Your were able to reproduce it? Or did you mean to say unable?
had dual surface selected; changed it to None; got same results...
had dual surface selected; changed it to None; got same results...
I got the same results as you when I set NUC to Dual surface. Don't forget to restart ABEC after the change.
AH! remeshing and recalcing wasn't enough; restart means close, clear results directory, and rerun! works now!!!!
How the “Damping” parameter influences the result? Which material could be used for that? Is this 0.5 acually used close to some foam or a fabric?
Maybe because the model assumes the same frequency response radiation pattern front and back across the full bandwidth. Linkwitz said the rear pattern/frequency response was different from the front due to an acoustic filter created between the cone and basket. So it might not look that good above whatever frequency that filter starts to operate in a real system?
https://www.linkwitzlab.com/models.htm#D
I would expect that to be higher than 1 or 2 kHz, but it surely will affect the results at some point. That's one of the many things that must be verified empirically.
This is the BEE0 example, 100, 400 and 800 Hz (horizontal).
The first time I find this diagram useful 🙂
The first time I find this diagram useful 🙂
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Would not produce nulls in the horizontal plane, as drivers are aligned vertically.
It is a port resonance issue, after all. Or cabinet resonance escaping through ports. Port separation is ~36 cm, deepest null frequency is 1650 Hz. I threw a quick sim in interference applet (https://www.falstad.com/interference/)
You can't input exact values, but with 34 cm separation and 1881 Hz frequency it showed nulls at +-65 degrees, which agrees with JBL measurement showing the deepest nulls at +60 and -65 degrees. In vertical plane two ports would as a single ~60 mm wide-directive source, which agrees with the +70/-100 directivity from the polar map. Sorry for digging into last year's snow, but port resonance this high and this intense (and in a $900 loudspeaker by a respectable company
:) is fascinating.The horn is, after all, blameless, and performs good for seemingly simple shape. It seems broad facets work as "good enough" termination for 100 degrees horn.
The 5" example shown earlier - here are the responses of the front and the back side of the diaphragm isolated and then combined.
FRs at 0, 90 and 180 deg horizontally.
Front, back, combined (magnitudes):
Front, back, combined (phases observed at 2m with propagation delay subtracted):
FRs at 0, 90 and 180 deg horizontally.
Front, back, combined (magnitudes):
Front, back, combined (phases observed at 2m with propagation delay subtracted):
So what do you think, can it be realized passively? Because this is what it would need to look like.
The slope starts at about 550 Hz, if a crossover frequency is chosen to be, say, around 200 Hz, then EQ correction should be approx. 10 dB. It is clear that such the loudspeaker will have not the best linearity and not the largest dynamic range.
As I read the data, at 500 Hz the summed on-axis response is about 4 dB higher than with the front (monopole) radiation only. And it is lower only below ~240 Hz.
Ported vs closed, the on-axis response. This doesn't seem as a bad trade-off to me.
- Perhaps these are the secondary effects 🙂
- Perhaps these are the secondary effects 🙂
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Now it's more clear. Interesting thing is that the front and back sides in the cardioid speaker seem to radiate in-phase above ~250Hz (cardioid speaker on-axis SPL is increased compared to that of monopole).
Yes, these are the on-axis phase responses extracted from the above graphs.
There's a range around 650 Hz where the two sum constructively.
There's a range around 650 Hz where the two sum constructively.