Q-Spots Series: Bach Invention in D Minor

For my first piece in the Q-Spots Series I have chosen Bach’s Two-Part Invention in D minor, and identified two Q-spots that very often cause players to falter (click here for an introduction to the series). If you are a piano teacher you will immediately know that I am referring to the places where one hand has a long trill, and the other hand a passage of even semiquavers (16th notes):

• Bar 18 – Downbeat of 23
• Bar 29 – Downbeat of bar 35

The idea behind Q-spots is to identify and isolate awkward places where we stumble and fumble, and go through a systematic sequence of practice activities that helps us break the section down into stages. We practise each stage until our inner quality control inspector is happy to sign it off, before moving on to the next stage. We repeat these stages for a few days in a row, by which time we should find the passage is not only possible but actually feels easy.

Let’s look at the first Q-spot in the Bach Invention and analyse the nature of the difficulty. There are two main problems here – coordinating the two hands together at the required speed, and managing the trill without tightening up. Part of the solution is to play a rotary trill (from the forearm) rather than lifting the fingers from the main knuckle; for the trill to fit together with the left hand we will need to organise it rhythmically. Probably the neatest way of doing so is to play a measured trill in demisemiquavers (32nd notes), beginning on the upper auxiliary (D) and stopping on the main note on the last demisemiquaver before the tie.

Before we can expect the hands to fit together comfortably, I suggest knowing the left hand so well by itself that it happens automatically when we play hands together. We might begin by practising the left hand very slowly in two ways:

1. Firmly with active finger tips, each note exactly equal in tone. Make sure the wrist remains loose and supple.
2. In a more cantabile style, with hairpin crescendo and diminuendo shapings.

Being able to control the left hand in a variety of different rhythmic patterns can really help here. Here is just one of many rhythmical variants you will find in the detailed Online Academy article – alternating one bar at full speed with a bar at exactly half the speed, with added dynamic contrasts (for practice – we’re not going to play like this). Do this extremely precisely, making the contrasts sudden:

Now that we are fluent with our left hand, it is time to add the right hand trill. We might proceed by playing the two notes of the trill together, loosely holding onto the thumb and gently tapping the Ds with the 3rd finger. The first stage will look like this:

The following video provides a demonstration of some of the practice procedures I recommend for this Q-spot:

Ten further practice stages for daily work on this Q-spot are available on the Online Academy as part of our Q-spot series. Click here to view this article on the Online Academy or click here for a blog post with more information on quarantining and the Q-spots series.

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