I am currently having a little trouble understanding some bass horn stuff, I would greatly appreciate your input on this:
It occured to me that with a restricted horn mouth size, I could in many cases achieve better response simulations in hornresp when the horn ended with a segment that had an expansion lower than the segment before it, or no expansion at all, in other words a tube. See attachment. I understand that I am lengthening the horn and thus the "better" response is understandable, but it seems I can't achieve something similar with a classical, ever-increasing expansion rate without increasing mouth area.
Why is that so?
I am aware that the wavefronts would be unnaturally guided and some diffraction is probably present as well. how critical do you think it is for a basshorn for below 150Hz? Thanks a lot for your help!
It occured to me that with a restricted horn mouth size, I could in many cases achieve better response simulations in hornresp when the horn ended with a segment that had an expansion lower than the segment before it, or no expansion at all, in other words a tube. See attachment. I understand that I am lengthening the horn and thus the "better" response is understandable, but it seems I can't achieve something similar with a classical, ever-increasing expansion rate without increasing mouth area.
Why is that so?
I am aware that the wavefronts would be unnaturally guided and some diffraction is probably present as well. how critical do you think it is for a basshorn for below 150Hz? Thanks a lot for your help!
Attachments
Hi,
Response is not the only issue. Maintaining flare rate (and a bigger mouth)
maintains loading on the driver. You could just build an expanding flared
pipe of any sort to just extend the bass. Also note the termination of
the mouth has a huge effect on the response, what are you modelling ?
rgds, sreten.
Response is not the only issue. Maintaining flare rate (and a bigger mouth)
maintains loading on the driver. You could just build an expanding flared
pipe of any sort to just extend the bass. Also note the termination of
the mouth has a huge effect on the response, what are you modelling ?
rgds, sreten.
Thanks for your response, Sreten!
I know the loading suffers, I realized that the excursion simulation looks like a plus of 2mm in certain areas. however, for this purpose, the driver will not be subjected to a critical voltage. I am just trying out a bunch of things for my next experimental horn system- I am trying to get close to 106 dB down to 35Hz with one double-driver folded horn. It is huge. But mouth size can't be over a certain value.
Would it make any sense to really consider such a weird flaring?
I know the loading suffers, I realized that the excursion simulation looks like a plus of 2mm in certain areas. however, for this purpose, the driver will not be subjected to a critical voltage. I am just trying out a bunch of things for my next experimental horn system- I am trying to get close to 106 dB down to 35Hz with one double-driver folded horn. It is huge. But mouth size can't be over a certain value.
Would it make any sense to really consider such a weird flaring?
If the system you're designing meets the SPL requirements without driving the driver into over-excursion, I don't see why not.
I must say you've made me curious though. Can you post up more details of your design, e.g. the HornResp inputs?
Hi, it's good to tinker etc without full knowledge, as it's often surprising where it can take you 
When i started experimenting with HR, i discovered that narrowing the length achieves a lower f3. But as usual no free lunch, because it reduces efficiency !
Also having a wierd looking throat and/or back chamber "can" do nice things.
Some of the above also applies to other designs, not just FLH's
When i started experimenting with HR, i discovered that narrowing the length achieves a lower f3. But as usual no free lunch, because it reduces efficiency !
Also having a wierd looking throat and/or back chamber "can" do nice things.
Some of the above also applies to other designs, not just FLH's
That occurred to me too a few years ago so I did a little experiment. I made something very similar to this. (6 inch driver in ~100 liter flh, shown corner loaded at xmax.)
An externally hosted image should be here but it was not working when we last tested it.
For this one I did everything wrong to see how it would work out. Extremely abnormal horn flare, compression ratio too high, throat too small, built from 12mm plywood with no bracing.
To make a long story short, it worked fine although I didn't test it rigorously.
There was a small unexpected notch around 90 hz but that might have been due to construction error.
In every horn you have a few impedance peaks to work with. Changing the flare (both the segment lengths and cross sectional areas) changes the location and amplitude of the impedance peaks and you can get just about any response curve you want, although it may take an extremely unusual flare shape to get there. In this case, the negative taper at the end of the flare kills the high frequency efficiency to provide almost ruler flat response despite being massively undersized (100 liters for a 30 hz LF knee).
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I'm intrigued - you were able to get to 125dB in a 100 l box with a 6" driver??
Just to be clear, the design did change a bit from that graph, I moved on into Akabak to simulate it with more segments, ended up raising the tuning for a LF knee closer to 35 hz and a bit more spl. I don't have the Akabak sim anymore but it did measure very close to the final Akabak sim with the exception of a bit of a notch around 90 hz likely due to a construction error.
Haha! I LOVE it! It is indeed a great field of discoveries and doing things your very own way, that's why I am so addicted to it I guess. That flare is absolutely insane.
Well, considering my project, I was just trying to understand this concept. I once more realized that there is no free lunch and after DAYS of calculating and folding, I came to the conclusion that - for my specific problem - the solution would probably be "true" loading with a "proper" flare and mouth termination. But it certainly is interesting what this flare shape can do. It is almost EQ-like. Well, I guess that's because it is a in a way...
If anyone is interested, I (for now) settled with a stack of two massive subwoofer units, each driven by a single Eighteensound 18NLW9600.
Thanks to everyone contributing to this so far and kind regards
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