Hey fellas,
I'm working on a Yamaha T100C, its basically a Soldano SLO knock off. There is some ghosting going on that I have been trying to eliminate, but I'm having no luck.
I find that the ghosting first become visible on my scope at the output of the V2b which is a cold clipper. It is not present at the grid of V2b but it is present on down the chain after the coupling cap from V2b.
So, the problem, as I see it is happening inside the cold clipping stage. For that stage there is a 20uF filter, 100k plate load bypassed by .001 cap, and a 39k cathode resistor.
I'm posting a picture of my scope screen so you can see the two notes. At the particular frequency that I have my signal generator set to, the extra note is very clear on the scope screen. At other freqs, it oscillates wildly. I just need it gone.
I have changed power supply filter caps, preamp filters, chopsticked everything, changed the tubes, further isolated the two channels than that which is stock. Can't find it. I'd appreciate if someone would give me some ideas.
Oh, just as a side note, in case it has any value... When you turn the power off to the amplifier, the second note disappears while the amp is still running on the juice stored in the filter caps.