I have a pair of hlx 3-way speakers (circa 1970 from HALE Electronics in Groton, CT, no longer in business); 3" tweeter, 6" Mid & a 12" woofer, all w/ paper cones! These are hooked up to a TEAC AG-D9260
Long ago i replaced the torn fabric covers; then recently i decided to investigate an annoying sound that came along with the deep bass from "Star Wars, the empire strikes back" ( i was finally tweaking my surround sound). i removed the cover and found that a couple of screws holding the woofer were loose & the speakers were very dusty. There was also some kind of whitish material on the bottom portion of the cone itself. so, i brushed off the speaker oh so gently... but the stuff was still there!! i then used a microfiber cloth gently but to no avail:
i wanted to get these buggers clean!!
I then used my homemade window cleaning concoction of water w/ a little alcohol(R-OH) & vinegar on the microfiber cloth so it was just damp & surprise, the white stuff came off! So i gently did the entire surface of the cone then all of the speakers of both sets! Then i removed the loose screws, applied hot glue to the site of the old screws & quickly put in new screws securely! i cushioned the grille w/ some foam & secured them back on the front. Lo & behold the speakers worked great! Even when tested w/ the THX optimizer they sounded terrific; & when THX tested the sub-woofer, these 12" 40+ y/o woofers stood out!!
I listened to the entire movie at half volume & was excited to feel
the bass just like having a sub & without distortion!
So, i cleaned the paper cone speakers w/ water, R-OH & vinegar w/ no damage whatsoever!!