The Physics of a self de-tuning guitar

The B and G strings of my Gibson Les Paul regularly go out of tune up(!!) a semitone when playing and sometimes a whole tone if left over night.

Can anyone explain the physics of how a guitar can tune itself up? - please do not try the "Little pixies run into your practice room when you are not looking to turn the machine-heads just to piss you off" explanation as I have stayed overnight and watched it; and it isn't true!

Better still does anyone have a remedy?

I'm by no means an expert on the area, but I've experienced a similar problem with my own guitars, and there are a few thing I can recommend you try.

First off, is the room temperature stable or does it change greatly (f.ex. do you have open windows in the room)? This caused my guitars to go out of tune frequently, because the string length increases the warmer the room is, and decreases the colder the room is. This either increases or decreases the tension, leading to unstable tuning. Try making sure to close any windows or other entrances to your practice space about an hour before practicing (if possible, and only viable if you always practice at a certain time of the day). This gives the room time to temperate, even if you've just had all windows in the house open. And since the room has the right temperature every time you practice, your guitar won't have to be re-tuned every time, as long as you don't choose to change the practice-temperature.

Secondly, are there two or more complete windings around the tuning machines? If not, the tension from the strings can in some cases pull the string a bit looser so it goes out of tune. If there aren't 2 windings, you may want to re-syring your guitar and make sure there's the required number of windings.

Those were the two biggest issues I had when my guitars wouldn't stay tuned. Hope it helps a bit :)

Originally Posted by: Shostakovich
Can anyone explain the physics of how a guitar can tune itself up?

http://www.physicsforums.com/showthread.php?t=459222

Essentially, wood (guitar) & steel-nickel (strings) contract & expand at different rates. Overnight, both lose heat, metal faster, the guitar & strings contract, making the strings go sharp. There is also the possibility that the steel truss rod is a factor here!

When you pick it up & start playing, the strings are sharp because everything has contracted. But gradually your hands & body transfer heat to the neck & strings. But, if you retune at this point, the strings & guitar will heat up unequally, so the difference between them can make the strings go sharp a bit at first again until everything is equally "warmed up".

I usually just play for a 5-10 minutes until its warmed up & then retune. Sometimes I get impatient & tune it though. :)

This shows the importance of warming up your guitar as well as your hands! In order to avoid (as much) overnight contraction keep the guitar in a warm, stable temperature room.

Hope this helps!

I just started experiencing this same outa-tune problem and, yes, I just started opening the windows at night bringing in really chilly air to combat the next day's summer temps.

Only the semi-hollow electric has the problem, the acoustic not at all. But there's a significant difference in the proximity to the window between the two.

I'm gonna move the electric to beside the acoustic and see what happens...

Haven't read through the other responses completely, so sorry if I'm reiterating something...

The most common culrit to a guitar tuning itself UP by itself are changes in atmosphere (temperature and humidity). I think the one post up above explains this. As you look at a guitar in terms of basic materials, all those materials react differently to changes in temerature and humidity. Metals stretch and contract much more rapidly under temperature changes than wood does... Wood reacts much more rapidly to changes in humidity. It's important to regulate these things as much as possible to some sort of consistency. If you're into aged guitars, humidity will speed this process. Often you'll see checking and cracking in the finish where the wood swells and contracts during increases and decreases in humidty. It's particularly bad for guitars like Les Pauls with neck joints that are glued. Over time this will weaken the joint. More than likely this is your issue...

Strings expand with heat and contract as they cool. Basic metallurgy. A string that contracts goes sharp and a string that expands goes flat...

Also, binding at the nut and at the bridge can cause a guitar to suddenly seem sharp a bit while playing. Try some simple graphite lubricant at the nut when you change strings and at the bridge... This will help your guitar to return to its natural state after big bends and lengthy playing periods.

Thanks every one for your replies and advice.

Yep! it is probably room temperature fluctuation. Still intrigues me though that the problem is predominantly the G string with a little bit of the B.

Cheers.

Originally Posted by: ShostakovichThanks every one for your replies and advice.

Yep! it is probably room temperature fluctuation. Still intrigues me though that the problem is predominantly the G string with a little bit of the B.

Cheers.

May want to see if those tuners are holding in place. On a guitar from years ago, I had a tuning peg that was too loosey-goosey and was a chronic tuning issue for me. May not be with yours and with an LP, no matter if the are the 'green ivory' ones or Grovers, they should be good.

...though you did not consider invisible pixies...just sayin'

My Les Paul has the same problem (if you can call it a problem). The G and B strings are usually out of tune when I pick up the guitar. The cure? Get the guitar warmed up by playing it for a few minutes (mine can take about 20 minutes to stabalize). Make sure you do a lot of bends too, to make sure you stretch the strings.

Also, keeping it in the case will reduce the effects of temperature variations.

Every guitar has a quirk or personality as I call it, you just learn to live with it and find work arounds

Itchin' to play,

Izzy