Doubling notes in orchestration - inversions and extensions

Question

Just a very quick question, because I've found similar answers about doubling notes (for instance, when arranging for four- or five-part harmony), but nothing specifically involving inversions.

So, suppose that I have a C major chord. I know that I can safely double the C multiple times, quite safely double the G (or the fifth), and that I should avoid doubling the E note (the third).

For example, I can play the chord, say, in the fourth octave, and have a high pitched instrument play C on the fifth octave and a bass instrument play C on the third octave.

The first question is: what about extensions? If I don't have C major but C7 or Cmaj7, how safe is it to double the Bb or B note (i.e., the seventh)?

The second question: how about inversions? If I have C/G (second inversion), does the "safe note to double" become G since it's acting now as the root note?

Answer 1

The "rules" for doubling stem from the desire in polyphony to keep voices independent from each other. Since the third of a major chord is often a leading tone, we don't double it, because then two voices would both move together to the tonic in the following chord.

This same principle applies to all "tendency" tones. For example, we wouldn't double the seventh of a dominant seventh chord, because both voices would resolve together, creating a parallel octave (or unison).

These "rules" apply regardless the inversion a chord is in. It's fine to double the fifth, even if that fifth is the lowest pitch (i.e., in a second inversion chord.

However, these rules are designed to apply to the polyphony of Palestrina (or Bach, with some modifications that don't relate to doublings). If you're not writing polyphony, or if you're not writing in an "ancient" style, then it's fine to double as you please. For example, if you have trumpets and violins playing in unison, then they very well might double the third of a major chord -- in that scenario, they are being treated as a single instrument, not separate, independent voices.

Answer 2

There's a principle that says the harmony should be complete within each section of the orchestra - strings, wind and brass.

There's also a quoted example (but I forget where) of a massive tutti chord including the major 3rd just once, in a 3rd trumpet!

What you DON'T have to do is follow the rules of Bach-style 4-voice harmony.

Answer 3

The rules you're citing are the general rules for harmonizing, which are generally applied for classical 4 voices harmonization - and usually for the same family of instruments.

When dealing with an ensamble, those rules still apply, but that mostly depends on two aspects:

• the instruments (type and amount) that are going to play a specific voice, and the octave they're playing it;
• the harmonic/musical result you want to achieve;

For instance, consider a simple string ensemble: you could have 8 first violins and just one doublebass, this doesn't mean that those violins can't play the same note.

Doubling voices (even for the same type of instrument) changes the "colour" of the harmony. It's not just about the dynamic each voice reaches, but the harmonics generated by that amount, also counting the harmonics each instrument has.

So, unless we're talking about a melodic movement (melody or counterpoint), doubling rules still apply according to the result you want to achieve. If you need a more balanced result (close to what you'd do with the same harmony using 4 voices), then you should also consider balancing the doubling in the same way, considering how those instruments's sound results and is perceived and possibly the amount of players for that section/voice.

BUT. That also depends on the style you want to use. For instance, in classical/early romantic style, it was common to have some instruments to double notes that are generally not doubled; a classic example is the usage of timpani and trumpets, which often doubled leading notes or thirds just because those were the only notes they could play^[1], but since they added a more "triumphant" result, the doubling wasn't a problem.

Then again, doubling notes that are normally not doubled is not that an issue, especially if their voice has some importance (consider the E/D# bass/cello "pedale" in the finale of Beethoven's 7th), and in more modern styles those rules (like almost any other rule) are obviously much less strict, so the choice depends on the musical result you require.

^{[1] Historically, timpani and trumpets only played the tonic and dominant of the whole composition tonality; this was due to technical and practical reasons: natural trumpets were common even in early 19th century, mostly because the more advanced valve trumpets were more expensive and difficult to build, and it was also rare to find virtuoso players, so composers didn't "push" their limits on those instruments by using basic root/fifth notes and specifying in which key the instrument was (coincidentally, the habit was kept for long time exactly because of this: since the repertoire didn't require high skilled players or advanced instruments, players rarely became skilled). The same for timpani, but mostly due to technical issues: modern foot-activated timpani was created only in mid-1800, before that they could only be tuned by turning each screw of the head, so it was almost impossible to change tuning while playing (even between movements).}