Acoustic Horn Design – The Easy Way (Ath4)

[Ro808]

An estimate of the DI can already be made based on this on-axis measurement.

DI will be fairly constant in the midrange and coverage should remain relatively wide in the upper octave.

This is the measured on axis response of a "Novel Constant Directivity Horn".
Smoothed (upper) vs. unsmoothed (lower).

 

[mabat]

An estimate of the DI can already be made based on this on-axis measurement.

How it works?

 

[JSS]

It's great to see such progress. Now it really gets interesting.
Really looking forward to see more measurements. I'd use the throat as the center of rotation, at least this is used in the simulations (unless you change it). 10 deg step is fine.

Thanks Marcel, I will take more measurements after I make the throat smoother.
I made a typo on the distance it's not 10cm it is 100cm.
Windowing was set to blended, so there was a bit of room interaction on the posted response.

I will move the mic closer and limit the capture time.
What's a good setting, 5msec?

 

[mabat]

Keep it 1m, that's fine. You have to limit the "capture time" (if it's the same thing) so that it ends just before the first room reflection arrives - you'll see it in the impulse response chart.

 

[JSS]

Yes it is the same as you call it windowing. I will enable it next time

 

[Flaesh]

How it works?

https://audioxpress.com/files/attachment/2705
http://www.speakerlab.it/resources/Horn.ell.a_datasheet.pdf

 

[mabat]

No, I meant how to "estimate" DI from the axial frequency response.

 

[mabat]

Voilà

ATH - Advanced Transition Horns

 

[atico5007]

Oh! Those look gorgeous! Congrats!! ( I envy you😁)

 

[mabat]

Finally, they are real -

 

[jcarothers]

Phenomenal!

 

[TNT]

Very nice!

//

 

[JSS]

Wow those look really solid, what is the weight on each?

 

[mabat]

3.75 kg

 

[JSS]

Ok here's a new measurement, I drilled the throat a bit as it was constricted and sanded it smooth. Set the window to 5msec.

How does it look?
Let me know if there's anything else you want me to measure...

 

[mabat]

The polar response

It's strange that it truncates the frequency response so high. For 5 msec I would understand it would be 200 Hz, not 750... Isn't this just the time at which the window ends?

 

[JSS]

I'm not sure, I just click the only to button I like how it looks now. I just wish I had a bigger printer and print it big enough so I can cross at 800hz

 

[mabat]

I woudn't be afraid at all to cross it at 800 Hz now.

 

[JSS]

Should I move the mic closer? It's set at 1M right now...

"OMNIMIC "only to": for suppressing reflections. This is calculated only from the impulse response within the time selected. To select a different ending time, click the mouse at the desired time point within the impulse response graph. Impulse response information after the selected time will be excluded from the frequency response calculation. Select this time to totally exclude later reflections visible on the impulse response plot. Lower frequencies can't be measured using this option, limited by the length of the time selected. This mode works best when the OmniMic is relatively close to a loudspeaker."

 

[bushmeister]

Wow - stunning! I have been closely following this thread.
Are these horns to become available to DIY'ers Mabat??
If so where do I sign up?!