# Why is E major a secondary dominant in the key of C?

I have searched the forum and found answers stating that E Major is a secondary dominant in the key of C because it is the V chord from A Minor. What I don't understand is why the E chord is Major and not Minor. The key of A Minor is simply the relative to C Major, right? So, how is the E Major when neither C Major nor A Minor contain an E Major chord? E Major IS the V in the key of A Major.. but that's a whole different key. So, do we take C and look at its relative Minor(A) then jump to its parallel Major, and take its V chord???

• In addition to the answers that you're receiving, note that in later music, this E-major chord doesn't have to be a secondary dominant in the key of C; plenty of composers playing with third relations would write something like I–III#–V, moving that E major directly to G. But typically E-major chords in C are understood as V/vi. Oct 26, 2022 at 21:06
• @Richard - At that point, those foreign chords that do not resolve like foreign dominant chords would are often chromatic mediants, not secondary dominants. Oct 27, 2022 at 11:52
• @Dekkadeci Correct! Sorry, using that terminology would have made my comment more clear. Oct 27, 2022 at 12:03

A secondary dominant means we are using a dominant 7 chord on a different root the V. This of course then implies a resolution into a different chord than the dominant. As secondary dominants require chromatic alteration of course many chords can be reached in this manner. The probably most classic secondary dominant would be the double dominant, that is the dominant of the dominant, i.e. the dom 7 chord on the II. In C major this would then be D dominant 7 (so a D major chord), resolving into a dominant 7 chord on the actual dominant G.

In your case E dominant 7 would either resolve to A minor as scale degree of C major, or it could resolve into an A domiant 7, which could resolve into said double dominant of D. So in fact E major could be seen as the quadruple dominant of C. Both these meaning are useful and not uncommon. The first one kind of relies on the ambiguity between tonic and parallel mediant, while the second one naturally forms a circle-of-fifths sequence.

• if you want to get technical (and who doesn't!), I think the extension of the term "secondary dominant" would probably be something like "tertiary dominant", "quaternary dominant", etc :P Oct 27, 2022 at 21:13
• @user45266 The "secondary" just means it is not the dominant of the main tonic, but of a secondary tonic. I’m not sure how one is supposed to extend this further, but feel free to get creative :) The double dominant on the other hand is the dominant of the dominant, and can thus be extended former.
– Lazy
Oct 27, 2022 at 21:24

What I don't understand is why the E chord is Major and not Minor.

Dominant chords always have a major third (in classical harmony, or at least in the core era of classical harmony, which is known as the "common practice period"). The dominant chord is built on the fifth scale degree, so it consists of the fifth, seventh, and second degree of the scale.

In the major scale, this gives you a major chord. (For example in C major it's GBD, G major.) In the (natural) minor scale, it gives you a minor chord, but the seventh is raised, which makes the chord major. This raising of the seventh is what led to the invention of the harmonic and melodic minor scales. For that matter, this raising of the seventh is what led to the convention that dominants are always major.

The key of A Minor is simply the relative to C Major, right? So, how is the E Minor when neither C Major nor A Minor contain an E Minor chord?

What are you talking about? They both contain an E minor chord! The chord built on the third scale degree of the major scale, containing the third, fifth, and seventh scale degrees, is a minor chord. In C major, the third, fifth, and seventh scale degrees are E, G, and B, which is an E minor chord.

The chord built on the fifth scale degree of the (natural) minor scale is also a minor chord (unless it's functioning as the dominant). In A minor, that's the E minor chord.

E Major IS the V in the key of A Major.. but that's a whole different key.

E major is the V of both A major and A minor, thanks to the convention of raising the third of the dominant chord.

But let me suggest a different way of thinking about secondary dominants. A secondary dominant is a chord that functions as the dominant to any scale degree other than the root of the key. It doesn't matter whether the chord built on that root is major or minor -- the secondary dominant always has a major third (and, if it's a seventh chord, it always has a minor seventh, which is how you can differentiate between a major chord that's just part of the key and a major chord that's a secondary dominant).

So, for example, in C major, in addition to E major as a secondary dominant, you could have D major as a secondary dominant (this is the "original" secondary dominant because it's the dominant of the dominant). Other possible secondary dominants: A major, B major, F♯ major, and even C major -- if you have a C major with a B♭, that is to say, a C dominant seventh chord, it's probably functioning as a secondary dominant to F.

