Here is an old post from MGW, regarding an early Santana tone with the Mark V.
QUOTE
With my Boogie Mark V, I changed the speaker to an Altec (that makes a big diference) and I changed all the power tubes to Winged 'C' and the V1 Preamp tube is a Low gain Jan Philips with all the others Harm Croyo tubes. Its great now I have a smoother gain over the whole amp and Mk1 channel is rely useable now. Have fun a play music.
Cheers.
P.S. Santana on Mk1 setting Treble about 1 o'clock, mids about 3 to 5 o'clock (play with that one), bass just below 9 o'clock. That's using a Clapton Strat with a bit of Mid Boost on middle pick up/treble pick up.
UNQUOTE