"Something" inside a 2225H?

Hi guys.

I just got a pair of used 2225H 15" woofers. I haven't put a signal through them yet. They are definitely used (cones are dusty, a little faded, even a little paint over-spray on one of 'em) but do not appear to be abused.

While unpacking them I could see through the vent screen on the back, a couple of pieces of "something" that actually looked and behaved like a couple of small slender plant leaves, or feathers, or "something." I didn't have time to get out the high intensity light to investigate further.

Any ideas what could be in that vent space? And how it might have gotten in there? And if it could be necessary to remove it?

I'm just curious and I know this forum can always answer JBL-related questions.

Thanks.

JBL's tech wizzards decided to use the same type foam as the surround that's on the VLF woofers to filter the air that's vented in from the rear of the magnet. 10 years and it reverts back to a tar substance.

Unfortunately ( as you've discovered ), this falls apart and bounces around inside the dust cap where it awaits being ground into *just* the right size pieces to fall into the gap and do the nasty between the magnet and former.

If this happens during heavy use the coil will overheat and weld the parts together and you will be buying a recone kit ( which has gone WAY up in price ) to add to the fun.

GO to a decent recone center and have the caps removed and the gaps cleaned out. Then tell them to put in new foam + new cap and you will get many years of use from them assuming there was no previous damage...

:cheers:

sub

A lot of speakers use these and I still wonder if they can make something better.The filter is a usefull way of telling what enviorment the speakers lived in.We at the recone shop here at Audio Light named all the more familiar crap found in this trap.
Barfur....the brown fuzzy stuff grown in bars,nightclubs and smoke filled rooms.
Rollerfuzz....a white waxy powder found in roller rinks this is flammable stuff.
Churchdust....a white cotton and plaster combo found in church which is a light abrasive.
Bargum and Bargoo...different stages of drying times of I did not pass the Pepsi challange,Aka got something spilled on it.

Loudspeaker forensics.

COOL! :thmbsup:

- I believe Giskard mentioned a few years back , that a premanent fix is to cut up plastic mosquito netting ( which is a pretty tight weave ) and glue it into place on the pole piece under the dustcap ( replacing the foam type filter ).

- Considering that I have around 16, 2225H woofers in service ( most about 15 to 20 years in age ) I guess I better start doing some preventative maintenance. :o:

Quote:

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Originally Posted by Earl K

- I believe Giskard mentioned a few years back , that a premanent fix is to cut up plastic mosquito netting ( which is a pretty tight weave ) and glue it into place on the pole piece under the dustcap ( replacing the faom type filter ).

- Considering that I have around 16, 2225H woofers in service ( most about 15 to 20 years in age ) I guess I better start doing some preventative maintenance. :o:

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Another good permanent solution is to cut out a circle of double knit grill cloth...color choice is yours....Zilch will say JBL Blue.;)

I save my scraps from grill cloth replacement and use it for vent hole screens. Need to pull it taught so it doesn't "chuff"...works great.Glue it down with recone glue...Brown Bostik, Moyen, 3M 867

Quote:

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Originally Posted by subwoof

GO to a decent recone center and have the caps removed and the gaps cleaned out. Then tell them to put in new foam + new cap and you will get many years of use from them assuming there was no previous damage...

:cheers:

sub

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Hi subwoof.

I'm a DIY kind of guy. What's the best way to remove the cap? What's the best way to clean the gap? Any advice or tips you can offer?

Thanks.

I reconed a pair of E155s that had both obviously died of foamgum in the gap. I used the nylon version of window screen for replacement. I wouldn't recommend that anyone put new foam back on the pole vents unless you love to recone every so often. Replacing foam surrounds every 10 years isn't a big deal, but it takes a recone job (or some MEK, a steady hand, and the patience of Job) to get the gap de-gooed.

You can dissolve the dustcap glue with sparingly brushed MEK, but it's a real pain and you can cause more damage if not very careful doing it. As long as the foam hasn't crumbled and ended up in the gap during use, I'd trim out the old caps right next to the glue with a razor, and put new ones right on top of the old glue joint once you've got the foam removed. $10-12 well spent, and not to big a job. If you can't remove what appears to be the bulk of the old foam, it's just a matter of time before it will let you know it's there.

JBL did use a better method with the D and K series - it lookes like a fender tweed grill cloth and they NEVER failed....

I guess they needed to save that .01 cent per unit to make a production price quota...;;

I would cut out the cap with a utility knife set on VERY VERY SHALLOW DEPTH and glue the new one over it. Peeling the old glue off will probably remove one layer of paper and cause a weakness but that's only at the extreme power levels where that becomes an issue.

You DON'T want to dribble old glue / spooge ( our term for barfuz ) or solvent into the gap....the caps were put on at the factory with the "black" cement and it doesn't like to soften like the "red" stuff that's used on the spider.

...sigh...

Quote:

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Originally Posted by subwoof

JBL did use a better method with the D and K series - it lookes like a fender tweed grill cloth and they NEVER failed....

...

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Problem with the old style stiff coated cloth screen on the D series is the oil can effect is very audible...and quite annoying.

I pulled my 2225 woofers out this past winter while revenerring the cabs. Nothing came out of the back. I have them 21 years. No sign of drying out.

Ron

could one do without the plug in a home environment?

frank

Hi Frank23.

That seems like a good question. What is the purpose of the screen? What is the consequence of not using it? Anyone? Anyone?

Thanks.

Quote:

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Originally Posted by Benkev

Hi Frank23.

That seems like a good question. What is the purpose of the screen? What is the consequence of not using it? Anyone? Anyone?

Thanks.

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The filter over the vent hole is there to keep debris out of the VC gap. The breathing action from the dust cap will suck little bits of airborn dust, fiberglass insulation, cockroaches, mice...okay, the last two climb in there... and whatever else is in the cabinet air into the gap. It's simply a preventative measure to keep things clean since the gap/voice coil have about .005-.007" clearance from each other.

How's that for consequences ? Hope it helps.