Yeah, after all these years I've finally come to the conclusion that it really doesn't matter who signed their paychecks. Altec, JBL, TAD, whatever...Originally Posted by fpitas
Yeah, after all these years I've finally come to the conclusion that it really doesn't matter who signed their paychecks. Altec, JBL, TAD, whatever...
It looks like it is loosely related to the mass breakpoint frequency formula:
f = BL^2 /(Pi*Re*Mms)
This is the frequency above which the SPL will rolloff at a 6dB/oct rate if a constant directivity is maintained.
It is typically around 3kHz for a compression driver, and in the realms of 500Hz for midbass woofers.
It only impacts high frequency response though (think 2234H vs 2235H)
Hi Ruediger ( Pos ),
The dynamic indexing formula ( as I see it ) is a product ( of sorts ) for displaying potential energy transfer ( & really, it's not very different from simply using Sensitivity ) .
I use this formula ( as well as the EBP product, ie; mass break point ) to identify & compare different woofers to the known entities that I've used for decades( such as 2225 & 6s ) .
I realize that for most, these numbers might be meaningless / but for those of us with a few decades experience ( with specific Pro products ) the numbers help me relate to how JBLs' competitors ( such as all those Italian speaker manufacturers ) might perform ( if purchased ).
Futzing about with EBP & this DPI index, also allow me to quickly execute a bunch of "what if scenarios" ( for altering a systems over-all voicing ).
Running these numbers do show ( for instance ) why someone ( GT ? ) bothered to create separate 2108 ( and 112 transducers ) as well as the 2 distinct classes of Le5-x, 5" mids ( I'm sure you can guess which have the lower dynamic numbers ) .
I will have to re-read this formula thing a few times. It seems intriguing.
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