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Multi-Way Conventional loudspeakers with crossovers

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Old 12th September 2019, 02:16 PM   #191
mabat is offline mabat  Czech Republic
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If you google for "Windows error 0xc000007b" you will see it's quite a common problem but a one I can't really help you with, sorry. I have no such experience myself.
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Old 12th September 2019, 03:26 PM   #192
natehansen66 is offline natehansen66  United States
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Ok thanks I see a few things I can try
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Old 13th September 2019, 06:05 AM   #193
martingc is offline martingc
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I had the same error when I used the 32 bit dll but when I used the 64 bit dll the error went away
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Old 13th September 2019, 09:21 PM   #194
FredrikC is offline FredrikC  Norway
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So I finally had an hour to play around with ATH4 today, trying to design a waveguide to mate with a 6.5-7" woofer around 1.6-2kHz somewhere.

I ended up turning the Depth.ConicSectionPart almost all the way to the lowest setting, leading to a very gradual change in slope almost all the way from the throat to the exit.

This lead to a profile that looks quite beamy/narrow when looking at the profile.
10-proto.PNG

but according to the BEM, it is not:

10-proto-polar.png
10-proto-polar-curves.PNG


Will be interesting to compare a 3D printed version to the BEM once I settle on a design.

Anyone who has some favorite combo of parameters they want to share?

Again, thanks to mabat for this excellent piece of software.

Here are the settings used to obtain the above polars:


Code:
ThroatDiameter = 16                 ; [mm]
  ThroatAngle = 0                       ; [deg]
  Coverage_Horizontal = 90             ; [deg]
  Coverage_Vertical = 90                ; [deg]
  Depth = 94                          ; [mm]
  Depth.ConicSectionPart = 0.12        ; 0.1-0.9
  Shape = raw                      ; raw | raw2rect
  Shape.FixedPart = 0.2                 ; 0.2
  Shape.CornerRadius = 38.0             ; [mm]
  SEExp = 2                     ; superellipse exponent
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Old 13th September 2019, 09:30 PM   #195
mabat is offline mabat  Czech Republic
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Fredrik, there will be a substantial mismatch of curvatures when joined such close to the throat. That's because I forgot to take a curvature of the hyperbola into account - now it's allways connected to a clothoid that starts from zero curvature. It's OK for junctions more into the waveguide but in this case it gets much more evident. I would recommend to wait until I fix this. Or, you can try this... It will "only" create a little more diffraction in the throat than necessary I guess. (And who knows - it may be better after all )

Or you could just prolong the conic section part a bit..

Last edited by mabat; 13th September 2019 at 09:42 PM.
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Old 13th September 2019, 09:40 PM   #196
FredrikC is offline FredrikC  Norway
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Quote:
Originally Posted by mabat View Post
Fredrik, there will be a substantial mismatch of curvatures when joined such close to the throat. That's because I forgot to take a curvature of the hyperbola into account - now it's allways connected to a clothoid that starts from zero curvature. It's OK for junctions more into the waveguide but in this case it gets much more evident. I would recommend to wait until I fix this. Or, you can try this... It will "only" create a little more diffraction in the throat than necessary I guess. (And who knows - it may be better after all )
Okey, but how substantial can it be? Looks pretty smooth both in CAD and BEM
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Old 13th September 2019, 09:45 PM   #197
mabat is offline mabat  Czech Republic
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Yeah, it does indeed. It is smooth in tangency but not in the curvature (second derivative, i.e. the osculating circle radius). I'm not sure you would see such subtle things in a simluated field. But you may hear it.
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Old 13th September 2019, 09:51 PM   #198
FredrikC is offline FredrikC  Norway
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I see. Looking forward to your update then.

In the end, it is the real-life result that matters. I'm curious how close the BEM gets to the real deal.
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Old 13th September 2019, 09:55 PM   #199
mabat is offline mabat  Czech Republic
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Also don't forget that this is still only for an infinite baffle. In reality the baffle with all its edges might make a big difference (for the worse). But I would say you have quite a good starting point.

- Haven't you tried making it a bit shallower? For such a small woofer it seems pretty deep...

Last edited by mabat; 13th September 2019 at 09:58 PM.
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Old 13th September 2019, 10:01 PM   #200
FredrikC is offline FredrikC  Norway
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For sure, but first I will be interested in mounting the WG to a large baffle to mimic the infinite baffle.

Then if the correlation is good, it would be tempting to measure them in a more normal narrow baffle and try to recreate this in BEM. When you have something that matches there, the system could be optimized together.. baffle, edges and WG as a system.
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