about 3 year ago i put jj's in my uber. they went bad after 6 months....which might be expected with 500 + volts on the plates. then i replaced them with jj's AGAIN. received a bad set right of the box. got replacements no big deal. swore off jj's. as of late i retubed another uber i now own with a brand new set of jj's. i have decided i would try a sip of the "cool aid". guess what...ANOTHER BAD SET. i returned them to c.e. and they replaced them with =c='s( (which after over a dozen retubes on my presonnal and customer/friends amps) and i'll NEVER try them again. just my rant. i guess when they work they sound great, but when they dont , they dont in a bad way? i dunno.