(The appearance that currently has me troubled is not accompanied by any notation- otherwise I’d everygoodboydoesfine it out for myself. Also, I ain’t about to try a search for “+”.)
I’m certain I’ve encountered such chords before, but accompanied by a chord chart so that I just learned the formation without really understanding what it was.
So, first off, what’s the chord called? And how do you build one?
IIRC, a cool thing about the augmented chord is that it’s moveable on a guitar, assuming that you are using a fully-fingered inversion–i.e., no open strings. I don’t remember what the interval is, but if you move an augmented chord up or down the neck by that interval, you will wind up with an inversion of the same chord, without having to change the fingering.
*Biffy, is the interval a fourth? I don’t remember.
It’s a major third. The augmented triad is itself two stacked major thirds; if you go up another major third you return to the root. So there are really only four augmented chords:
C E G# (= C+ root position, E+ second inversion, or G#+ first inversion)
Db F A
D F# A#
Eb G B
…after that you start repeating the same combinations of notes.
Spectre
Being a guitar player, yes, the augmented chord, when moved four frets upward or downward becomes the same augmented chord.
The *diminished chord * requires only a 3 fret jump to become the same chord.
Pretty much right. A plain vanilla Cdim is only C, Eb, and Gb, though. You can usually add the diminished 7th (A) on top of it.
C7 is, as you said, C E G Bb. It’s also known as the dominant seventh chord. You also have the major seventh which is C E G B. It is notated either as Cmaj7 or C[symbol]D[/symbol]7.
Then, of course, there’s the minor versions of these chords.