What Is A Locking Tuner?

what is a locking tuner

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If you’re looking at buying a guitar, especially if it’s your first, you’ve probably heard about locking tuners, but you might not understand what they are or why they’re used.

So what is a locking tuner?

A locking tuner is a mechanism, first invented in the 1980s, that mechanically clamps a guitar string into place on the tuning post, preventing the string from slipping out of place. They can improve tuning stability and they make changing strings faster, though they usually weigh more than standard tuners.

There is an awful lot of information — and misinformation — out there about locking tuners. Let’s wade through some of that together as well as looking at how locking tuners work and the possible advantages and disadvantages of locking tuners.

How Do Locking Tuners Work?

Let’s start by making sure we understand the basics.

Pretty much all guitar tuning mechanisms have the same basic idea: The player turns a knob that’s connected to a gear, and when the gear turns, it moves the post the string is attached to.

Because the pitch of a string is determined by its mass, its length, and the tension that it’s under, the direction that post rotates determines whether the pitch of the string goes up or down.

Pretty much all — with a few exceptions — guitar tuning posts are the same in concept, as well. A string goes through a hole in the post and is secured in place, then winds around the post when tightened.

With non-locking tuners, there is an ongoing debate about how to lock the string in place, as well as how many times you should wrap the string around the post. Locking tuners make the entire process much, much easier.

We’ll look at the specifics of how to use them in a bit, but the basic idea is this: You pull the string through the hole in the tuning post and a pin or other kind of clamp is screwed down to hold it into place.

That is why locking tuners have knurled rings, or, in some cases, a place for a screwdriver, at the rear, to activate the post or other kind of clamp.

Who Invented Locking Tuners?

The concept that strings slipping out of place would send a guitar out of tune isn’t news. But unlike a nearly contemporary innovation, the double locking tremolo system that used a locking nut, locking tuners aimed to fix the problem in a different way.

A locking nut clamps the strings in place at the nut, which is potentially much more effective at keeping a guitar in tune, but requires both a locking bridge and a different kind of tuning method. The idea was first marketed by guitarist Floyd Rose under his own name in the late 1970s.

Around the same time, a new company was starting to make tuning machines. A few years later, in 1983, that company, Sperzel Tuners, would launch the Trim-Lok, the first locking tuner.

The idea, as Bob Sperzel has said, was to find a way to attach strings more quickly and securely. Even when you lock strings in place with a knot and stretch them, certain kinds playing can still cause strings to slip off the posts.

Part of that is just physics — if there is string on the post, there’s a chance it could slip off. A locking tuner, on the other hand, eliminates the need to wrap strings at all, so there isn’t any extra length to worry about slipping.

Are Locking Tuners Worth It?

Before Sperzel launched the Trim-Lok, it was already making high precision tuning machines for guitars. The founder saw that sloppy design and manufacturing of tuning mechanisms was causing tuning problems for players.

The original goal of his company was to make premium tuners that solved that problem. When the locking mechanism came along, the two ideas were married.

But high precision manufacturing and a novel, more complex mechanism for attaching the strings and clamping them in place also meant higher prices. That is still the case today.

Sperzel tuners are normally between a third more to about twice the price of some other locking tuners and are even more expensive when compared to non-locking tuners. But are they worth it?

Whether locking tuners are worth it depends a lot on what kind of guitar you play, the style of music you perform, and your budget, among some other things.

If you play a guitar with any kind of tremolo or vibrato system, for example, especially if you aren’t using one with a locking nut, then you’ll almost certainly notice a marked improvement in tuning stability if you go with locking tuners. The same is true if you’re replacing older tuners that are worn out or were inexpensive to begin with.

If you’re playing, say a steel string acoustic, you might not notice much of a difference at all when it comes to tuning stability. You’ll definitely notice the ease of changing strings, still, but whether that’s worth the extra cost is a judgment call.

Pros And Cons Of Locking Tuners

When making the decision about whether it’s worth it to invest in locking tuners, it’s important to consider the pros and cons.

This is mostly a question for players who want to replace their existing tuners, as opposed to for someone buying a new guitar. After all, there are a lot more important considerations than whether to get locking tuners when you’re choosing a guitar.

As we’ll look at more later, the tuners don’t really affect the sound and are much less of a sonic decision than, say, neck and fret board wood or pickup configuration.

We’ve already covered most of the pros, but it’s worth making a list to keep track of them.

  • Strings locked in place for better tuning stability
  • String changes are faster and easier
  • Most locking tuners also offer higher precision tuning gears for better results

But are there any cons to going with locking tuners?

That depends a lot on your perspective. Let’s look at a few possible drawbacks.

  • Most locking tuners weigh more than non-locking tuners. We’ll discuss that more in a bit, but whether it’s a drawback depends a lot on personal preference.
  • You might need to modify the head stock to install locking tuners. That might include installing a bushing and drilling new screw holes. The procedure is easy, but not everyone is comfortable doing it.
  • Most locking tuners are more expensive than standard tuners. This might be a burden on your budget, and whether they are worth the extra money is a choice each player has to make.

How Much Do Locking Tuners Weigh?

As I mentioned in the last section, locking tuners can weigh slightly more than their non-locking counterparts.

