foam over or under on 122A

[badman]

Hi:

I have an 'okay' set of 122A that need a refoam. Chassis and magnet (and VC, thankfully) are in good shape, but the foam (surrounds) is/are gone. Looks to me like someone previous did foam on top but the original foam was on bottom. Can anyone confirm which side to mount the foam on once I get them cleaned up? Should be a nice woofer, maybe good in a big scoop cab or imperial style enclosure.

I've refoamed woofers before, but any tips and tricks for mounting it below the cone (if that's where it goes) would be appreciated. Do I need to remove the dustcap and insert shims if the spider seems to be maintaining centering well?

[John]

Behind the cone.

[Mr. Widget]

Do I need to remove the dustcap and insert shims if the spider seems to be maintaining centering well?No. Well, most people don't bother if the coil is well centered.


Widget

[badman]

Thanks guys!

[3dbdown]

Hi, Rick here...

The foam surround always goes on the bottom side of the cone. Many aftermarket repairers place it on the front because it's easier and cheaper. But that will affect the frequency characteristics of the cone, and besides, it looks ugly.

If the dust dome is in place, and the spider is still glued down well, then if you are careful, you dont need to open it up and shim it. It's always better not to anyway, as en exposed gap invites free floating magnetic particles into itself. Believe me, they are in the air everywhere. In LA, we call it "smog", which is also some of the reason we have to redo our surrounds 3 times as often as the rest of the world!

Also, I hope the woofers were not played too much with defective surrounds, and there is no damage to the voice coils. It would be a shame to go through the re-foaming exercise only to wind up needing new cone kits.....Hope this helps.

Rick