mech986
06-21-2007, 11:27 AM
Hi all,
I've had these questions in my head for awhile and have done some research here but I'm trying to get a little more in depth on the answers so here goes.
I've got a bunch of JBL 15 inch woofers and almost all of them have foam surrounds. Most all of them are currently stored in cardboard boxes. About 2/3 of them are in JBL OEM boxes with the styrofoam bottom liner that encircles the frame and supports the front gasket/frame lip. Others are in plain cardboard boxes and will soon be lined with high density styrofoam sheet or with a layer of thin medium density styrofoam (think packing foam sheets for glass cups). The last part was from a Giskard post stating that the surround will deteriorate faster if in contact with cardboard (due to adding and/or wicking away moisture from the foam?)
What I am curious about was how to store the woofers positionally? I read in a number of posts that the woofers should NOT be stored (at all, or for long periods of time) with cone down/magnet up. I think this would because of the weight of the cone tending to push down and rest on the surround, deforming it or eventually creasing it, then more likely to fail. OTOH, I would think it a PITA to go around periodically rotating the woofers onto their magnets or sides. And can the OEM JBL packaging keep a stored woofer on its side? I don't have all the cardboard rings for the woofers to keep them held into the bottom styrofoam base although they wouldn't be hard to make.
Giskard, you mentioned that JBL found out the hard way about driver/woofer storage, can you eleaborate on what happened and what is the recommended practice now? What do we do with stock that may be expected to sit on a shelf for some time instead of flying off to someones enclosure?
Also, regarding the 2231/2234/2235 type refoam, I understand the correct foam is a narrow roll (about 3/8") instead of a wide roll (1/2 inch or greater)? I've seen both but I believe the OEM is narrow. Can youse guys confirm the dimensions?
Also, I've noticed quite a difference in the compliance (firmness, softness, springyness) and possibly thickness influencing compliance on many woofers I've examined. I suspect this is due to the various aftermarket suppliers that provide surrounds. I would assume (carefully) there are grades of thickness, materials, compliance, and roll size you "could" use as opposed to the "correct" or as "close as possible to OEM (since JBL doesn't supply it)" type available?
Or do you basically have to stick with the better known suppliers (ReEdger, Rick Cobb, etc) for the right product.
Lastly, I've got quite a few 15 inch woofers that have the "wrong" foam size (very large roll, way too stiff/thick) or placed on front. Cleaning up the wrong ones on the back should be straightforward as it won't be visible. But how or can you clean up old surround on the front of the cone so that it is reasonably or cosmetically acceptable while you correctly refoam on the cone back? Do we have to consider using that "woofer restorer" spray paint? :banghead:
2nd lastly, while I'm here, is there any practical sense to trying to replace worn out/fatigued spiders or lead wires? Or is the time, effort, and general complexity pretty much add up to the same price for a recone? Does that also suggest that cones themselves can have fatigued to a point where they don't work properly anymore (altered pistonic or breakup modes, voice coil area buckling, ragged frequency response if correctly measured)?
Thanks in advance for the replies and enlightenment.
Regards,
Bart
I've had these questions in my head for awhile and have done some research here but I'm trying to get a little more in depth on the answers so here goes.
I've got a bunch of JBL 15 inch woofers and almost all of them have foam surrounds. Most all of them are currently stored in cardboard boxes. About 2/3 of them are in JBL OEM boxes with the styrofoam bottom liner that encircles the frame and supports the front gasket/frame lip. Others are in plain cardboard boxes and will soon be lined with high density styrofoam sheet or with a layer of thin medium density styrofoam (think packing foam sheets for glass cups). The last part was from a Giskard post stating that the surround will deteriorate faster if in contact with cardboard (due to adding and/or wicking away moisture from the foam?)
What I am curious about was how to store the woofers positionally? I read in a number of posts that the woofers should NOT be stored (at all, or for long periods of time) with cone down/magnet up. I think this would because of the weight of the cone tending to push down and rest on the surround, deforming it or eventually creasing it, then more likely to fail. OTOH, I would think it a PITA to go around periodically rotating the woofers onto their magnets or sides. And can the OEM JBL packaging keep a stored woofer on its side? I don't have all the cardboard rings for the woofers to keep them held into the bottom styrofoam base although they wouldn't be hard to make.
Giskard, you mentioned that JBL found out the hard way about driver/woofer storage, can you eleaborate on what happened and what is the recommended practice now? What do we do with stock that may be expected to sit on a shelf for some time instead of flying off to someones enclosure?
Also, regarding the 2231/2234/2235 type refoam, I understand the correct foam is a narrow roll (about 3/8") instead of a wide roll (1/2 inch or greater)? I've seen both but I believe the OEM is narrow. Can youse guys confirm the dimensions?
Also, I've noticed quite a difference in the compliance (firmness, softness, springyness) and possibly thickness influencing compliance on many woofers I've examined. I suspect this is due to the various aftermarket suppliers that provide surrounds. I would assume (carefully) there are grades of thickness, materials, compliance, and roll size you "could" use as opposed to the "correct" or as "close as possible to OEM (since JBL doesn't supply it)" type available?
Or do you basically have to stick with the better known suppliers (ReEdger, Rick Cobb, etc) for the right product.
Lastly, I've got quite a few 15 inch woofers that have the "wrong" foam size (very large roll, way too stiff/thick) or placed on front. Cleaning up the wrong ones on the back should be straightforward as it won't be visible. But how or can you clean up old surround on the front of the cone so that it is reasonably or cosmetically acceptable while you correctly refoam on the cone back? Do we have to consider using that "woofer restorer" spray paint? :banghead:
2nd lastly, while I'm here, is there any practical sense to trying to replace worn out/fatigued spiders or lead wires? Or is the time, effort, and general complexity pretty much add up to the same price for a recone? Does that also suggest that cones themselves can have fatigued to a point where they don't work properly anymore (altered pistonic or breakup modes, voice coil area buckling, ragged frequency response if correctly measured)?
Thanks in advance for the replies and enlightenment.
Regards,
Bart