Help me understand why Lo Input on 2203/2204 doesn't have a grid stopper

[PharmRock]

Or does it?

This may be the weekend where I can finish this 1987/2204 build, and am in the "quadruple check" mode on the layout and wiring. 

In reviewing the 2204 schematic, when the Lo Input jack is used, the cascade from the previous stage is disconnected and the signal goes straight into V1b grid.  On its way, the signal path goes through the treble peaker 470k/470pf and to the preamp volume which has a cap across it, and then to the grid. 

Obviously this is the way the amp was designed, but I'm having a hard time why this doesn't have a grid stopper.  Or is the 470K resistor serving in that capacity?  The 470pf cap in parallel makes me think that any RFI would actually have an easier path to the grid. 

why is there not a 33-68k grid stopper resistor right on the grid, like we see with other inputs?

[sluckey]

That 470K as well as the volume pot act like a grid stopper.

[PRR]

Probably does get more RFI to the grid. But there is MUCH less gain from this grid than the Hi input grid. And there is that whopping 10k cathode resistor spoiling the stage's gain. Apparently it has not been a problem.

[HotBluePlates]

why is there not a 33-68k grid stopper resistor right on the grid, like we see with other inputs?

All of what PRR said, plus:

The preamp design of this amp really extends from the Hi input to the phase inverter.

The Lo input jack going to the 2nd gain stage grid appears more like an afterthought, to add a "2nd channel."  At least, this is not a great "input gain stage" if someone was trying to design a good "Clean channel."

[PharmRock]

Thanks for all of the responses.  While designing the input stage of this amp, which is sort of like Doug's "Hot Switch" but uses the 10k unbypassed cathode resistor on half of V1 and a lo input, i wanted to keep the traditional low input of the 2203/2204, as some of the clips I heard on youtube had an incredible clean tone in this setting. 

I've been inching closer and closer to finishing this off...maybe I will get the final solder connection done this weekend, and then wait a week to do one final check.  I also plan to make a schematic for this amp and post it to the forum.