The mesh frequency parameter is what controls much of the resolution in CircSym,
ABEC.MeshFrequency = 40000, it can be set higher without too much time penalty. It is only solving in one axis so the way it shows as segmented around the axis doesn't matter.
Mesh.LengthSegments will change how smooth the curve is represented by the points which can matter too
Your driven element looks very strange, I would start there to see what is going on.
Your results are weird because the interface is in the wrong place, likely it's set at a point that's closer than where the baffle actually is
It's set to 1 since I'm only simulating the source without a waveguide. Changing the last numbers defining the points seems to have a minimal effect
Yeah I don't mean the look around the axis, but the radial steps (which aren't super bad but could be better for sure).
I can't change LengthSegments simulating only the source. I also tried simulating the coaxial cone instead of the tweeter (Velocity set to 2) but the results are pretty much the same so I guess I'm doing something fundamentally wrong.
There's no interface defined as it's not required in a freestanding sim. I tried adding it but it made no difference.
Here's a slightly simplified example giving similar results
Code:
Length = 0 ; [mm]
Source.Contours = {
point p1 4 0 0.5
point p2 0 12 0.5
point p3 -1.26 50.5 0.5
point p4 -97.1 0 0.5
cpoint c1 -16 0
cpoint c2 -14.8 30.8
cpoint c3 -35.9 0
arc p1 c1 p2 1.0 ;tweeter
arc p2 c2 p3 0 ;woofer cone
arc p3 c3 p4 0 ;enclosure
}
Mesh.LengthSegments = 1
Mesh.SubdomainSlices =
ABEC.SimType = 2
ABEC.SimProfile = 0
ABEC.f1 = 200 ; [Hz]
ABEC.f2 = 20000 ; [Hz]
ABEC.NumFrequencies = 100
ABEC.MeshFrequency = 40000 ; [Hz]
ABEC.Polars:SPL = {
MapAngleRange = 0,180,37
NormAngle = 10 ; [deg]
Distance = 3 ; [m]
}
Report = {
Title = "Demo"
NormAngle = 10
Width = 1024
Height = 768
}
Output.ABECProject = 1
I've never done what you're doing so I don't know if this is the correct approach. This is a Dayton DC200-8 woofer where the dust cap is the source and the cone is deactivated - works like a waveguide. It covers an OSSE Horn that is the same outside diameter as the woofer but does not interfere with the woofer cone. The OSSE Horn is used to create the rear enclosure using the Mesh.RearShape and Mesh.RearCubic commands. You could modify the DC200-8 woofer settings to look like the woofer and tweeter you're going to use and to roll back to the rear enclosure.
You can activate portions of the woofer in the bolded lines. If you modify the dust cap to look like your tweeter you probably want a higher resolution than I used to properly model your high frequencies (more than 10). Or maybe you don't need to worry about that in CircSym mode, I'm not sure.
Source.Contours = { ; Dayton DC200-8 Woofer
zoff -24 ; -24 = external mount, -30 = flush mount, -49 = recessed mount w/ 19 mm plywood, -32 = rear flush mount
point p1 12 0 20 ; center of dome
point p2 0 35 20 ; inner edge of cone
point p3 24 75 20 ; outer edge of cone/ inner edge of surround
point p4 31 82 20 ; peak of surround
point p5 24 89 20 ; outer edge of surround
point p6 24 93 0 ; outer edge of divot/ inner edge of mount bracket
point p7 31 93 0 ; inner peak of mount bracket
point p8 31 104 0 ; outer peak of mount bracket
point p9 24 104 0 ; outer edge of mount bracket
cpoint c1 -50 0 ; center of dome arc
cpoint c2 24 82 ; center of surround arc
arc p1 c1 p2 10 ; dome arc (replace 10 with 0 to turn off)
arc p3 c2 p4 0 ; inner half of surround arc (replace 0 with 10 to turn on)
arc p4 c2 p5 0 ; outer half of surround arc (replace 0 with 10 to turn on)
line p2 p3 0 ; cone line (replace 0 with 10 to turn on)
line p5 p6 0 ; divot line
line p6 p7 0 ; divot to peak mount line
line p7 p8 0 ; inner to outer peak mount line
line p8 p9 0 ; outer peak to mount edge line
line p9 WG0 0 ; connect woofer mount edge to waveguide line
}
Depending where you cross your tweeter you may want to modify these settings as well.
