WHAT’S THE BUZZ?

Finding why an instrument buzzes while playing is a task that bedevils luthiers. Dmitry Tarakanov presents a checklist for the most likely causes

FIGURE 1 Knocking on an open edge

Sometimes, looking for the part of an instrument that’s causing it to buzz is a task that can flummox even the most experienced luthier. The rattle resonates all over its body and we can hardly rely on our ears as we search for the place to blame.

Often our eyes are no more helpful than our ears for this task, as the area that is buzzing might not be easily seen. All we can do is to check the instrument, part by part, to find the reason for the unwanted sounds.

Over the past couple of years I’ve been inspired to combine all of the reasons for an instrument buzz into one checklist, with short instructions (where needed) on how to solve each particular problem. I have found it a useful guide in the dark, tangled forest of unwanted sounds. Here is the full list in its entirety. I’ve organised the reasons from the most to the least common, in my experience. It should be noted that this list is intended for fellow luthiers; nearly all these repairs should only be attempted by professionals, especially where glue is concerned.

Unglued places around the edge. These could be open seams or unglued corners. To look for those, you can hold your instrument by the neck and gently knock the body all around the edge with a knuckle (figure 1). The sound of an open seam will be fairly obvious; you’ll get a feeling that something is loose there. Often the open seams are visible to the naked eye. Make sure to check the place that is clamped by a chinrest. To find an unglued corner, you can slightly push the corners one by one out of the block. All loose and open spots should be glued.

Fingerboard bumps. A buzz can be caused by a fingerboard that doesn’t have an even scoop all along its length. If you don’t have a straightedge to hand, you can push down the strings, one by one, to the fingerboard with your left index finger just next to the nut, and your right index finger on the end of the fingerboard. Then look against the light or a white surface. You can easily see the scoop relative to a string this way (figure 2). If there are any irregularities, the fingerboard should be planed.

Any stickers on the fingerboard also can cause the string to buzz against them. Avoid stickers if possible.

Fingerboard wear from playing. Point the scroll end of the fingerboard straight to the light and look along the fingerboard. Under this hard backlight, you will easily see all pits and ditches that have developed from the pressure of strings and fingers (figure 3). If you can see any of these on the fingerboard, it should be planed. As well as causing a buzz, they can alter the intonation.

Grooves in the bridge. Strings shouldn’t lie too deep in the grooves. A depth of roughly one-third of the string diameter is a good one to aim for (figure 4). If you have one string buzzing but the buzz disappears if you push it slightly with your finger on the bridge (to force it to vibrate up to your finger), then it’s likely there’s a problem in the groove of that particular string on the bridge. Fix the extra depth problem, or if the depth is correct, make the groove smoother with a needle file.

Grooves in the nut. Push the string straight after the nut, and make it vibrate with a bow. If the buzz disappears there’s a good chance that the problem is in the groove of the nut. If it’s too deep (again, more than a third of the string diameter) or has some high, edgy spots (the string doesn’t flow nicely into the pegbox), it can cause a buzz. Remove the extra material if the grooves are too deep.

To find the high spots you need to remove the string and look attentively at the groove. If you can clearly see a shiny burnished place and it’s far from the nut’s edge, attack it with a needle file. It’s a high spot that raises your string above the groove and allows the rest of the string to rumble against the walls of the groove, instead of lying there with a good contact. Figure 5 shows a nut with a good shape and depth of grooves.

Very low nut, so the string can buzz against the fingerboard (figure 6). The easy way to fix this is to add a piece of black veneer under the nut. Adjust the grooves and reshape the nut if needed.

FIGURE 2 The ruler rests on a bump

ALL PHOTOS DMITRY TARAKANOV

FIGURE 3 A fingerboard like this needs to be planed

FIGURE 4 Grooves should be smooth and not too deep

FIGURE 5 A nut with a good shape and groove depth

FIGURE 6 Low G string with noticeable kinks in the groove

FIGURE 7 The fine tuner is dangerously close to the top

FIGURE 8 Decorative parts of pegs can cause problems

FIGURE 9 This small fret can easily move

FIGURE 10 The tailgut’s free ends are too long

FIGURE 11 Adding a piece of leather

The bridge is too low. Even if your fingerboard has a perfect shape, the strings can buzz because they are too low. This will create a buzz mostly in the low positions while playing forte. There’s a good chance that this bridge should be changed.

