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.
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.
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"
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?
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.
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.
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.
The shorting ring you refer to is actually part of the pole piece and not the voice coil.
My avatar: 4520 loaded with 2225H on E140 frames,
1x 2202H on custom front loaded horn, 2x 2426 on 2370.
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.
There are currently 1 users browsing this thread. (0 members and 1 guests)