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Old 8th December 2012, 07:27 PM   #521
xrk971 is offline xrk971  United States
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Quote:
Originally Posted by SprockeT1597 View Post
ok, so its very late here, and im way too many bourbons past being able to work things out matematically....

Would it be possible to scale this up to use the 6x9's I have sitting in front of me. Or would it have to be stupidly big.

BTW Cal, they look top shelf, and are an inspiration!
The 6x9's could work but just the aesthetics are not pleasing. There is something nice about a circular driver in a square. Maybe if you scale the plan unevenly in one dimension so that the overall dimensions produce a rectangle with proportions of 2:3 it will look cool (unique since we are all square). It will work, give it a try. It is all about experimenting and the foamboard (at least in the US makes it possible without expending a lot).
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Old 8th December 2012, 07:37 PM   #522
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Quote:
Originally Posted by xrk971 View Post
but just the aesthetics are not pleasing.
yes, that was my main reservation in this prospect. Especially using a 6X9, but I thought if i can do it cheap enough, I might at least learn something. so its function over form!


Quote:
Originally Posted by xrk971 View Post
There is something nice about a circular driver in a square. Maybe if you scale the plan unevenly in one dimension so that the overall dimensions produce a rectangle with proportions of 2:3
Yes I agree about the beauty of the square design. but I though seeing as ive already violated that with a 6X9 may as well keep going! Ive been roughing something up in blender. Ignoring all theory of horn design and just concentrating on "6 BY 9"... Also thinking about doing it first in paper mache, because it would be a waste of foam core!

But thankyou for giving my drunken idea purpose!
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Old 8th December 2012, 09:10 PM   #523
xrk971 is offline xrk971  United States
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Paper mache speakers! Nice.
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Old 8th December 2012, 09:56 PM   #524
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Quote:
Originally Posted by xrk971 View Post
Maybe if you scale the plan unevenly in one dimension so that the overall dimensions produce a rectangle with proportions of 2:3 it will look cool.
This would also be the 1st option to explore if one wanted to equalize the length of the horns.

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Old 9th December 2012, 12:22 AM   #525
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Quote:
Originally Posted by xrk971 View Post
Don Hills,
One more question. Does your sim model the outputs of the radiators combined with effect of room walls to redistribute and mix everything like MJK's models? The room may be the effect that makes these sound great as the output from all edges is key to design, and placement in room is critical.
Thanks,
Xrk971
No, it just sums the outputs. AkAbak does allow full physical modelling - you can specify the spatial relationship of the radiators to each other, and add up to 3 surfaces orthogonal to each other to simulate walls / ceiling / floor. Feel free to do so...

Code:
| Cornu style horn. 
| Model developed by printing Dave's drawing and measuring
| the path lengths and widths. It was 23.3 cm wide, 
| so it is scaled up to the required width.
| For example, a 70 cm horn is 70 / 23.3 = 3 times as large,
| so the dimensions are scaled up by 3. 
 
  
Def_Const
{
| Required inputs:
| ================
| Horn width in centimetres
| Horn depth (wall height) in centimetres
| Driver Thiele-Small parameters (in Def_Driver further down)
| Do not delete the semi-colons;
Width = 70;
Depth = 11.5;

| All dimensions are converted to the AkAbak default unit (metres)
| and scaled up. Horn segment areas are doubled because there are
| 2 of each horn sgment. 
Scale = Width / 23.3;
Walls = Depth * 1e-2; 
Tcvol = Walls * Scale * 4.5e-2 * Scale * 4.7e-2;
SxDx2 = Scale * Walls * 2;

H1S1  = SxDx2 * 0.75e-2;
H1L12 = Scale * 2.5e-2; 
H1S2  = SxDx2 * 1.0e-2;
H1L23 = Scale * 5.0e-2;
H1S3  = SxDx2 * 1.2e-2;
H1L34 = Scale * 12.0e-2;
H1S4  = SxDx2 * 1.5e-2;

