Key of C or Dm?

Dm isn't the relative minor of C. That's Am.

Haha.

Always at the first stumbling block... :D

C= C D E F G A B
Am= A B C D E F G
Dm= D E F G A Bb C
F=F G A Bb C D E

C=Am
F=Dm

Now you also have modes, you could play a song in Dm using the notes from C: D E F G A B C. The only difference between this and natural Dm is the B vs Bb. This changes tree triads directly: Em vs Em/5b, G vs Gm and Bm/5b vs Bb.

Myxolydian mode of C Major has the same notes as Dm. Myxolydian's the "standard tuning" for dulcimers, and you can play most any folk music and lots of old standard songs in that. Dorian mode of C Major has the same notes as C Major or Am, starting and ending on D. I get all confused when Noteboat starts talking about modal theory. I think of the modes as scales. That doesn't seem to be theoretically kosher.

Well I'm kind of lost.

I was just noodling over Dm - C6/G - C/G and D5-C5 and it just naturally lead back to the D on the E string to finish on.

Oh well. I'll come back to it when my theory's a bit more sound.

Myxolydian mode of C Major has the same notes as Dm. Myxolydian's the "standard tuning" for dulcimers, and you can play most any folk music and lots of old standard songs in that. Dorian mode of C Major has the same notes as C Major or Am, starting and ending on D. I get all confused when Noteboat starts talking about modal theory. I think of the modes as scales. That doesn't seem to be theoretically kosher.

Ricochet, I think your confusion lies in how you're using the terms.
The terms 'mixolydian mode of C major' and 'C mixolydian' are used differently.

The mixolydian mode of C major is the fifth mode of the C major scale, so it starts on G: (G A B C D E F G). This is also called G mixolydian
C mixolydian, on the other hand is: C D E F G A Bb C. which is also called the mixolydian mode (or mode 5) of the F major scale.

Clazon - that progression you wrote is in the key of D minor.

Dm is the supertonic chord in C Major, and is also used for modal playing - D Dorian is probably what you're looking at, it's got a B natural instead of B flat (which you get in Dm) and F natural instead of F# (which you get in D Major)

Best,

A :-)

D Dorian is probably what you're looking at, it's got a B natural instead of B flat (which you get in Dm)

If you look at Clazon's chord progression, you'll see it contains neither the note B or Bb. It can't be assumed to be in the dorian mode without the B natural. Even if it did have the note B, instead of Bb, and the mode was dorian, the fact that the tonal centre is D and the minor third F is present in the tonic chord puts it in the key of D minor. If he was to notate it, it would be correctly written with the D minor key signature (Bb) - which would be contradicted by an accidental wherever the mode required it.
In other words, whether or not the mode is dorian, it's still in the key of D minor.

Ricochet, I think your confusion lies in how you're using the terms.
The terms 'mixolydian mode of C major' and 'C mixolydian' are used differently.

The mixolydian mode of C major is the fifth mode of the C major scale, so it starts on G: (G A B C D E F G). This is also called G mixolydian
C mixolydian, on the other hand is: C D E F G A Bb C. which is also called the mixolydian mode (or mode 5) of the F major scale.Yeah, I know that. :D

I was just noodling over Dm - C6/G - C/G and D5-C5 and it just naturally lead back to the D on the E string to finish on.

That looks very much like D natural minor to me, not C of any kind.

D minor is the relative minor of F major and has the notes D_EF_G_ABb_C_D. None of the chords mentioned has Bb nor B and thus you really can't tell whether you're in D minor (with a Bb) or D Dorian (with a B natural). Either would do fine for soloing.

Your ear (rightly so) tells you that you're in D and not in C.