In this article, Ray Carlton tackles the topic of string buzz.
Buzzing Strings –
The article refers to both guitars and basses. I don’t specifically mention basses throughout the article but they suffer the same issues that plague guitars.
Guitars and basses are built to resonate. Strings oscillate to and fro producing vibrations our ears perceive as musical sounds. As you mature as a player your ears become hyper sensitive to the sounds emanating from your guitar. Any errant buzzing or unwanted vibration is a maddening issue that gets in the way of your enjoyment of playing.
Buzzing is a solvable mechanical problem. It is useful to widen the discussion to include any irritating buzzing or vibrating sounds that may or may not be directly attributed to strings rattling or buzzing on frets. Because you only hear it when you strike a string or chord it is commonly associated with the strings but this may not be the case. Any offending rattle or vibration can be attributed to various causes. There are different types of buzzing or vibrating noises that can provide clues to its source and suggest a solution.
Inappropriate *action settings
On inspecting an instrument that arrives with problem buzzing it is sometimes found that a set of .008” strings is installed and it is set-up with very low action. This is never going to work unless you can play with the lightest of touch. As soon as you dig in or hit a power chord, the strings will begin bouncing off the frets and buzzing.
Determining the ideal action and string gauge for your style of playing is the starting point for diagnosing fret rattle. Low action and light strings require a light touch. Raising the action will allow you to hit harder and dig into single notes more strongly. The heavier the strings and the higher the action the harder you can play.
Low action and heavy strings can allow more strident playing in certain music genres. Heavier strings offer more resistance to the pick or fingers giving a more powerful tone. Ultra light strings have a floppy elastic feel and a weaker tone.
If you are unsure of the best setup parameters for your playing style, any decent guitar mechanic will be able to determine ideal setup parameters by watching you play for a minute or so.
Incorrect adjustment of neck relief
Neck bow is adjusted with a truss rod which is these days in pretty much all guitar necks. Incorrect truss rod settings can cause buzzing all over the finger board in the case of a back-bow or it can localise it to the upper registers in an up-bow situation. An incorrectly adjusted truss rod can also cause fret out or choking when bending strings. eg: when a high note is bent up to a certain pitch it suddenly cuts short when it contacts the next fret up. Other parameters contributing to fret-out are discussed later. It doesn’t take much of a bow in either direction to cause problems especially if action settings are low.
Adjusting the truss rod should be left to experienced hands. You never want to hear the sound of a snapping truss rod. It doesn’t sound like much, just a click followed by a dramatic loosening of the adjusting tool. Repairing a damaged truss rod is expensive. If it has a set neck [glued in] and it is an entry or mid level instrument you’ll be looking for a new guitar. If it is an entry to mid level bolt on model you’ll be after a new neck.
Inaccurately cut nut slots
Nut problems are easily diagnosed. When you fret the string, the buzzing goes away. An open string[s] may be buzzing or rattling against the first fret. This indicates the nut slot is too deep and the clearance between the first fret and string is too little. The nut should be removed and either packed with a shim of hardwood or replaced.
The nut slot may be higher at the back edge of the nut [tuner side] and when the open string is struck it rattles against the front edge of the nut [bridge side] making a sitar like buzzy, weak tone with short sustain. This is easily fixed by reshaping the nut slot so the string is bearing solidly across the entire width of the nut. Often this issue will be with one or two strings only. If it is all strings it will be truss rod adjustment or overall action settings.
Localised buzz
Buzzing that is limited to a certain position on the fret board can be attributed to a fret or frets that are not level with the surrounding frets. On a new instrument it is most likely there will be a high fret. It is easily corrected by filing down the fret until it is the same height as those around it. Once level it can be crowned and polished. The problem may only be obvious on one or two strings at a single position on the fingerboard. If it is a single low fret, replacing it may be the solution.
On well played instruments you may find there are areas that have wear grooves [ruts] under the strings causing buzzing on surrounding frets that show less wear. A level crown and polish job or a partial or full refret will correct the situation.
Localised buzzing can be caused by a fret that has come up out of the fret slot and will most likely be at the edge of the fingerboard under the outer strings. You can generally press the fret down with finger pressure but it will pop up when pressure is released. The offending fret can glued and clamped or pulled and replaced.
There may be a high spot or hump in the fingerboard causing buzzing right across the board or on one side. Fingerboards after years under tension may compress and bunch up causing a hump in the fingerboard. Obviously the frets in this area will be higher than adjacent frets. This often occurs in the 10th to the 15th fret area. The solution is to remove the frets, plane the fingerboard flat and refret it. In the case of a bolt neck a replacement neck can be considered.
Acoustic guitars and arch tops may have buzzing in the section that is glued to the guitar top. It may be necessary to remove the frets and plane the fingerboard to correct the problem. This may vary depending on the weather and the relative humidity. Lightly built instruments are not lacquered internally and the timbers act like a sponge equalising with ambient humidity. Extreme damp or dry will cause things to start moving about. Solid body guitars are not so prone to changes in humidity.
New acoustics will sometimes move a little in the first year or so. It is quite normal and generally doesn’t cause a problem. Moving an acoustic instrument from hot dry conditions to very humid conditions or vice versa can cause damage if not managed correctly. Consult your acoustic guitar retailer or builder to ascertain the best methods to protect your guitar.
Hardware Vibration
If you guitar buzz is not related to frets it will likely be sympathetic vibration in the hardware eg: tuners, tailpiece or bridge. In an acoustic or hollow body it may be related to a loose brace[s] or internal wiring. Sometimes it can be tricky to locate and you will need to narrow in on the area the vibration emanates from.
If you are playing amplified in a small room anything that is loose will vibrate eg: windows. To locate the source of vibration turn off your amp. It may seem to be coming from everywhere but when you get your ear close up the location can quickly be found
Look for a loose screw in the bridge or the tuners. Nasty sounding oscillations and buzzing can be caused by bad strings. The guitar is a vibration machine and anything loose will oscillate making nasty noises.
Sympathetic Resonance
Guitars that have a tailpiece attached to the heel are prone to vibration as everything behind the bridge including the extra string length vibrates in sympathy with the strings. Sometimes this can be unpleasant and a change of tailpiece can often help. Damping the strings behind the bridge can also be useful.
Undertones or sympathetic vibrations can be heard by a closely listening pair of ears. You may hear extra notes or ringing when a string is struck. Other strings will vibrate and we may not hear exactly what we expect to. This can be a source of annoyance to some players or to others an extra richness adding to the sum of the tone.
*Action – distance between underside of the string and the top of the fret.
http://www.carltonguitars.com.au/
Ray Carlton is Melbourne-based luthier and guitar repairer
Got a question? Go ahead .. Ask Ray!