Transposition Supports

In chapter 18 we will be working on the transposition feature of the harpsichord. When you study this chapter, you will see that the keyboard is slid to right to play at modern A-440 pitch, and slid back to the left to play at the original A-415 pitch. In order for this to work, we must have an extra 8' string and an extra 4' string at the top end of the instrument. We must also have 52 jacks. As you will soon see, we will indeed have 52 eight foot strings, 52 four foot strings, and 52 jacks, even though our keyboard has only 51 keys.

Given a moments thought, you will see that jack #1 will have no key to rest on when the keyboard is slid to the right. Conversely, when we slide the keyboard back to the left, the 52nd (extra) jack will have no key to rest on. This can cause the unsupported 1st or 52nd jack to fall below the level of the other jacks and give us a problem when we attempt to slide the keyboard in either direction. In order to prevent this, we must add a support block at each end of the keyboard to give these two jacks something to rest on.

As you can see in the illustration, we have room to the right of the last key and a similar amount of room (unseen) to the left of the first key. If there isn't enough space, you may have to cut a notch into the cheek block to make room for the new support block, but this shouldn't be necessary.