what is an a7

[lowendisthebest]

i hope im not starting a new thread on something thats already been hashed out. i fiddled around a guitar (that didnt stick.) i noticed that some of the notes were a7, e7 ect. i played an a7 and then played a reg a. other than they sounded a little different, whats the therory or whatever with the 7th notes or chords?

 

[Jools4001]

A major scale has got 8 notes in it, starting at the root note and going up an octave to the next root note. The seventh note in the scale is the one before you reach the octave, so in this case the G. An A7 chord is made up of a major triad (A, C#, E) with the G added on top.

I'll put a disclaimer in here that my knowledge of musical theory is pitifully small, so somebody who knows what they're talking about might be along soon

 

[Alvaro Martín Gómez A.]

When you are presented with a chord chart and see just the root name followed by a "7", it means a major chord with an added minor seventh from the root. G-B-D is the G major triad. G-B-D-F is the G major triad with a minor seventh from the root (From G to F) added, so that's a G7 chord. These chords have a "dominant" quality, which means that a tritone interval exists between the third of the chord (B, in this example) and the seventh (F) and this interval creates a tension that needs to be resolved. The way to resolve it is raising the third by a semitone and lowering the seventh by the same amount if the dominant chord resolves to a major chord, or by a whole tone if it resolves to a minor chord:

So, the explanation above points to a dominant 7th chord. Don't forget that just the root followed by a 7 (G7) should be understood like that. Now, there are other 7th chords that don't have that "dominant" quality, and it's due to the fact that the tritone interval is absent. Those chords are:

- Minor chord with minor 7th added = m7 = Gm7 (Example) = G-Bb-D-F. There's a perfect fifth instead of a tritone between the third of the chord (Bb) and the 7th (F).

- Major chord with major 7th added = Maj7 or M7 or Δ= GMaj7 or GM7 or GΔ = G-B-D-F#. There's a perfect fifth between the third (B) and the seventh (F#).

- Minor chord with major 7th added = mM7 or mMaj7 or mΔ = GmM7 or GmMaj7 or GmΔ = G-Bb-D-F#. There's an augmented fifth between the third (Bb) and the seventh (F#).

There are other 7th chords like augmented/diminished Maj7/7, but I think these ones are enough to get you started. Hope this helps.

 

[mutedeity]

Basically A7 is a dominant chord. It has the notes A C# E and G, which gives it the degrees [1,3,5,b7] and will have a strong resolution to the note D.

It's probably a good idea to read up on some relative diatonic theory to understand how chords are formulated and how they function.

 

[lowendisthebest]

thank you, i think ive got it but ill try to read up on it some more. Are the 7ths something bass player play alot or is it just something cool to know about?

 

[tmw]

thank you, i think ive got it but ill try to read up on it some more. Are the 7ths something bass player play alot or is it just something cool to know about?

It is something you should know about... Never thought of it as cool, but I guess it could be

 

[mutedeity]

It depends on the context of what you are doing. If you are playing only root notes, and you see A7 on a chart, you can just play the note A. On the other hand when you are playing things like Latin music or jazz it will benefit you to know the context of any chord you come across in order to translate it to an arpeggio or walking line.

The typical 12 bar blues walking line is based on a series of dominant chords. Also, knowing the function of chords in context will help you in making choices about which notes you will play and where you play them.

 

[Alvaro Martín Gómez A.]

One of the most common chord shapes for bass is that of a dominant seventh chord. Try this: An A on the A string, 12th fret with your middle finger, a C# on the D string, 11th fret with your index, and a G on the G string, 12th fret with your ring finger. There you have a dominant chord shape for bass (Part of an A7 chord, in this case). The fifth of the chord is missing (An E), but that's a chord note that can be safely omitted.

 

[LowDown Hal]

A maj 7th = 1, 3, 5, 7
A min 7th = 1, b3, 5, b7

 

[David1234]

You definitely want to know about it, since part of your job is to outline the correct chords in your playing, and at the very least your job is to not outline the incorrect chords!

The main chord types in most pop styles are Major, Minor and Dominant. Playing the 'wrong' 3 or 7 in particular means you're outlining the wrong chord and misleading your band.