; -------------------------------------------------------
; ABEC Project Settings
; -------------------------------------------------------
ABEC.SimType = 2 ; 2= Free Space, 1= Infinite Baffle
ABEC.SimProfile = 0 ; 0 = CircSym
ABEC.MeshFrequency = 33000
ABEC.NumFrequencies = 1000
ABEC.f1 = 200 ; [Hz] (increase to your tweeter cutoff)
ABEC.f2 = 20000 ; [Hz]
I'm not sure this is the right way to approach your simulation but maybe it will give you ideas.
You can activate portions of the woofer in the bolded lines. If you modify the dust cap to look like your tweeter you probably want a higher resolution than I used to properly model your high frequencies (more than 10). Or maybe you don't need to worry about that in CircSym mode, I'm not sure.
Source.Contours = { ; Dayton DC200-8 Woofer
zoff -24 ; -24 = external mount, -30 = flush mount, -49 = recessed mount w/ 19 mm plywood, -32 = rear flush mount
point p1 12 0 20 ; center of dome
point p2 0 35 20 ; inner edge of cone
point p3 24 75 20 ; outer edge of cone/ inner edge of surround
point p4 31 82 20 ; peak of surround
point p5 24 89 20 ; outer edge of surround
point p6 24 93 0 ; outer edge of divot/ inner edge of mount bracket
point p7 31 93 0 ; inner peak of mount bracket
point p8 31 104 0 ; outer peak of mount bracket
point p9 24 104 0 ; outer edge of mount bracket
cpoint c1 -50 0 ; center of dome arc
cpoint c2 24 82 ; center of surround arc
arc p1 c1 p2 10 ; dome arc (replace 10 with 0 to turn off)
arc p3 c2 p4 0 ; inner half of surround arc (replace 0 with 10 to turn on)
arc p4 c2 p5 0 ; outer half of surround arc (replace 0 with 10 to turn on)
line p2 p3 0 ; cone line (replace 0 with 10 to turn on)
line p5 p6 0 ; divot line
line p6 p7 0 ; divot to peak mount line
line p7 p8 0 ; inner to outer peak mount line
line p8 p9 0 ; outer peak to mount edge line
line p9 WG0 0 ; connect woofer mount edge to waveguide line
}
Depending where you cross your tweeter you may want to modify these settings as well.
; -------------------------------------------------------
; ABEC Project Settings
; -------------------------------------------------------
ABEC.SimType = 2 ; 2= Free Space, 1= Infinite Baffle
ABEC.SimProfile = 0 ; 0 = CircSym
ABEC.MeshFrequency = 33000
ABEC.NumFrequencies = 1000
ABEC.f1 = 200 ; [Hz] (increase to your tweeter cutoff)
ABEC.f2 = 20000 ; [Hz]
I'm not sure this is the right way to approach your simulation but maybe it will give you ideas.
Last edited:
Sorry. DECREASE the number. Lower than 10 not higher.
Also, I realized you might want to make the horn larger than the woofer to go from the woofer cone to a waveguide. You'd attach the start of the waveguide somewhere close to the woofer cone surround. And you might want to use R-OSSE rather than OSSE to shape and rollback the waveguide.
This produces errors in the node formation for me. If you want to PM your ABEC project I can look to see if I can notice anything wrong.
Because for me the error is created somewhere in Ath, if you already have an ABEC project I can look at that to see if something looks wrong there.Thanks, not sure what the point is if the example produces errors too?
I never pass up a chance to post Zoolander memes even though the horn isn't finished yet. Excited to see another concrete horn in the thread. Looking forward to learning best practice with concrete + forms and molds from everyone who makes them. In addition, this shape as well as the ATHex allows additional materials. Also especially curious to see how concrete and other materials affect measurements because I'm currently struggling with measurements on a single enclosure I want to match with two different R-OSSEs. Earl Geddes mentioned how the horn material/construction can cause sound artifacts but I won't understand it until I see a practical example.