Have you tried "doping" your speaker cones?

I should mention that the main reason I tried it was to tame a small peak in the upper midrange and to take a little "edge" off the highs that was causing sibilance. You should try one thin coat at a time,let dry, and listen test. You can go too far with this and it can "deaden" the highs, if you are not careful. With woofers and mids, though, I think there is less risk of going too far,because of their lower frequency nature. It really stiffens the cone and creates better piston type action and reduces any cone breakup modes you may have. I should add that this is for paper cones only.

Sean, I've not only got my drivers "hooked" on doping, but I've got myself hooked at the same time. It really worked exactly as I thought. Great fine-tuning tweek. Only adds a few grains of weight, but alot of stiffening. About the whizzer cone mods, mine don't have any, but I've heard of 2 mods for them. They both are aimed at reducing the whizzer cone's propensity to vibrate out-of-control at the unsupported outer edge. This is the cause of the upper mid anomaly commonly known as "Lowther Shout", and some "tizzly" high end effects. One mod uses fiber glass insulation material, the other uses lamb's wool. In either case, a small amount of material is gently tucked in and lightly glued between the back of the whizzer cone and the main cone. All the way around. The idea being to support and damp the whizzer cone without adding any more mass than absolutely necessary. I have not tried this myself, and the Lowther people don't recommend it, but I have read many posts and articles that said it helped. This idea could be tried on any whizzer cone driver that is exhibiting peaky and irritating upper mids and highs. And if you don't like it you can take it out. That "glue stick" like kids use in school is good for temporary testing purposes. Albert - I guess this mod is how to get the "whiz" out of the whizzer!

Herman, I've doped the Fostex FE-103's in my full range single driver speaker system. After numerous adjustments to the T-lines and other aspects, I've refined them quite well. The upper midrange peak and sibilance problems were about the only things I hadn't overcome. This helped, not only for those things, but improved the sound overall by reducing cone breakup modes.

Just to add a little to this topic, I rearranged my room and moved my speakers out further to get closer to the "typical" placement formula, and wow! I don't know if the doping gave more coherent phase info or what, or maybe it was just the placement diff, but the soundstage now is incredible! I played Madonna(Immaculate Collection) and the soundstage now ranges from about 6ft behind the rear wall to about 4ft in front of the speakers in depth, and about 4ft outside each speaker in width! This is about 13ft depth and about 20ft width. And the imaging is rock solid, well to the outside of the speakers. With this kind of depth, who needs surround sound? I know I'm raving, but I am flabbergasted. Really, guys, this is the first time I have ever gotten soundstage and imaging like that from a speaker. Oh, sure, you get imaging, but alot of times it is centered and smallish. And, you get big soundstage, but the image focus is lacking, but the combination of both is a real mind bender. And, having the speakers disappear while providing solid imaging thet's well outside the left and right boudaries that is "palpable", is alot different than having the speakers disapper and provide nice imaging within the left/right boudaries.I suppose this is why people spend $30k-50k on a set of speakers.Pardon my lunatic rantings, but I am really enjoying this. I feel like after all the speakers I built, I finally hit the bullseye.

Sean, this is great fun. I am noticing large heighth improvements also. Sometimes, I think it might be too high. The drums are low, where they should be, and the instruments and voices are at middle height and about natural proportion and location, but sometimes tinkling bells and such seem to come from the ceiling. It's eerie, as my ceiling is vaulted to 16ft. Kind of a neat effect though.