speaking of the mesa sound just to digress a bit,i've got a marshall valvestate head(i know your gonna tell me to buy a real tube head but i bought it because it was a reasonable price,3 channels,built in reverb,effects loop and emulated line out,nice and versatile and a bit smaller so easier to cart around)and was thinking about putting a mesa 12ax7 in it,do you think that would make a notable difference to the sound of the amp,i bought the amp 2nd hand and its got the marshall tube in it,i've read that tubes in general sort of fade over time so if this is the original tube then its gotta be 20+yrs old,just thought someone on here might know,and to reply to Kyle,yeah i cant say that i'm all that keen on the sound of the HM-2,i bought it years ago because someone told me they were great,maybe through the clean channel you might get some metal type sounds,i dont use it anymore though,i've switched to a tube overdrive,more organic sounding and enhances your sound rather than change it as much but havn't had it long enough to swear by it.
YOU'VE ASKED THE RIGHT GUY....
let me preface this-i'm not baised in saying this because i think mesa boogies are the best amps in the world- i own several currently and have owned MANY of them
MESA TUBES ARE GARBAGE
they used to be good
now they are crap
all the tubes in the world come from one of 2 or 3 factories that make tubes
mesa now uses the cheapest china tubes you can get and scare people into thinking they must use them
you can use any tubes in the world AND be fine- and although they say they're 'fixed bias' you can really adjust the bias.
If you wanted to improve the tube/preamp there are special NEW OLD STOCK tubes you can find-maybe a good local amp tech has a bunch and can try and play around with the best tone
BUT my opinion is> in this amp given the circuity and tubes- there will be NO noticeable difference between tubes in that thing... although a fresh tube wont hurt
either way- a mesa preamp tube is only $20 so its no big deal if you get one- its not like its giong to break the bank $10vs 20 or so-but its not the best tube out there and its not a good value- and in your amps case wont make a difference.
Get a Marshall DSL its the best marshall amp you can get (other than an expensive 1959slp)
but anyway a good amp tech may have some favs and can try in person different tubes and go from there-in this case its no difference
but in an expensive amp with 4-8 preamp tubes...better tubes in certain positions (1 or 2 i think i dont know) will have a big difference and good techs can try different ones out and get better tone