Acoustic Horn Design – The Easy Way (Ath4)

I guess the things above 11k are given by the 1.4" throat size, am I correct?
Yes, that's due to the bigger throat. How exactly it will look in real depends on the driver and its exit wavefront - the "better" the driver, the more it will match the simulation.

You could make the DI rise more gradual, at the price of making it rising across a wider frequency range. There's yet no definitive answer to what is better.
 
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What is wrong here? I still get
error: polar map 'SPL_H_T' not found in the results

ABEC.Polars:SPL_H_W = {
MapAngleRange = -180,180,72
Distance = 2.0
NormAngle = 0
Offset = 66

FRDExport = {
NamePrefix = hor woofer
PhaseComp = -2.0 ;[m]
}
}

ABEC.Polars:SPL_V_W = {
MapAngleRange = -180,180,72
Distance = 2.0
NormAngle = 0
Inclination = 90
Offset = 66

FRDExport = {
NamePrefix = ver woofer
PhaseComp = -2.0 ;[m]
}
}


ABEC.Polars:SPL_H_T = {
MapAngleRange = -180,180,72
Distance = 2.0
NormAngle = 0
Offset = 66

FRDExport = {
NamePrefix = hor tweeter
PhaseComp = -2.0 ;[m]
}
}


ABEC.Polars:SPL_V_T = {
MapAngleRange = -180,180,72
Distance = 2.0
NormAngle = 0
Inclination = 90
Offset = 66

FRDExport = {
NamePrefix = ver tweeter
PhaseComp = -2.0 ;[m]
}
}

I also think treating OSB as the minor wood it is, making it suffer from a bright DI, could still turn on you as bad karma, @pelanj. Watch out!
 
@mabat, I think there might be an error on page 4 of https://at-horns.eu/release/R-OSSE Waveguide.pdf. I think y2(L) should be y2(1).

rosse_formula.png
 
Took me a while to generate clean export. And some things have well changed:

WG50_FRD Power+DI.png


This is based on a LR24 LP @ 1.3k and a Bessel 24 HP @1.2k. XO is not even closely in phase, but gives the best summation for Power and DI with a flat LW. One thing that comes with this is that the axis center is actually shifted by about 10 degrees down, I do not really appreciate that:

WG50_FRD Directivity (ver).png WG50_FRD Directivity (hor).png

I had entered an offset for the length of the waveguide, but it was not displayed in ABEC3.

side.png

Also, when I enter an offset with the offset parameter, must this be added/subtracted from phase compensation?
 

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XO is not even closely in phase, but gives the best summation for Power and DI with a flat LW.
This is what it's all about. Forget about the phase itself, it only has to be correctly calculated&used. Whatever comes best in the overall amplitude and power, take it.

Also, when I enter an offset with the offset parameter, must this be added/subtracted from phase compensation?
All the polars exported must use the same setting, that's the only requirement (besides a reasonable point of rotation itself). You can use the manual phase compensation to eliminate the major part of the propagation delay so the phase data look nicer. Again, the same value in all the polar definitions. The exact value itself is not important.
 
1650438287228.png

Looking at the picture, perhaps you could try to set an additional small delay for the WG source (manually in observation.txt) because with a CD there will be some additional delay due to the diaphragm to throat distance. With the woofer, I'm not sure.

- You can probably do it in the crossover simulator, should give the same result.
 
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I have noted a little complication, when I had a look at the shifting of the reference axis due to my crossover attempt: Up is down and down is up! It is also visible (only now to me) from the VCAS output that I had posted in my previous post. Woofer axis is shifted upward, tweeter downward, where it should be the other way round. Muting the woofer in VCad shows the main vertical baffle diffraction caused by the downward enclosure pointing up:

WG50_FRD Directivity (ver)1_noXO.png

I had used the following ath parameters to generate spectra:

ABEC.Polars:SPL_H_W = {
MapAngleRange = -180,180,72
Distance = 2.0
NormAngle = 0
Offset = 66.5

FRDExport = {
NamePrefix = hor woofer
PhaseComp = -2.0
}
}


ABEC.Polars:SPL_V_W = {
MapAngleRange = -180,180,72
Distance = 2.0
NormAngle = 0
Inclination = 90
Offset = 66.5

FRDExport = {
NamePrefix = ver woofer
PhaseComp = -2.0
}
}

ABEC.Polars:SPL_H_T = {
MapAngleRange = -180,180,72
Distance = 2.0
NormAngle = 0
Offset = 66.5

FRDExport = {
NamePrefix = hor tweeter
PhaseComp = -2.0
}
}


ABEC.Polars:SPL_V_T = {
MapAngleRange = -180,180,72
Distance = 2.0
NormAngle = 0
Inclination = 90
Offset = 66.5

FRDExport = {
NamePrefix = ver tweeter
PhaseComp = -2.0 ;[m]
}
}

Is there a way to solve this internally? To my eyes I figure that both woofer and tweeter are mirrored, I could rename them in this case. But I'd rather like to double check before I rely something on this.

Regards
 
I'm also having troubles with the x values. I can't get them to match with the earlier formulae. Glancing over the formulae gives me the impression they are different and I implemented both and I get different results. I haven't done the hard labour yet, but I suspect the L scaling...
I made some silly mistakes in the document, this is how it should be: https://www.desmos.com/calculator/redw2gvf9e

(Alternatively: https://www.desmos.com/calculator/4xnabjmxm6)
 
Tick the Spectrum Hints item in the view options panel on the right, that will show you where the measurement is being taken from. The axis going through the speaker is about how the meshes are positioned.
Good to know. The Spectrum Hints follow the offset.

This visualization is dedicated to mabat, and his arguments against a baffled device. Negative angles in front, we are seeing the disruption of vertical respose due to the enclosure below the waveguide:

WG50_FRD Directivity (ver, neg front).png


versus up

WG50_FRD Directivity (ver, pos front).png


Obviously, this can still make for a good system performance, but from a perspective of absolute performance, the baffle obviously has a detrimental effects within a +- 90 degree window up to 20k.
 
Well the truth is that the vertical performance suffers even with a free standing WG. I already made some quick simulations, then I had to concentrate on other stuff. So it's not a universal cure. I don't know yet the extent to which it's better or worse than all-in-one box. This all is to be found out.
 
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