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I have run across this several times in the past 3 months on refoam drivers as well as a NOS recone kit. These are very hard to center as the tolerances are even tighter because of the out of round condition. Anyone know of a way to repair this or correct it. :banghead:
Thanks in advance for any help
MB
tough one.
Some time ago I removed the center section of a shifted 2225 and by adding layers of tape around it was able to at least *prove* to me / others that a recone kit or pull was not round.
I think rebending by hand until it can pass evenly over such a template is the only answer.
Did the same with a 2420 driver phaseplug for the small format diaphrams. By sticking adhesive backed 400 grit on it I was able to remove the heat bubbles from diaphrams for emergency " friday afternoon before the gig " repairs.
BTW I have seen a number of frames that had a warp that WILL cause a coil former to *twist* or deform. Take the cleaned off frame ( without magnet attached! ) and put it facedown on a decent LARGE tablesaw or similar machine that has a very flat metal surface and see if it "rocks".
If it does, toss it. My woodshop was full of 12 and 15 ( those damn E guitar speakers ) bent frames and shifted magnets. They were simply TOO heavy to move around.
sub
I would gently massage the vc in my hands hoping for a more perfect cylinder. Never had good luck withit, though. Also had some brand new cone kits from JBL exhibit the same thing out of the box. We melted the conekit back out of the basket and reconed with another kit. We always order two kits for any recone job. One to go, and one to show concept. We were always pretty sure the customer would be back with its partner driver, later.
It also sounds to me like a blistered coil.
Question: did you remove the dust dome to visually inspect the "out of round" vc?
If the coil is not perfectly cylindrical, recone is the only fix I know of.
I have also sanded the inside blistered coils on McCauley 6256 18" woofs trying to stop the rubbing. It was futile! 6256 drivers have removable magnets to make the job super easy. And still, no luck.
Good luck with your refoaming project, but I gotta tell you, reconing is sometimes the best/only option!
Scott.
There's got to be a way to do this.
Edgewound once advised me the answer was to true it up on a coil former.
I don't have an adjustable coil former, of course, but a tapered mandrel or hub of the appropriate diameter would likely work for that....
It is possible to true up an out of round voice coil, at least in some cases. I have had good luck by fitting a suitably sized round metal disc (straight sided, not tapered) to the inside of the coil and massaging the outside of the coil all around with a stout metal bar. The disc must fit tightly to the inside of the coil former. Some old field coil woofers have a removable center pole insert which I have used for this by building up the diameter with clear packing tape until it fit the coil tightly.
Maybe you could use a tubing expander as used to flange pipes for mufflers. 3" and 4" are large, but fairly common sizes in the racing world.