Em/C: Sound Notation, or Dirty Shorthand?

Question

A recent post about slash chords got me started thinking about whether it is technically "correct" to use a slash chord to mark a root position chord. For example, in C/E, the root is C. In Gm9/F, the root is G. In general, slash chords follow the pattern A/B where A would be the root of the chord and B the bass note. In other words, slash chords usually denote inversions. If I had to guess, that meaning probably comes from the old figured bass notation.

However, slash chords are also sometimes used to indicate not only inversions, but also marking specific voicings with upper structures. For example, C/D. The root of this chord is often not C, but instead D, in a D9sus context. In this case, the slash chord notation isn't so much of an inversion as it is an indicator of a voicing or a selected interpretation of the chord. The same logic can also be applied to other slash chords where chord A does not normally contain the note B: Em/C is a way to express Cmaj7, even though Em does not contain a C.

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My current understanding on slash chords would be best stated as:

Slash chord notation is meant to signal to the reader that the bass is acting independently of the rest of the chord above.

I have seen a few sources online define slash chords more strictly such that the root note cannot be in the bass:

"A slash chord [...] is a chord whose bass note or inversion is indicated by the addition of a slash and the letter of the bass note after the root note letter." - Wikipedia

"In simple terms, a Slash Chord is a chord where the bass note – the lowest note heard in a chord – is different from the root note." - Hello Music Theory

"A slash chord is a chord which indicates emphasis of a bass note other than the root of the chord." - StudyBass

Emphasis above is mine. I recognize that these are not among humanity's most reputable or rigourous sources, and that not all sources agree with that definition. However, there's something to be said for a number of top search results all turning up this non-root-bass definition, and I also did interact with at least one person on this site echoing similar sentiments. In fact, the Wikipedia article makes the claim that slash chords can be the bass note in easy arrangements "to avoid writing chords more complex than triads" for beginners, implying that this is not the intended usage of the notation.

I already know that both usages of slash chords are common. My question: is using a slash chord in this voicing/independent bass context an accepted standard concept for chord symbols? Or is it more of a fast and loose shorthand notation that is (getting) adopted for convenience? Should Em/C always be taken to mean E is the root with C in the bass, or should it be equally valid to use the symbol to write C as the root and Em as upper structure?

Bonus points: for those in the "accepted and valid notation" camp, is there any difference between the chord symbols Em/C and Cmaj7 (or C/D vs. D9sus)? I would assume the stricter "inversions only" theorists would argue that there is no difference whatsoever. Would the "inversions-only" camp accept any bass notes that are not in the upper chord (e.g. G/F vs. G7/F)? My thinking is that the looser group is fine with either notation.

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I did read this very similar question. However, from what I can tell, that question asked whether it could be used. My question hopefully is more about whether it is technically correct notation vs just a common shortcut.

Answer 1

Slash chords serve several distinct functions. You already identified the first two:

1. they describe inversions (e.g., C/E)
2. they offer alternate spellings of known chords (e.g., C/D instead of D7sus)
3. they describe chords that might not be otherwise easily described (e.g., B/C or Gb/A)

So, can we define slash chords in ways that only capture the first usage? (E.g., "slash chords are chords where the bass is different from the root.") To answer, we need to look closer at usages #2 and #3 and determine if they're valid.

The second usage: a chord like C/D may initially seem like an equivalent spelling of D7sus. (And sometimes, it is.) But when we write C/D on a lead sheet, we're telling the chordal instrument how to voice the chord. On the other hand, D7sus doesn't come with this same constraint and leaves room for interpretation. D7sus could be voiced in many ways (G-B-C-E, A-C-E-G, A-D-E-A, D-G-A-C, etc.) that don't contain a strong sound of C triad. This is totally fair. Sometimes, songs have iconic sounds/voicings that we want to convey in the chords. There might be scenarios where C/D captures how the pianist played the chord on the original recording.

The third usage: there may be some instances where the harmony isn't extremely well-defined. In this case, a slash chord might show the only notes that will sound good in that context. In a scenario like that, an alternate spelling may not be available, because the alternate spelling would imply other notes or a harmony that isn't accurate.

