Understanding Fret Buzz with Acoustic Guitars

March 08, 2017

Fret buzz is one of the most common calls we get into our repair department.  The environment your guitar lives in and the changes in season cause changes in humidity and temperature.  If you aren't controlling the humidity in your home or the case of your guitar, it can commonly cause fret buzz. Fret buzz is a buzzing noise that occurs when the string vibrates against one or more of the frets.  It may show in the open position, but other times it is specific strings or frets. 

Typically you can isolate which strings and frets are buzzing.  Generally speaking, if the buzz seems to be only at the 1st fret, that usually means the nut is too low, or the grooves in the nut have worn down too low.  If the buzz is concentrated in the middle frets, 3rd to 9th, the truss rod may require adjustment.  If the buzz is coming from the fingerboard extension, it’s likely humidity related.

We sat down with Dod in our warranty and repair department to get some tips on how to troubleshoot fret buzz.
 
What do we do first?

Dod: Check your string height first.  You do that by measuring your string height where the neck joins the body.  To give the strings enough clearance to vibrate without causing fret buzz, we set guitars up at 3/32” on the bass side and 2/32” on the treble side.  You get this measurement at the 14th fret for most guitars and on a parlor at the 12th fret. Measure the gap from the top of the fret to the bottom of the string. 

If my measurements are below those settings then what?

Dod: You’ll need to raise the action back to the factory specs.  You do this by adjusting the truss rod and then lowering or raising the saddle according.   You should have received a truss rod wrench in you case when you got your guitar.
 
Learn how to adjust your truss rod here.  We recommend a proper relief of .005-.007”:  View Video.  Once the truss rod is adjusted, check the string height measurements again.  Remember - only turn the truss rod a 1/4 turn at a time.  Then allow the guitar to acclimate.

What if I do that and the measurements are still low?

Dod: If you are still below the factory setting of 3/32” on the bass side and 2/32” on the treble side, you should start with a tall saddle and sand it down to the factory specs for string height of 3/32” on the bass side and 2/32” on the treble side.  You want to make sure when you sand the saddle down you do it little bits at a time.  You might also need to adjust the nut when necessary.
 
What other options are there for fixing fret buzz?

Dod: Get a setup.  I recommend getting somebody with experience to do the setup.  They should have general guitar repair knowledge. 

Can humidity play a significant factor?

Dod: ABSOLUTELY!  Humidity can play a significant role in both causing and avoiding fret buzz.  Ideally, the guitar should be stored between 40% and 50% humidity at all times. 

When an instrument experiences humidity below the recommended level, the wood will dry out and cause the top to drop down or sink in.  When the top drops down, the bridge and strings drop with it and lower the strings to where they may cause fret buzz.
 
On the reverse, if over-humidified, the top will rise and appear bloated.  The fingerboard extension (frets 14-20) are glued to the top, and when the top rises, the fingerboard extension rises with it.  This results in the neck looking like a “ski jump”  and the frets on the fingerboard extension being closer to the strings than the rest of the neck.  This can cause fret buzz in the upper register.
 
How do I check if my guitar is properly humidified?
 
Dod: Carefully lay a long straight edge across the top of the guitar.  Your guitar was originally built with a slight arch in the top.  When properly humidified, the straight edge should make contact with the top, except for a small gap at the outer edge of the top (measuring approx. 1/32’ at either end).  If the gap at the outer edge of the top is greater than 1/32”, your guitar is bloated and over humidified.  If you lay, the straight edge across the top and the straight edge is not in contact with the top, that is an indication that the top has dropped down and dried out.

What do I do if my guitar is over humidified?

Dod: Put some desiccant packs in the guitar body or the case to help dry it out.  Lower the overall humidity levels with a room dehumidifier.  Continue dehumidifying until the gap you previously measured is down to 1/32” at the outer ends.   
 
What if it's under humidified?

Dod: In this case, you will want to raise the overall humidity levels until you lay a straight edge on the top and achieve the desired measurement of 1/32” gap at either end of the straight edge.  Get a humidifier that you can put in the case with the guitar.  Adding room humidifiers is also good.