Alright, I have recently started learning theory, I'm truly loving it! 'cause theory gives me a great deal of insight into what I am playing, and I can even think out what I'd be playing without actually having a guitar with me! However, since I'm learning it all by myself, there are some things that I'm confused about concerning theory:

1) I know the diminished chord has the formula of 1-b3-b5 (a couple of minor thirds stacked). Say, C diminished would be something like C-Eb-Gb. However, I looked up for the formula of the diminished arpeggio in Guitar Pro and also in the notebook of a friend's, and I saw that the diminished arpeggio has four notes, so for C it'd be something like C-Eb-Gb-A (I think). Why is it like this?

2) The modes (yea I know you guys get this a LOT! ). I have heard a lot of conflicting statements over this topic. I have read in various lessons and articles that a mode is just a normal scale, but starting from a different note other than the root of that scale. If this is so, then what exactly is the point of learning modes? I mean say I have C Ionian and D Dorian, which have the same notes and the same chords, so why exactly do I have to learn them separately if everything in them is basically the same?

Elsewhere, I've heard that modes should not be viewed as a scale starting from another note, but as a completely different scale or an alteration to the major scale in some way. So should I learn modes this way?

Thanks in advance to anyone who helps me out here!
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Last edited by BassTalk at Jul 5, 2007,
1) The 4-note one is probably a fully diminished seventh chord.

2) They contain the same notes, but they resolve to a different note. I'm too tired to give a full, coherent explanation now. Sorry.

Note that I'm somewhat of a theory n00b. I might be wrong about the first one.
I can't answer your first question any more than Werty22 can.
As for the modes, try to learn them, and see them as separate scales. I assume you've probably come across their formulas already. The key to noticing how modes such as C Ionian and D Dorian differ, lie in their respective formulas. It's how each note is arrange within the scale that gives the scale its sound. The interval structure is what it's called. Different scale formulas give different sounds, based on it's interval structure.
1) Because a full diminished chord has as well a double flat 7th (which is just the same note as a 6th) This is the way a fully diminished chord differentiates from a half diminished chord, as a half diminished chord only has a flat 7th.

2) With the modes, the notes in the scales maybe the exact same as its sisters, however, the intervals are completely different, giving it a very different feel. For example, try playing a simple C major scale, then try an A minor scale. They sound completely different, but have the same notes, due to natural minor (Aeolian) being the sixth mode of the major scale (Ionian).

You can hear the difference in all the modes too, for the one example you gave, C Ionian and D Dorian, try playing them like this:
C Ionian:

D Dorian:

They have the same notes, but are completely different.
^That'll probably all just sound like C Ionian. I find that to really hear the modes characteristics you need a solid root. Playing D dorian just after playing C ionian, your ear will probably still hear the centre as C.

The way to use modes and get their different sounds is to think of the intervals it is made up of. Phrygian has a b2, a dark, dissononant interval. Lydian has a #4, which sounds... I dunno how to describe it but it sounds cool. Mixolydian is like the major scale but has a b7, making it bluesy and dominant.

Just drone the low E string, keep it ringing (clean setting works best). Then on the remaining five stings, play E Phrygian, E lydian, E Aeloian, E Ionian etc. and emphasise the unique intervals in each. Really listen to each scales' characteristics. Try making a melody from each mode while droning the E string.

Once you have done this, watch this video:

Regarding your first question:
A diminished TRIAD is 1 b3 b5
Cdim: C Eb Gb
A diminished 7th chord is 1 b3 b5 bb7
Cdim7: C Eb Gb Bbb

The Bbb is enharmonic to A, but you write Bbb because it is a diminished 7th interval, not a major sixth.

Edit: Standard Response to Modes Threads Follows

Okay, a mode of the major scale contains the same notes as the major scale, but the root is a different note. This is just explaining where modes come from, but I don't think of them like this when actually using them.
D Ionian (major) is D E F# G A B C#
E Dorian (second mode) is E F# G A B C# D
A mixolydian (fifth mode) is A B C# D E F# G
They contain the same notes but start on different root notes.

So, they contain the same notes but they are definately different scales. I think of modes as alterations to the major scale.
Ionian (Major) 1 2 3 4 5 6 7
Dorian 1 2 b3 4 5 6 b7
Phrygian 1 b2 b3 4 5 b6 b7
Lydian 1 2 3 #4 5 6 7
Mixolydian 1 2 3 4 5 6 b7
Aeolian (Natural Minor) 1 2 b3 4 5 b6 b7
Locrian 1 b2 b3 4 b5 b6 b7

So, for F Phrygian you start with the F major scale, F G A Bb C D E
Then flatten the 2 3 6 and 7 to get 1 b2 b3 4 5 b6 b7
And you end up with the notes F Gb Ab Bb C Db Eb.
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Last edited by Ænimus Prime at Jul 5, 2007,