Cool clip, thanks.
A Major is loud as hell by itself, and often they sound like crap. They had a reputation for self-destructing. Blackmore's was modified - there is a lot of misinformation on this floating around (including from Blackmore). I believe, though, that it is essentially a master volume mod; there may be an additional preamp stage.
With the Major, Blackmore would run an Aiwa tape recorder as a preamp. It is a KT88-based amp. I have not looked at the tube specs, but my experience is that it doesn't really sound like the EL-34 based Marshalls.
I commented earlier "which Blackmore tone" - because there are tremendous differences in his sound on different albums; Burn is the biggest example. There is one song on Burn that was recorded through a transistor amp, I believe. And, I believe he often used AC-30s with treble boosters in the studio. There are also rumors that there were empty Marshall cabinets with an AC-30 inside, for stage use.
You can look at
Dawk Sound Limited for more info from one of his longtime techs. There is also some info available at
..::**BSM - Finest Treble Booster**::..************, but more of it is about guitars, pickups, and pedals.
