Realising a Continuo part
By Terry Dwyer

What does “continuo” mean?

It is short for “basso continuo” = “continuous bass”. The absolute foundation of Baroque concerted music, since the composer could expect to write anything from one to many independent parts above it, and they would all fit the harmonies indicated in the continuo part. (There are similarities with jazz improvisation, which assumes a common harmonic framework or background to work against.)

The actual instruments required are seldom clear beyond dispute, and the safest explanation is to define continuo as “At least one melodic bass instrument and/or at least one harmonic instrument.”

So an absolute minimum could be one cello. Or one harpsichord or lute. Or a bassoon. Preferably the above definition should be taken, whenever possible, to mean at least one melodic AND one harmonic instrument. So if you are sequencing a Baroque piece with continuo, it is just permissible to dispense with a keyboard part, but so much more authentic and satisfying to include it. If your score gives an editorial realisation of the continuo, by all means use it. You won’t need the rest of this article then.

A common combination in Baroque times was one cello and a harpsichord. This would be used for solos (vocal or instrumental) and recitatives. In an orchestral piece we could expect two or three cellos and a double bass, plus harpsichord or organ (the latter depending on the building used). Organ seems to have been preferred when available – sometimes a small portative organ. Bigger ensembles would add bassoon (if treble wind instruments present) and perhaps lute. Mix it how you may. However, for most of the music we are likely to encounter, adding a harpsichord to the normal cellos and basses will do it. For church music the organ part should mostly be pretty light, pedals being used only in big pieces. The criteria are that the melodic bass line should be clearly heard, and the harmonic part just barely heard, certainly in the tuttis – it will be more audible in the solos, where the bass line might be reduced to one cello. We need not get paranoid about exactness, so long as the above criteria are met. (Though I was appalled at a concert I attended once. They performed Monteverdi’s magnificent Beatus vir for choir and soloists with accompaniment of just two violins and a small pedal-less organ (electronic, I think). This was reprehensible enough since the composition depends on an ostinato bass line which needs to be clearly heard at all times. But several times the idiot keyboardist turned over the page with his left hand, thereby losing the bass entirely.)

Figured Bass

We come now to the job of the keyboard player. He is confronted with a single bass stave bearing the same music as the cellos, etc. (In fact cellist and harpsichordist often played from the same part.) The bass line would probably be figured, that it is to say, each note would have below it some figures which were a shorthand for the chords required. The idea was for the keyboardist to play the given bass part with his left hand and the necessary chords with his right hand. These chords could be at any convenient pitch, usually around or a bit above Middle C so as not to appear above the treble instruments. So long as this right hand part clearly showed the right chord, the exact spacing was left to the player. Moreover, he could improvise freely around the chord with decorating notes, etc., so long as he did not draw undue attention to himself. If the part was unfigured, his job was harder, and it would be too much to expect a proper realisation without a view of the upper parts from which to deduce the chords. So it was only fair of the composer to leave a continuo part unfigured if the keyboardist was playing from a full score, or the part was excessively simple, or he was the composer himself anyway.

The Code

On the face of it, the code is a simple matter of indicating by numbers the notes to be played above the bass. E.g. 3 means a 3^rd above the bass, 5 means a 5^th, and so on (these intervals to be calculated within the prevailing key of the piece.)

A simple triadic chord is given as 5/3 (N.B. For the purpose of easily printing this article, such “fractions” are meant to represent what would actually appear, which is the 3 directly beneath the 5 (no slash)).

So with a bass note F and 5/3 below it, we add A and C. Remember, these need not be literally a 3^rd and a 5^th higher than the bass, they will be transposed up one or more octaves, and may be duplicated according to the laws of harmony. So perhaps (F) C F A. Or many other ways.

Let’s move on. So, a root position triad is 5/3. A first inversion is 6/3 and a second inversion is 6/4. These three signs will cover a great deal of music already. But because they are so common they are abbreviated even further, 5/3 to nothing, 6/3 to just 6, and 6/4 kept in full to avoid confusion.

So, in a figured bass, lack of figures under a note implies a root position (unless the composer or copyist forgot to put something in.). Actually the 5/3 does appear if it resolves a 6/4 on the same bass, so we can expect to see 6/4 5/3 in succession now and then. Of course in an unfigured bass we must not presume all chords are in root position!

Table of commonest signs:

(nothing) = 5/3 (root position triad)

6 is short for 6/3 (1^st inversion triad)

6/4 is second inversion triad

7 is short for 7/5/3 (root position of 7^th chord)

6/5 is short for 6/5/3 (1^st inversion of 7^th chord)

4/3 is short for 6/4/3 (2^nd inversion of 7^th chord)

4/2 is short for 6/4/2 (Last inversion of 7^th chord)

9 simply indicates a 9^th chord in root position (not too common in Baroque)

4 or 5/4 followed by 3 indicates a suspension, the 3 shows the real chord.

