The Steel Guitar Forum

Hey Mark !! talking about fractional chords got me to thinking . Steel guitar probably more so than a lot of other instruments would be able to play fractional type of chords. But most people would probably call it out of tune !! LOL !!

I've always thought that a diminished chord is 3 notes, and a diminished 7th is 4 notes. Am I wrong?

The triad based on the 7th note of the scale is a diminished chord, right? And then if you add another third from the scale on top of it, you get the half-diminished (m7b5) chord.
[tab]chord scales
root triad extended
C C CMaj7
D Dm Dm7
E Em Em7
F F FMaj7
G G G7
A Am Am7
B Bdim Bm7b5
C C CMaj7 [/tab]
If calling a triad "diminished" is wrong, then my chart above should say Bmb5 instead of Bdim.

What we think of as the dim7 is more often actually a 5-note chord, the 7b9, where the bass player plays the root.

The triad based on the 7th note of the
scale is a diminished chord, right?
And then if you add another third from
the scale on top of it, you get the
half-diminished (m7b5) chord.

b0b,
You're correct on both counts.
Many will say, or write 'diminished' rather
than 'diminished 7th' when refering to the
four-voice chord, just as many say (or write)
'7th' when they are refering to 'dominant
7th' (as opposed to major 7th).
~Russ

B0b,

I don't know what is right or wrong... but if I see dim on a chart I would assume it means the 4 note chord. If you think of diminished as just a triad, it won't repeat every 3 frets like the 4 note chord.

I would say that to complete your chart, you should have the option of either the Bm7b5 (half diminished) or the Bo7 (Bdim7) which is awkward because your chart is based on a major scale and that bb7 is Ab, not in the major scale of C.

What we think of as the dim7 is more often actually a 5-note chord, the 7b9, where the bass player plays the root.

Thats exactly right and the bass note is the difference. If we called it a D#dim7, bass player would naturally grab a D#. Those b9's sound rough in the bass.

Scale choice on these chords is a big difference also. Here as in the chart, you could and probably would use the C major scale on that Bmin7b5.

However, full diminished scales have a choice of two scales commonly used. Either half, whole, half, whole, half, whole, half, whole steps; or,
whole, half, whole, half, whole, half, whole, half steps.

So Bdim7 scale= B, C, D, Eb, F, Gb, Ab, Bbb (An "A" note but called B double flat cause we already have the Ab in the scale.) Weird? Yes. Cause it has 8 different notes not the normal 7.

OR:

Bdim7 scale= B, C#, D, E, F, G, Ab, Bb
Same weirdness. 8 note scale.

Both scales have the same chord tones: B, D, F, Ab of the full diminished 7 chord. But the steps are different. These steps give an entirely different sound and tension leading different places.

I can't say I have mastered the use of these scales. Its hard.

Some like the whole tone scale against dim7 chords.

B, C#, D#, E#, F##, G##, A##
This double sharp thing is nonsense unless you are writing on staff.
I would think of B, C#, D#, F, G, A
Whole, whole, whole, whole, whole steps.

Now a 6 note scale, even weirder. But it has a sound. Kinda modern. A nice choice if you want to emphasize being "out." Can't say I would use it as second chord scale in "Crazy." (unless I was miffed at the singer!)

Hope I don't come off as loud mouth but there is a lot of cool music theory involved with dim chords. And of course, knowing theory and playing music don't necessarily go hand in hand. But its a good beginning....

Hey is that a lawyer joke?

Made a mistake. I meant to say I wouldn't use the whole tone scale in the second chord of the first turnaround in Crazy.

How do these things apply to pedal steel? I am not a good enough steel player to use these dim scales or whole tone. I do use them on jazz and swing guitar stuff, though.

I am practicing though.....

Many many thanks for this thread.
The light bulb (over my head) is dim but getting brighter...

Russ, your explanation for the term "half diminished" makes sense as I always considered it less than half. Thanks. The minor 7th flat 5 also serves well as a dom9th voicing minus the root. Ex. the root of the m7b5 is the 3rd of the missing root. Or f#m7b5 = D9th. Don D.

Don Drummer wrote:Russ, your explanation for the term "half diminished" makes sense as I always considered it less than half. Thanks. The minor 7th flat 5 also serves well as a dom9th voicing minus the root. Ex. the root of the m7b5 is the 3rd of the missing root. Or f#m7b5 = D9th. Don D.

It would be so much easier on us steel players if the chart in G just said D9/F# (D9th over F# bass) instead of all this confusing m7b5 and half diminished stuff. Ninths I can understand. It's just a 5 chord!

