Tuesday, April 18, 2017

Troubleshooting Rosin, Cotton, and String Problems by Arle Lommel


Even for experienced players of the hurdy-gurdy, problems with rosin, cotton, and strings can be a challenge. The following guide tries to demystify some of these problems by listing common symptoms and their solutions.
Before going through the this process, remember that the simplest explanations are usually correct. The vast majority of sound problems can be resolved by fixing rosin and cotton. In addition, if you have tried everything with no luck, consider trying a different cotton or rosin. Sometimes you’ll find that particular batches simply don’t work for your instrument, and changing them can make a big difference.

Weak or Tenuous Sound

  • SYMPTOM: The instrument has a weak or tenuous sound or jumps to overtones rather than the proper pitch. CAUSE: Weak sound generally indicates that you need to add rosin to the wheel. Many players apply insufficient amounts of rosin due to fear of “too much” rosin or to hide other problems in the set-up of their instrument. As you play the instrument, it will gradually lose volume as the rosin on the wheel is consumed and the wheel can no longer create the “slip-stick” friction needed to cause the string to vibrate. SOLUTION: Apply more rosin. IMPORTANT: Solid rosin should have a flat surface with no jagged edges. When you apply it, gently hold the flat surface against the wheel and move it back and forth as you turn the wheel.

  • SYMPTOM: One or more strings have a weak sound that does not improve when you add rosin. CAUSE: The string’s pressure on the wheel is insufficient and the wheel cannot make the string vibrate effectively. This indicates that the string is either sitting too high at the bridge or that it does not have enough cotton. Because bridges move with changes in temperature or humidity, previously ideal set-ups may no longer work and need adjustment. SOLUTION: Examine the relationship of the string to the wheel. If you have a reasonable amount of cotton on the string and you can see that the string is not making solid contact with the wheel, you may need to remove shims or lower an adjustable bridge. If you cannot lower the string at the bridge, you may need to add additional cotton.

Harsh Sound

  • SYMPTOM: One or more melody string has a harsh sound, particularly on high notes. CAUSE: The string is pressing too heavily on the wheel. This effect is most obvious on higher notes. There are two primary reasons for this condition: (1) The string has too much cotton; (2) The string is sitting too low at the bridge. SOLUTION: With experience, you can generally see whether the problem is cotton or the bridge and address it directly. For newer players, it may be easier to address both issues at the same time. To do this:
  1. Remove the cotton from the string.
  2. Check the pressure of the wheel on the bridge. The ideal pressure of the string without cotton should be such that the wheel barely deflects the angle of the melody strings. If you can see a noticeable bend, you need to raise the string at the bridge by adding shims or using the jack screw if you have a adjustable bridge.
  3. Apply cotton and check the sound. You will probably need to add rosin after reapplying the cotton. The amount of cotton you use depends on the instrument and string type you use. Higher-pitched strings generally require less cotton than lower-pitched ones.

  • SYMPTOM: All of the strings have a harsh or scratchy sound. As you turn the crank you may hear that it is worse at some positions than others. CAUSE: Poorly applied rosin. This is the classic case of “too much rosin,” but is actually not caused by the amount of rosin. If rosin is applied with too much pressure or by using a broken or jagged block, it leaves ridges of broken and jagged rosin on the wheel. This prevents the free movement of the strings on the wheel. SOLUTION: In the vast majority of cases, you can resolve this problem by disengaging all strings and then pressing a clean, lint-free cloth against the wheel as you turn it. Use a fair amount of pressure: Your goal is to smooth the rosin out and the friction and heat between the cloth and wheel help to achieve this goal. You will generally need to recotton the strings at the same time because the cotton picks up the bits of rosin and can redeposit them on the wheel and create the problem over again. If you are not lucky, you will find that the scratching sound persists even after you use a cloth on the wheel. If you have repeatedly tried to use a cloth and the problem persists you may need to be more aggressive. Usually you will notice that the scratching corresponds to one or more particular spots on the wheel. This indicates uneven build-up of rosin. In such cases you can either use a sheet of 600-grit or finer sandpaper on the wheel while turning it to remove the buildup or use a razor blade to gently scrape the rosin on the wheel. You scrape it by holding the blade in the direction the wheel is turning and letting the edge pick up any high points. You are not cutting the wheel and should never have the blade face into the wheel where it could cut or gouge it. [NEED A DRAWING OR PICTURE HERE.] This build-up is most likely to occur on the edges of the wheel, so focus on those areas. Be very careful: You do not want to scrape the wheel’s surface. You want to remove only the uneven rosin. I have only had to take this approach twice in twelve years with my primary instrument. In very rare cases, you may have serious problems with rosin that require stripping the rosin from the wheel with alcohol on a rag. This is a last-resort solution and you should take this approach only after you have tried everything else. Note that if you strip a wheel you will need to apply rosin more frequently until the wheel builds up an even coating.

