Need info Jbl-l19

Kwb

AK Subscriber
Subscriber
I recently acquired a pair of L-19's in need of re-foaming. Starting researching "how to's" I noticed the center cone on images I looked at was inverted (concave). Mine are convex. They are jbl woofers with serial numbers.
Any reason why my center cone would be different?
Thank you in advance for any guidance.
Keith
 
I recently acquired a pair of L-19's in need of re-foaming. Starting researching "how to's" I noticed the center cone on images I looked at was inverted (concave). Mine are convex. They are jbl woofers with serial numbers.
Any reason why my center cone would be different?
Thank you in advance for any guidance.
Keith

Congrats, you have the original dust caps intact. That's the way they left the factory. Consider yourself lucky someone hasn't butchered them by replacing the original dust caps with ill fitting, incorrect generic replacements.

The L19s are GREAT speakers. I restored a pair and gave them to a gal I was dating.

Get the foams from Rick Cobb and install them correctly (foam glued to the rear of the cones). Use Rick's CD for centering the cones. No need to destroy those original dustcaps. I did two pair of the 116H (L19As and 4301Bs) woofers using Rick's foams and they turned out perfect - dust caps intact, looking, and sounding, like the day they left the factory.
 
Actually, the 116A or 116H dust cap should be concave; see:

attachment.php
 
I recently acquired a pair of L-19's in need of re-foaming. Starting researching "how to's" I noticed the center cone on images I looked at was inverted (concave). Mine are convex. They are jbl woofers with serial numbers.
Any reason why my center cone would be different?
Thank you in advance for any guidance.
Keith

So, to re-answer your question...

Someone who didn't care about authenticity refoamed them, sliced off the beautiful original concave dust caps and slapped on cheap, generic replacement dust caps. With such little attention to detail, I'd also recommend you check to see if the new foams are glued to the front, or back (correct way) of the cones.
 
Thank you all very much for the replies and your knowledge.
I must say though, I'm still confused which way the dust cap should look. I'll post a pic of mine in current condition.
Also, where might I purchase the Rick Cobb products?
Thanks,
Keith20180822_210017.jpg
 
KWB, if both dustcaps were replaced as convex, they probably used a shimming method of voice coil centering during the refoam. If both woofers are done this way, the dust cap probably is wider than the original to hide the old glue line and would not be easy to restore to concave cleanly, cosmetics wise. I’d Leave them as they are and reform using the test sine wave centering method, then use them. If you want the absolute original look, the 116A or H woofers come up frequently on eBay and you could always sell yours to compensate.
 
KWB, if both dustcaps were replaced as convex, they probably used a shimming method of voice coil centering during the refoam. If both woofers are done this way, the dust cap probably is wider than the original to hide the old glue line and would not be easy to restore to concave cleanly, cosmetics wise. I’d Leave them as they are and reform using the test sine wave centering method, then use them. If you want the absolute original look, the 116A or H woofers come up frequently on eBay and you could always sell yours to compensate.

Thanks Mech for the info.
 
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