Technically, that isn't accurate at all.
What you "need" is a high ratio of electromagnetic force (BL^2/Re) to diaphragm mass (Mms)...
Which, lo-and-behold, is the same as EBP = Fs/Qes = [1/(2*Pi)] * (BL^2/Re)/Mms.
But even so, there are other important factors that concur in determining how high in frequency you can take a Woofer...
It's more complicated than any single spec, and of course it's all a balancing act. Pro's and Con's to every design choice.
it is always interesting when new laws of physics are invented 🙂
be my guest for sarcasm 😉 it doesn't change the fact that the 2216nd is not the right choice to cross high. a 416will do better..
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it think there is a misunderstanding , perhaps my frenchy english , it is not a porblem of box issues or crossover , i use a digital crossover and had the time to try multiples frequency crossing with my 6.5 full range mid from 100hz to 800 with the JBL2216 and the best "subjective" results are crossing between 250Hz and 400 . and yess crossing higher doesn't sound right to me... end of the off-topic ..🙂
Many factors at play...
But sure, cross over wherever it sounds best in your system/application!
The old JBL 2216 is not the same as the new JBL 2216ND-1, and that ND-1 one is measured in boxes crossed way higher without any distortion or frequency response issue (see my links above). The old start to resonate way earlier and distortion also rises a lot way earlier than the JBL 2216ND-1 that is used in the modern M2 and 4367. This are both drivers side by side:
Relatively few modern 15" drivers have the desired parameters.
Basically you want more or less the characteristics of a typical horn woofer, but with a higher Qts for a reflex cab and a curved cone.
That old 2216 seems to be quite rare... and looking at the available data it appears to be a typical (sub)woofer, not a midwoofer.
Even older, but with appropriate parameters:
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Well a bit rare not a sub!
Rob 🙂
https://www.lansingheritage.org/html/jbl/specs/home-speakers/1973-l200.htm
Are there any large format tractrix horns that might be a good match to the TD-4001? (For use down to 600Hz worst case 700Hz) Based on comments from Limono possibly not. Alternatives to TH-4001 and Yuichi A-290? (Similar size)
Hi,
Are you saying that freq response looks normal? I will test wit Arai 290 horn next. Do you think seos 30 is better?
That has not been my experience. What are you wanting it to do that it does not?
Absolutely true.
Agreed on everything except the curved cone. The latter typically leads to progressive controlled decoupling of the inner part of the cone at higher frequencies... which is akin to a crude kind of mechanical crossover. I prefer a stiffer cone, low-passed with a steeper slope if need be.
Not better nor worse. But objectively worse-matched to the internal geometry of the TAD driver.
Tractrix is based on shaky/flawed theory. I'd avoid it on those grounds to begin with.
Back to the topic. Maybe the best driver is two drivers? Just saw the new Joseph Сrowe experiments, he got very decent results with Y-Adapter dual 65CDN-T and big horn. Great measurements, no cone breakup, good low end.
This opens up the prospect of a new look at a Y-adapter, for example, with two good 1'' drivers. Of course, you need to model and print the adapter and make a horn for it (or experiment with available line array adapters and horn selection for them).
By the way, he also found that removing the RCF 950 back cover can have some advantages at home volume levels, which confirms my observations as well.
This opens up the prospect of a new look at a Y-adapter, for example, with two good 1'' drivers. Of course, you need to model and print the adapter and make a horn for it (or experiment with available line array adapters and horn selection for them).
By the way, he also found that removing the RCF 950 back cover can have some advantages at home volume levels, which confirms my observations as well.