Recently we have been asked to help solve a buzzing problem long distance, so I will discuss this.
Buzzes in a harp can be very frustrating and elusive to locate even when we have the harp in our workshop. But I will cover a number of possible sources of buzzes in both pedal and lever or folk harps.
Buzzes generally fall into two categories. The first is a string buzz where the string is actually hitting something when struck. These are usually easy to solve once you know where to look.
A common instance is untrimmed string ends. This is where either at the back of the soundboard a long tail was left from the knot and it is vibrating against the soundboard, or likewise excess string at the tuning peg can also vibrate against the neck. Make sure that any string tails are trimmed. Also on metal wound strings there is a metal washer at the ball end and if this is not seated fully can vibrate causing a buzz. If this is suspected push the string end with your finger while plucking the string to see if the buzz stops.
On a pedal harp the place to look if it is the string etc itself causing the buzz is that discs are correctly regulated. If the disc pins are too close to the string in the open position or not gripping the string completely when engaged either of these situations can be a source of a buzz.
On lever harps where it is the string itself is causing the buzz, check the string ends and then determine if the buzz stops when engaging the lever. If so this usually means that the bridge pin needs to move in or out to move the string into the centre of the lever opening when in the open position. Or something maybe loose on the lever, try pushing or holding the lever with your finger while plucking the string.
The other more challenging category is a sympathetic buzz. The whole harp and possibly an object near by can vibrate when a string is set in vibration by playing it. If there is a loose connection somewhere that vibrates in sympathy with a particular note or notes the buzz is created.
For any type of harp the first and easiest thing to do is to try the harp in another room. Although this may sound too simple it has sometimes been the solution. What is happing is that something in the room near the harp is vibrating sympathetically with the harp.
Sympathetic vibrations can easily send you on the wrong track as it is not always the string itself being played or even close to it that is buzzing but simply that it has set something else in motion. If two parts anywhere on the harp are touching and do not have a tight connection, playing a certain string can result in a buzz as those two parts vibrate in sympathy with the vibration frequency of the string.
Although you may hear a buzz when you paly a certain string it may not be anything that that particular string is touching. What you need to do is to try holding onto or pushing on various parts of the harp while playing the offending string. What you are trying to isolate is a loose part that when held securely or damped causes the buzz to stop. Once you have successfully played detective it is usually straight forward to then eliminate the cause of the buzz.
Some things that have been known to create a buzz are any loose bolt or screw especially on the feet or base, levers on a folk harp, the soundboard itself, any internal braces that may have come loose, and if a pickup is installed, any wire that is touching the harp and the pickup jack which usually has a an outer cap and an inner cover or housing which can vibrate loose. On pedal harps it is possible that two of the chains in the action are touching or have worn rivets. Even the pedal rods, pedal caps and any of the many screws on the action plates can be the culprit.
Dusty Strings has a very useful interactive guide to buzzing which is mostly for lever harps and includes some good photos of lever problems.
In conclusion not only can buzzes be extremely difficult to pinpoint but there is a good chance that it is not coming from where you think it is.