Combination flare on front (Azura) horn - Page 2 - diyAudio
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Old 24th December 2007, 06:36 AM   #11
Frode is offline Frode  Norway
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Quote:
Originally posted by Brett
Frode, what driver did you use in those sims
I used the B&C 8PE21.

Frode
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Old 25th December 2007, 03:25 AM   #12
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Quote:
Originally posted by Frode


I used the B&C 8PE21.

Frode
Thank you. Looks like I have some more simming to do. Hornresp gave me lots of difficulty when I tried to model the Azuras a while back.
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Old 25th December 2007, 04:27 PM   #13
Frode is offline Frode  Norway
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I haven't had any problems with Hornresp, but I'm still learning to use all the functions. It's a nice tool.

Frode
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Old 25th December 2007, 04:43 PM   #14
limono is offline limono  United States
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Frode
Could you simulate 8PE21 in exponential horn with the mouth size of 80cm and 4" throat? Also in your previous simulations I'm not sure how to interpret those spikes at 2khz 4khz and if they will be a problem to deal with in real life application.
Regards, L
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Old 26th December 2007, 10:07 AM   #15
Frode is offline Frode  Norway
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First of all I would say that I'm NOT an expert in horn design. I've just played around with Hornsresp and software/formulas found at the Single Driver Website.

The spikes are resonance in the back chamber. In the sims I've used an 8 cm back chamber depth which gives a wavelength of 4300Hz or half a wavelength at 2150Hz. I'm not sure how much this affects the sound, but I guess it could be reduced/avoided by using non-parallell walls in the back chamber.

A 140Hz exponential horn would have just below 80cm mouth diameter and 80 cm length. Here's a sim:

Click the image to open in full size.
Click the image to open in full size.


According to one of the formulas at the Single Driver Website, the 8PE21 would like a throat size of ~40cm^2 or 2.8" diameter. Then it would look like this:

Click the image to open in full size.
Click the image to open in full size.

The two compared, with the 4" throat in black:

Click the image to open in full size.

Frode
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Old 26th December 2007, 10:28 AM   #16
Frode is offline Frode  Norway
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I changed the input voltage on the 2.8" throat horn in order to make the level at 300Hz the same. It looks like this(2.8" in grey):

Click the image to open in full size.

Frode
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Old 26th December 2007, 03:20 PM   #17
GM is offline GM  United States
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Greets!

Some stuffing or lining of the walls in the rear chamber takes care of any horn HF resonances and just click 'yes' when asked if you want resonances masked to see its effect. ~0.2 lbs/ft^3 density is usually sufficient unless the chamber is very deep or wide, so golden or acoustic ratios is a good plan. Excessive damping will reduce its gain BW and in case you don't know, Hornresp only shows the horn's BW, not any of the driver's HF BW and how the horn's throat reactance and directivity affects it.

GM
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Old 26th December 2007, 04:13 PM   #18
Frode is offline Frode  Norway
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Quote:
Originally posted by GM
Greets!

in case you don't know, Hornresp only shows the horn's BW, not any of the driver's HF BW

GM
Hi Greg!

Do you mean that the HF is only a function of the horn? When I change the Le of the driver, the HF response also changes. And two different drivers on the same horn gives different HF response.

Frode
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Old 26th December 2007, 06:26 PM   #19
GM is offline GM  United States
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No, I mean the horn system's (horn gain BW + driver's theoretical on-axis pistonic BW) isn't shown as it is in MJK's WS.

Yes, for a given horn design, the horn's HF response will be affected by the driver's HF mass corner (2*Fs/Qes) and its rising inductive response, so both these should be taken into account when designing an optimum gain BW horn.

GM
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