There is a time and place for playing octaves in the left hand. But those times are far fewer than most of us think. In fact, it should be a last resort. I only do it when I am trying to get a certain powerful sound or when I don’t have anything better to do.
I have talked about this before I think, but here are the reasons to avoid octaves in the left hand.
1) Creates an unnecessary doubling (normally of the root). Doubling is not ideal unless you want a very big sound.
2) Creates a scenario where the left hand is contributing very little harmonically and is forcing the right hand to do all the work. As a result, it unevenly distributes the harmony notes on the keyboard. And the result of that is an inferior sound.
Let’s take a look at a practical example. Play this line. (If it sounds familiar, it is the first few bars of The Savior is Waiting from Portraits of Hope).
Notice what I play in the left hand on the first beat of the first two bars. I am playing an interval, but intentionally not an octave. In the first bar, I play a major 7th. In the second bar, I play a minor 7th.
Take a moment and play this line the way it is written and then play it with octaves rather than 7ths in the left hand. Then play it one more time with octaves in the left hand but add the 7ths to your right hand.
There will probably be no debate on which one sounds best. At least, I cannot imagine that there would be.
That is why I recommend that you get used to playing intervals other than octaves in your left hand and especially the interval of the 7th. That is by far the most common interval that sounds good.
And that leads me to a quick tip for doing that. All you have to do is drop your left thumb down to the next diatonic note of the key. That means to go down to the next note you would play in the scale. In this case, we are in Db. So rather than playing Gb as an octave in bar 1, I drop down to F because F is the note before Gb in a Db scale.
In bar two, rather than playing an Eb octave, I drop my left thumb down to Db. I skip D because D does not belong in the Db major scale.
I have been teaching this concept for years, but in a different more complicated way. Someone pointed out this little shortcut to me this week and I thought I would pass it along.
This is one of those little, big things that really will help you. Give it a shot and work toward the goal of doing this instinctively.