A Short Guide to Wurlitzer Electronic Piano Sustain Problems
The most common sustain problem on a Wurlitzer 200a (or earlier) keyboard is too much sustain: the note continues to ring out, even when the pedal is not depressed. This is almost always caused by damper felts that are excessively compressed or otherwise deteriorated. In other cases, the Wurlitzer’s sustain pedal doesn’t do anything when depressed, and the piano never has sustain. This is usually because the pedal is not making the proper interior connection. This guide will help you address both problems.
How does sustain work on a Wurlitzer electronic piano? Each Wurlitzer key has a corresponding damper arm. The damper attaches to the whip at one end, and has a small square of felt at the other. When the key is not being played, the damper felt rests on the reed. When the key is depressed, the whip lifts the damper arm and the reed vibrates freely. Once the key is released, the damper arm falls back into place and the note is silenced. Depressing the pedal lifts all the damper arms, so that all the reeds may vibrate indefinitely once struck.
How does the sustain pedal work? Since the very first Wurlitzer 112 was made available right up until the last 200 series was made, Wurlitzer sustain pedals functioned very similarly. The changes made to the sustain design were very slight over the years, but the principle of how it worked remained the same.
All series used a flexible Bowden cable. The inner cable is attached to a spring-loaded foot pedal, while the other end attaches to a mechanism which grabs the damper rod. The early 112 used twist/pull force to directly twist the damper rod, while the 112A and onward (sometimes known as the more “modern” pedal design) used downward pull to move the damper rod.
In the more commonly-seen modern pedal design, the interior of the Wurlitzer has a damper connecting rod loaded with a damper spring for more return force. In this design, the cable adapter, which is the end of the pedal that connects to the instrument, consists of a knurled ferrule which screws onto the threaded damper connecting rod and flange, which acts as a stop to add leverage. As the sustain pedal is pressed, the cable pulls the damper connecting rod, which in turn pulls the damper assembly. By using a lever motion, the assembly then lifts the dampers felts from the reeds. With the damper felts up in the air, any reed that is struck can sustain freely until the pedal is released and the dampers return to their resting position.
How to Fix Excessive Sustain in Wurlitzer Keyboards
Why would a note sustain even when the pedal is not depressed? Over time, the force of the damper connecting against the reed will cause the damper felt to compress. If the felt becomes too compressed, it won’t make adequate contact with the reed and the note will sustain even after the key is released. Repeated contact with the reed will also transfer oxidation residue from the metal onto the felt, which further decreases the felt’s ability to make good contact against the reed.
Often, a bad felt can be visually identified. Normally, treble felts are square while bass felts have a chevron-shaped cutout, which allows the felt to make better contact and more thoroughly dampen the larger bass reeds. Worn felts will have a distinct reed-shaped channel in the center.
How to fix old, ineffective damper felts. The best way to fix ineffective damper felts is to replace them. However, you can also use a needle or a pushpin to de-compress the felts. This will often solve the problem - at least temporarily - so that your Wurlitzer remains functional until you can get around to replacing the whole set of damper felts. Here’s how:
Wear gloves, because you don’t want to accidentally stab yourself with a needle covered in 40-year-old felt fibers. You should also wear a dust mask, particularly if you plan to pin multiple dampers.
Turn off and unplug the Wurlitzer. Remove its lid.
If you’re working on a Wurlitzer 200a or another 200-series model, you must remove the hum shield before accessing the dampers. Remember that you don’t need to completely unscrew the hum shield screws. Just loosen them, and the hum shield will lift away.
Confirm that the damper is in fact resting on the reed, and that there is nothing preventing it from doing so. This would include a too-tight damper regulating screw, or a problem with the pedal itself. These issues are dealt with in the following section.
You can gently lift the damper arm with your fingers in order to access the damper felt. However, if you need to pin multiple dampers, you may want to remove them first because loose fibers find their way to the reed bar and create a short. On a 200-series Wurlitzer, the entire damper assembly can be removed as a unit. On earlier Wurlitzers, you must remove each damper, one at a time.
If you choose to remove the damper entirely, first remove it from the whip by gently popping out the damper regulating screw from the fork-like fastener at the back of the damper. Then, unscrew the damper.
Using a pushpin or needle, gently stab the damper felt. You are trying to decompress the felts, so you can also give the felt a gentle downward pull before you remove the needle. Definitely do not pull hard enough to rip the felt off the damper. Also, you’re trying to de-compress the fibers, not loosen them. If the felt looks like it’s starting to fall apart, your technique is too aggressive. Be particularly gentle with older models, such as the Wurlitzer 120 or 112.
Replace the damper and test the key. If it still sustains, try pinning the felt again.
How to fix other problems resulting in excessive sustain. Compressed damper felts are the most common cause of excessive sustain, but it’s not the only cause. More rarely, the damper regulating screws or the pedal itself is the culprit.
Excessive sustain caused by the damper regulating screws. The damper regulating screw is the screw at the back of the damper that connects it to the whip. If it is screwed in too tightly, it could be preventing the damper from resting properly on the reed. Proper height of the screw should be 1/32” above the grommet. Note that the screw shouldn’t be too high, because you want it to instantaneously lift the damper when you depress the key. For the most consistent feel, all of the damper regulating screws should be at the same height.
Excessive sustain caused by the pedal. If attaching the pedal causes excessive sustain, the screws holding the knurled nut in place may have loosened, allowing the cable to slip into a poor position. In this case, the pedal will cause the dampers to lift slightly, even when the pedal is not depressed. When the knurled nut is properly positioned, the pedal will have a small amount of lost motion, so that the dampers do not move unless the pedal is depressed past a certain point, preferably about 1/32” or 1/16”. If you encounter this problem, adjust the two screws underneath the knurled nut until a small amount of lost motion is achieved.
What if my Wurlitzer does not have its original felts? This is fine. Felts have a finite lifespan and are meant to be replaced. However, in some cases, the previous replacements are not actually felt, but some other material, like styrofoam. Styrofoam deteriorates over the years, and any Wurlitzer we’ve seen with styrofoam felts had to be immediately re-felted. In addition to ineffectively muting the reeds, styrofoam pieces can crumble away and short the reed bar.
Note that the composition of Wurlitzer felts has changed across models. The Wurlitzer 200a and other 200-series keyboards have firm, dense damper felts. On earlier electronic pianos, such as the Wurlitzer 112 and 120, felts are often softer and more cottony in appearance.
What if my Wurlitzer has an extra piece of styrofoam mounted behind the actual felt? During certain years, Wurlitzer added a second piece of felt on certain dampers, made from a thin layer of styrofoam. This seems to have been factory-applied, but today these extra felts are always in deteriorated condition. You should remove them if you see them, because if they crumble with use they may short the reed bar.
To remove the extra styrofoam damper felt, first take off the damper in question. Using any small tool, flake off the styrofoam. This will leave behind remnants of the glue that originally adhered the styrofoam to the wood. You can file or sand these glue remnants away.
Fixing Notes that Don’t Sustain, Even When the Pedal is Depressed
If notes don’t sustain, even when the pedal is depressed, the pedal is probably not making contact with the sustain rod. The pedal should be able to fit snugly into the hole underneath the Wurlitzer, and you should be able to turn the knurled nut so that it is flush with the bottom of the keyboard. If there is an obstruction here, the pedal will not be able to make contact with the mechanism inside.
If the pedal seems to be connecting fine, but notes still aren’t sustaining, you should open up the Wurlitzer to check that the internal mechanism is in good condition, and that it is correctly screwed into the damper assembly.
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