I have used the Pioneer HPM 100 for many years, Yes we all know the issues, Bright, Lousy imaging, Weigh a ton and a half, Cabinet to small, Etc. With a few tweaks here and there(900 tweeter/Mid range, Recap, EQ), They have sounded very nice for a few years. I recently redid the veneer, And while they were apart, I was reading an article written by a guy who designs for Morel drivers, And was on the diffraction subject, And the use of felt around the driver, And even installed on the baffle surrounding the tweeter, And in some cases the mid-range driver. I was not prepared to cover my freshly smoothed painted baffles, But thought I would give a spare set of original 100 tweeters the treatment, These drivers are a night and day change from the later HPM line of drivers, In a bad way. I went to my nearest craft shop and bought some black self stick felt, They had different thickness's, The article stated no more than a 1/4" and no less than 1/8". Installed the covered tweeters(Just the mounting plate, Of course!), And fired everything up. First impression was, Damn, Forgot to wire up the tweeters, They really were tamed down, Did a bit of tweaking on the L-Pads, And boosted the EQ a few steps at a time, And have to say, That tweak really worked, For my application anyway. Most of the inherent harshness was cut with adjustments stated above, But the felt gives the speaker more focus is the way to put it I guess. I'm rethinking the felt baffle, Maybe it really would bring these to another level, Stay tuned.