Imrovising over chords

Playing the chord tones of the current chord will always work. They're already being heard anyway so you playing them too can't cause any problems. Where you have to take care is in the non chord tones.

If the chord is C major and the key is C major then the passing notes D & F between the chord tones C, E & G will also work fine because they still agree with the song's key of C major whose notes are CDEFGAB.

If the chord is C major but the key is G major then the passing note D will work fine as it agrees with the key of G major but the F won't agree with the key because the notes of the key of G are GABCDEF#G.

That doesn't mean it can't be used - just that it creates a musical dissonance that, if handled without care will give everyone the impression that you don't know what you're doing. Handled with care they are responsible for some of the world's greatest music.
As a musician you're expected to learn how to handle them well guided either by ear or knowledge or, preferably, both - because it's the skillful and inspired handling of non-chord notes or out of key notes that really reveals the improvisational abilities of a musician.

Unless you've got a valid reason, don't go changing scales on every chord (e.g C maj on C chord then E maj on E chord) - that's a recipe for disaster. You'll be introducing out of key notes on almost every change, with no hope of dealing with them properly.

THANKS for the quick reply fret so is it better to use scales, and know each of the notes in the scales and where they are on the fretboard to improvise or just play the chords arpeggio

THANKS for the quick reply fret so is it better to use scales, and know each of the notes in the scales and where they are on the fretboard to improvise or just play the chords arpeggio

Just playing the chord arpeggio is far too limiting and you wouldn't be adding anything to the music that wasn't already there - just filling out the sound a bit. If you did only that in a band, you'd soon find yourself 'out on your ear' - "surplus to requirements" :lol:
Use the chord tones as anchor points around which you weave melodic phrases including the other notes. All the other non-chord tones can be included but it's up to you to know which of them are 'in key' ones and which are out of key so that you can treat them accordingly. Learning the notes of the scales is how to acquire that knowledge, especially the major and minor scales which are responsible for most of the harmony we hear. Using other appropriate scales is a controlled and orderly way of introducing 'out of key' notes.
Knowing the notes of scales doesn't just mean being able to name them. When actually playing you don't have time to name them, even mentally - they pass by too fast. So you recognise them by their 'character'. Each note doesn't just have a sound, it has 'tendencies'... for want of a better word. Depending on other factors such as the key, the underlying chord and the previous notes, it often tells you whether it wants to rise a semitone or fall a tone, etc. in order to construct a phrase. Remember, at that level you are thinking in phrases rather than individual notes. A great solo is a collection of great phrases, not a collection of great notes.

Unless you've got a valid reason, don't go changing scales on every chord (e.g C maj on C chord then E maj on E chord) - that's a recipe for disaster. You'll be introducing out of key notes on almost every change, with no hope of dealing with them properly.

Would modes be useful for this? For example, in the key of C, using the D Dorian scale over the ii (D) chord, G Mixolydian over the V (G), etc. I've had two different bass teachers present this as a way to build melodic bass lines, and it seems to make a bit of sense ... maybe not for lead guitar solos, but for bass lines. What do you think?

1. listen to the chord progression

2. Think in your head what notes you would sing over the progression

3. Play those notes on your guitar.

Unless you've got a valid reason, don't go changing scales on every chord (e.g C maj on C chord then E maj on E chord) - that's a recipe for disaster. You'll be introducing out of key notes on almost every change, with no hope of dealing with them properly.

Would modes be useful for this? For example, in the key of C, using the D Dorian scale over the ii (D) chord, G Mixolydian over the V (G), etc. I've had two different bass teachers present this as a way to build melodic bass lines, and it seems to make a bit of sense ... maybe not for lead guitar solos, but for bass lines. What do you think?

But if you do that you're not really changing scale - you're still playing C major even if you change to the fingering pattern associated with the notes of D Dorian. They have the same notes.

So it's useful in the sense that those mode patterns let you play C major (in this case) all over the fretboard starting from any given degree of the major scale. Just be aware that you're not actually playing the Dorian mode. It just 'looks' like it to someone familiar with fretboard patterns. Anyone listening would still hear you playing notes of the same major scale you were playing over the C chord, probably with more emphasis on note 2 (D) as it's now a chord tone.

So it's useful in the sense that those mode patterns let you play C major (in this case) all over the fretboard starting from any given degree of the major scale. Just be aware that you're not actually playing the Dorian mode. It just 'looks' like it to someone familiar with fretboard patterns. Anyone listening would still hear you playing notes of the same major scale you were playing over the C chord, probably with more emphasis on note 2 (D) as it's now a chord tone.

That seems like one of those things that should be obvious but doesn't become apparent until it is explained well. I just had an "a-ha!" moment. Thanks! :D

I remember when I first started learning about this stuff I was trying to do the whole new scale for each chord idea.

Really what you want to do eventually is leave the idea that you are going to use the c major scale and only the c major scale behind, but still not think about a new scale for every chord change.

Personally I am aware of the chord progression, but you let your ears tell you what to play, not matter what scale it might come from. (this is where ear training and learning a million scales will help) Eventually you are just aware of the root, harmony, and how all 12 notes will (or better yet CAN) behave.

Practice by SINGING THE INTERVALS of any and every scale you can find while you play them on your guitar.