Major: Play 1 3 5 and 7 from the major scle.
Minor: 1 b3 5 b7 (that is, flatten the 3 and 5 by one semitone which is one fret)
Dominant: 1 3 5 b7

There are also augmented and diminished chord types but don't worry about them just yet!

 

[mutedeity]

When you are presented with a chord chart and see just the root name followed by a "7", it means a major chord with an added minor seventh from the root. G-B-D is the G major triad. G-B-D-F is the G major triad with a minor seventh from the root (From G to F) added, so that's a G7 chord. These chords have a "dominant" quality, which means that a tritone interval exists between the third of the chord (B, in this example) and the seventh (F) and this interval creates a tension that needs to be resolved. The way to resolve it is raising the third by a semitone and lowering the seventh by the same amount if the dominant chord resolves to a major chord, or by a whole tone if it resolves to a minor chord:

So, the explanation above points to a dominant 7th chord. Don't forget that just the root followed by a 7 (G7) should be understood like that. Now, there are other 7th chords that don't have that "dominant" quality, and it's due to the fact that the tritone interval is absent. Those chords are:

- Minor chord with minor 7th added = m7 = Gm7 (Example) = G-Bb-D-F. There's a perfect fifth instead of a tritone between the third of the chord (Bb) and the 7th (F).

- Major chord with major 7th added = Maj7 or M7 or Δ= GMaj7 or GM7 or GΔ = G-B-D-F#. There's a perfect fifth between the third (B) and the seventh (F#).

- Minor chord with major 7th added = mM7 or mMaj7 or mΔ = GmM7 or GmMaj7 or GmΔ = G-Bb-D-F#. There's an augmented fifth between the third (Bb) and the seventh (F#).

There are other 7th chords like augmented/diminished Maj7/7, but I think these ones are enough to get you started. Hope this helps.

Personally I think that is an extremely hard to understand explanation of the function of a dominant. I doubt many beginners are going to understand that you are playing your tonic chord as a 2nd inversion of the chord let alone why you would do it.

I think the explanation about raising thirds is misleading too. Really you resolve tension by following the movement of the leading tone to the implied tonal centre. It's probably more relevant to explain that the chord moves upwards a P4 to resolve from the V to the I.

One other thing I thought of to reiterate my last point. You are suggesting that the downward movement of the 7th of the chord to the relative 3rd of the tonic chord is involved in the release of tension. I would say that this is incidental since the 7th of the dominant is the 4th of the tonic and will move upwards to the 5th rather than downwards. Really the only function of the b7 in the dominant is in creating tension as a tritone to the leading tone of the tonic. It has nothing to do with the movement of the chord in resolution.

 

[ryco]

I would read an "a7" as a minor triad with a b7. Sometimes used in Classical on the title page; ie e moll = E minor.
I've never seen music notated as such, but would be my best guess on the fly.

A lower case letter usually refers to minor chords, borrowed from lower case Roman numerals designating minor chords; ie ii iii vi
A "7" posted after a chord usually means b7 (min 7) for minor, Dominant, dim, and Aug chords

 

[mutedeity]

I would read an "a7" as a minor triad with a b7. Sometimes used in Classical on the title page; ie e moll = E minor.
I've never seen music notated as such, but would be my best guess on the fly.

A lower case letter usually refers to minor chords, borrowed from lower case Roman numerals designating minor chords; ie ii iii vi
A "7" posted after a chord usually means b7 (min 7) for minor, Dominant, dim, and Aug chords

I think I had this argument not long ago where I was saying exactly what you are saying here. I think you are right to say that using the lower case a is bad notation. I personally would just assume that it was notated badly though, rather than automatically jump to the conclusion that it mean amin7 or Amin7 as the case may be. I would read it as an A7 and if there was any confusion I would ask for clarification.

 

[Chris Fitzgerald]

One other thing I thought of to reiterate my last point. You are suggesting that the downward movement of the 7th of the chord to the relative 3rd of the tonic chord is involved in the release of tension. I would say that this is incidental since the 7th of the dominant is the 4th of the tonic and will move upwards to the 5th rather than downwards. Really the only function of the b7 in the dominant is in creating tension as a tritone to the leading tone of the tonic. It has nothing to do with the movement of the chord in resolution.

