see any obvious damage? if so, replace the damaged tweeter.

more frequently, you will see no obvious damage. however, tweeters are sensitive to high frequencies or high sounds. they are not designed to handle low bass or mid-range at ALL. they may have failed due to underrated parts installed by the manufacturer.

Many times, manufacturers use underrated parts that do not properly manage the separation of high and low sounds. It's then the tweeter malfunctions: it either goes dead, can literally melt and create annoying, distorted sound.

tweeter has melted during heavy use! (click the image and get a closer look)

Treatment

Be careful! if you have replaced a blown tweeter more than once, the design of the entire speaker may be flawed. So don't throw good money after bad, replace the culprits now.

Check out AME replacement speakers while you're here. you'll get $40 off for your speakers in trade, a lifetime warranty and the highest quality components and cabinetry available today.

or...talk with sound medic for further problems.