i decided to put a crusty old Holden 100w tube head into service while my B2R is being looked at. internally, it's made up of 3 x ECC83 (12AX7), 1 x ECC82 (which is?), and 4 x KT88. 2 of the ECC83's had died, along with the ECC82. the KT88's are (well, were until the other tubes died) making alot of noise (similar to dirty contacts but i've been through the whole machine cleaning and re-seating so i'm betting the tubes are on their way out). i found a surplus store here that had ECC81 (12AT7) for $5 each. better'n $38/ea for 12AX7's, i thought i'd give it a go! hey presto, a working amp again! i tried it @ practise last night into my Ampeg 410, and boy was it nice! couldn't get past about 1/4 volume b4 it was too much for me! similar to an SVT in tone, so i'm starting to think about losing the B2R and using this POS! now, what is the difference between the ECC81, 82 and 83 tubes? and, are there any cheaper alternatives to replace the KT88's with? less output doesn't worry me, actually it would be nice to be able to use more than 1/4 of the volume knobs! thanks!