rta-12 drivers seem frozen

ohskigod

I bought a pair of rta-12 6 1/2" drivers off ebay. I have a pair of rta-12's, and figured having replacement drivers would be a plus. I recieved the package and I must say the drivers were packed extremely well. the problem is, the drivers, while they produce sound, do not move at all. they seem to be frozen. Is there a simple fix to this, or am i hosed here? the drivers cosmetically look fantastic, like they are brand new. any help would be appreciated. thanx

[Deleted User]

Hello,
Thanks for posting to the Forum. There's one of two things that might have happened. One is the voice coil has been blistered by excessive heat, causing it to become jammed in the voice coil gap. Think of a metal cylinder with a great deal of wire wrapped around it in layers. This is attached to the driver's cone and rides in the center of donut shaped permanent magnet. At the end of this assembly, opposite the end attached to the cone, is a metal disc with a short piece of metallic rod on it's axis. This is placed so the short rod goes down the middle of the cylinder, this is called a pole piece and it transfers the magnetic field to the inside of the coil, working to increase the efficiency of the driver. All's well as long as everything remains free of distortion or within the forward and backward capability of the driver's motion. If excessive amounts of heat cause the voice coil to expand it will be jammed in the gap and nothing will move.
The second potential problem is if the driver were subject to a sideways jolt, it could shift the permanent magnet slightly against the coil. You could look at the back of the driver and see if it appears that the magnet is slight off center with respect to the pole piece disc. If it is, you could very gently tap the opposite side of the permanent magnet and very carefully try an re-center the magnet on the coil. If you have a rubber tipped medium sized hammer or place several layers of cloth on the magnet to dampen the strength of the tap. If you go too far the shift will be too much and the coil will be pinched on the opposite side. Go easy until you see what movement the magnet achieves after each time you tap on it.
I hope you are able to get the drivers working.
Regards, Ken Swauger

ohskigod

if i wanted to buy a pair of mw6501 drivers, how much would that run if i orderred them from polk audio direct?

ohskigod

correction, 2 mw 6500 drivers

F1nut

MW6500 ea BD0600-A List $60.00 Club price$48.00