IIB -> IIC+

[steve_k]

Here's a Mark that started out as a IIB, SN9XXX. Upgraded to a IIC+ with GEQ at some point. Looks like whoever had it done dropped the RP11A preamp board into the chassis, reworked for V5 and the 7C power board. Export PT. It has the correct IIC+ faceplate. I had an original IIC+ at one point (13XXX) and believe this sounds every bit as good. It is a beast. Still looking for another original though. Came with a low hours quad of STR415's and Tungsram's across the board in the pre. Swapped out V1 for an RFT and a GTC8 in V2. I need to get the bias supply sorted for the outer sockets though so I can run some 34's there. Bias supply is running a little high for my liking.

Steve

 

[gts]

Mesa dropped the RP11A into this when the upgrade was done.
There was no other way to upgrade a IIB->IIC+ without doing a pre-amp board swap.
The IIB's original pre-amp board could not be upgraded to C+ specs so a swap was necessary.

 

[Boogiebabies]

The bias supply is higher on the export amps because the plate voltage is only 450-460V.
Don't mess with it if you are looking at the negative voltage to pin 5.
You can run EL34's in the amp with no problem, just make sure pins 1 and 8 are connected on the outer two sockets.