Check this site out:
http://www.brianmayguitars.co.uk/
All you'll ever need to know!
(Go to the FAQ section)
What's great is Brian's tech tell's you EVERYTHING (strings, picks, amps effects & settings etc) - it's VERY rare that a techie is so willing to share his time and knowledge to such a great extent - I was just reading this last night - coincidence!
Great guy, great tone & gear & an even greater tech! ?