I will apologize in advance for my lack of music theory. I play guitar but self taught with no real theory. My son has been playing alto saxophone for about 6 months and has come along quite nice. His school does not have a band and he wants to jam with two other friends who play trumpet and french horn. I have watched many videos on the concept of a transposing instrument...but it's still very unclear to me. I do know that the instruments are as follows: Eb sax, Bb trumpet, F horn.
What I would like to do is get some blues backing tracks for them to jam with. There is an endless supply of blues backing tracks in lots of different keys. I was looking at YouTube videos of various blues scales for the sax. But I have no idea how to put it all together and find the right key of a backing track to match with a scale to jam with. And to complicate it further...I assume all instruments will be jamming in different key signatures.
I'm a computer person...I think I need to see this all in a spreadsheet...there has to be some kind of algorithm to figure it all out.
So to recap: If I find a blues backing track in say Em - what would be a nice blues scale for each of the kids to play on their respective instruments?
Thank you for any advice.