Inflections:

#, b, or natural on its own refers to the third of the chord

Same, directly in front of a figure affects only that note. Also a slash through a figure sharpens it.

A line ---- under a bass note means “keep the previous chord going”. This allows passing notes in the bass to go their merry way.

“Tasto solo” (Literally “Only the key”) means play the bass part alone, no chords at all, until figures appear, or perhaps the word tutti..

The code illustrated

Keyboardists should not feel they must play a chord on every given bass note, especially if the chord is repeated for several beats, or if the bass part is running about madly. In these cases play on the main beats to define the chord and keep the underlying rhythm clear.

Coping with an unfigured bass part

Tricky! You need a good knowledge of harmony, keyboard facility in many keys, and an inkling of Baroque-style practice. In most cases you will have to examine the upper given parts to detect the exact harmony.

A few pointers can be given, but they are not waterproof:

(In the key of C)

Bass notes C F or G are likely 5/3, though sometimes G will imply 6/4 going to 5/3.

Bass notes E A or B are likely 6/3, so long as they move on by step. However, if they leap up a 4^th (or down a 5^th) it’s a modulation. Go figure!

That only leaves D. Could be a passing 6/3 if between C and E. Could be a root position if it leaps. Might be an inversion of dominant 7^th.; might be a modulation to dominant key. It really is tricky.

Bach’s harmony is more complex than other composers (Handel is usually a doddle) so if a Bach bass is unfigured, best avoid it.

For practice, why not try playing along with a recording, provided you’ve got the score. Start with a Largo!

Stylistic considerations

Let the realisation fit the music’s mood. For brisk music or dances, use some staccato, and in any case break up into short phrases. (This is particularly important with the organ.) For slow or solemn music a more continuous style is better.
The harpsichord, having little sustaining power, needs more notes than the organ. Long sustained chords can be broken up into repeated ones, perhaps in a different spacing each time. Arpeggios may be freely used when there is time for them. Extra decorating notes and free runs are acceptable if not overdone – this applies chiefly to the harpsichord, though even the organ may indulge occasionally.
The keyboard part should never steal the limelight from the upper instruments*, though that is not to say its part should be dull. The idea is to be a co-operative partner, sometimes even on equal terms, sometimes reticent. Artistic and tasteful, never flashy.

* Except in rare cases where the composer indicates or implies this, see below.

Examples
Taken from my own improvised performance of Vivaldi’s Four Seasons. They are typical, not definitive. They are what I actually played spontaneously, so are imperfect here and there. But that’s what a live performance can be. (N.B. In these examples I have made the aural balance favour the keyboard for clarity. In practice it should not dominate.)

1) Normal style – one chord per bass note, with convenient exceptions.

Example 1 (harpsichord)

Note that I don’t bother playing the two semiquavers, nor harmonising the descending quavers with new chords (I had to look at the violin parts to detect the harmony because the bass is unfigured in this passage – I have added the above figures for your information.)

Also note that I don’t play exactly the same stuff on the repeat.

Listen to Example 1

It is a good idea to minimise your mp3 player as soon as it appears, so you can watch the score.

Example 1a – possible realisation for organ

Listen to Example 1a

2) Greatly simplified style, for over fast bass parts

Example 2

The object here is to mark the main beats; this helps to keep the ensemble together.

Listen to Example 2

3) Elaborate style, for special passages. The composer here has specified arpeggios, and the orchestra does very little anyway in this piece. It is a rare opportunity for the keyboardist to shine.

Listen to Example 3

Getting the notes into your sequencer

Method 1

If your knowledge of chords and keyboard fluency are up to it, the most satisfying way is to play along with the orchestra, as in real life. If you want to try this, beef up the volume of the harpsichord temporarily so you can hear yourself; or failing that, solo just the harpsichord and string bass lines. Most of the time you will want to slow the tempo down considerably, to give yourself thinking time. I suggest that you concentrate on the right hand part only, and play it in, using both hands if it helps to get it right. The left hand part can be added later, either by copying the string bass part across, or, if a simplified left hand is preferred, as in the above examples, play it in separately. If things go wrong but not too badly, just edit the result to correct errors. Or start again. Keep trying, it’s fun!

Method 2

If you know what notes you want to put in, but don’t feel up to doing it live, step input may be a good idea, or staff input in the sequencer.

Method 3

Make a MIDI file of the given bass part on its own. Import it into your notation program (Sibelius, Overture, Finale, whatever), having set up a two-stave keyboard instrument. Now enter the chords on the upper stave by whatever method suits you. Play the result back until you are satisfied. Now export a MIDI file of the result and load it into your sequencer, Copy it to your main file. Laborious but it should work.

Method 4

Proceed as method 3, but when all is in the notation program, print it out and revert to method 1. You now know what to play.

Terry Dwyer, with thanks to Bill Pearson for a useful suggestion.

January 2005

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Realising a Continuo part By Terry Dwyer