Cornwall 4 Speaker Mod - Pickleball Weights

Nice, added mass makes sense. Even physically having something taped to them might help. 

My experience with mass damping the back side of the horn is that it totally kills the horn dynamics. Damping from the front is much easier to tune "on the fly" so to speak without endlessly unscrewing and re screwing the horn in and out of place. The lead strips are thin enough that they don’t outright blunt the acoustics or the dispersion of the horn, and they can be cut down to smaller pieces for fine tuning and tweaking placement on different parts of the horn. Using this technique truly tamed the horn just so without sacrificing dynamics, imaging or anything else. It's a cheap easily reversible hack that can be adjusted in "real-time" so to speak so that "listening" for effect happens instantly and can be mitigated or enhanced instantly - in your room and also in your room as it changes with acoustic treatment.

I also have an 18 lb lead weight in the bottom of the Cornwall. It is thin enough to slip through the center bottom front port. I found that adding too much weight on the bottom actually increased treble to an injurious extent, so the bottom weighting is just as critical as damping the horns.

You're better off putting damping on the back side of the horn then inside the horn, inside you're effecting dispersion and damping the actual sound coming out of the horn, if you can hear it or not is subjective.  

I spent the time damping the back side of both horns (tweeters/midrange) with significant sound improvements so I will always recommend damping the back side. It's only a few screws on each not that hard to remove. I would also suggest damping the cabinet some as well. those Klipsch cabs are not that well damped at all, very boxy sounding. 

good suggestion....