How To Inspect a Secondhand Acoustic Guitar Before Buying

Buying your first secondhand acoustic guitar? How do you know you’re not buying a lemon?

In the following article, I’m going to break down exactly how to inspect a secondhand acoustic guitar using my ‘tried and true’ checklist I’ve developed over the years buying acoustic guitars.

What do you need?

  • A mobile phone

Before mobile phones were common, a small mirror and torch were needed to inspect the guitar’s internal cavity, but nowadays, we carry our mobile phones with us everywhere, and this can be a useful inspection device. So, make sure you have it with you.

If you really want to take things to the next level, a fret rocker, straight edge and hex key will also allow you to check the neck and fretwork, but this won’t always be practical.

Before Getting Started

When inspecting an acoustic guitar, it’s up to you if any of the potential issues listed below are show-stoppers.

Take any sign of a problem in the context of price and the hassle of having the guitar repaired. For example, replacing a worn saddle isn’t going to cost you a great deal of time or money, but that combined with fretwork that requires repair may cause you to walk away, it’s really up to you.

The following are just things to look over when inspecting a secondhand acoustic guitar.

You can also use this list if buying online, although product photos tend to hide potential issues, so if unsure, ask the seller for more detailed photos.

Ok, with that out of the way let’s get started by inspecting the most important component of any guitar, the neck.

Evidence of Neck Repairs

If you see evidence of a neck repair I’d be careful about proceeding.

The faint line doesn’t match the finish of the guitar, and is just below the headstock, indicating a previous repair to the neck

While more of an issue for guitars with 1 piece necks, guitar necks can be susceptible to cracking at the back of the neck just below the headstock, as this is the weakest point of the neck.

2 piece necks that utilize a dovetail joint (e.g. Martin) are stiffer and more capable of withstanding tension over time, but if the guitar has been dropped, it won’t make any difference.

To check, inspect the back of the neck and look for changes in the finish that would indicate a neck repair e.g. a slight color variation in the finish, evidence of a hairline crack, or suspicious masking of darker paint between the top of the neck and headstock.

This may be quite subtle.

But, if so indicates the neck has at least been repaired by a professional. When necks are repaired professionally there is minimal chance of further structural problems developing, but it’s definitely something you should be aware of as it can affect the weight of the neck and headstock, which can affect things like sustain, not to mention the resale value of the guitar.

Neck Twist

You might have seen guitar players when first checking out a new guitar, holding the guitar body out in front and looking directly down the fretboard?

Doing so will allow you to see if the neck has a twist.

If the neck is twisted e.g. you can see a visible twist (indicated by the action being higher on either side of the neck) this can indicate a real problem.

If only minor, in some cases, this can be repaired by adjusting the truss rod, or planing and/or fret dressing, but it’s more often than not a serious issue and not something most people will want to deal with when buying a first guitar.

The Nut & Saddle

The nut and saddle are the endpoints for the strings, and despite being relatively minor components have an outsized impact.

The nut and saddle will usually be made from the same material e.g. plastic, bone, or graphite. Plastic is usually seen on cheaper instruments and yellows over time, bone is a denser material and better for sustain, while graphite is self-lubricating, and is more often seen on higher quality instruments.

You may not be able to tell the difference simply by looking, so ask the seller, or research the specifics of the model you are inspecting.

Check the nut

What we’re really looking at here are the nut slots.

Acoustic Guitar Nut Width

These are important as the strings run through them, and if too tight can cause the string to catch, resulting in tuning issues, or if too loose can cause the strings to move around within the slots leading to unwanted noise and less sustain (due to absorption) from the open strings.

If the nut slots are cut at the correct depth, you should be able to fret each individual string at the 3rd fret and see a slight gap between the first fret wire and the underside of the string. This gap should only be very slight e.g. 0.1 mm.

If the string sits hard up against the fret wire the slots are too deep. If too high the slots are not cut to the correct depth and this will affect the action (height of the strings from the fretboard).

If the action is too high, pressing down on the strings causes the strings to stretch more than they should and result in intonation issues.

Check the nut slot width

The nut slot should match the width of each individual string, from the high E through to the low E string. If too wide, the nut slots are beginning to wear and the strings will experience sideways movement within the slots, causing an unwanted buzz and a deadening of the open strings.

Replacing your nut isn’t a huge problem, but if you are on the fence about the guitar to begin with, this is definitely something to keep in mind as it will need to be replaced. 

Check the height of the saddle

Checking the Height of the Saddle

If the saddle is badly worn, it can have an impact on the action of the guitar, as the height will be insufficient to allow the string to clear the fret wires when played. This will also mean there is no further room to lower the height and address string action that is too high.

Otherwise, look out for cracks in the saddle.

This will affect things like sustain, and may also impact the sound of the guitar amplified if the guitar utilizes an under-saddle pickup (more on this shortly).

