Simple cathode bias question on Fender amps

[rutledj]

If you look at the Deluxe Reverb schematic

http://www.ampwares.com/ffg/schem/delux ... _schem.gif

You will notice that the Tone stack recovery stage shares the same cathode resistor/cap between the normal and vibrato channel.

Why didn't they do that with the input stage also? Why is it ok in one place but not another?

Thanks,
Rut

[Firestorm]

It's not an especially good idea in either place. Look at the early Twin circuit -- it had all four input preamps sharing one cathode resistor and cap. Since Fender figured you were going to plug your guitar into one channel and your mike into the other, I can only assume that there were some undesireable interactions when used that way.

[Andy Le Blanc]

its an old hold over approach to electronic mixing...... early RCA
recommended circuit.... showes up in military manuals too
it..... so depending on what your design needs are and what refferences
you use ....it pops up all over the place..... as a way to optimize parts
where you can get away with it