The Dreaded P.R.T.B.

What the heck is a P.R.T.B.? It stands for pedal rod tubing buzz. It is a sympathetic vibration caused by a harp’s pedal rod tubing assembly, the system of parts inside a pedal harp’s column that connect the pedals at your feet with the mechanism above your head. It can cause very prominent unwanted vibrations, primarily in the 5th and 6th octaves, when they are played loudly.

Why Do They Happen?
P.R.T.B.s happen when either: 1.)one of the pedal rods or 2.)some part of the tubing assembly vibrates along with the playing of one or more of the of the strings. Since the rods and tubing are as long as some of the harp’s longest bass strings, these vibrations can be rather loud. They can develop because lubrication that was originally added to the tubing dries up, leaving more room for vibration, or the tubing itself widens over time, causing the same result. There have been a variety of different materials used for tubing over the years. All of them can develop buzzes, the reasons why can vary.

A harp’s pedal rods can start to vibrate sympathetically along with the strings.

Diagnosing a P.R.T.B.
P.R.T.B.s are almost always heard on 5th Octave B or below. The most common one by far is the 5th Octave A flat. 5th Octave G and 6th Octave C are also more frequent troublemakers, but these buzzes can happen throughout the lower register. If you hear a loud, low rumbling sound when playing in this range, it may well be a P.R.T.B., especially if it only occurs in one particular pedal position on a given string. Playing the offending string as well as the one an octave below it may make the tubing buzz more prominent. Another way to diagnose a tubing buzz is to play the offending string plus an adjacent one. If this causes a pulsating sound in the buzz, chances are it’s the tubing.

It’s also important to try and rule out loose linkages in the mechanism, which can cause similar buzzes. If your harp’s mechanism needs reriveting, it may cause buzzes similar to those in the tubing. Linkage buzzes, in general, are higher pitched and more metallic than tubing buzzes.

Does it Mean Something’s Broken?
No. It is merely an unwanted sound. You have to play pretty hard before hearing a tubing buzz. I often hear them when the harp’s owner does not, because I play very hard when I regulate, in order to detect potential problems. A tubing buzz is not a sign that anything is damaged or about to break.  If it doesn’t bother you, or you only hear it when you play really hard, you can ignore it without worries.

The pedal rods need to be disconnected from the mechanism before the buzz can be fixed.

Fixing a P.R.T.B.
Eliminating a P.R.T.B. is a labor-intensive project, as it is necessary to disconnect all the pedals and springs, as well as disconnect the pedal rods from the mechanism. In some cases, the tubing assembly has to be removed as well. On newer instruments, it is often possible to cure this buzz by pushing grease into the tubing to fill any voids that have defeloped between the rods and the tubes. This is often called lubricating or “greasing” the rods. Lubricant is used, though the point of the excercise is not actually to increase lubrication, but to cut down on free space inside the tubing. If this alone doesn’t work, sometimes removing the tubing assemly itself and adding some additional padding to fill any voids between it and the harp column can do the trick. In other cases, it is necessary to replace the entire tubing assembly, though the pedal rods can generally be reused. Regardless of which solution is used, this is a job best left to a technician. Because of the disassembly and reassembly involved, it is time consuming (technician-speak for “expensive”). Another reason why, if this buzz isn’t bothering you too much, you can just ignore it.

Make Sure it’s not the Room
Last month I wrote about ruling out sympathetic vibrations coming from somewhere in your harp’s environment, not the harp itself. If you’ve already followed those instructions and made sure your room is innocent of all charges, and the buzz you’re stalking is in the lower register, see if you can determine if it is, in fact, the dreaded P.R.T.B.

 

Advertisements

Harp Buzzes 101: That Annoying Room Buzz

The lighting fixtures in rooms like this crowded harp studio just love to vibrate sympathetically.

The lighting fixtures in rooms like this crowded harp studio just love to vibrate sympathetically.

When is a harp buzz not a harp buzz? When it’s coming from somewhere else in the room.

The world we live in is teeming with objects that want to deceive us into thinking our harp has a buzz. Disguised as ordinary lighting fixtures, heating registers, even as innocent tchotchkes on glass tables, they sit patiently, waiting for us to play that one particular note, then–

BUZZ!

You think it’s your harp. You curse that scheister who just did the regulation. How could he miss this? You play fourth octave F sharp and it sounds like a swarm of bees is heading right for you. You can’t get good help these days! But before you fire off an angry email to that son of a bleep, take a minute to rule out unwanted noises coming from elsewhere in the room.

Every object has a resonance frequency, meaning when sound vibrations of a particular frequency or pitch hits it, it vibrates. In most cases, these vibrations will not be noticeable. If an object is too thick, for instance. But certain items, such the thin pieces of metal found the covers over every fluorescent light fixture in every harp practice room in America, vibrate very easily. These are known as sympathetic vibrations, wherein sound from one vibrating object (your harp string) excites another (that confounded light fixture).

In other cases, two objects that are touching each other can make a noise when one of them vibrates. Sometimes, when I’ve found myself tuning up a harp next to a desk, I’ve heard a noise and found that two metal objects, a pen and a stapler, for instance, are vibrating against one another. Steel wastebaskets are also good for this, especially when you replace your bass wires and throw the old ones into it. More than once, part of my procedure for “regulating” a harp has involved kicking the wastebasket or the desk to rearrange the items inside, thus disrupting the marriage of whichever objects are too close to one another.

