I just started to play the harpsichord this past year, and though I initially disliked the harpsichord because I was unfamiliar with how to play it, the harpsichord has led me to a greater understanding of baroque keyboard pieces. So much so that I feel every pianist should play on the harpsichord a few times, especially when preparing baroque repertoire.
Perhaps the most superficial difference is the respective sound of each instrument. In the harpsichord, the strings are plucked. In the piano, the strings are struck by a hammer. Therefore, the harpsichord notes are sustained for a lesser period of time and sound more detached. It is a common error to assume that the harpsichord cannot sustain at all–once you press the key, the note dissipates almost immediately–which is false. If I press the key for longer than I should be, I can still hear it. In fact, the length of the notes is one of the ways in which harpsichord players create the illusion of dynamics.
Another obvious difference is the presence of two keyboards in the harpsichord, one on top of each other, as contrasted with the one set of keys in the piano. However, despite the two keyboards, the range of the harpsichord keyboard is smaller, around 4-5 octaves, while the modern piano has 7 octaves. Well, then, what is the purpose of the two keyboards? As I mentioned before, harpsichord players create an illusion of dynamics by varying note lengths, and also from switching from playing the lower keyboard to the higher keyboard, vice versa. Generally, the lower keyboard is louder, and the higher one is softer. Aside from these two volumes, the harpsichord cannot vary in dynamics, no matter how gently or determinedly one presses the keys. Whereas in the piano, all one needs is a softer touch for a quieter sound, etc.
The physical keys of the harpsichord are slimmer than those of the piano. Also, the touch of a harpsichord takes some getting used to:
The harpsichord feels “crunchy.” This is because in depressing the key you must overcome the resistance the plectrum is exerting against the string. You can *feel* when the plectrum passes by the string. — Martha Beth
I play very close to the inside of the keys, where you can reach the sharp and flat keys without moving your fingers upwards, but just sideways. If that sounds weird to you, it probably is. I play piano all the wrong ways, apparently. If you have taken any physics at all, you know that more force is exerted if you are further away from the center of lever. So, since there is resistance, playing on the inside is not good, because I have to exert more finger power to press the key. Therefore, especially for my left hand, I always underestimate the leverage needed, so this usually results in (a) the note doesn’t sound at all (b) I press the note, but a millisecond late and with a huge accent. However, despite this initial resistance, the harpsichord keys are less heavy than the piano keys, so it is easy to play ornamental items like trills and mordents.
Actually, let me correct that last statement: it is fun to play ornamental items like trills and mordents. This insight I gained has helped me understand the virtuosity intended in Bach’s music–not only are you supposed to be in total control and trill like it requires no effort, but you are supposed to have fun doing it. It is not Bach if you do not have a bit of pride.
However, the most important insight of all that I gained was about the sound. When you play a Bach on the piano, on has to manually and deliberately make sure every note is separate. To do this, on has to lift your hands or fingers after every detached note. At first, I thought that ubiquitous practice was unnecessarily cumbersome, and I had no idea why I needed to use this technique. Yet, on the harpsichord, without any special hand movements, each note is plucked and already sounds detached. This automatic default of sorts helps the player to grasp the instrumentation that existed in Bach’s time. In this way, the player then can more finely imitate this sound on the piano. Also, as I said before, the harpsichord cannot vary in volume–so when playing on the same keyboard, the left and right hands are the same volume. This equality of voices is crucial in Bach, especially in his fugues, in which I always struggled in the piano to make all of the lines heard and the voices clear. Another implication of this invariability in volume is you must pay more attention to articulation–articulation in Bach, for me, was always a huge pain, because it was so intricate, and I would always get lazy and maybe group a few slurs together.
If the world were perfect and harpsichords were as half as ubiquitous as pianos, then most, if not all, baroque pieces written for harpsichord, would be played on harpsichord. The harpsichord is what Bach wrote for, not the piano. Bach’s vision comes through truest and most naturally on the harpsichord. So if you’re serious about piano and your baroque repertoire, make sure to play on a harpsichord a few times in your life. If you’re in conservatory and haven’t touched one yet, what are you doing?! Go!
Extra: listen for yourself! compare these two renditions of Scarlatti’s Sonata K141–