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Discussion in 'Amps and Cabs [BG]' started by pablomigraine, Jul 16, 2005.
Anybody have instruction on how to change the tube in the bmax??
Unplug the unit. Unscrew the top of the unit. Remove tube, grasping gently, but pulling firmly. Replace.
Why do you want to replace the tube? Preamp tubes last for 10's of 1000's of hours if they're not heavily overdriven constantly, and even then, some makes last for years of use.
Remove the four screws from each end of the top cover. Then remove the two screws that go into the cover at the top rear through the back panel. Then remove the top center allen screw from the front panel. Carefully pull up the cover on the right side and lift it off. If it doesn't lift off stop and check to see if you have removed all the correct fasteners. Then grab the tube, and wiggling it gently, pull it to the rear. And out she comes.
I replaced my tube with a 12AU7 and now I can turn my gain all the way up to "2". Also, on mine, the two screws that go through the back panel into the rear of the cover were a smaller size than the four that go in each end. On re-assembly both of these stripped out with a very gentle tightening and had to be replaced with the next size larger screws. It looked to me like the holes were meant for the larger screws that are used everywhere else on the cover. So if yours has the smaller screws, just barely tighten them. Which means they will fall out later, so a little dab of contact cement on the threads might help them to stay in. Good Luck.
Yours has a different chassis then mine. I've got just the faceplate screws, and 6 top ones. Hm.
Mine has four on each side going into a panel behind the cover. Two going in through the back. And the one through the front cover. None through the top.