buzz from speaker..

I may be way off base with this, but I would first check and make sure your driver screws are tight. If they have worked loose, it could cause such a noise from vibration.

If that isn't it, then try others suggestions. But I would start out with the ultra simple stuff.

What are dustcaps ?

The sound that I am getting is at certain frequencies, so I am sure it is not due to any source amp, pre, etc. I checked the speaker cones all for rips or torn dust caps and the screws to all drivers and all are fine. The woofer cones are all new and I was wondering could it have gone bad, and could the magnet have lost its strength, or even loosened on the back of the driver? I thank you all again for your suggestions.

One possiblity is a non-centered voice coil. If not perfectly centered, you can get mechanical noises, and worse, a dead short to your amp when the VC rubs in the magnetic gap which many amps do not tolerate well. The tolerances here are quite fine. Just because it looks OK from the front does not mean all is well on the back end. Proper suspension is everything. Good luck.

Thank you all for your suggestions. I have determined that it is the speaker by switching. I was curious if it is a non-centered voice coil can this be repaired or should I just replace cone?