Maintaining Sorli Harpsichords
Keyboard Height Adjustment -
Instruments by harpsichord builder,
Steven Sorli are made from solid wood. Even wood with a protective finish
will shrink and swell with changes in relative humidity. It is advisable to
maintain the level of humidity in your music room between 45% and
75%. One adjustment you may have to make as result of a gradual
change to a new level of humidity is the height of the keyboard. In
the dry season, the case sides shrink and tend to lift the keyboard
slightly (1/16"). This causes the jacks to rise as well. What you
may notice is that most of the dampers are not damping, the plectra
are too close to their strings and the key dip may seem shallow. In
the humid season, the case sides swell and the keyboard falls. What
you notice is that dampers tend to push strings sideways when moving
the hand stop from off to on position and the key dip may seem deep.
The keyboard can be adjusted to compensate for these humidity
changes. There are two screws in the bottom of the case to make this
adjustment. Look under the case, directly below the two ends of the
jack rail and about 2 to 4" in from the case sides. The screws are
recessed into the bottom, so you will see holes about 1/4 inch
To make the adjustment, remove the jack rail so you can watch the
jacks move up and down as you turn the screws. Decide which
direction you want the jacks to move (up in the humid season or down
in the dry season). Try to position yourself to observe the jacks as
you turn the screw with a screwdriver (or allen head driver for
single manual instruments). If jacks are too high, turn screw
counterclockwise until the dampers make contact with the strings.
Play a few notes at the end you are adjusting. Some players prefer
absolute damping, others allow a little resonance. Adjust the second
screw and check dampers throughout the keyboard range. Be sure not
to lower the keyboard too much. Check by moving hand stops on and
off. The dampers should not push strings sideways. Make any further
adjustment and finish by adjusting individual dampers at the
jack itself. Most likely you will only need to make this adjustment
twice a year, after the onset of the dry or humid season.
Voicing Harpsichord Jacks
The procedure for replacing and voicing a Delrin plectrum is as follows:
Use a small pliers to grasp the plectrum and push it out the back of the
jack tongue. Insert the new plectrum, with any curve pointing upwards, into
the back of the tongue and wedge it firmly in place. You can use the pliers
to squeeze it tight or place the jack and tongue face down on a block with the
plectrum overhanging the block. Use a small screwdriver to push it firmly in
place. Adjust the top adjustment screw so that the back of the tongue is
slightly proud of the jack body.
The plectrum is now much too long and thick and needs to be trimmed to the proper
shape. Start by shaving the sides of the plectrum to taper the width down to an
almost point at the tip. Use the sharp voicing knife supplied with your harpsichord.
Place the jack in the instrument and check how much needs to be cut off the end to
obtain the correct length. Make a chopping cut at the tip at a 70 degree angle.
Check the length and make any adjustments with the knife or adjustment screw. Play
the note to check the volume. It most likely will be too loud and the trimming
should now be done on the underside of the plectrum, tapering the thickness
gradually from base to tip. Have the jack upside down against the voicing block
as shown in the above photograph. Start with the blade flat down on the plectrum
and rotate it so the edge begins to cut into the surface of the delrin. Carefully
push out towards the tip and take a very fine shaving off the plectrum. Always be
aware of how the rotation of the blade effects how fine a shaving is being removed
and adjust this rotation as you are sliding the blade toward the tip.
Remove and examine an adjacent jack that plays well to determine the proper shape
and taper of the plectrum. Keep testing the new plectrum for volume after each shaving
removed. If it becomes too weak, start over. When you are pleased with the sound and
volume, raise the jack with its key, hold it there and stop the string from vibrating
with your other hand. Let the jack down extremely slowly to make sure it does not hang
on the string. If it does, cut a cleaner end bevel and adjust the length with the
adjustment screw. If it still hangs, try weakening the tongue spring with a
tweezers.Bend the spring in the direction that would cause it to weaken. For more information
about harpsichord regulation and voicing refer to the book: The Harpsichord Owner's Guide
by Edward L. Kottick.
Procedure For Regulation:
1.) Check "off" position of all registers that will
turn off. The plectra of any notes that sound in the off position should be cut shorter.
Cut a clean bevel at the plectrum's tip. 2.) Check for evenness of volume. Trim plectra of
loud notes as described above. For soft notes, advance plectrum and cut it to length.