This may all seem very confusing. It makes more sense in terms of roman numeral analysis. There, you have these chords in the major scale: `I ii iii IV V vi viiº`. Upper case for major, lower case for minor, a degree symbol for diminished. In C major, the chords of course are `C Dm Em F G Am Bdim`. The Roman numerals for E major as the secondary dominant to A major, therefore, is `V/vi`, read as "five of six." D major as the dominant of the dominant, similarly, is `V/V` or "five of five."

Now all this is very firmly oriented toward classical music, especially of the 17th through the 19th centuries. In jazz and other popular styles (and in more harmonically adventurous 20th-century classical music) it's common to have a chord that has the form of a dominant seventh chord but doesn't have a dominant function. There are all kinds of chords that don't resolve "properly" according to the classical rules because, well, the extra notes aren't necessarily treated as dissonances that need to resolve. They're often just there for color and texture. I mention this because the concept of secondary dominant is also far more useful in classical theory than it is in jazz or popular music. You're not going to find many D major or E major chords in classical C major pieces that are anything other than secondary dominants. The same isn't necessarily true of other musical styles.

• I think he meant to write "neither C Major nor A Minor contain an E Major chord..." I didn't even notice until reading your answer. Oct 27, 2022 at 13:00
• @MichaelCurtis that seems very likely; the possibility hadn't occurred to me. Oct 27, 2022 at 20:46
• That's correct.. I edited it. Thanks, for everything! Oct 27, 2022 at 21:13

So, how is the E Minor when neither C Major nor A Minor contain an E Minor chord?

The key signature of `A` minor indeed does not include an `E` major chord.

But harmony in minor keys is not determined merely by the key signature.

When it comes to keys in the major/minor system of harmony both major and minor keys have a leading tone which is one half step below the tonic. In the case of a tonic of `A` - whether the key is major or minor - the leading tone below tonic `A` is always a `G#`.

Now let's get back to that secondary dominant chord. The basic dominant chord is one rooted on the dominant scale degree and whose third is the leading tone. So, the purely diatonic dominant triad for the key signature of `A` minor is an `E` minor triad where the chord's third is `G` natural, but when making a proper dominant chord the leading tone `G#` is used and the chord is then a major triad.

The big take away from this should be that dominant harmony, the full variety of dominant type chords, is characterized by the leading tone. A major triad rooted on the dominant (which then contains the leading tone), diminished seventh chords rooted on the leading tone, tritone substitutes (which contain the leading tone but not the dominant scale degree), etc. are all types of dominants, because they include the leading tone.

E Major IS the V in the key of A Major.. but that's a whole different key.

...whole different key signature.

The actual difference between `A` minor and `A` major is a difference of mode.

A summary of minor key harmony is not appropriate here. You should get a good harmony textbook and read the part about minor key harmony. In short, minor key harmony is more complex that major, uses more chromaticism for basic harmony. In other words the difference between major and minor key isn't wholly different. It is modally different.

• I do have to admit that, despite having the leading tone of the dominant, augmented 6th chords make for pretty poor secondary dominant chords. (E.g. Italian Aug. 6th of C minor = Ab-C-F#, note the F# as the leading tone of G) Oct 27, 2022 at 3:26
• Augmented sixth chord - in their traditional form - are modifications of the subdominant and resolve to a dominant. Sure, the modification of the subdominant is raising the root, so `#^4`, and that looks like a leading tone to the dominant. Oct 27, 2022 at 12:46
• The devil's in the details. Traditionally, augmented sixth chords come from the minor mode. `iv6` has `b^6` in the bass. Root `^4` is above. Raise root to `#^4` to get the alteration of `iv` and it becomes and augmented sixth chord. Oct 27, 2022 at 12:48
• Take the same sonority but put it in a jazz context. Start with a regular dominant seventh chord, root on the dominant. Lower the fifth of the chord. `^2` moves down to `b^2`. That's an alteration of a dominant, `V7b5`. The sonority is the same as an augmented sixth chord. The various intervals of the chord are relatively the same, but the two chords are positioned differently within the key. Oct 27, 2022 at 12:52
• A leading tone is the `^7` scale degree. In an augmented sixth chord progression the leading tone is not in the augmented sixth chord but in the dominant it resolves to. The progression is a half cadence. In a jazz altered dominant `V7b5` the leading tone is in that dominant, but it isn't the altered tone. Oct 27, 2022 at 12:55

What I don't understand is why the E chord is Major and not Minor.

