Extra triad in iOS GarageBand Smart Piano.

[enuenu]

I'm teaching myself basic theory and started with major scales then deriving the major triads. Starting with C major I believe there are 7 chord triads as follow;

I - C

ii - Dm

iii - Em

IV - F

V - G

vi - Am

vii° - Bdim

 

However I just started playing with the Smart Piano in iOS GarageBand. You select a key and it allows a bunch of auto play features based on the chords in the key. When you select C as the key it presents the chords I detailed above but an extra chord is added, Bb. Why is Bb in there? It sounds like it fits but how was it derived as being part of the key of C?

 

The chords are also shown in the following order on the screen from left to right;

Em - Am - Dm - G - C - F - Bb - Bdim

 

That's 8 triads. I notice that every key chosen presents 8 triads, Always with the 7 usual triads I - vii° plus the extra mystery chord.

For example if you select G as the key the triads presented are;

Bm - Em - Am - D - G - C - F - F#°

Why is F included as a chord within G?

 

Thanks

[1001gear]

They add the b7 triad to every key? Truthfully, it will function as a V chord but with a more "modern" rock bent than the vii diminished and is probably included for that reason.

 

Try a simple rock progression with the bVII and then substitute the vii diminished.

 

[onelife]

Apple put it in there so you could play 'With A Little Help From My Friends'.

 

In the key of C the verse would be: C, G, Dm, G, C with the chorus: Bb, F, C.

[onelife]

... and 'Let It Be'.