So ultimately, I don't think we can use a definition like "slash chords are chords where the bass is different from the root." This doesn't quite encompass everything slash chords can achieve, and there isn't always a suitable alternative like D7sus.

(As an aside, I don't think Em/C should be used to convey CMaj7. Em/C would look more confusing, and Em/C doesn't convey anything that CMaj7 fails to capture. But if the underlying harmony truly is Em, and the bass truly should be playing the b6, then Em/C is a perfect use of slash chords for inversion.)

Answer 2

Who is it meant for, are you writing the notation for jazz players, pop/rock or is it a hymnal or what? Cmaj7 is not that strange, but it's just written communication from people to people, so you are allowed to take your target audience into account. If you mean that the keyboard player should keep the same right-hand chord and the bass should step down, you can write Em - Em/D - Em/C - Em/B. Chord symbols were developed to get accompaniment done, not for harmonic analysis.

I don't want to demand all players to care about analysis stuff and know about extended chord symbols. A lot of people just need to play the tunes and see the chords in terms of something familiar, and every added letter and number creates a bigger obstacle. I've noticed that a good way to explain slash chords is: the guitarist plays the chord on the left side of the slash, and the bassist plays the note on the right side. For piano and keyboard players, play the chord on the left side of the slash with the right hand, and the bass note with the left hand or leave it out if you're just playing a string pad.

"C/D" gets the job done right, without talking about elevenths etc. Yes, it works as a V chord and it's a D dominant, and there's the sus4 aspect, which might not be obvious from the symbol "C/D", but it's a very tiny minority of players who would benefit from something like "D7 sus4 add9 omit5" and didn't already know what C/D is. I don't think such players exist at all. But there are lots of players who would balk at "D11" or "D7 sus4 add9", which I guess is what's usually meant when someone writes "C/D", i.e. C6/D but the extra 6 doesn't add anything that a competent player wouldn't add at will anyway.

I also like to do combinations like C/D - D/C - G/B. It looks clean and understandable and easy to play. Those who know what they're doing can add all kinds of extra notes, and those who don't can still play the song. :)

Answer 3

Slash bass is widely used for both inversions and what we might call 'rudimentary polychords' such as C/D.

The whole point of C/D is that it DOESN'T include A. And the chord has a quite different flavour with and without an A.

OK, the jazz improviser won't take any notice of that. But most musical performances are not jazz improvisations, the aim as accurate a copy of the composer's intention as possible. And, if we can't have full notation, C/D is a very useful and precise indication of something quite commonly written - a C triad over a D bass note.

Answer 4

I agree with most of what has been written. The one exception where I would rather write Em/C than CMaj7 is if the C is a pedal tone/point that has been started before that chord and probably continues after. (example of C as a pedal point is Jump by Van Halen, though it uses G7/C rather than Em/C).

It's a subtle distinction. Many listeners and musicians will hear the chord as containing an Em sonority over a drone tone C bass. Others will hear it as a CMaj7.

Answer 5

The idea of slash chord is that the first part indicates the overall harmony of the chord, and the different bass alters the "color" of that harmony, but without changing its role.

This is very important, as the chord indicates not only the triad, but the possible scale intended for that chord.

Let's take your example of E-/C and Cmaj7.

Given an E minor chord, the player assumes that the notes that can be played (the harmonic context) is that of E minor: the root - as in the most important note of that chord - is E, no matter the bass, and the scale includes F#, which does not exist in C major.

So, while those chords are conceptually very similar, they are not, as their function and harmonic context is different.

Answer 6

Slash chord notation is meant to signal to the reader that the bass is acting independently of the rest of the chord above.

I disagree with this. Bass is an independent voice, and it might be well expected that a good bass player won't stick to the roots of the chords, appropriately for a given style, and in accordance with other musicians, in particular the soloist.

Slash notation is used when:

1. A specific bass line is strongly suggested in specific arrangement (rather than a bass line chosen by the performer),
2. A specific chord sound is strongly suggested (like in Laurence's example).

Chord symbol notation is not very precise in specifying the voicing and it's not meant to be. The main usefulness of the chord symbols is that they mark the harmonic motion while leaving freedom of selecting the actual notes to play to the performer/arranger.