Ultimate question

If I want to solo over a rock/metal riff that goes Em , G , Am , Em

Lets say i decide to solo in pentatonic. I can just use the E minor pentatonic scale all the way? Or do I have to change to G major penta and Am penta when those chords are played?

or lets say the riff goes, Am , F , G , Bm

I can just use Am penta over these chords?

yup.

Pentatonic minor is a bit of a ho really. It'll go with anything :D

Originally Posted by: Swe_ShredderIf I want to solo over a rock/metal riff that goes Em , G , Am , Em

Lets say i decide to solo in pentatonic. I can just use the E minor pentatonic scale all the way? Or do I have to change to G major penta and Am penta when those chords are played?

With those chords you could use an "E minor Pentatonic" or an "E minor scale"
Or you could take the [U]chord by chord approach[/U], just determine the quality of the chord over which you are playing(major, minor, diminished, etc),
and play whatever scale or mode is compatible with that chord.

Originally Posted by: equatorWith those chords you could use an "E minor Pentatonic" or an "E minor scale"
Or you could take the [U]chord by chord approach[/U], just determine the quality of the chord over which you are playing(major, minor, diminished, etc),
and play whatever scale or mode is compatible with that chord.

I can also use an G major scale right?

Yes, you can. Technically, the Gmaj and the Emin scale uses the same frets. And since the progression you are playing in is in (or seems to be) in the key of Emin, It'll work beautifully.

Originally Posted by: Swe_ShredderI can also use an G major scale right?

Called relative majors and minors. If your working with a major scale to find it's relative minor just go down three frets from the root note, and vise versa to find the relative major of a minor scale. Pretty simple for these scales but it's a good start if your theory is minced like mine. :D

Originally Posted by: Swe_ShredderI can also use an G major scale right?

Please don't. Just use the Em scale for now.

The Major Scale or Ionian Mode, has two notes that produce tension, they are the (2nd/9th) and (6th/13th).
[G-A-B-C-D-E-F#]

The Minor Scale or Aeolian Mode, has two notes that produce tension, they are the (2nd/9th) and (4th/11).
[E-F#-G-A-B-C-D]

As you can see both scales share the same notes, but they have different tension notes and target notes.
So you can use Relative Scales, only if you know, what notes you want to target, and which notes need to be resolved.

On the other hand... Jazz players use the tension notes in extended chords; to leave some sort of suspense hanging in the air.

I like to play what I feel. Damn the tension and the resolution.