Fine tuners. Make sure that the fine tuner doesn’t touch the top plate (figure 7). A loose screw and nut will also cause a buzz. Sometimes the nut just keeps loosening because of the vibration. A small amount of thread locker or super glue (very small, like a needle tip) will help.

Moving parts of pegs. These can be tips, rings or other decorative pieces (figure 8). They can just be glued in place with super glue.

Old or damaged strings. A string’s ability to create harmonic movement depends on its evenness along its whole vibrating length. If the string is old the wiring can become detached from the core, but even if it is new, the wiring can easily be damaged by negligent handling – or a poorly shaped nut and bridge. Both of those cases can cause buzzing from the string.

Small fret on the tailpiece. This is actually a separate piece of wood, plastic or bone, and on commercial tailpieces it can often be badly glued (figure 9). Sometimes you can see a clear gap between the fret and the bottom of its groove. It can definitely move and cause a buzz. You should remove the tailpiece from the instrument and glue the fret well.

Parchment touching the string or the bridge protector that’s on it. Glue the parchment back on the bridge using PVA or super glue. Remove the bridge protector or move it to the part of the string with silking on the peg or tailpiece end, making sure that it sits there firmly.

Cello endpin. The free end that’s inside the instrument might be too long; there could be a loose screw; or any of the endpin’s moving parts might come loose. It’s easy to diagnose that problem: ask a friend or colleague to hold a hand around the plug while you play the cello. If the buzz goes away, look for the moving parts in the endpin and fix them.

Tailgut. Free ends (figure 10) or metal parts rattling against the top plate of the tailpiece can cause a buzz. Cutting the free ends and adding a piece of thick leather between the metal parts and the tailpiece (figure 11) usually helps.

Tailpiece touching the body or chinrest. You could find another model that doesn’t touch, or you could carve a piece off the existing tailpiece (if it touches the plate). You can also take a piece off the chinrest, or possibly move it away slightly.

IF THE STRING IS OLD THE WIRING CAN BECOME DETACHED FROM THE CORE

Unglued fingerboard. Gently try to push the end of the fingerboard upwards, away from the body. If you see a gap between it and the neck, this will definitely cause a problem (figure 12). It needs to be glued in place.

Fluff or dirt in the f-holes. Have a look at the points where the upper and lower f-hole wings are almost touching the rest of the plate. There should be a noticeable gap to allow the wing to vibrate freely. If you notice that some sludge has built up there, clean it out with a small piece of fine sandpaper, or just a piece of cardboard. In a really bad case you might need a knife to cut through it!

Purfling. Loose purfling is the sneakiest and most hard-tofind cause of a buzz. It can be a piece of purfling that’s become unglued from the sides of the channel. Or it could be a small wood shaving or a piece of glue rattling in the space between the purfling and the bottom of the channel. In the first case, rubbing in some hot liquid glue can help. In the second, you need to get access to the inside of the purfling channel. To do that, you can carefully separate a piece of purfling from the side of the channel with a small, sharp spatula (figure 13a). Then you can squeeze in the glue with a prepared syringe. I learnt the trick of creating a prepared syringe in Peter Prier’s workshop, where it was called a ‘plunger’. The trick is to glue the seal part of one syringe to the end of another (figure 13b). This creates a tool that allows you to put the glue inside a tiny crack or space under pressure.

Trash inside the violin. A rattling wood shaving or a piece of glue can dangle inside causing trouble. Remove it via the f-hole. An air compressor could be helpful if you have one around.

Chinrest touching the top plate (figure 14). Obviously you can change the model, but alternatively you can add some extra material (leather or cork) under the contact spots (not the unwanted spot) to lift it up higher relative to the plate. Don’t forget to put some chalk on your leather or cork so it won’t stick to the varnish.

Strings crossing in the pegbox or free ends of strings. Simply put, they should never be touching each other at all. The extra piece at the end can be easily cut away.

If you’ve gone through all of the above-mentioned variants and haven’t found a cause of the buzz, it is probably something inside. But even then, you might be able to rectify it without opening the instrument. If it’s just a loose cleat or a piece of lining, it might be an option to use a syringe with a tube attached to it, or a curved brush to apply the glue to distant inner spots, and then use magnets if you need to put some pressure on those places.

So, although looking for a buzz can be really challenging, I hope this list can at least make the process more organised. And of course there’s one other place a buzz can reside… in the player’s imagination!