H2S1  = SxDx2 * 0.7e-2;
H2L12 = Scale * 3.2e-2; 
H2S2  = SxDx2 * 1.0e-2;
H2L23 = Scale * 6.2e-2;
H2S3  = SxDx2 * 1.3e-2;
H2L34 = Scale * 5.0e-2;
H2S4  = SxDx2 * 2.3e-2;
H2L45 = Scale * 7.3e-2; 
H2S5  = SxDx2 * 2.5e-2;
H2L56 = Scale * 6.6e-2;
H2S6  = SxDx2 * 2.6e-2;
H2L67 = Scale * 10.8e-2;
H2S7  = SxDx2 * 6.6e-2;

H3S1  = SxDx2 * 0.8e-2;
H3L12 = Scale * 1.4e-2; 
H3S2  = SxDx2 * 1.5e-2;
H3L23 = Scale * 5.1e-2;
H3S3  = SxDx2 * 1.6e-2;
H3L34 = Scale * 3.9e-2;
H3S4  = SxDx2 * 1.8e-2;
H3L45 = Scale * 7.0e-2; 
H3S5  = SxDx2 * 2.1e-2;
H3L56 = Scale * 17.4e-2;
H3S6  = SxDx2 * 2.6e-2;
H3L67 = Scale * 11.3e-2;
H3S7  = SxDx2 * 6.6e-2;

}

| Specify your driver here. You can use AkAbak's Def--> Def_Driver
| tool to enter the parameters. 

Def_Driver  'FF125K'
SD=66.5cm2   |Piston
fs=72Hz
Vas=9.12L
Qms=9.04
Qes=0.27
Re=7.2ohm
Le=0.73mH
ExpoLe=1

Def_Driver  'TC9FD'
SD=36.3cm2   |Piston
fs=123Hz  
Mms=2.43g  
Qms=2.6
Qes=1.5  
Re=6.3ohm  
Le=0.1mH  
ExpoLe=1


System 'System'

| Enter the name of your defined driver. 
|=======================================
Driver Def='FF125K' 'Driver 1'
Node=1=0=3=4

Radiator 'Front_Rad' Def='Driver 1' 
Node=3

Waveguide 'Horn 1 seg 1'  
Node=4=5
STh={H1S1}  
SMo={H1S2}  
Len={H1L12}
Vf={Tcvol}  
Conical

