Cheap tweak from Virtual Dynamics:

The bass driver of my mains and its crossover both have resonance control brass tuning bolts that do make for a obvious change when tightened or loosened. My amps also can be tuned in a similar manner. Vibration can be given direction. Tom

The screws that matter most are those that hold the diaphragm and voice coil in place to the magnet assembly and face plate. The ferrous screws do just that, they screw with the field of flux as the coil moves back and forth in the gap. So the smallest speaker with the smallest coil is held in place with ferrous material at the closest distance to the motor assembly. Replace those screws one at a time that hold the dome in place. All of these that I have ever replaced have been metric size. Tom

Tom, besides switching to brass screws for your drivers, have you experimented with the torque? I'm curious what the proper torque should be for those inner screws for the tweeter, or maybe it depends on the type and brand of tweeter. I recall finding a thread on AA how the Merlin speaker driver's screws are properly torqued at the factory and some owners check for torque maybe twice a year. I remember that the inner screws on the tweeter are torqued higher than the outer screws.

Torque would indeed be a factor. As I said my bass driver,crossover and amp are tuned ..by ear. I have not recorded the settings by torque measurements but by ear and then recording the postion like the hands on a clock. During shipment of any device that is "tuned" at the factory the tuning will change in transit to the end user. The tuning will also "relax" with use. Retuning may also be required with changes in cables, electronics, tube brands and room acoustic additions. Increased resolution as I found with the addition of the modified Altmann Dac, D-Clock, PS Audio transport all AVM treated and Rick's magnetic replacement fuses made for quick apparent retuning by ear. Yep that feels right! Now sit down and enjoy. Right was obvious. Tom

Sherod, The torque to "tune" applied would vary from speaker to speaker. Cabinet structure and material.. driver frame material and even the number of fasteners.....T Nuts used? Hey what about speaker stands? Coupling or de-coupling materials? How about the flooring material, it too would make for a difference. Yea but its easy. Tom