The saddle is easy enough to replace, but if you don’t know what you are doing it’s something you may need help with.

The Fretboard and Frets

Inspecting the Fretwork

Fret Sprout

Run your hands up the sides of the neck. If you feel jagged ends digging into your hands, this is known as fret sprout. This occurs when the neck contracts due to a lack of moisture, leaving the edges of the frets exposed.

Again, this is usually not difficult to repair (fret end dressing – by sanding), but you might want to take extra care if the neck is bound.

Loose Frets

If the frets are loose they may need to be reseated

You can check for loose frets by taking a piece of hardwood and pressing down on one end of the fret wire, if the other side of the fret wire lifts, the fret is loose and requires reseating.

You may not be able to do this if taking a guitar for a test run in your local music store but if you notice fret buzz or dead notes and can’t attribute this to neck relief it’s worth investigating further.

Check the Fretwork

If the frets are worn, indented (look for indents, especially aligned to the unwound strings), or require dressing this should also be factored into your decision.

Depending on the extent of the problem e.g. the frets are badly worn, the guitar may even require a complete refret, which will cost you quite a bit of money and should be factored into the price.

Fret Dressing

Fret Dressing

There are a couple of ways to check the fretwork, aside from a visual inspection. If you have the time, you can adjust the truss rod, straighten the neck by checking with a straight edge, and then use a fret rocker to check the individual height of each fret.

But the simplest way is to play every note on each string up and down the neck.

If a note doesn’t ring out e.g. a dead note, the next lowest fret is going to be higher, canceling out the note after it. This can be due to the frets requiring leveling or the fret wires being loose. Either way, the guitar will require dressing, which may or may not be a showstopper depending on the price being asked.

This will be especially prevalent above the 12th fret if it’s going to be an issue at all.

If the top of the fret wire (crown) is too flat the frets may require crowning.

The problem with frets that require crowning, is the surface area of the top of the fret wire is too wide increasing the chances of the string ‘buzzing’ the fret wires. Ideally, the crown of the fret should be filed down to a narrow edge, reducing the surface area, and minimizing the contact with the strings.

* Note if the fret wires are particularly worn (e.g. on an older guitar) and have been leveled and crowned more than a couple of times already the fret wires may need to be replaced, which is an expensive repair.

The Neck Joint

Inspecting the Neck Joint/Pocket

Is there evidence of cracks around the neck joint or gaps?

If so, this will usually be a showstopper.

The neck joint should be structurally sound. A set neck (glued – not bolted on) that has any movement will need to be repaired and this isn’t a small job, as it involves removing the neck, cleaning out the joint, and resetting.

If the neck happens to be bolt-on (not common, but not unheard of either) the bolts may simply be loose due to years of playing and the tension placed on the guitar from the strings.

Inspecting the Tuners

Exposed gear tuners
  • Are the tuners loose?
  • Are the ring nuts tight?
  • Are the small screws that hold the tuners in place tight?

The tuners (aka machine heads) are largely responsible for the tuning stability of the guitar. Poor functioning tuners result in a guitar that won’t stay in tune, and make a guitar more difficult to tune.

First, check the tuners operate smoothly.

The tuners shouldn’t be difficult to turn but shouldn’t be loose e.g. they should begin to turn as soon as you begin turning the tuning button.

To check tuning stability, I’d recommend slackening the strings and then tuning the guitar again, and then carrying on with the remainder of the inspection before checking the tuning again after playing.

Is the truss rod worn?

Truss Rod on acoustic guitar

The truss rod (in most cases) will be found inside the soundhole on an acoustic guitar.  On some models, this will appear on the headstock like the majority of electric guitars.

I usually check the end of the truss rod nut to see if it is badly worn when inspecting an acoustic guitar.

For one, if badly worn/rounded, the truss rod will no longer be adjustable, at least in its current form. Secondly,  this would also indicate the neck has inherent problems as it has been adjusted often.

You can check this by attempting to adjust the truss rod using a hex key, by sighting the truss rod within the soundhole, or by taking your mobile phone’s camera, taking a photo, and then providing a visual inspection.

Neck Relief

The neck should have a small amount of relief (bending inward) to help the strings in the center, and subsequently the widest part of the string’s vibrational arc, clear the fret wires.

Neck relief can be adjusted using the truss rod, as shown here, but the truss rod must be adjustable (see above) and should have some play in it so further adjustments can be made.

String Action

If the action is particularly high this will affect the guitar’s playability e.g. the higher the strings the more effort is required to fret notes, and when pushing down the notes on the fretboard will cause the string to stretch more than they should, causing intonation issues.

Usually, this is resolved through adjustments made to the height of the nut and saddle to affect the clearance height of the strings from the fretboard, but as mentioned above the saddle must have sufficient height to allow for some material to be removed.

If you are new to the guitar this is hardly the kind of thing you will want to be doing. For one removing the nut and regluing once the height is adjusted, while not difficult, can go badly if you have never done this before.

