Question about jtm45

[Impetus]

The resistors next to the bias caps are between the screens feed and PI. Anything down stream of these is regulated by the voltage in from the rectifier and the value of these resistors (study the schematic). Early amps (some very early JTM45s and PA 100w used 4k7 here). Usually you will see a single 8k2 and on the board for v1 and v2 another 10k and a 16uF filter cap.
Later the extra 10k for v2 was introduced and an dual 32uF for an extra preamp node. Yes you can call the resistor a decoupler or dropper, both will be interpreted the same way.
Later on as lower headroom/more preamp distortion was desired the 8k2 became 8k2+10k or 8k2+8k2 or 10k+10k between PI and screens. The preamp resistors were 10k and 10k during this era.
You are talking about a JTM45 so 8k2 between screens/PI and a 10k in preamp are all that was ever used.
If you want to go to different values, added nodes that is your custom/mod choice to adjust your preamp voltages to suit your sounds and your preamp tubes etc.

Man, you folks are great. Thanks. Yeah I've been slowly learning but I'm not the quickest with picking stuff up sometime.

 

[Impetus]

To help with your learning process, have a good read through Merlin’s site. The section under the ‘smoothing filters’ heading here being particularly relevant to your queries in this thread.

Thank you!! Gonna spend tonight doing just that