valves...positions/alternatives/mixing

[fourmations]

hi all

a couple of tube questions I havent been able to google successfully..

i have done lots of reading and have come to believe
that position 1 (nearest transformer) is the main pre-amp
and has the biggest influence on the sound.

so.. can i buy one each of a few types and just
try them in position 1 and see where i get
(my amp gets muddy and loses clarity and treble when driven)

also, i believe that i can use alternatives to the 12ax7's it takes
can i mix the types, (4 12ax7's and one alternative)

any good links welcome

thanks

4

rgds

[blacktiger]

I'm not sure what you mean by "nearest transformer", but V1 is the preamp tube closest to the input jack, and it corresponds to the first gain stage and will have the biggest effect.  You can substitute a 12AT7, 12AY7, 5157 or 7025.  You might also want to try different brands of 12AX7.  If you aren't using NOS tubes, you might want to invest in one for this spot.