Plectrum may need replacing if it cannot be advanced. 3.) Check staggering. When more than
one stop is engaged at a time, the jacks should pluck successively rather than simultaneously.
If two jacks pluck at the same instant the action will be heavy. Use the bottom adjustment
screw to regulate the plucking order. Find notes nearby that play comfortably and match the
plucking order to be the same. After making an adjustment, check that the plectrum will fall
below the string when let down slowly and be sure the damper is damping properly. 4.) Check
all dampers. Watch strings as you turn a stop on and off. If a string is being pushed to the
side by a damper, the damper should be raised slightly. Any dampers that are not damping
properly should be lowered. Use the needle-nose pliers to grasp the damper and slide it up
or down. After making an adjustment, check that the plectrum will fall below the string when
let down slowly. If it hangs on the string the damper is too low. You may need to screw in
the bottom adjustment screw to provide more space for everything to work. Then check staggering
again. 5.) Check slow repetition. Play each note, dampen the string with a finger and let the
jack down very slowly. It should not hang on the string. If it does, cut a cleaner bevel at the
tip and adjust the length with the adjustment screw. If this fails, weaken the tongue spring
by bending the spring. 6.) Check for quick repetition with the jack rail in place. Write down
any notes that do not repeat quickly. Usually tightening the tongue spring will help. Always
check that the plectrum does not hang on the string after tightening spring. Another cause is
a plectrum that is too close to the string. Screw in bottom jack screw, adjust staggering and
dampers. Or the damper may be too low. A sticking jack or key may also be the cause. File jack
slot or free key.
Procedure For Tuning Harpsichords
The most difficult aspect of tuning is setting the temperament. This can be done by
ear with the help of the pamphlet The Equal-Beating Temperaments
by Owen Jorgensen.
An easier approach is to use an electronic tuning device such as an app on your phone or
the Korg Chromatic Orchestral Tuner OT-120. In addition to equal temperament it offers 8
of the most common historical temperaments. Using one of these temperaments will provide the most
satisfying resonance from your harpsichord.
You only need to set the temperament to one octave of one of the 8' choirs. If tuning
by ear, tune the octave just below middle c. I prefer to tune the octave starting at middle c
and above when using the Korg. In my opinion, tuning by ear to the generated tones
provided by the tuner can be more accurate than using the pointing needle method. I find
tuning middle c to the c4 tone (a lower octave) is easier to hear the beats and ultimately
the lack of beats when the note is in tune. When a note is out of tune, you will hear the
wavering vibrato-like sounds known as beats. As you change the pitch more in tune the beats
slow down and stop when in perfect tune. When tuning, hold the T-shaped tuning hammer very
lightly and use only your finger-tips to rotate the tool for the best sensitivity. Always
first tune a note slightly flat and bring it up to pitch.
Once the twelve note octave is tuned, simply tune by ear all the other notes of the choir
to that original octave. Work up the treble, tuning octave intervals and finally down to the
bass end. Turn on the second 8' choir and tune this choir in unison with the one you just
tuned. Shut off the louder 8' and tune the 4' choir to the softer 8'. Usually start at the
bass end and work up to the treble.
Harpsichord String Replacement
If the tuning pins have holes for threading the string, it is not necessary to remove
the pin to replace a string. Remove the jack rail and old string. Place loop of new string
on hitchpin and use a small spring-loaded clamp to hold it in place. Cut string to length
about 6" beyond tuning pin. Thread string into tuning pin hole and turn pin clockwise with
the tuning hammer. Guide the string with a finger to wrap neatly around pin as you turn.
If your tuning pins do not have holes, you need to remove the pin by turning it counter-clockwise
with a pulling motion on the hammer. If the pin seemed at all loose, put 2 or 3 mylar shims
in the hole. Cut the shims about 1/8" above the level of the wrestplank. With the top end of
the pin to the right, wrap the end of the string under the middle of the pin and spiral it
widely down the pin once or twice. In mid-air with steady tension on the wire, turn the pin
clockwise while orienting it so that the wire will wrap crossing tightly over the top-most
spiral. Continue steady tension and using both hands, wind pin toward tuning pin hole and
stop just above the hole. Cut the excess end wire hanging off pin with wire cutter and push
pin into hole keeping it taught at all times. Use a small carpenter's hammer to bang the pin
to the same height as adjacent pins. Rubbing rosin on pin before starting will help prevent
the wire from slipping.