat entrance would be assumed. And that may be the catch.
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Old 19th September 2019, 09:48 AM   #207
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What would be a better junction point, A or B?
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Old 19th September 2019, 11:03 AM   #208
Dave Zan is offline Dave Zan  Australia
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Quote:
Originally Posted by mabat View Post
What would be a better junction point, A or B?
I don't understand the question.
Can you provide some context?

Best wishes
David
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Old 19th September 2019, 11:26 AM   #209
mabat is offline mabat  Czech Republic
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The question is where to cut a clothoid to be joined to a hyperbola, A and B are the two possible places. In the current release of the tool it is allways cut in the middle (between A and B) and connected to a hyperbola disregarding curvature of the latter - that is wrong. I need to find a point of the same curvature on the clothoid and take if from there. I can do it either in point A or in point B, the curvature is the same.

I would tend to choose B but it could be made as an option.
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Old 19th September 2019, 11:41 AM   #210
Dave Zan is offline Dave Zan  Australia
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Quote:
Originally Posted by mabat View Post
The question is...
I would tend to choose B but it could be made as an option.
Now I understand.
If it was an option then it would be educational to see what difference it makes.

Best wishes
David
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