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.


About Author

Steve Moss has been regulating and repairing harps for over twenty years. During his eight years with Lyon & Healy, he trained and worked with Master Regulator Peter Wiley. Steve oversaw the company’s lever harp production for two years before moving into pedal harp assembly and regulation. He also specialized in training new employees and visiting apprentices. Steve holds a Bachelor's Degree in Music Theory and History from Yale University. He has been active as a performing musician and songwriter, both as a solo artist and in groups. He has produced two CDs and plays the guitar, banjo, fiddle, harmonica, and jaw harp. As a traveling technician, Steve has serviced harps in the Midwest and across the country. Recent clients include the principal harpists of the Milwaukee Symphony, the Omaha Symphony, the Toledo Symphony and the Utah Symphony, as well as the University of Michigan , Eastman School of Music, Northwestern University , Brigham Young University, the University of Utah, and the University of Toledo.He makes frequent regulation trips to Lyon & Healy West in Salt Lake City. Steve is the author of Harp Care with Steve Moss, the first instructional DVD on harp maintenance, covering tuning, string replacement, cleaning, and moving of pedal and lever harps. Steve lives in West Lafayette, Indiana with his wife and two daughters.


  1. Steve- You left out the most important explanation of why pedal rod tubes vibrate, and that is because the material is no longer brass tubes soldered together. For most of Lyon & Healy’s history, they used brass tubes to house the rods. The tubes were soldered together in several places and then wrapped in felt. They never caused any noise. NEVER. After Salvi bought Lyon & Healy in 1986, Salvi eliminated the brass tubes and used instead the nylon tubes that had always been in use on Salvi harps. And guess what? The pedal rod vibrations that were very common on Salvi harps are now common on Lyon & Healy harps. What angers me the most is that every time Lyon & Healy rebuilds a harp, they take out the brass tubes and replace them with nylon ones. This is in their minds “updating.” So old Lyon & Healy harps that never had any problems with vibrating tubes now are prone to that as well. I would recommend to anyone having their harp rebuilt by Lyon & Healy that they insist that the brass tubes be left in place, and not changed for nylon tubes.

    • Thanks for your comment, Carl. I’d prefer not to get into the weeds regarding a particular company’s policies. I’ve heard tubing buzzes, at least occasionally, in nearly every brand of pedal harp, including some with the brass tubing assemblies.

  2. Once in a blue moon it can happen when the harp has brass tubes. Usually when the solder breaks and the rods are loose. But that is very rare.

  3. carl-swanson on

    Steve- I think one of the big problems with all harp companies is that almost any idea they try will work, for a while, on a brand new instrument. But time is the ultimate test, and many ideas that were tried in the past, with the best of intentions, didn’t work for one reason or another, and the people at the factory were not aware. It is only those of us who work out in the field that see what happens to many of these ideas. The plastic or nylon tubes is one good example. I think that the harp makers at any factory should be required to spend a part of the year(each year) out in the field working on instruments the way we independent technicians do. That would sure change their perspective!

    I don’t like the idea of pushing grease into the tubes because it tend to make the pedals sluggish, and over time it will thicken and make them even more sluggish.

    • Carl – Yes, I definitely agree that sometimes the consequences of a new idea are not apparent until time has passed. Certainly keeps our work from getting boring, doesn’t it? 🙂

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