Dead Spots on the Wheel

  • SYMPTOM: The wheel has a dead spot that does not make sound. CAUSE: Part of the wheel has insufficient rosin or you have grease or other contamination on the wheel. SOLUTION: There are four solutions you can try, in the following order based on how involved they are:
  1. Reapply rosin to make sure that you do not simply have an area with insufficient rosin. Often reapplying rosin will address small skips or stutters on the wheel.
  2. If reapplying rosin does not address the problem, use a clean, lint-free cloth and press it firmly against the wheel while turning it so that the cloth absorbs the contamination. Reapply rosin and check the sound. This approach will address most minor contamination, such as from people touching the wheel.
  3. Strip the wheel with rubbing alcohol on a cloth. Alcohol will remove most greases from the wheel. Note that if you strip a wheel you will need to use apply rosin more frequently until the wheel builds up an even coating.
  4. For cases of severe contamination, you may need to use sandpaper or a razor blade to scrape the surface of the wheel as described above. Be very careful with this approach, as you want to remove as little material as possible while still getting rid of the contamination.

Tangents Do Not Line up Properly

  • SYMPTOM: You have to point the tangents for high notes on one or more melody strings toward the bridge. You find that the amount of deflection increases as you get closer to the bridge. CAUSE: You have too much cotton on the string. Too much cotton adds mass to the string and requires that it have a shorter vibrating length than it should to reach a given pitch. This effect is more pronounced for higher notes because the cotton constitutes a higher proportion of the mass of the vibrating portion of the string for higher notes. SOLUTION: Remove the cotton and reapply a smaller amount. Retune the strings and adjust the affected tangents.

  • SYMPTOM: You have to point the tangents for high notes on one or more melody strings away from the bridge. You find that the amount of deflection increases as the tangents get closer to to the bridge. CAUSE: You have too little cotton on the string. They tangents are positioned to adjust for a certain amount of cotton on the string. If there is not enough, the vibrating length of the strings has too little mass and is sharper than expected, so you have to angle the tangents away from the bridge. Note that this condition is relatively uncommon because most instruments are set up with a small amount of cotton in mind. SOLUTION: Remove the cotton and reapply a greater amount to the string(s). Retune the strings and adjust the affected tangents.

  • SYMPTOM: All of the tangents systematically face toward or away from the bridge, without affecting the higher notes more than the lower ones. CAUSE: The distance between the bridge and nut is incorrect or the keyboard is poorly designed. SOLUTION: If the keyboard has a design problem, there is little you can do. However, most instruments have an adjustable nut that allows you to change the vibrating length of the open string. If the tangents all point toward the bridge, adjust the nut to increase the length of the string. If the tangents all point away from the bridge, adjust the nut to decrease the length of the string. Tune the string and check the position of the third and tenth keys in the lower row (the two Cs on a G/C instrument or the two Gs on a D/G or the two As on a Hungarian instrument). Adjust the position of the nut to find the smallest deviation for the tangents on these two keys. After finding this position, tune the string and adjust the tangents for all of the keys.

Problems with Individual Tangents

  • SYMPTOM: Individual notes warble or have an unstable pitch. CAUSE: Individual tangents have worn spots or notches. These cause the tangent to have uneven contact with the string, which vibrates or moves against the tangent. SOLUTION: Put tape or heat shrink on the tangent, or sand the face of the tangent (if wooden). Your goal is to create an even surface on the tangent to press against the string. Note: Before you attempt to solve problems with individual tangents, make certain that your cotton, rosin, and shimming or bridge adjustment are all correct. Sometimes problems in these areas are apparent only on a few notes, usually those closer to the bridge. If you have corrected any problems in this area and you still find issues with unstable pitch on particular notes, focus on the tangents.

  • SYMPTOMS: When you press in a key you hear different pitches on different melody strings. CAUSE: The tangents do not touch the melody strings at the same time or one tangent is twisted. They touch one string but not the other. SOLUTION: Check the tangents to find out why one is not making contact with its string. Adjust as needed to ensure that they touch the strings at the same time. If you have recently changed the gauge of one string, you may find that you need more involved work to get the tangents to work properly. Such work is beyond the scope of this guide.

Pitches Wobble

  • SYMPTOM: The pitch of the instrument wobbles rhythmically in time with the wheel. CAUSE: The wheel is out of true. It is not perfectly symmetrical about the axis of rotation. As a result it applies more uneven pressure on the string as it turns, leading to fluctuations in pressure. SOLUTION: Truing a wheel usually service by the maker. Most modern instruments with laminated or composite wheels should never have this problem unless they have been exposed directly to significant moisture. If you find this problem, it may indicate other damage as well, and you should have the instrument evaluated by the maker or a luthier experienced with hurdy-gurdies. Truing a wheel is not difficult, but if it is not done properly, attempts to true the wheel can make problems worse.
This guide is available under a Creative Commons 4.o Attribution license.


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