Custom Vibrolux Moyer mod ground reference Resistor question

[Blue_n_Jazz]

Can some of you guys who have some knowledge share some please. I think this is a somewhat easy question, but I understand I might be wrong.

What is the ground resistor for? Primarily, R62 and R63 on the Custom Vibrolux Reverb. Furthermore, what does changing the Lux 100Ω to 47Ω do?

http://support.fender.com/schematics/guitar_amplifiers/Custom_Vibrolux_Reverb_schematic.pdf

 

[phsyconoodler]

nothing in my opinion.It's to reference the heaters to ground.100 ohms is just fine.I notice no difference in the noise floor when switching from 100 ohm to 47 ohm.

 

[Blue_n_Jazz]

Yeah, I didn't notice any problems with it. I just wanted to make sure I wasn't going to hurt anything internal. I didn't add the negative feedback loop, but it sounds great. I did change the mid point in both channels.
On Bright channel (with the bright cap removed) I bumped the 6.8k to 10k. I heard that is called the Nashville mod. Whatever it is, keeps the highs and lows full with a touch more warmth.
On the Normal channel, I changed the 6.8k to 21k. I lost some highs, lows are still there, but a nice, nice warm mid bump. Sounds great cranked. Overdrive is very smooth. Not raspy like before.
Bright channel sounds great cranked also.

Reverb is nice and full. I could not find a 3300pf cap locally, so I didn't change that cap, yet. I am worried that the 12AX7 will not be tuff enough like the 12AT7 that was in there. I shall see.

Over all, the mod is great. The volume controls are more usable. As, it isn't distorting at 2-3 on the dial any longer. It is a nice clean and full sound. Want some overdrive, keep turning the knob.