I know this is a pedal forum but I have a question that should be easily enough answered. I have a Marshall tsl 100. Is it possible ti change the EL34 tubes to 12ax7's or any other tube or are the sockets different?
EL34's are power tubes and 12ax7's are preamp tubes. Totally different animals. Trying to put a 12ax7 in an EL34 socket (and circuit) would fry it and possibly the circuit in no time. If you want to swap El34's for something else, make sure your amp is cathode biased and then you can try 6l6's or 6v6's (and possibly KT66's depending on the circuit).