Checking Intonation

Checking Intonation

A guitar with poor intonation can be caused by any of the reasons listed above.

Intonation essentially means, the pitch accuracy of the guitar.

For beginners, who spend most of their time in the lower position of the neck this will be less of a problem, but when venturing further up the neck will quickly become evident.

For example, when playing your open E string, the same note should be recognizable when played at the 12th fret, just one octave higher.

To test intonation, using an accurate tuner. If you do notice the intonation is out on your guitar (usually it won’t be by much) either the neck relief, action, or saddle (or all three) may need to be adjusted.

The Body

Acoustic Guitar Body Bulge

Body Bulge

Acoustic guitars can develop a bulge just below the bridge.

The easiest way to check for this is to simply sight the guitar from a side-on perspective. The lower bout will ideally be dead flat. A small bulge isn’t particularly uncommon on secondhand acoustic guitars, due to the tension from the string pulling on the bridge over time, gradually forcing structural changes to the top of the guitar.

 Taking it to the extreme this can lead to cracking or separation at the seams of the 2 piece soundboard. This can also lead to separation between the body and bridge causing the bridge to lift which can have all kinds of impacts on the action and intonation of the guitar.

Check for Evidence of Cracks or Separation

Cross-grain cracks usually occur nearer the lower bout of the guitar, so be sure to pay attention to this area.

Cracks and separation usually occur due to changes in relative humidity, causing sections of the body to expand and/or contract, placing additional tension on the seams of the guitar’s body.


The Bridge

Repairing the Bridge on an Acoustic Guitar

We’ve already addressed the potential issue of the bridge lifting, but you should also check for evidence of the bridge cracking. This will usually be in the form of hairline cracks in line with the bridge pinholes.

Check the bracing

The bracing is responsible for managing and distributing the tension placed on the top of the guitar, and to a lesser extent the back of the guitar. If the individual struts are loose or have been removed altogether, this will affect the guitar’s ability to withstand the tension from the strings.

X-bracing

In most cases, if a beginner guitar, this is a showstopper unless repaired properly as it will eventually lead to some of the issues we’ve already touched on above, including body bulge, bridge separation, and/or separation at the seams of the soundboard and edges of the guitar.

To check the bracing, tap the guitar in different sections of the body, especially the top.

If you hear rattles, indicating loose struts from inside the guitar this should be inspected further using your phone’s camera again. Drop the camera into the soundhole and take video while moving the phone around to inspect all parts of the internal cavity of the body.

Is the guitar an acoustic-electric?

Checking the wiring on an acoustic-electric guitar

If the guitar is an acoustic-electric will also need to check the electronics by plugging the guitar in.

Once amplified adjust the EQ and volume slider (or tone and volume knobs) up and down and listen for static indicating problems with the connections.

This may only require a quick clean or may indicate a larger problem. Obviously, also ensure the battery isn’t going flat before doing so.

If there is no sound at all, the wiring is likely broken inside the guitar, most likely due to the output jack being loose and twisting when inserting a cable, causing the wires to break.

You also want to ensure the pickup is providing a balanced signal by playing each of the strings and comparing their output in terms of volume.

If the guitar has an under-saddle piezo pickup, this may indicate the saddle isn’t sitting flush against the pickup, e.g. the bottom of the saddle isn’t level,  resulting in some separation between the saddle and pickup.

Again, this is simple enough to fix but should be considered.

Check for A Counterfeit Logo

It won’t always be this obvious 🙂

Lastly, if buying a more expensive guitar e.g. a brand, such as Martin, Gibson, or Taylor with one ‘L’, check the guitar itself is authentic.

While less common in the acoustic guitar world (acoustic guitars are just harder to make) you will still hear reports of counterfeit Martin guitars, especially older D-28s.

If you are looking at spending this kind of money, be sure you are buying the real deal. Check the small details including the quality of the finish, and subtleties of the logo and branding.

If you have any hesitation, get the guitar checked out including matching the serial number and having someone with more experience cast an eye over the guitar.

On the remote chance, that the guitar is a counterfeit, it may well be the case that the seller is completely unaware also.

Final Thoughts

If you go through each of the inspection steps above, you can be confident the secondhand acoustic guitar you are buying won’t have any inherent problems that are going to cause you to regret your decision. Obviously the more you spend, the less likely you are to encounter problems, but there are plenty of quality guitars that fly under the radar, that are well worth your time to inspect.

Of course, if you are just getting started on the guitar, and lack the confidence to really be sure of all the steps outlined above, one of the best pieces of advice I can give you is to take someone else along with you that knows more than you, or just to get a second opinion. It just might save you buying a lemon.

Marty

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My name’s Marty. I’ve been into guitars, songwriting, and home recording for over 30 years. Theacousticguitarist.com is my blog where I write about everything I have learned along the way.