2000 Mesa Boogie Dual Rectifier Solo

The ubiquitous amp for hard rock and metal of the 1990’s-2000’s and beyond - this guy came in with flubby mushy low end and muddy highs/treble. The effects loop also was causing the customer issues producing too much white noise/hiss. The tubes had never been changed and many of them were shot or worn out.

The bias on these is a non-adjustable fixed bias - which in order to use tubes that are not “Mesa” branded, either the bias circuit has to be modded with a mini trim pot, or the power tubes need to be in a specific range of current draw. I went with sourcing the right power tubes for this repair as the customer did not want it modified.

This one needed a full re-tube. I like using a specific tube compliment with these amps. A JJ 5751 - which has %30 lower gain than a 12AX7 but otherwise is the same tube - was used in position V1 to help with noise and put the gain in a sweeter spot. In V3 I put a JJ 12AX7MG to help sculpt the mids of the hi-gain channel and help with noise. V5 (Phase Inverter) has a EHX 12AX7 to push the power tubes harder. V2/V4 = JJ 12AX7’s. The power tubes are a matched quad of Tungsol 6L6GC-STR which help tame the fizz. The lineup is rounded out by two EHX 5U4GB rectifiers. All problems solved.