'54 Super high frequency noise at volume: parasitic oscillation?

[anteriorl5]

With no grid stoppers on the 6L6 power tube sockets I'm going to solder them in and see if that takes care of the problem. Wanted to make sure they go on same as on a Twin Reverb with same R values. Do I need both the 470K and 1500 ohm?

[sluckey]

The TR uses 1.5K for stoppers and mounts them between pins 1 and 5 on the socket. It also uses 470Ω (not 470K) for screens and mounts those between pins 4 and 6.  Look at this layout for an example...

     http://sluckeyamps.com/misc/AB_Lite_II.pdf

[anteriorl5]

Just looking at the layouts for the supers; the 5E4 has 1500 ohm grid resistors across pins 5 and 6 and the grid input is soldered to pin 6. They are absent on the earlier models. So should I switch the grid input to pin 6, put the 1.5K resistors across 5 and 6 like the 5E4?

[sluckey]

You said "Wanted to make sure they go on same as on a Twin Reverb with same R values." That's what I showed you.

But you can put them on any way you like.

[anteriorl5]

Perfect. I understand now, just wasn't sure if it mattered what pins to use. Thanks much!

[Willabe]

Do I need both the 470K and 1500 ohm?

I always use both grid and screen stoppers on power tubes.

And they work best mounted as close to the grid socket lug as possible.