I have a Sorado I just bought. I can't figure out what preamp tube I need. I looked at the side of the tube and the writing says Mullard but the tube type number is not there. I looked at some schematics for the sorado and it looks like they have been through a few revisions because the one I saw was a little different from what I have. I tried a 12AX7 in the amp and all the amp would do is hum. I know the 12AX7 is good because I put it in another amp and it worked. Does anybody have any info on this amp?
Brandon