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Stevedel
11-19-2011, 10:50 AM
Greetings one and all,
I have been following this forum, with great interest, for some time. This is my first posted question. Not that I don't have them, but in searching this forum, you guys have always shed light on whatever seemed to be my interest at the time.
I have acquired a pristeen 2245h to use as a subwoofer. In checking it out, it has a 5.0 volt
resistance across the voice coil. Applying an AAA battery voltage with the cone facing up, I get a scratching sound (just like other woofers I have tried) and plenty of cone movement.
With the magnet facing up, I get the same sound but no cone movement. (Neither pos. or neg.) In moving the thing around, I can hear a distinct rattle. Something is definitally loose in the magnet assymbly. There is no foilcal or screen covering the voice coil hole, just some spongelike material inside.
I would think that anything steel would stick to something inside the magnet. I really don't want to power this thing up and destroy the voice coil. How do I take it apart without ruining anything? Can I pull the spongelike material out and put it back without damping the cone movement? Anyone have any suggestions?

Thanks so much.

Stevedel

Eaulive
11-19-2011, 01:10 PM
Greetings one and all,
I have been following this forum, with great interest, for some time. This is my first posted question. Not that I don't have them, but in searching this forum, you guys have always shed light on whatever seemed to be my interest at the time.
I have acquired a pristeen 2245h to use as a subwoofer. In checking it out, it has a 5.0 volt
resistance across the voice coil. Applying an AAA battery voltage with the cone facing up, I get a scratching sound (just like other woofers I have tried) and plenty of cone movement.
With the magnet facing up, I get the same sound but no cone movement. (Neither pos. or neg.) In moving the thing around, I can hear a distinct rattle. Something is definitally loose in the magnet assymbly. There is no foilcal or screen covering the voice coil hole, just some spongelike material inside.
I would think that anything steel would stick to something inside the magnet. I really don't want to power this thing up and destroy the voice coil. How do I take it apart without ruining anything? Can I pull the spongelike material out and put it back without damping the cone movement? Anyone have any suggestions?

Thanks so much.

Stevedel

I will advise you to remove this foam from the vent as it will eventually deteriorate and crumble, if it haven't start already.

I posted a message a while ago with instructions how to do it, let me check.

--------------edit-------------

Found it: http://www.audioheritage.org/vbulletin/showthread.php?31661-Help-identifying-OEM-Original-or-Aftermarket-JBL-cones&p=319420&viewfull=1#post319420

Lee in Montreal
11-19-2011, 04:38 PM
With the 2245 resting on its magnet, cone facing uo, you should get a movement of the cone, up or down, depending on the polarity of the connection with the battery. When putting your woofer with the cone down, if you get no movement possiby because the speaker is resting on the cone's suspension and blocking it.

As Eaulive said, remove any foreign object from the back. Use a piece of sticky tape to remove rotten foam. But as foam bitses shouldn't rattle, there should be something else in there...

Stevedel
11-20-2011, 02:35 AM
Greetings again,
As the woofer is tilted, with the cone facing down, the rattle is more of a sliding noise.
Is there anything, besides foam, behind the cone dust cap that could be jarred loose?
The sliding sound seems to be coming from the outer edge of the back of the magnet structure, but sound radiations can be deceptive.

Thank you again.
Stevedel

rdgrimes
11-20-2011, 07:35 AM
Lay it on it's magnet facing up. Take one finger and press down right next to the dust cap. Repeat at 90' intervals. Does the scrape happen at all locations or just one, or none?

Stevedel
11-20-2011, 12:33 PM
Thank you, one and all.

I found it! It seems that one of the screws holding the2245h to a plywood backing for shipping had come loose and found it's way into the basket somewhere. I had turned the darned thing every whichway listening to the rattle. Nothing had fallen out and the sound seemed like it was coming from the magnet structure, so I feared the worst. I still cannot even guess where it was.

Next time, I will know to count the screws and make sure that none have found their way into any delicate area. I had packed the thing away and was going to deal with the proplem at a later date, but rdgrimes had asked if, and where, there was any scraping. I opened the box and pulled it out from under the bubblewrap. Out that little devilscrew popped! No more rattle.
:applaud:
Thank you rdgrimes, Eaulive and Lee in Montreal, for your suggestions.

Stevedel

Eaulive
11-20-2011, 03:02 PM
Good, happy you found your problem, and even more that it was nothing serious. :applaud: