Hi, has anybody info on the travel of the 2108 midlow speaker? Mine seem to have only 8 mm of travel. I bought them two years ago and they were already reconed. So I do not have any comparison.
Any clue?
Thanks!
Hi, has anybody info on the travel of the 2108 midlow speaker? Mine seem to have only 8 mm of travel. I bought them two years ago and they were already reconed. So I do not have any comparison.
Any clue?
Thanks!
For linear response the excursion will be a lot less than 8mm unless that's a peak to peak distance, though I would still be skeptical of that number. The voice coil depth is .17 inch in a gap the depth of the top plate. I believe its an underhung design. It's meant to play upper bass and lower midrange--not actually a woofer per se. It was used in the L212 down to 70 Hz, but not at punishing volume.
Hi, thanks for your quick repons. I did the check manually. Not with brutal force though... ;-)) So my estimation seems to be a bit high.
Your 0.17 inch is less than half a centimeter (as a European JBL fan, I am used to ISO...) and that could be close to the truth.
This gives me some confident having bought the right speaker set.
I will upload some photos soon. Thanks again!
Hi Luigi,
JBL publishes the TS parameters for their old & new drivers . These parameters include the drivers' Xmax rating ( "travel" in your vernacular ) .
Here's a link to the latest JBL Publication of TS Parameters .
>< cheers
Looking at an Alnico 2108 frame, I think the plate thickness is about 13/32, which is about .41 in. Subtracting the .17 coil depth leaves about .24. That divided by 2 yields .12 one way excursion with the coil remaining fully withiin the gap. That's about 3.5mm in each direction, and would seem about right to me.
Many JBL's used a .280 top plate, I'm pretty sure the 112/2108 was one of them but I don't currently have any to measure. I could have sworn I posted all that many years ago.
I do know that the 112/2108 worked just fine down to ~ 70 Hz in the L212 system without any over excursion issues.
On the 112A I have I am measuring about .350 on the top plate. It's thicker than the 108H from the L250.
Rob
"I could be arguing in my spare time"
I find that hard to believe...
It is not let in and it's .350.
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