B0b, my thinking directly relates to playing these chords on 6 string; you can see it so much better. On the other foot, it still works the same on some level with PSG. Most steelers know a Dom 9th on either kneck so the extrapolation for finding the correct m7b5 when it is called for in a tune is to know the major triad note names. Knowing the major third gets you there. I am not aware of anyone who calls a V9 chord m7b9. Don D.

if the chart in G just said D9/F# (D9th over F# bass)

bOb,
I see what you're going after, but in writing it that way
you'll still have D notes (which are not in the F#m7b5)
coming from the chordal players.

Try this way: Am/F# (A minor over F# bass)
This way you wont have any D notes 'in the way'.

I first seen this way used in charts for 'Swing Shift Band'
(Buddy Emmons & Ray Pennington) in the '90's then
have seen it used elsewhere since.

As astute as you are in the mechanics of music I find it a
bit surprising this four-note chord troubles you, whereas you
have 9th chords, which are five-note chords under control.

It may help to realize how the thirds are stacked up to build
this chord: From the Root upward, a half-diminished chord is
a minor third then a minor third then a major third.

In similar thinking, a ninth-chord is, from the Root upward,
a major third, then a minor third, then a minor third,
then a major third; a minor ninth chord would be a minor
third, then a major third, then a minor third, then a major third.

I find that realizing chords by their make-up of thirds this
way, along with a good knowledge of the intervals within your tuning,
make for negotiating the fretboard, chordwise, much less baffling.
~Russ

Russ Wever wrote:As astute as you are in the mechanics of music I find it a bit surprising this four-note chord troubles you, whereas you have 9th chords, which are five-note chords under control

The 9th chord is a simple extension of the 7th chord. It is based on a major chord that I can easily hear in the progression, and I can fall back onto the major chord easily.

The m7b5 is a whole different beast. I see it quickly and easily on the keyboard, but I have a hard time finding it on steel. As a country player, I play majors, minors and 7ths all the time. I have many positions for each of them, and the extensions of them (6ths, maj7, 9ths, even 13ths) are just notes added on top. But I don't see b5 chords very often in my chord charts.

The positions for the m7b5 chord seem counter-intuitive on steel, especially on E9th. Take Bm7b5 for example. The root B would send me to the 7th fret or the 2nd fret, but in fact the easy positions are at the 8th fret and the 3rd fret. It's actually a "normal" sounding chord in the key of C, but it's spelled so exotically.

To get back to the subject of substitutions, people say that the Bm7b5 is a substitution for a G7 chord. Is there any real difference (on steel) between substituting a G9 or a Bm7b5? We're only playing the top part of the chord anyway. It's a lot easier to find the G9 positions, IMO.

Lastly, the m7b5 usually serves as a dominant 7th. Like a G7, the Bm7b5 is almost always followed by C. It really is a rootless version of the 7th chord, with a more confusing name.

b0b wrote: Like a G7, the Bm7b5 is almost always followed by C.

Often it is 2 of A minor. In that case it would be followed by E7.

A familiar example would be bars 7,8,9 of Moon River:
key of C major
Bm7-5 = II7 of VI
E7 = V7 of VI
Am = VI

I totally agree, Earnest. The m7b5 is almost always used as 2 of a 2- 5 progression to a minor.

Bm7b5, E7, AM

F#m7b5, B7, Em

If the progression resolves to the C as in your above example, B0B, then I would call it a G9. Same chord same notes except for the G.

Look at How High the Moon. Am7b5 D7 Gminor

I stand corrected. See how totally wrong I can be?

b0b wrote:I stand corrected. See how totally wrong I can be?

b0b, you are not wrong at all.

Walter Piston, Harmony p. 19 wrote: The triad on the seventh degree .... In its action and effect this triad is really an incomplete dominant seventh chord and is so treated.

"Incomplete" simply means the root is omitted. Later in the book he explains the similar case of how the seventh chord on the seventh degree [which is a m7-5] is often an incomplete (root omitted) ninth chord on the fifth degree in the case where it resolves to the tonic.

The 9th chord is
a simple extension of the 7th chord.

Likewise, the "half-diminished", or m7b5 is
a simple extension of the diminished chord.

Locate a diminished chord on the fretboard, and add
a Major Third to the diminished chords highest note.

For example, on the common E9th tuning you
have an F# diminished at fret 7 on strings
8, 9 and 10 with the 'F' lever.
Adding the 6th string with
the B-pedal makes an F#m7b5.

Likewise, you have an F# diminished at
fret 4 on strings 6, 8 and 9 with the 'F' lever.
Adding the 5th string with a 'half-pedal' on
the A-pedal makes an F#m7b5.

On the C6th tuning, you have an F# diminished
at fret 9 on strings 6, 7 and 8 with pedal 6.
Adding string 5 makes an F#m7b5.

Likewise, you have an F# diminished at fret 5
on strings 5, 6 and 7 with pedal 8.
Adding the 4th string with pedal 7 makes an F#m7b5.

These are a few examples; There
are other places to find them.

~Russ