Hey Dazza,
There have been times with Karaoke that they have published some of their backing tracks in one key but, upon listening to it, was actually in another key–a recent example was a song I’m working on by the Bee Gees “How Deep is your Love”; they advertised it to be in Bb major and when I started working on it I could tell immediately that it didn’t match….and that is because it was in Eb meaning on alto I play it in C and Tenor in F as I’m going to do this song like a duet. This hasn’t happened a lot with their tracks, but there are some that are not in the key that they advertise. Unfortunately, there are times that we do have to transpose it to play it and there is not, to the best of my knowledge, any other solution to it other than to transpose it.

In transposing music to make sure we are playing in the correct concert key, depending whether we’re on a Eb of Bb Sax, we have to make sure that our transposition is correct/doing it correctly. Here’s a video Johnny made that deals specifically with this subject. Hope this helps.

The way to basically match up sheet music for Alto to any backing track is the following: Look at the concert key of a backing track and count DOWN 3 semi-tones (a minor 3rd); regardless of what Key the backing track was in. So, like Johnny explains, if your backing track were in the key of Eb, you would play it on the Alto in C. Or say your backing track was in the key of G, if we count down 3 semi tones that takes us to the key of E. If your backing track were in the key of F#, if we count down 3 semi tones we come to the key of Eb. That’s why it helps to use a keyboard like he does in the above video; really helps to have that visual aide.
In terms of getting a song in the correct Octave, it kind of just depends on the piece your playing. If a song featured a singer with a deeper voice, you would want to play this in the mid/low Octave range. You can also get creative and mix the 2 Octaves up, playing some notes in a low Octave and some in the mid Octave. This type of stuff sounds really great on the Saxophone when we change things up. Johnny does that a lot—you’ll notice him playing in a certain Octave and throw in a few high-screaming Altissimo notes and it really spices it up. If you were playing a song where the Singer had a high-pitched voice, like the Bee Gees have in their songs, then you typically would play it in the middle-to-higher range of the Sax; but don’t count out playing a few notes in the lower Octave in this kind of situation. That can add a lot to your playing just like high-screaming notes do. The main thing to do is get a feel for your song, experiment, get creative and have fun doing it!
If you go to Johnny’s music selection and check out in the beginner’s music, there’s 4 great/beautiful songs that with a modest amount of practice you can pick up. Elvis’ song of “Can’t Help Falling in Love” is a mega-tune and one of the most simplest to play. Also, go to his “Improvisation” lessons in the lessons section on the home page and there’s some great stuff there where you can actually create your OWN music with less than 5 notes! Even a beginner can pick up those lessons with a little work and have fun making some great music. In those lessons there’s free backing tracks he lets you download/use for the lessons. Improvisation is starting to become my main focal point in my Saxophone playing; I’ve been working on his ebook “How to Play Killer Blues” and it’s fantastic. But it requires that you have, at the very least, learned the fundamentals of the Saxophone first. For that, get his ebook on “How to Play the Saxophone” and it’s a superb way to get a good, strong foundation under your belt. There’s lots to “chew” on here at Johnny’s site–would love to see you upload something to the blog/member’s videos.