The difference is often less than an ounce per tuner, so the total added weight to the head stock would be no more than a few ounces, which might possibly be enough to be noticeable. Because the weight is at the head stock, it wouldn’t make nearly as much difference as a similar addition to weight to the body itself.

The reasons for the additional weight are obvious enough: Locking tuners have a more complicated mechanism, so it makes sense they would weigh more.

But here’s a secret some players don’t know: Not all locking tuners actually weigh more. Let’s look at some real world examples.

A set of Grover Rotomatic tuners weighs about 9.6 ounces, while the Grover Roto-Grip Rotomatic tuners are about 9.4 ounces for a set.

The difference can be even larger, but it’s rarely very large in absolute terms, if for no other reason than tuners are relatively small items.

Let’s look at the Golden Age Oval Knob six in line tuners from Stew-Mac, for example. They’re modern tuners in a somewhat vintage style, are non-locking, and weigh in at almost exactly 8 ounces for a set of six.

A set of six in line Grover Mini Locking Rotomatic tuners weighs about 7.7 ounces, while a set of six Sperzel Trim-Lok six in line tuners weighs almost exactly 7 ounces.

Do Locking Tuners Affect Tone?

One of the things you might hear is that locking tuners help with sustain because they weigh more and that helps keep the guitar resonating. Like so often, this bit of folk wisdom takes a basic fact, expands it beyond what it’s supposed to mean, and then draws the wrong conclusion.

Even in an extreme case, a set of locking tuners would add less than half a pound to the overall weight of a guitar. And that weight is being added to an already dense part of the instrument.

The overall change in weight might be noticeable, but it might not be, depending on the player. Because of how a guitar balances on a player, though, the effect on how the guitar hangs from a strap or feels in the hand will be imperceptible.

No matter what, the tuners won’t have an effect on tone, though.

That’s because locking tuners hold strings in close to the same way as non locking tuners and both kinds are made of the same material. Other than a possible weight difference, there isn’t a way for locking tuners to change the tone compared to non-locking tuners.

The tuners aren’t really part of the tone of a guitar, because their effect on the strings happens before the nut, which is what has a much larger impact on how the guitar sounds. If your tuners are not installed properly or if their internal mechanism is loose, you might notice that, however.

That would sound like a buzzing or ringing caused by the tuner hitting the head stock or cause the strings to not hold tune while being played.

As long as your tuners are functioning properly, though, you would be hard pressed to tell the difference in tone between otherwise identical guitars with locking compared to non-locking tuners.

Do Locking Tuners Really Make A Difference?

But locking tuners aren’t really supposed to change the tone, after all. They are, however, supposed to help your guitar stay in tune better.

Do they do that? Do locking tuners really make a difference?

Whether you think locking tuners make a difference will depend on a number of things, including how picky you are about tuning, how hard you play, the guitar you use, the kind of tuner installed, and whether you’ve installed the strings correctly.

To start out with, not everyone notices tuning problems in the same way. Some people find a string that is more than just a few cents off pitch grating, while others have a far wider acceptable range.

If you’re very picky, then the extra tuning stability that locking tuners give you will probably be appreciated. If you don’t really notice until things are quite out of tune, then you might not see much change.

Playing style and what kind of guitar you use have a dramatic impact on whether you notice a difference from locking tuners. If you have a blues-y style of playing and do a lot of string bends, then you already understand how strings can go out of tune if you bend them too far or if you don’t use the right technique.

This video looks at the basics of string bending and how to do it properly.

Whether you play a guitar with a tremolo or vibrato system will also change how much locking tuners help with tuning stability. Any kind of non locking tremolo or vibrato system runs the risk of pulling the strings out of place, which means the guitar doesn’t return to tune when you release the whammy bar.

You can mitigate that with a proper set up and by using a low friction nut, but locking tuners will make a much more noticeable difference.

If, on the other hand, you play mostly rhythm guitar on an acoustic guitar or a solid body with a stopped or hardtail bridge, you might not notice a huge difference in tuning stability.

That’s because while locking tuners will help keep strings in place, they can’t mitigate tuning problems from things like temperature or humidity changes, which cause guitar strings to shrink or stretch and send the guitar out of tune.

And if you aren’t using the locking tuners the way they were intended, you could be hurting your tuning stability.

How To Use Locking Tuners

As I mentioned above, locking tuners make changing strings very easy. You simply put the string in the bridge, bring it over the nut and through the tuner post, pull it tight, and turn the locking screw to clamp the string in place.

Then you can tune up and trim your strings.

This video demonstrates Grover locking Rotomatic style tuners and how to string them up.

This is a bit of a different procedure than many people are used to. With non-locking tuners, you often leave a bit of slack when first installing the string so you can properly wind the string around the tuner post and lock it in place.

If you do that when installing a string on a locking tuner and you risk defeating the entire purpose of the mechanism.

No matter how snug the knot might be, if there is extra string around the post, the risk of slipping is still there. When you clamp the string in place with a locking tuner, it should be taut, eliminating the possibility of slipping.


When it comes to locking tuners, their original advantage of better tuning stability is really only part of the story. They definitely help with that, especially on guitars equipped with a non-locking tremolo system.

Where they can really shine for just about every guitar is ease of restringing, though. They make the process faster and more repeatable.

Whether locking tuners are the right call depends on what you want from your guitar, but the extra security of better string attachment and the extra speed are definitely advantages worth considering.