Waveguide 'Horn 1 seg 2'
Node=5=6
STh={H1S2}
SMo={H1S3}
Len={H1L23}
Conical

Waveguide 'Horn 1 seg 3'
Node=6=7
STh={H1S3}
SMo={H1S4}
Len={H1L34}
Conical


Waveguide 'Horn 2 seg 1'
Node=7=21
STh={H2S1}
SMo={H2S2}
Len={H2L12}
Conical

Waveguide 'Horn 2 seg 2'
Node=21=22
STh={H2S2}
SMo={H2S3}
Len={H2L23}
Conical

Waveguide 'Horn 2 seg 3'
Node=22=23
STh={H2S3}
SMo={H2S4}
Len={H2L34}
Conical

Waveguide 'Horn 2 seg 4'
Node=23=24
STh={H2S4}
SMo={H2S5}
Len={H2L45}
Conical

Waveguide 'Horn 2 seg 5'
Node=24=25
STh={H2S5}
SMo={H2S6}
Len={H2L56}
Conical

Waveguide 'Horn 2 seg 6'
Node=25=26
STh={H2S6}
SMo={H2S7}
Len={H2L67}
Conical

Radiator 'Horn 2 mouth'
Node=26
SD={H2S7}


Waveguide 'Horn 3 seg 1'
Node=7=31
STh={H3S1}
SMo={H3S2}
Len={H3L12}
Conical

Waveguide 'Horn 3 seg 2'
Node=31=32
STh={H3S2}
SMo={H3S3}
Len={H3L23}
Conical

Waveguide 'Horn 3 seg 3'
Node=32=33
STh={H3S3}
SMo={H3S4}
Len={H3L34}
Conical

Waveguide 'Horn 3 seg 4'
Node=33=34
STh={H3S4}
SMo={H3S5}
Len={H3L45}
Conical

Waveguide 'Horn 3 seg 5'
Node=34=35
STh={H3S5}
SMo={H3S6}
Len={H3L56}
Conical

Waveguide 'Horn 3 seg 6'
Node=35=36
STh={H3S6}
SMo={H3S7}
Len={H3L67}
Conical

Radiator 'Horn 3 mouth'
Node=36
SD={H3S7}
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Old 9th December 2012, 05:17 AM   #526
xrk971 is offline xrk971  United States
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Don Hills,
Thanks for providing the script. I have a lot of questions as I am new to Akabak - hope you don't mind.... Can you explain how the bifurcation is coded into the 'System' part? I think this is the tricky part because if it just a divided channel or is it actually two separate channels? Doe the fact that there is the bifurcation point, does that basically break the longest length from the throat out to mouth? As now it would seem that the horn path has a big "leak" where it bifurcates. Also, how does one add stuffing? You mentioned ability to add walls and specify location of radiators. Are there examples of how to do that? I thin the section near the mouth is more exponential than linear conical, not sure if that makes a difference.
Thanks,
Xrk971
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Old 9th December 2012, 08:59 AM   #527
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Quote:
Originally Posted by xrk971 View Post
Don Hills,
Thanks for providing the script. I have a lot of questions as I am new to Akabak - hope you don't mind.... Can you explain how the bifurcation is coded into the 'System' part? I think this is the tricky part because if it just a divided channel or is it actually two separate channels? Doe the fact that there is the bifurcation point, does that basically break the longest length from the throat out to mouth? As now it would seem that the horn path has a big "leak" where it bifurcates.
The mouth of the "inner" horn is connected to the throats of the "outer" horns at node 7. The "outer" horns are two separate channels of different lengths. There is a significant discontinuity (area change) where the three horns join, which will cause significant reflections at that point. I thought it was poor drawing, but the drawing in the patent shows the same discontinuity so I'll assume for the moment that it is deliberate. There is no "leak" at the join, AkAbak accurately models such joins.

Quote:
Originally Posted by xrk971 View Post
Also, how does one add stuffing? You mentioned ability to add walls and specify location of radiators. Are there examples of how to do that? I thin the section near the mouth is more exponential than linear conical, not sure if that makes a difference. ...
One adds stuffing by adding Impedance elements, or building them from AcouMass, AcouResistance and AcouCompliance components. There's some math involved in finding the physical characteristics of the stuffing material and converting to AkAbak parameters. That's in my "things I'll get around to someday" list. As for the mouth sections of the horns, converting them to exponential makes only a small difference. You can try it yourself: on the two "Horn 2/3 Seg 6" waveguide sections, change the "Conical" to "T=1".

To more accurately model the speaker, you need to use the coordinate system to specify the locations and directions of the driver radiator and the horn radiators. (Net --> Acoustic --> Radiator, "Position of Radiation Centre".) You'll also need to define the speaker shape (on the Radiator coupled to the driver cone) and add a wall behind the speaker: Def --> Def_Reflector.

When displaying the horn characteristics, limit your graph range to the frequency range 20 Hz to 1 KHz to view the significant parts. The jaggedness in the higher frequencies can be ignored. It is due to the "perfectness" of the simulation (no losses in the horns, so HF from the back of the driver passes un-attenuated.)

Last edited by Don Hills; 9th December 2012 at 09:28 AM.
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Old 9th December 2012, 09:36 AM   #528
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(Missed the edit window time limit...)
I'm not going to add walls etc until I've investigated the problems with the horn bifurcation. I can see the reasoning behind the design - it appears to be intended to work the same as Host Moller's DoppelHorns - but I think equal length horns will perform better.
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Old 9th December 2012, 12:12 PM   #529
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Ive never used akabak so do these numbers translate to hornresp at all?
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Old 9th December 2012, 12:43 PM   #530
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Foam core seems a great idea, but to take this a stage further, has any one tried laminating sheets of corrugated cardboard to a thickness of say 18mm nd using that? I just fitted a flat pack kitchen for someone and ended up with a lot of the stuff, tempted to give it a go.
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