Combining Chords and Scales

[Blitz]

Hi. I have a basic understanding of music theory. I know how a scale works, and how to harmonize it.

So my question is, is there some general rule concerning the combination of scales?

e.g. Say I'm laying down some chords in D Major, and I want to add some chords from another scale to 'spice it up.' What scale(s) would I use, and why?

Thanks for any help in advance

[EricV]

Hi there,

I would explain it based on the theory regarding key changes ( changing from one key to another )... if you look at the cycle of 4th´s, you see the rule:
The more you move around the cycle when switching keys, the more dissonant it´ll be. Does that make sense ?
Here is an example.
This is the cycle of fifths: C-G-D-A-E-B-F#
Now, if you change your key signature from C to G, you actually only change one note ( F to F# ). If you´d change the key signature from... C to E, there are 4 notes changing, and the change will be rather big, rather dissonant.

And you can look at this with chords too... hope this kinda answers your question.

One of my songs, "Cab To Queens", is in the key of Gminor. But for one of the parts, I "borrow" one chord from Dminor... I play a C major chord, instead of the Cminor which is part of the Gmin-key.
Also, there is a passage where the rhythm guitar and bass play only two powerchords, F5 and G5.
Over those, I play leads in three different keys... Gminor, Cmajor ( only 2 notes are different, and the F5 and G5 occur in C major too ), and Fmajor ( Dminor. Here, only one not is different, and again, F5 and G5 are part of that key ).
Hope this helps
Eric

[Blitz]

So, what your saying is that the further away the key is on the circle of fifths, the less cohesive the combination of chords will sound?

[EricV]

Yes. That´s what I mean.

[szulc]

This is generally true but there are some exceptions.
You can jump over several intermediate scales and go to the parallel minor ( or major) and borrow some chords.

C F Bb Eb Eb Major is the Parallel minor of C Major you could borrow the C minor chord from this and the transistion wouldn't sound so far away ( in this case 3 flats)