Tube Amp Archive

As a follow up, I replaced the JJ's with NOS GE long plate 12AX7's. Amp runs great, beautiful tremolo. Just a heads up if troubleshooting an Ampeg, don't assume a bug or circuit problem just because there are new tubes, JJ's in this case...

-Reverb is great with both Ampeg and JJ tubes. -Clipping another 25uF cap across the existing bypass cap resulted in no change to the weak tremolo with the JJ tube. -Voltage across the V7b cathode resistor is 0.8V for both Ampeg and JJ tubes (tremolo ON). In fact all the voltages from each V7 pin to...

Hi all, new to the site and have a question. I have a great running 1968 Gemini 1 (G-12) with original tubes except for the 7199 PI. It has superb reverb and tremolo. After the original 7199 died, I decided that after 55 years I’ll splurge for a new set of tubes, so I put in all new JJ’s. Sounds gre...