How do I play this song in a different key?

I play bass in my band and we are doing a cover night. One of the songs I need to learn is "Let's Go" by The Cars.

http://www.youtube.com/watch?v=ExYsh1W22Wo

My guitarist says we are going to play it in the key of G. No idea how to even go about figuring that out. I know how to play it normally though. The song starts out by riding an A. I figured G is a whole step down, so can I just play the song a whole step down and it would be in G?

You can do that, but it will sound different to you. So play it a few times to get used to the new sound

In terms of "theory", how does that work though? Changing the song from whatever key it's in to G. What are the rules that I should be following?

Think of the I..IV...V of any key...If you were to play in the key of C for example
C...F...G---the I,IV,V
Key of D
D...G....A
Key of G
G...C....D
Key of A
A...D...E
Key of E
E...A...B
All the same way to play a song in different keys. If you figure out the pattern in the key of A.....then figure out the same pattern in the key of G. But like I said...it may sound different. But it is the same exact pattern in the key of G.

the instructors here encourage us to learn the songs we know in different keys. So it becomes a simple thing. So think of several of the songs you know, and play them in at least one other key and you will get used to it. Just figure out the pattern of the chords and pick another key, and use the same pattern

Originally Posted by: hunter1801The song starts out by riding an A. I figured G is a whole step down, so can I just play the song a whole step down and it would be in G?

Yes, that is how transposition works. Play every note two frets lower.

Transposition on fretboard instruments is easy (& string instruments in general). Since guitars, bass, etc. do not distinguish between sharps & flats you simply play the same visual, graphic fretboard patterns but so many frets higher or lower.

Transposition on piano keyboards is harder. You can still see graphic patterns, but you have to distinguish between sharps & flats. So, sometimes when you have to "just play everything a whole step lower", this results in a completely different "set" of white & black keys.

Transposition on brass & wind instruments is harder still. First there is very little graphic, physical pattern symmetry. The embrochure (mouth positions) and fingerings do not easily show "shifting patterns" of key signatures. This is one reason orchestral players practice scales & sight reading from the beginning of their training. Unlike the guitar, there is virtually no way to "just look at the shapes & patterns & start to play something."

Before the invention of valves brass instruments were limited to one key by physical structure. In order to transpose at all (to a limited set of other keys), players had to slide a different length tube ("crook") in part of the horn! That way they could play the same physical motions, but the sound coming out of the horn would be higher or lower.

Hope this helps. That's a neat Cars song, enjoy. :)