can someone explain this to me ~ scale length question

[Kuroyume]

I think that what everybody is trying to say here is: The distance based on scale length is not the only determination of the length between the contacts (bridge->nut) for proper intonation of each string. Tension, string thickness, string height all play a part in requiring the 'ideal' length to be adjusted so that intonation is correct.

 

ETA: Hello? Pythagoras' Law of Strings. Every single guitarist should at least know about this.

[GCDEF]

Ah now I understand. You took three posts to explain something obvious and which doesn't answer the question. Well done.

I had to repeat myself three times before you got the simple point I was trying to make. Seems some people still don't get it. :poke:

[joseflovesyou]

 

 

To keep the guitar intonated...

[Oosell]

I think you dudes are missing it.

The saddles are in different places because the guitar is Tempered Tuned.
Same as the piano. If the piano was tuned either way from middle C , as per mathematical, it would be out of pitch in the high and low registers.
So they adjust the tuning so it is fairly in tune over all the neck or keyboard.
It's called Tempered Tuning.
Pedal Steel players go though hell getting some strings in tune with an open chord and then find its out with a pedal combination.

And it you were to play a violin with guitars or pianos, and then went and played with an orchestra, you would find you would have to adjust finger pitch to suit.

Col.

[MahaloVision]

Compensation has nothing to do with a tempered scale,though.

[Kuroyume]

I think you dudes are missing it. The saddles are in different places because the guitar is Tempered Tuned. Same as the piano. If the piano was tuned either way from middle C , as per mathematical, it would be out of pitch in the high and low registers. So they adjust the tuning so it is fairly in tune over all the neck or keyboard. It's called Tempered Tuning. Pedal Steel players go though hell getting some strings in tune with an open chord and then find its out with a pedal combination. And it you were to play a violin with guitars or pianos, and then went and played with an orchestra, you would find you would have to adjust finger pitch to suit. Col.

 

 

Bull...mostly

 

Go look at almost any classical guitar. What does the bridge look like? (It is parallel to the nut)

 

Slanting bridge contacts, like on steel-string acoustics, are to compensate for the bass strings (see "Complete Guitar Repair" by Hideo Kamimoto). Why? Because they impart more tension due to their material (metal instead of nylon) and are thicker than their unwound counterparts. Compensation is required to attain equal-tempered tuning because of the aforementioned variations in strings (thickness, tension, height).

 

I'd say, get "Complete Guitar Repair" and read the "String Compensation" section from pp. 60-61. He is rather thorough in the explanation.

[hondro]

 

Because the bass strings are heavier and stiffer than the treble strings. They need more compensation.

 

 

so when a guitar has a 25.5 scale length where are they measuring it? The length from nut to bass string is not the same as the length from nut to treble string

[Kuroyume]

so when a guitar has a 25.5 scale length where are they measuring it? The length from nut to bass string is not the same as the length from nut to treble string

 

 

Usually, the nut to a 'furthest back' position of the bridge which is slightly greater than the scale length wherein compensation is forward to shorten the length.

 

This will all depend on the guitar bridge type. Some classicals have a 'staggered' bridge piece (the nylon/bone/ivory) where the scale length is at the median. For steel strings it is most likely at the median of an angled bridge. For guitars with individually adjustable saddles it is probably somewhere midway between the extremums of the saddle adjustability.

[Brewski]

One WORD:

AWESOME!!!!!!!!!!

Nope. Length does affect frequency, as does mass and tension. f= 1/(2*Length) * (Sqrt(Tension/Linear Mass)) The reason you need to vary the length for intonating is that due to imperfections in equal tempered tuning means that the length term needs to vary for each string to get the most equal tuning. There is that system of wavy fret wire out there that attempts to resolve the length term in the equation, but until you adopt that system the only way to address the imperfections of equal tempered tuning is to change the overal length of the string such that the intonation is perfect at the 12th fret.

 

[Otis McGonigle]

so when a guitar has a 25.5 scale length where are they measuring it? The length from nut to bass string is not the same as the length from nut to treble string

 

 

 

Scale length is theoretical, not exact. Scale length is 2 x the distance from the nut to the twelth fret, not the actual exact distance from the bridge to the nut.

[MahaloVision]

Usually, the nut to a 'furthest back' position of the bridge which is slightly greater than the scale length wherein compensation is forward to shorten the length. This will all depend on the guitar bridge type. Some classicals have a 'staggered' bridge piece (the nylon/bone/ivory) where the scale length is at the median. For steel strings it is most likely at the median of an angled bridge. For guitars with individually adjustable saddles it is probably somewhere midway between the extremums of the saddle adjustability.

 

 

Nope. What we do is lay out the fret positions by calculating them according to the scale length with no compensation. Then the compensation is added in. If you want to find out the scale length (on most guitars), measure from the nut to the 12th fret, then double it. This will not work for a compensated nut, obviously.

