zero interrupt

Are the output tubes the originals as supplied by Rivera? If they are, there should be a sticker on the base, blue and silver, with a number. Le me know the number. If they are not the stock tubes, then let me know what they are. Also, if not original tubes, you should probably have the bias checked just to be sure. They don't seem to be the original tubes. No blue sticker. This is what is printed on the side of the tube: SVETLANA ELECTRON DEVICES INC EL34 MADE IN RUSSIA 9804 There is also a stamp to the right of that: OTH55 I'm not sure if the preamp tubes are stock either: MARSHALL ECC83 is printed on them. Thanks Max

Myles, You responded to a post I had earlier about my Rivera Knucklehead 100. I'm writing to now to troubleshoot. I bought the amp used, so I probably need to change the tubes anyway. I've had the amp for about 2 years and so did the previous owner. I need a sweet jazz tone and a very tight crunch. I'm not really familiar with changing tubes(although I read thru your site) and I also don't have a manual for the amp head. What preliminary steps do you reccomend I take? Or can you reccomend someone who does blueprinting in the NY Metro area? Thanks. I appreciate any help. Max