Tube Amp Archive

Also, I want to be sure what I'm seeing is red plating. With a normal functioning tube is there any red coloration of the plate? What I see is around the creases in the plate closest to the center of the tube, a faint red/orange glow. It is more easily seen with the lights off. It is not coming from...

Don't sweat it Ampgeek! Last night I unjumped R147 and put the original El34's in to undo the whole modification.. I found that one tube has what looks like cathode oxidation rattling around within the tube and the other one has become microphonic! So because I'd rather not but another new set of tu...

You can determine that by measuring the voltage drop across the screen resistors (R113 and R106) and using ohms law. Current (in amps) will be the voltage drop divided by the resistance. 1000 ohms in this case. Screen power dissipation will be the voltage drop that you measure times the current tha...

The photo you posted shows tubes operating normally, not red plating. The camera on my phone didn't really do it justice, but in the middle of the plate it glows red after running for several minutes. I also didn't mention earlier that after first testing the svetlana 6l6gc's and finding the bias t...

I own a Randall rg50tc. Basically its one of Randall's few tube amps, it's a 50 watt combo. Stock it has 2 el34's. The amp is well suited for high gain styles. Even the clean channel breaks up very readily, and with clean boost takes on even more distortion. In the back of the amp are test points fo...