1 Topic by moddish (edited by moddish 2007-06-23 14:04:29)

  • From: Scotland.
  • Registered: 2006-07-13
  • Posts: 218

Topic: Chord structures

I've been trying to get a grasp of some theory regarding chord structures and I'm stumped with this one at the moment.

What's the difference between a Cmaj7 and a C7 chord?

I know how to work out the differences between add9 and maj9 etc, but I'm totally stumped on this one. The Maj7 is, i, iii, iv, vii (played C,E,G,B,E)and the C7 i'm working with appears to be, i, iii, no 5th and a flattened 7th (played C,E,Bb,C,E). Does it have something to do with the difference between the Major and Dominant scales?

Can anyone help me out and explain whats going on here please?
I daresay it's blindingly obvious once you know what's going on. But, for the moment it's got me stumped and is preventing me from moving on at the mo. I dont have a great grasp on things yet, so if the explanation is kept as simple as possible I'd appreciate it greatly. smile



Thanks,


Craig.

Blind acceptance is a sign, of stupid fools who stand in line.  John Lydon.

'Mod' is a shorter word for 'young, beautiful and stupid' - we've all been there." - Pete Townshend.
  • From: Starkville, Mississippi USA
  • Registered: 2006-03-04
  • Posts: 2,069

Re: Chord structures

Hello moddish - great question!  Both the C7 and Cmaj7 chords are built upon the same basic triad (3 notes).  The difference between these chords is the 'top' note in the chord.

The C7 has the major triad (CEG) plus a Bb (which is sometimes referred to as a flatted seventh since it is 2 half-steps below the C one octave above the root).  The Cmaj7 chord has the same major triad (CEG) plus a B (which is sometimes referred to a a major seventh and it is only 1 half-steps below the C one octave above the root).

All of this is far easier to 'see' on a piano keyboard than on a fretboard since most guitar chords include doubling of various notes within the basic chord.  For instance your Cmaj7 chord (x32000) contains these notes (xCEGBE) so it doubles the 3rd.

One fingeringing for the C7 is (034310) and contains the notes (ECEBbCE).  This variation does indeed omit the G (the 5th) from the chord.  Other versions of the C7 fingering will include the G in the chord.

The many different ways of forming a chord on a guitar fretboard yield versions of the chord that double, triple, invert, or maybe even omit tones.  Different versions of the same chord will have slightly different 'flavors'.  The flavor of a C7 is decidedly different than the flavor of a Cmaj7 - the 1/2 step between the B and the C creates a lovely dissonance that begs for resolution or attention.

Here is a link to a nifty-keeno article in Wikipedia that focuses on the basic structure of chords using a really cool grid to indicate the tones contained in a chord. 
http://en.wikipedia.org/wiki/Chord_building_grid
These grid shapes are the same no matter what key you in . . . the grid shape for a C7 is a major triad (CEG) with a tail off the bottom right to the Bb.  The grid shape for a Cmaj7 is a major triad (CEG) with an inverted pyramid down to the B.

I know you said to keep it simple, but this is a great opportunity for you to understand some elements of the dreaded 'music theory'.  Just for giggles you can go the massive chord grid on chordies 'Resources' page and click on various chords to view alternate fingerings - by figuring out which notes are actually in each version, you can see how they voice the same chord differently.   James

"That darn Pythagorean Comma thing keeps messing me up!"
[url]http://en.wikipedia.org/wiki/Pythagorean_comma[/url]

James McCormick's Website

  • From: Scotland.
  • Registered: 2006-07-13
  • Posts: 218

Re: Chord structures

Thanks James,  smile

Now if that's a simple explanation I'm not sure I'd like to know the technical one! lol

So from what you're saying I take it that as long as the chord has the 'basic flavour' of a C triad along with the flattened 7th, then it will be a C7. But if the 7th is not flattened and the Major triad is present then it's always a Major7?

Thanks for the link, I'll go have a look see at it.....even though I know it's gonna pickle my brain! lol

Craig.

Blind acceptance is a sign, of stupid fools who stand in line.  John Lydon.

'Mod' is a shorter word for 'young, beautiful and stupid' - we've all been there." - Pete Townshend.