Tube Amp Archive

Hi everybody; I'm thinking about increasing a 2061x's headroom. What can i do? I guess, i can bias EL84s cooler, remove V1's cathode bypass caps etc... I can change 12AX7 preamp tubes to 12AU7 or 12AY7. I know lo-gainy tubes does not increase headroom. But amp stays cleany. How do you think about ad...

Ok masters; Now i am adding a 1 x 6 rotary switch for negative feedback resistor. Original 100K resistor still stays. Rotary switch adds extra resistance above it. Positions are: 1: bypass 2: 10K 3: 33K 4: 47K 5: 68K 6: 100K At first position of switch, negative feedback resistor is 100K (original),...

Thanks vibrato you are really king!

vibratoking wrote:Glad you got it straightened out. Enjoy.

Wow! I swapped the leads and there is no oscillation! Thanks dudes! Yes, swap the blue and red wires. The tell tale sign is that DECREASING the negative feedback helped, which implies it's actually POSATIVE feedback. Swapping the two wires will change posative feedback to negative feedback. Assuming...

Thank you all! I am trying to swap leads now.

https://www.tube-town.net/ttstore/image ... 2205_1.jpg

I connected white cable to B+ (before choke), blue and red cables to the tube's plates. Do you tell about swapping blue and red cables?

Hi Guys; I have a Marshall JCM 800 2204 with horizontal inputs (pcb mounted pots and jacks). I changed the original transformers with Hammond 1750N OT and 290GX PT. Please watch the video and help me for this issue. My amp self oscillating! it was much worse before i changed the grid stoppers 5,6K t...