Probably the biggest problem in playing Figured Bass is doubling. For this class you should strive to play in four discrete parts. This is harder than you might think, because most of the chords we play are triads, meaning that in these cases, one chord tone must be doubled.
But this little fact spawns a host of parallel problems. Try playing the Descending Tetrachord (Exercise #3 from the next section) in three voices – it’s impossible to play a parallel fifth or octave. Now play it in four voices and suddenly each chord change has possible parallels.
Why do we need to play in four parts? Well, to start, although most chords are triads, there are chords (e.g., 7/5/3; 9/7/3) that absolutely require four parts. And if we vary the number of voices we play (in other words, if we lose control of our voices), our music doesn’t sound polyphonic, it becomes chordal. Now, if you are accompanying Handel’s Messiah on the harpsichord amongst hundreds of other musicians, it doesn’t matter if your improvised accompaniment changes between three and four or even ten voices– no one will notice. However, you will not able to improvise a polyphonic texture as a soloist. You’ll be reduced to strumming a series of chords, which sounds amateurish.
Try to avoid going insane looking for parallels. The guidelines are pretty simple:
Parallel perfect fifths and octaves between any voices should always be avoided.
Don’t worry about hidden parallels at all, that’s a job for modal contrapuntalists.
Diminished fifths don’t count, only consecutive perfect fifths. A diminished fifth followed by a perfect fifth (and vice versa) sounds a little strange but sometimes it can’t be avoided.
On the keyboard, we will sometimes have to double at the unison (i.e., the alto and tenor have the exact same note). This means we will be in effect only playing three voices. That can sound a little strange too, but there’s no way around it.
My advice on doubling/parallels is:
Don’t let parallel-watching paralyze you. It’s far better to play the right chord at the right time with a parallel, rather than to wait a few seconds before every chord as you double- and triple-check for parallels. Don’t worry too much at the beginning, just get the sound of harmony in your ears!
Learn that parallels sound bad. When I started keyboard harmony, I didn’t mind the sound of parallels. Now they really bother me. I didn’t take parallels out of my playing because a teacher told me I needed to -- I took them out because I gradually became aware of how bad they sounded. That’s when it became easy to get rid of them.
When in doubt, play in contrary motion in the hands. If the bass goes up, move all the upper voices down, and vice versa. This greatly reduces the chances for parallels.
6/3 and 6/5/3 chords will have either a fourth or a fifth interval between two voices in your right hand. When it is a fifth, just be aware that you need to watch out as you get to the next chord.
If you are playing two of the same type of chords in a row (for example, two 6/3 chords), alternate your doublings. In other words, if you double the bass on the first chord, double the 3 or the 6 on the second chord.
If you ever want more information on how to avoid doublings, consult the harmony section of CPE Bach’s “Treatise on the Art of Playing the Keyboard”, where he goes into staggering detail on every possible parallel and how to avoid them.
Keep a steady tempo and go slow enough that you can quickly think about each voice. But play the chord on time! Harmony has a profound relationship with meter and if you hesitate before every chord, you will never understand this relationship.
Your grade will not suffer from playing parallels (I’ll point them out, of course). Your grade will suffer if you don’t play the chords on time.