 

In any case, the length from nut to saddle can never be less than the scale length. If you were to measure from the nut to the middle of the saddle on an acoustic steel string, the treble strings would be shorter than the scale length.

[MahaloVision]

One WORD: AWESOME!!!!!!!!!!

 

 

The first part is OK, and it's something you can find on the D'Addario site. The formula is very useful for helping to figure out what gauge strings to use for various scale lengths and tuning to help approximate the feel of another set.

 

The second part is interesting, but has absolutely nothing to do with compensation over the whole scale length. Tempered tuning doesn't matter a lick when it comes to compensation. The speaking length of the string would need to be changed whether you were using a natural or tempered scale because you're pressing it down to a fret/fretboard.

[Mind Riot]

HO. LEE. CRAP.

 

Reading this thread made my head hurt. I know everybody wants to help, but MAN.

 

Okay, here's the deal. Intonation adjustment is a form of compensation. Compensation for what? For the physical realities of the way strings behave.

 

When a string is fretted, it stretches from it's resting position. Naturally, stretching a string from it's resting position raises it's tension slightly, just as when you do a bend. Meaning this raises its pitch slightly.

 

So completely aside from the fret positioning, the fact that the strings are suspended ABOVE the frets means they'll stretch out of tune slightly when they're pressed down to the fret. So a string may play perfectly in tune when you pluck it open, but when you fret it it goes slightly sharp.

 

Adjusting the saddle back increases the overall length of the string slightly, and the result is that the tension is raised less when the string is stretched from it's resting position because the increased length of the string (however slight) means more mechanical give. Just like stretching a taut one foot rope and a ten foot rope, the increased length of the ten foot rope means the tension will be changed less if you only pull it an inch or two off center.

 

The bigger wound strings add more variables to the equation. Oftentimes they actually have less tension than plain strings. In addition, they have a wider range of travel when struck due to their greater mass and inertia. This requires them to have higher action to avoid buzzing.

 

So think about how each variable affects intonation compensation.

 

1) Less tension means they'll stretch out of tune easier, since they have more mechanical give. Which means more compensation is needed.

 

2) Wider range of travel when struck means they'll more easily sound sharp if struck hard. More compensation needed.

 

3) Higher action means they'll stretch further off their resting point when fretted. More compensation needed.

 

So you can see why saddles need to be set further and further back the bigger the strings get; there's several variables that require it to make the strings all play reasonably in tune across the neck. (Guitars are what's known as even tempered instruments, meaning they play close but not perfectly in tune, but that's another topic.)

 

In general, lighter strings will require more intonation compensation than heavier ones. They stretch easier, have more give, and go out of tune easier when hit hard.

 

Heavier strings generally require less compensation, all else being equal. They have less give being at a higher tension. That higher tension means the action can often be set lower, requiring less pulling off center when fretted.

 

The variability in tensions is particularly pronounced with electric guitars, because they use strings with much less tension in general than other instruments, including acoustic guitars. Bending and ease of play take priority with electric guitars, as well as the fact that their being an amplified instrument means that big, tight, powerful strings aren't needed to produce their sound like they are with acoustic instruments.

 

This is also why adjustable bridges aren't often seen on acoustic instruments; they require tighter strings to excite their soundboards and create resonance in their chambers, and so their bridges are usually set when they're built in anticipation of the strings that will be required to produce optimal sound.

 

And if anyone is wondering why classical guitars don't have angled bridges, it's because nylon and gut strings behave differently than steel ones. They have a more even tension with each other, whether wound or unwound, they have the same action across the board with a flat bridge and flat fretboard radius, and they are much more elastic than steel strings. They can stretch more without it affecting pitch as much, because it doesn't affect their tension as much.

 

I hope this helps. I know it can be a bit of a confusing subject, but once you get down to it it's all just physics, mechanics, and math.

[Kuroyume]

Nope. What we do is lay out the fret positions by calculating them according to the scale length with no compensation. Then the compensation is added in. If you want to find out the scale length (on most guitars), measure from the nut to the 12th fret, then double it. This will not work for a compensated nut, obviously. In any case, the length from nut to saddle can never be less than the scale length. If you were to measure from the nut to the middle of the saddle on an acoustic steel string, the treble strings would be shorter than the scale length.

 

Correct. But I wasn't talking at all about fret positions which are layed out using the scale length in very exact measurements. But the position of the bridge is 'fuzzy' at best. It will be dependent upon its adjustability and the type of strings and tensions involved so as to achieve that 12th fret equilibrium.

 

As I said, the distance from nut to bridge is 'overcompensated' so that adjustments can be made forward (towards the neck). This is out of Hideo's book so that's my source.

 

Your last paragraph contradicts itself: 'can never be less than scale length' and 'treble strings would be shorter than scale length'. But if you mean 'overcompensation' then we are in agreement!

