Cone strength
"I'm looking at acoustic bandpass alignments in Hornresp, and achievable bandwidth seems to be limited mostly by Mmd."
Have you noticed whether the maximum SPL over the wide bandwidth is limited by the compression ratio (maximum pressure on the cone)? There has to be a limit somewhere, is there a danger that very light cones will deform or even tear? In the usual (sub) woofer application that is an important limit.
Ken
"I'm looking at acoustic bandpass alignments in Hornresp, and achievable bandwidth seems to be limited mostly by Mmd."
Have you noticed whether the maximum SPL over the wide bandwidth is limited by the compression ratio (maximum pressure on the cone)? There has to be a limit somewhere, is there a danger that very light cones will deform or even tear? In the usual (sub) woofer application that is an important limit.
Ken
"But it gets much better when I arbitrarily lower the number in the Mmd field."
Careful.
If you truly only changed Mms, you're either looking at a physical impossibility, because that will change Fs, or you're looking at something different than you think.
For example, to maintain same Fs with lower Mms, Cms must go down, and it may be that which is giving the improvement.
Careful.
If you truly only changed Mms, you're either looking at a physical impossibility, because that will change Fs, or you're looking at something different than you think.
For example, to maintain same Fs with lower Mms, Cms must go down, and it may be that which is giving the improvement.
I had the same thoughts
But I dont have the required expert knowledge to explain it in detail
Maybe Qts will change too, but maybe that doesnt matter so much with a lower midrange horn
But surely no point in chasing the impossible
But I dont have the required expert knowledge to explain it in detail
Maybe Qts will change too, but maybe that doesnt matter so much with a lower midrange horn
But surely no point in chasing the impossible
To see if the same motor and suspension but w/lighter cone is really what's helping, take a given driver and using auto calculate "parameters" in WinISD, input Cms first, then the new Mms, and let it calculate Fs and Qe.
I think Qms should then be changed by the same amount that Qe did, but it's probably a small error.
I think Qms should then be changed by the same amount that Qe did, but it's probably a small error.
No doubt. It will be interesting to see what the limits are in actual testing. I don't have any way to simulate it.
Thanks for the caution, and what you say is true. But, if you look at Hornresp, the only driver parameters are Sd, Bl, Cms, Rms, Mmd, Le and Re. These are not mathematically linked in such a way that you can't change one at a time.
Also, in these alignments, the rear-chamber air compliance dominates almost completely. Doubling or halving Cms or Rms affects the passband less than one dB.
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"But, if you look at Hornresp, the only driver parameters are Sd, Bl, Cms, Rms, Mmd, Le and Re. These are not mathematically linked in such a way that you can't change one at a time."
Ah, a smart program that only asks for what's necessary.
I didn't realize it did anything besides horns.
Ah, a smart program that only asks for what's necessary.
I didn't realize it did anything besides horns.
Actually they are all mathematically linked. The program allows partial inputs and calculates others (by certain steps assisted by you). But if you type in all blanks by yourself (randomly), it can not check them for you (about their mathematical relationships) and actively stop you from running it. Within certain limits, the program still runs the simulation and gives you the 'results', which may not be correct.
For example, I once messed up with a big midhorn design without correct driver parameters -- I couldn't find the 'real' Mmd (or Mms), just the published one which seemed overly optimistic (Mmd of 4.8g for a 12"er):
http://www.diyaudio.com/forums/showthread.php?t=121986
As can be seen above, the program still managed to run a sim and gave a wonderful result, which was too good to be true. As unreal as the 4.8g Mmd for a 12"er.
Later I found other way to do that and got a much more 'down to earth' result, and it turned out very very close to the real thing built after that:
http://www.diyaudio.com/forums/showthread.php?t=125349
For your reference.
Yes, I'm sure Hornresp extrapolates other parameters from the entry fields. My point was simply that Sd, Bl, Cms, Rms, Mmd, Le and Re are not mutually dependent variables. If you had a driver prototyping facility at your disposal, you could theoretically build two drivers that differ in one of those parameter at a time.
Yes, indeed. I mean, no, they are not. Sorry I didn't pay enough attention in your previous post.
I Have RCF MR8N301 with its original horn H6000. Nice driver, i use it in my 3way Top as mid 500hz to 2,7Khz. With original horn there is no possibility to go lower, but when you use it larger horn, i think, better choice is to design and use MR10N301 driver, or some other drivers with lower Fs ( usually more mms, less dB ) .
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