Foam in the front instead the rear

[tweeter]

Is it possible to remove the foam in the front without damage the cone?

Thanks.

[MikeBrewster77]

Do a site search on resurround and/or refoam and you'll find a crap-ton o' information. The procedure for removal of the old foam and adhesive (which can be best summarized as "work carefully") is really the same irrespective of mounting location.

Good luck!

[grumpy]

Possible? yes. Difficult? yes. Some risk of damage, even if experienced and
careful? yes. Aquaplas can make this more difficult.

[MikeBrewster77]

Possible? yes. Difficult? yes. Some risk of damage, even if experienced and
careful? yes. Aquaplas can make this more difficult.

That's a good point. I've never done a re-foam on an incorrectly mounted JBL - just other brands that are factory front-mounted. Didn't consider the difficulties of working with the Aquaplas.

[badman]

I've always figured I'd use a directed flow of steam, through a very small wand or some such, a tiny bit at a time (1 pass around the edge of the surround) to see if it would 'work up'. Naturally you'd want to be extremely careful with this method, and inspect the cone after the first, and each subsequent pass.

On the upside, aquaplas/lansaplas is pretty hardy.

[rdgrimes]

Depends on the glue used, and the quality of the glue job. Consider that someone who put the surround on the front might also have used inappropriate glue. I've found that aquaplas is pretty easy to remove the standard clear flexible surround glue off of if it's not gooped on too thick. In some cases it has simply peeled right off. Age of the glue is also a factor. Isopropyl alcohol seem to work for softening the glue without harming aquaplas. Unfortunately, you never know till it's too late to change your mind.

[bigyank]

Not worth damaging a working driver. Other than cosmetic differences, mounting to the front should be fine. Using woofer tester, testing showed 2 2214H's with foam mounted to the front tested virtually identical to 3324H's with their foam mounted to the rear. Personally, I would like to always see foam mounted correctly and YMMV but I have never seen nor heard any difference.

Bottom line, why risk having to perform a recone. :)

Yank

[grumpy]

why risk having to perform a recone.A good question to ask, especially if the difference isn't personally audible.

1) Sometimes cosmetics is enough.

2) A very tired driver, that is having a 10yr old refoam start to deteriorate
(which was installed opposite the designed side, at the recommendation of
a nearby, authorized reconer, who has since recanted such practice)...
might be worth such a try.

3) Distortion (readily audible or not); a woofer tester will not show an
early or offset Xmax (based on distortion, not Xmech), or other distortion
products based on a non-centered (along motion axis) voice coil. If the
driver's spider is wonky, this may be moot... leading back to a recone
anyway. I can't imagine a business having the proper equipment to
readily measure this (e.g. Klippel gear) unless they -made- drivers...
one might be able to approximate this with DIY-type gear and a known,
"standard" driver to A/B against.

[rdgrimes]

Bottom line, why risk having to perform a recone. :)

Yank
A good point. But the now-absent OP didn't say he was wanting to do it for cosmetic reasons, only asked if it was possible. Maybe he has drivers with worn out surrounds. Anyway, I agree it's not worth messing with unless they are very easy to peel off. Still, faced with a similar situation on my L150A, I bought replacement drivers with the foam installed correctly. But that was because one speaker had them right and the other had them wrong and it drove me nuts looking at them.

[duaneage]

A good question to ask, especially if the difference isn't personally audible.

1) Sometimes cosmetics is enough.

2) A very tired driver, that is having a 10yr old refoam start to deteriorate
(which was installed opposite the designed side, at the recommendation of
a nearby, authorized reconer, who has since recanted such practice)...
might be worth such a try.

3) Distortion (readily audible or not); a woofer tester will not show an
early or offset Xmax (based on distortion, not Xmech), or other distortion
products based on a non-centered (along motion axis) voice coil. If the
driver's spider is wonky, this may be moot... leading back to a recone
anyway. I can't imagine a business having the proper equipment to
readily measure this (e.g. Klippel gear) unless they -made- drivers...
one might be able to approximate this with DIY-type gear and a known,
"standard" driver to A/B against.


If mounting to the front produces the same resting position as mounting to the rear then the mechanical difference will be negated. Obviously everyone wants surrounds done as they came from the factory but I've tested drivers done both ways and they measured the same. Resting position was the same as well since the spider has a lot more say about the zero position than the surround. In some cases a sagging surround might actually be aided by front mounting if it brings the cone into proper location.

[BMWCCA]

In some cases a sagging surround might actually be aided by front mounting if it brings the cone into proper location.
That sounds like the corporate line in a blast from the past. Check out posts #6 and #11[/URL] in this thread: [URL]http://audioheritage.org/vbulletin/showthread.php?t=9869 (http://audioheritage.org/vbulletin/showpost.php?p=101635&postcount=11)

[duaneage]

That sounds like the corporate line in a blast from the past. Check out posts #6 and #11 in this thread: http://audioheritage.org/vbulletin/showthread.php?t=9869
Sometimes even corporate lines are correct. A broken clock is right twice a day after all.

[grumpy]

...the spider has a lot more say about the zero position than the surround.

In some cases a sagging surround might actually be aided by front mounting if it brings the cone into proper location.I'm sure you meant spider in the latter, and I do agree that a front
mounted surround on say an otherwise healthy 128H will not likely cause
audible problems.

I do disagree with the idea of purposefully using a compliant surround
(foam) to correct for a -relatively- non-compliant spider (phenolic
impregnated cloth)... this has the smell of harmonic distortion all over it,
which may not show up with any apparent significance in a frequency
response plot (my admittedly presumed assumption of the fore/aft
measurements described).

Respectfully, -grumpy

[badman]

Front vs. rear makes little to no performance difference, as far as we're concerned, it's a pure cosmetic issue.

Which, as mentioned, is reason enough.