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Thread: jbl 2245 H

  1. #76
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    I cut out the dustcap today. I don't see any problem in the bond between the aluminum bobbin and the cone. Still have the rattle so it must be on the other side of the voice coil under the spider.
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  2. #77
    Administrator Robh3606's Avatar
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    I have a reconned 2225 core that also has a rattle. Try picking up the driver and giving it a little shake. I have something non magnetic floating around in the basket under the spider or under the gap in the magnet itself.

    Rob
    "I could be arguing in my spare time"

  3. #78
    Senior Member jerv's Avatar
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    Quote Originally Posted by dr_gallup View Post
    .... While playing the 30 Hz CD it was immediately obvious that this speaker has other problems. There is a rattling noise (NOT voice coil rubbing) that gets worse with increasing amplitude. I'm guessing something in the voice coil (the former?) is loose or partially separated...
    Maybe the leads from terminals to voice coils crashing into the cone at larger excursions?

  4. #79
    Super Moderator yggdrasil's Avatar
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    Quote Originally Posted by jerv View Post
    Maybe the leads from terminals to voice coils crashing into the cone at larger excursions?
    I had exactly that problem with one of my 2245's. After shortening the leads the problem was gone...
    Johnny Haugen Sørgård

  5. #80
    Senior Member ivica's Avatar
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    Quote Originally Posted by dr_gallup View Post
    I cut out the dustcap today. I don't see any problem in the bond between the aluminum bobbin and the cone. Still have the rattle so it must be on the other side of the voice coil under the spider.
    May the voice coil was overheated, but, unfortunately the whole cone has to be removed. May be some other member can suggest what would be the best way, and what to use for softening the glue on the spider side and the foam side, in order keep them 'alive'.

  6. #81
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    Quote Originally Posted by Robh3606 View Post
    I have a reconned 2225 core that also has a rattle. Try picking up the driver and giving it a little shake. I have something non magnetic floating around in the basket under the spider or under the gap in the magnet itself.

    Rob
    Thanks for the ideas guys.

    What ever is causing the rattle is not floating around loose. It's not the leads either. I can hear the rattle at low & high amplitude, obviously gets louder at high. It's interesting to stick your head right inside the speaker at ~1/2" peak to peak travel!

    I suspect it's time for the full recone. JeffW mentioned "Orange County" as a source for factory kits. Orange County what? Can you give a link?

  7. #82
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    Quote Originally Posted by dr_gallup View Post
    I suspect it's time for the full recone. JeffW mentioned "Orange County" as a source for factory kits. Orange County what? Can you give a link?
    I just check Orange County Speaker as a handy reference to see if they list a particular kit as being available.

    But they won't sell you a kit, JBL factory kits are supposed to be installed by JBL authorized repair shops.

    I also mentioned edgewound. He is Upland Loudspeaker Service and posts here, also an authorized JBL shop. He did a pair of 2245s for me and the work is top notch.

  8. #83
    Senior Member Eaulive's Avatar
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    I can see the former has been rubbing on the pole piece, the marks are very obvious.

    I also don't remember about an aluminum former on the 2245
    My avatar: 4520 loaded with 2225H on E140 frames,
    1x 2202H on custom front loaded horn, 2x 2426 on 2370.

  9. #84
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    Quote Originally Posted by Eaulive View Post
    I can see the former has been rubbing on the pole piece, the marks are very obvious.

    I also don't remember about an aluminum former on the 2245
    I will second that.

    Allan.

  10. #85
    Senior Member ivica's Avatar
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    Quote Originally Posted by Eaulive View Post

    I also don't remember about an aluminum former on the 2245
    I agree with you, on my coils from 2245 aluminum is not visible. or it may have been painted.

  11. #86
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    Quote Originally Posted by Eaulive View Post
    I can see the former has been rubbing on the pole piece, the marks are very obvious.

    I also don't remember about an aluminum former on the 2245
    Yes, the former did rub when the original surround was disintegrating, that's what caused me to take it out of service many years ago. It is not rubbing now. I was able to move the surround while gluing and could easily distinguish between the rattle sound that is always there and the voice coil rubbing sound when the surround was off center.

    I'm not sure that the aluminum is the actual former that the coil is wound on, there may be a layer of plastic or cardboard between the copper winding and the aluminum ring. I was reading somewhere (here or on JBL Professional) that the aluminum ring is called a shorting ring and is used to reduce high order distortion harmonics. The high frequency components of distortion will induce strong eddy currents that damp out those frequencies. I can assure you that this is original construction from ~1985. This speaker was bought new by me, has never been apart before & is clearly marked 2245 both on the back of the cone and the magnet structure.

    PS this is a pretty old cone, the back is white.

  12. #87
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    The shorting ring you refer to is actually part of the pole piece and not the voice coil.

  13. #88
    Senior Member Eaulive's Avatar
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    Quote Originally Posted by dr_gallup View Post
    I can assure you that this is original construction from ~1985. This speaker was bought new by me, has never been apart before & is clearly marked 2245 both on the back of the cone and the magnet structure.

    PS this is a pretty old cone, the back is white.
    So it is original, I just never saw one like this (not that I've seen thousands anyways )
    And yes, the aluminum shorting ring is on the pole piece, not part of the voice coil
    My avatar: 4520 loaded with 2225H on E140 frames,
    1x 2202H on custom front loaded horn, 2x 2426 on 2370.

  14. #89
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    The shorting ring moves with the voice coil it's not fixed to the magnet structure. It could not reduce distortion if it didn't move.

  15. #90
    Senior Member grumpy's Avatar
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    Google "technical note V1N22" JBL

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