Acoustic Horn Design – The Easy Way (Ath4)

The problem is not that it couldn't be simulated, but that seldom you have all the input data at hand.

But even if the required excursion was reliably known, what does it tell about the capabilities of a particular driver? What portion of its available excursion we can use without audible issues?

As we move lower in frequency, there is typically a sharp onset of the required excursion to keep a constant SPL, like in the simulation example below of an extended throat, including a simple CD model.

View attachment 1336981

I think that this will also be the frequency below which the distortion will just ramp up quickly. That's probably to fastest way how to get this information - to measure the harmonic distortion.
Generally 4 times the excursion per octave to keep a set SPL. So yes I agree that you cannot simulate these things. I design drivers and I can tell you that this really cannot be accurately simulated. The desk engineers believe that they can. But when you are actually making drivers in the real world it is not the same as computer land.
 
I think that until we know the audible relation to measurement data in detail, the only thing we can do is to attack the issue as engineers and just remove as much non wanted artefacts as possible in order to achieve an as clean signal as possible from the aspects we know: level SPL, level vs. frequency, any order harmonic distortion level, level of non harmonic energy addition, phase linearity, dispersion and all this as a function of time.
In other words test your drivers well under the conditions that you are hoping to use them. The horns will aid the reproduction and should lower excursion over their operating bandwidth, but a junk driver is not going to turn into a great driver.
 
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The three jigs are for different print tolerance clearances - the "JIG-1" is exact, the "OFF-Xmm" has the face offseted a fraction of mm. You can try the exact one.

There are no separate flanges with G2. You have already all you need.
I got all the prints and drivers here but it seems I actually do need the flange as the extension tube does not have a flange to connect the driver to. So which flange from the package I should print next?
 

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My first measurement of the DH450 with A520G2:

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DH450-MA.png


It definitely sounds promising (just like about any other compression driver out there 🙂).
- Take this still as rather preliminary, I was impatient and quickly put it together...

(Again, the SPL axis is not calibrated. It's actually very sensitive for its size. This will a tough competitor overall.)
 
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Yes, raw responses, no further processing. We have seen a similar response from the Lavoce driver, which is even smoother and more extended (probably not nearly as sensitive, but I haven't checked yet at absolute levels):

Lavoce DF10.171K
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B&C DH450
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Both sound very nice, at about the same price. The very high frequencies from the DH450 sound particularly "relaxed", maybe because half of the annoying top octave is missing 🙂

I believe that for a PA use, the DH450 will have an edge. For home reproduction, I'm not sure. I could definitely listen to both, if I was able to tell the different at all, not knowing which is which. All these drivers are really far more similar than different.
 
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That looks very promising!

What would be the most useful configurations with midrange drivers?
Midranges should have an equal dispersion at crossover frequency for overall horizontal dispersion... But regarding the diameter of the Horn and the resulting center to center distance - what about vertical dispersion?
 
Maybe a symmetrical MTM configuration with (small) mid drivers would be nice.
No, don't do that, that doesn't help anything...

15" woofer, or maybe 12", and ~700 Hz crossover seems like a natural first choice. With the extended throats it's possible to go even lower, as there are no "group delay issues" (i.e. mouth reflections).
 
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I have a preliminary design where I plan on crossing to a 15" woofer (AE SBP15) with a 600hz crossover but the measurements will dictate the results. So first things first, put the horn together and measure!

I am still sanding the individual parts. I will then glue them together, use fillers, sand again, then primer and paint.
 

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Yes, raw responses, no further processing. We have seen a similar response from the Lavoce driver, which is even smoother and more extended (probably not nearly as sensitive, but I haven't checked yet at absolute levels):

Lavoce DF10.171K
View attachment 1339439
B&C DH450
View attachment 1339440

Both sound very nice, at about the same price. The very high frequencies from the DH450 sound particularly "relaxed", maybe because half of the annoying top octave is missing 🙂

I believe that for a PA use, the DH450 will have an edge. For home reproduction, I'm not sure. I could definitely listen to both, if I was able to tell the different at all, not knowing which is which. All these drivers are really far more similar than different.
At least for myself, it would be interesting to see SPL, Impedance and phase on the same graph. That will let us look and see if there are internal resonances or structural resonances in the driver diaphragm. The other way is a CSD plot. A CSD can actually tell you a lot about how the driver and horn will really behave itself.
 
It is all minimum phase. Especially below ~5 kHz it's just a matter of a simple EQ and for the same amplitude target everything else will be the same as well (time response, phase, group delay, CSD, name it). Any kind of nonsmoothness above ~5 kHz is always the driver, virtually always a resonance. Not necessarily the diaphragm only, as there's a lot more going on in a compression driver, but I doubt that the exact cause can be determined from a far-field frequency response.

- I can later upload some raw impulse responses to see what others can get from it.
 
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You know how to make it easy 🙂
- So, there will be some stand, not shown?
Yes, there will be. I am working on some designs, I do not want a heavy and bulky looking stand but I want it to fulfill its purpose too.

The box may also be subject to changes however this would be the overall look. It is around 125lt and it models nicely in winisd. It will have a hypex 501 for the bass part, so it will have a dsp. The top will be a simple passive filter and some parallel impedance correction.
 
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