How to detect a room buzz? First, determine whether the sound you hear is a sympathetic vibration or not. In other words, is the buzz directly connected to the string you’re playing (and any parts it is in contact with, such as a disc)? Most non-sympathetic harp buzzes have a short duration, or cause the string to sound muted or snappy. They are most often caused by improper gripping of the discs (or levers, on a lever harp). Sympathetic vibrations tend to last longer. They also can start just a fraction of an instant after you play the string.

Once you are certain you have a sympathetic vibration, try to determine whether or not it is coming from your harp. It can be harder to tell than you might think. Stick your ear next to a soundhole and play the offending string. If the sound is louder, chances are it is coming from the harp. Do the same with the mechanism and column (on a pedal harp). If a sound gets louder as you put your ear right next to parts of the instrument, there’s a good bet it’s the harp. If the sound doesn’t get louder closer to the instrument, try leaning as far away as you can and playing the string. See if you can hear the direction the sound is coming from. Once you suspect a room vibration, take your harp in another room, ideally not one with the same type of light fixtures, which are the number one cause of these things. If the sound is gone when you play it elsewhere, it is clearly in the room.

If you have a room buzz, you may be able to fix it. Check around. I mentioned desks and metal wastebaskets. Glass curio cabinets are also frequent culprits. If it’s that darned light fixture, you may have to live with it. At least you’ll know it’s not your harp!

Want to get great articles like this delivered to your email inbox? Join the mailing list now!

Harp Buzzes 101: String End Vibrations

String ends can cause a sympathetic vibration when their tails are in contact with one another.

String ends can cause a sympathetic vibration when their tails are in contact with one another.

One of the most common and annoying harp buzzes is caused by unwanted vibrations where the strings are anchored in the soundboard. Fortunately this is also one of the easiest buzzes to eliminate. With a little patience and detective work, you can easily fix that annoying buzz yourself.

Have Some Sympathy.

You are probably already familiar with the concept of sympathetic vibrations, but if not, let me give an example. In your harp studio or practice room, have you ever had a light fixture or object nearby start buzzing every time you play a specific note? For some reason, that object is prone to vibrate at a particular frequency, and if your note matches, it will vibrate. If the vibrating object touches something else, it will cause a buzz, the same way a snare drum will sound when the band plays a particular note, even if no one is playing the drum. Depending on the thickness of the vibrating object and the acoustic properties of the room, the buzz may become loud enough to annoy the heck out of you.
A string end vibration is caused when the tail end of a string vibrates sympathetically with the note you are playing and the vibration causes it to come in contact with something else, usually a string anchor, another tail end, or the wood of the harp itself.
Since harps are designed to project sound, an unwanted buzz inside the body will be amplified and pushed right at your ear through the sound hole. The trick to eliminating it is to track down what two objects are touching one another and find a way to make them stop touching.

Diagnosing String End Vibrations

String end vibrations sound the loudest when you are sitting at the harp. To rule out noises coming from elsewhere, such as the action, play the buzzing string with your ear close to a soundhole, then with your ear close to the action. If the sound is louder at the soundhole, it is likely coming from inside the body, and the most likely culprit is a string end. Another common clue to a string end vibration is how many strings cause it. While most vibrations manifest in one particular string, some will occur in two or more adjacent strings, or in a single string in different pedal positions. In cases like this, the offending string end is so excitable it is vibrating along a range of frequencies.

It’s logical to think that if, for example, your harp buzzes when you play third octave C, that the problem is coming from that strings end, but this is rarely the case. Alas, it can be coming from practically any string end on the instrument. In most cases I’ve seen, though, it is probably coming from somewhere in the first through third octaves.

To locate a string end buzz, you can start by taking a look inside at where your strings are anchored. Can you see any places where two long string ends are touching one another, or where a long tail is able to brush against the soundboard? If so, carefully clip the tail shorter to see if you can stop the buzz.

If a visual inspection doesn’t do the trick, you need to play the offending note while using your other hand to push on each string end one at a time. If pressing against a particular string end stops the buzz, you’ve found your culprit. If not, keep trying. Press on each end more than once in slightly different places. You may need to hit some tiny little spot in order to stop the buzz. More than once I’ve checked every string and not found the source of the buzz, but then checked again and found it after another try, or even two more.

Once you find the location, try to determine what is likely to be buzzing. A string end that is very close to an anchor is a common one, as is a string end that is slightly long and touching wood. If you have a tail longer than the anchor, try to clip it shorter. If that doesn’t do the job, try rotating the string knot a quarter turn. Don’t overdo the rotating, as it can damage the string. In some cases, you can bend the tail so that it is farther from whatever it is in contact with.

If none of the fixes in the preceding paragraph work, and you are certain you are stopping the noise on this particular string, replace it. That should take care of the problem. Sometimes, there’s just something about the knot that is buzzing and there’s no way to fix it without starting over.

Not every buzz inside the harp’s body is a string end vibration. I have seen rib screws that were loose, braces that had come unglued, and handles that needed to be tightened. Once, we had a harp brought into Lyon & Healy to fix a bad buzz, and one of the technicians discovered that the problem was a ball point pen that had been clipped inside! However, over ninety-five percent of the buzzes you hear from this part of the harp are due to string end issues. It is well worth your time to try and eliminate them yourself instead of waiting months or a year for your technician. Happy hunting!