To create tension.

E Major IS the V in the key of A Major.. but that's a whole different key. So, do we take C and look at its relative Minor(A) then jump to its parallel Major, and take its V chord???

• Every major scale has only one dominant chord, the `V` chord. In the key of C, the dominant chord is G7.
• A dominant chord has a strong pull to the `I` chord which is a fifth below it. In the key of C, G7 has a strong pull to C.
• Sometimes, you might want a similar sound with a pull to a chord other than the `I` chord. In these cases you could a fifth above, and construct a dominant chord from there. Eg. If you wanted to create a strong pull to the Am chord, you could precede it with an E7. Here E7 is a secondary dominant chord.

Here are a few secondary dominants in the key of C:

Note Diatonic Chord Secondary Dominant
C C n/a
D Dm A7
E Em B7
F F C7
G G D7
A Am E7
• You seem to hint quite strongly that a secondary dominant chord is there to lead to its own tonic. That's not necessarily the case. And F(7) certainly wont lead at all to Bo.
– Tim
Oct 27, 2022 at 16:04
• @Tim - don't dominant chords—whether secondary or not—always lead to its own tonic? Whether or not we choose to take its lead is a different thing altogether. I agree that F7 does not have a leading tone relationship with Bdim, I will update the answer to make a note. Oct 27, 2022 at 18:07
• Your first two bullet points seem to be saying the same thing, consider merging them. Oct 28, 2022 at 2:38
• No, they don't. There are many pieces where, for instance, key C, there's E>F. Rather than E>A/m.
– Tim
Oct 28, 2022 at 16:44

A secondary dominant is, as stated, a dominant chord - in its own right. It doesn't actually have to lead straight to its own tonic, although it often does.

Taking your example of E. That's the secondary dominant which could lead to A, or Am. That Am just happens to be relative to C, but that's not particularly relevant.

Other secondary dominants used in key C would be A (to lead to D/Dm), D (to lead to G/Gm) or B (to lead to E/Em). Note that each secondary dominant chord has notes which are chromatic - don't belong in key C. Notably the leading note of the secondary dominant's tonic. Like I said, any secondary dominant may lead to its tonic, but it doesn't have to. I believe there should be a distinct name for those which do, but haven't found one yet.

• Answering your "I believe there should be a distinct name for those which do, but haven't found one yet" - for those that do not resolve like deceptive cadences either, that term is often chromatic mediant. This term also applies to chromatic submediants but notably does not apply to chords such as B in C major. Oct 27, 2022 at 11:56

Key is much more about the center of harmony than about a scale or set of notes. Being "in a key" does not mean "in a scale", it means what the center is.

If a C major chord feels like a "home chord" i.e. center of harmony in the song, then the song is in the key of C major, regardless of what notes and pitches are played.

As an example, in a song that's in C major, you can have a chord Db7, even though that chord requires the center pitch itself to be flatted to Cb. After that, when you play a C major chord, the C note is restored back to C natural. Such "chromatic alterations" to note pitches are denoted with accidentals in Western musical notation.

The key signature specifies a default, often-used set of pitches that's useful in songs in that key, if the song follows certain traditions and conventions of Western music. If the song diverts too far away from conventions of certain Western music for which the key signature system was developed, then it may be better to not use key signatures at all, but add an accidental to each and every note. This is sometimes done to e.g. transciprions of jazz improvisations which have an ambiguous key, or just wander around in different keys very quickly.

When you have an E major chord in the key of C, you have to sharpen the G note to get a G#. In musical notation, this is denoted by writing a sharp accidental next to the note in question.

Even if there are whatever sharps and flats, your song is in the key of C, if you feel that C major is a home chord. Claiming that a song or passage is in such-and-such key, is a statement from the person saying that, about what he or she considers the center of harmony to be. It is not a statement about pitches that are allowed to occur during the song or passage.

First, 'dominants', secondary or otherwise, are major chords. The major 3rd of the chord acts as the leading note of whatever it's the dominant of.

Second, A minor is not restricted to the notes of the natural minor scale. There's also the 'harmonic minor' scale, with a sharpened seventh note. In A minor, this will be G♯. So we can have that E major chord and still be strictly diatonic!

(Not that there's any requirement to be strictly diatonic. We can have chromatic notes/chords and still be 'in C major' or 'in A minor.)