For hundreds of years throughout the history of western music through the early to mid 20th century (i.e. - functional tonal harmony), 7ths of dominant and diminished chords always resolved down. It's one of the most fundamental tenants of voice leading, following only "leading tones resolve upward". I'm not sure what style of music you're talking about, but as a blanket statement about western harmony in general your claim that most 7ths resolve up to the fifth of the chord of resolution simply doesn't hold water.

 

[mutedeity]

For hundreds of years throughout the history of western music through the early to mid 20th century (i.e. - functional tonal harmony), 7ths of dominant and diminished chords always resolved down. It's one of the most fundamental tenants of voice leading, following only "leading tones resolve upward". I'm not sure what style of music you're talking about, but as a blanket statement about western harmony in general your claim that most 7ths resolve up to the fifth of the chord of resolution simply doesn't hold water.

You are right, but that is not what I am talking about. The movement of the 7th doesn't play a role in the directional release of tension, only the 3rd of the V7 chord does. The role of the b7 in a dominant is to create a tritone which emphasises the need for the leading tone to move upwards.

If the direction of the 7th was so functional in the direction of resolution then we wouldn't be able to resolve to a minor chord.

 

[mutedeity]

Apart from that G7 will still resolve to C/E

 

[Chris Fitzgerald]

You are right, but that is not what I am talking about. The movement of the 7th doesn't play a role in the directional release of tension, only the 3rd of the V7 chord does. The role of the b7 in a dominant is to create a tritone which emphasises the need for the leading tone to move upwards.

...and the 7th to move downward. Tritones tend to resolve inward, with the 7th of the dominant going down and the third going up. They have done this for hundreds of years.

If the direction of the 7th was so functional in the direction of resolution then we wouldn't be able to resolve to a minor chord.

That's an opinion, and you are entitled to it. However, you are well in the minority among theorists IME. The seventh resolves to a minor chord the same way it resolves to a major chord: it resolves down to the third. The fact that it's a whole step rather than a half step makes no difference. The tension resolves downward by whole step. Read any theory book and this will be in the first few chapters. Listen to any Beethoven sonata and try find a 7th of a dominant chord that resolves up to the 5th of the tonic - you won't find it, because it isn't there. Happy hunting!

 

[Alvaro Martín Gómez A.]

Tritones tend to resolve inward

Actually, and because of

the 7th of the dominant going down and the third going up.

The diminished fifth resolves inward and the augmented fourth resolves outward.

 

[mutedeity]

...and the 7th to move downward. Tritones tend to resolve inward, with the 7th of the dominant going down and the third going up. They have done this for hundreds of years.



That's an opinion, and you are entitled to it. However, you are well in the minority among theorists IME. The seventh resolves to a minor chord the same way it resolves to a major chord: it resolves down to the third. The fact that it's a whole step rather than a half step makes no difference. The tension resolves downward by whole step. Read any theory book and this will be in the first few chapters. Listen to any Beethoven sonata and try find a 7th of a dominant chord that resolves up to the 5th of the tonic - you won't find it, because it isn't there. Happy hunting!

I don't know that you understand what I am saying. I would agree that the tendency is more for the 7th to resolve downward, but, and you can play this on a piano/bass/guitar if you like, if the 7th moves upward to the 5th of the tonic does it still resolve? I would argue that it does. The leading tone on the other hand can't go anywhere else and still resolve the dominant.

So what I am saying is that what the 7th of the chord does is irrelevant in terms of directing resolution back to the tonal centre. Even if I am in the minority I would like to see a stronger empirical argument against what I am saying than what everyone else thinks is right, if possible.

 

[Chris Fitzgerald]

Actually, and because of



The diminished fifth resolves inward and the augmented fourth resolves outward.

Clarification: I meant that they tend to resolve inward according to the way they are spelled. Since tritones are symmetrical, the function of each note in the tritone (as determined by the spelling) matters. A common occurrance is the case of the tritone sub in jazz. G7 and Db7 share the same two notes as the tritone (and their roots are a tritone apart), but in both cases the tritone of each chord resolves inward: in a G7, the B is the 3rd (resolves up to C) and the F is the 7th (resolves down to E or Eb); in a Db7, the F is the 3rd (resolves up to Gb) and the Cb is the 7th (resolves down to Bb or [rarely] Bbb). In both cases, when the 3rd is on the "bottom" of the voicing, the tritone resolves "inward".