Something I tried recently and I think is worth sharing.
Baffle diffraction effects are well known and the reason many loudspeaker designs employ curved cabinet edges.
Essentially baffle diffraction occurs as a result of reflected soundwaves from the edges of a loudspeaker enclosure. This can cause comb-filtering effects, subjectively heard as “smearing”, although there is still some debate on the issue.
One method to reduce baffle diffraction effects at high frequencies is to use felt around the tweeter. This approach was used on the BBC LS3/5A below and more latterly Dunlavy loudspeakers.
I’ve tried this on a pair of Tannoy Reveal studio monitors I have using Neoprene strip rather than felt. The result, subjectively at least, is an immediate and obvious improvement in clarity and high frequency smoothness.
Neoprene Strip Code: 406-670 http://www.studiospares.com