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Apologies in advance for what might be a ridiculously tedious question...
JBL product literature (link below) gives the throat diameter of the 2441 as:
The fact is, however, that 49mm is significantly shy of 2" (by 1-59/64" ... so more than 1/16" but less than 1/8").
My question: is the 2441 compatible, throat-wise, with a horn that was set up for the TAD TD-4001, with its 49.2mm / 1-15/16" throat diameter? Basically, if the 2441's 49mm spec is to be believed, then it's a tiny bit narrow; and if its 2" spec is to be believed, then it's a tiny bit wide. Maybe someone here who knows the 2441 can shed some light?
Again, my apologies ... I know this is tedious. But, depending on tolerances, this may mean the difference between compatibility and incompatibility.
AS long as the step in size for increasing area is less than about 1/4 wavelength at the highest frequency of concern, the transition has no significant / measurable impact.
20KHz has a wl of about 5/8 inch fwiw.
Going down in size can act like a low pass or worse depending on how large it is.
Danley Sound Labs
In acoustics as you know "Not all that can be measured can be heard and not all that can be heard is usually measured" !! Psychoacoustis are rarely looked into or measured. According to Earl Geddes High order modes (HOM) can be produced by the inconsistencies of CDs to horns at the throat even if below the less than 1/4WL landmark standard.
I've used both TAD TD-4001s and JBL 2441s interchangeably with my Edgar Salad bowls and never noticed any issues. They're bolt on compatible.
You're absolutely right - the JBL 2441/2440 throat is smaller than 2" by just about 1/16. God only knows why JBL decided to make them this way. It has no impact on the sound and Dr. Bruce Edgar has routinely used a 2" forstner bit to manufacture mounting plates for 2" JBL compression drivers for his Edgarhorns.
Thanks for the information / confirmation.
I'm wondering if the horn that I have in mind for these, which has a 1-15/16" throat opening (measured carefully -- not based on specs), is going to be too tight for the 2441? I guess that depends on how my particular drivers match up to the "smaller than 2" by just about 1/16" figure you just gave!
I think why JBL did that is to avoid any horn throat obstruction
edge do to mfg. variations and misalignment due to the side
play due to the bolt holes.
Or, am I overthinking this?.
I think that sounds totally reasonable.
It also gives effect to the idea that, if there is going to be a slight mismatch between driver throat opening and horn throat, better the driver throat opening be the smaller of the two ... with the preference for any "step" to be in that direction (i.e., narrow-to-wide as opposed to wide-to-narrow)? Isn't this correct?
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