[Kuroyume]

HO. LEE. CRAP.

I cut the quote so that it wouldn't dominate.

Excellent!!!! Yes. And... Superb!!!

My explanations aren't perfect or don't completely explain what you are saying but you said it all. And I learned a few things more besides. Thanks!

[Mind Riot]

Glad to help.

[Les Paul Lover]

Mind Riot, fantastic explanation.

I think you settled that thread here!!!!

[MahaloVision]

Your last paragraph contradicts itself: 'can never be less than scale length' and 'treble strings would be shorter than scale length'.

 

 

I should have noted "middle of the saddle" being the midpoint side to side as well as thickness. On an acoustic, that would be right on the centerline of the top and bridge. Usually that's pushed back about 1/8".

[Metalrulez]

And to think playing guitar aint rocket science. You could have fooled me,after reading these posts.:thu:blah:

[hondro]

yay

[SuproSuper Man]

as mind riot said , its all about string physics, the material , how different diameters of that material behave and go out of tune when stretched,,

the high strings are solid metal and very thin, while the heavy strings of a set of steel stings are wound and are respectively much thicker than the thin high stings of the same set,,, so of course the thick ones will react slightly different than the thin ones when stretched ,,,,


generally the higher the action of the bridge and the string height is , the more the string will stretch and raise in pitch when a note is depressed on the fret board,,,

if the string stretches too much when pressed , then that raises the pitch of that string out of tune, so to compensate they put the bridge further back making the string longer and lower in pitch to compensate for when its pressed down that long stretching distance when the string is depressed to the fret board...

different thickness strings react differently, a thin string and a thick string if both stretched(or bent) the same distance will change pitch at a different rate from each other, so thats part reason why the bridges are set at different spots for different thicknesses of string...



NYLON - nylon or classical strings are different than those steel strings...first off the thickness between the heavy strings and the thin strings on a nylon set arent as drastic as they are in those steel sets,, so the thickness is fairly close to the same in a nylon set from thin string to thick string...

second is that Nylon dont change pitch as drastically as steel strings do when bent,,,if you ever tried to play blues licks and do any bending on a clasical guitar the first thing you notice is that your bends dont react the same as they did on your steel string guitar,,,you have to bend more to get the same or similar change in pitch on nylon strings than as you did on a steel set of strings...

even the wound metal strings on in a set of classical nylon strings have a nylon core, so again the material these strings are made from dont react the same way as the thick strings do on those all metal string sets that have metal cores ....the nylon core of a classical set of strings limits the strings sensitivity to pitch change when the string is bent...so again not much compensation is required at the bridge because of this...

so the physical (size) and material properties of NYLON strings is why with nylon strings classical guitars can get away with a straighter bridge rather than those angled bridges that you see on steel string guitars...its in part because of thickness and the way nylon reacts to bending or stretching ...


so yeah Its really simple , the compensated bridge is exactly as it says it is, a bridge to compensate for material differences and thickness variations in strings..its got more to do with compensating for physical properties of strings than anything else,,, its physics class 101...

[PlectrumPete]

HO. LEE. CRAP. Reading this thread made my head hurt. I know everybody wants to help, but MAN. Okay, here's the deal. Intonation adjustment is a form of compensation. Compensation for what? For the physical realities of the way strings behave. When a string is fretted, it stretches from it's resting position. Naturally, stretching a string from it's resting position raises it's tension slightly, just as when you do a bend. Meaning this raises its pitch slightly. So completely aside from the fret positioning, the fact that the strings are suspended ABOVE the frets means they'll stretch out of tune slightly when they're pressed down to the fret. So a string may play perfectly in tune when you pluck it open, but when you fret it it goes slightly sharp. Adjusting the saddle back increases the overall length of the string slightly, and the result is that the tension is raised less when the string is stretched from it's resting position because the increased length of the string (however slight) means more mechanical give. Just like stretching a taut one foot rope and a ten foot rope, the increased length of the ten foot rope means the tension will be changed less if you only pull it an inch or two off center. The bigger wound strings add more variables to the equation. Oftentimes they actually have less tension than plain strings. In addition, they have a wider range of travel when struck due to their greater mass and inertia. This requires them to have higher action to avoid buzzing. So think about how each variable affects intonation compensation. 1) Less tension means they'll stretch out of tune easier, since they have more mechanical give. Which means more compensation is needed. 2) Wider range of travel when struck means they'll more easily sound sharp if struck hard. More compensation needed. 3) Higher action means they'll stretch further off their resting point when fretted. More compensation needed. So you can see why saddles need to be set further and further back the bigger the strings get; there's several variables that require it to make the strings all play reasonably in tune across the neck. (Guitars are what's known as even tempered instruments, meaning they play close but not perfectly in tune, but that's another topic.) In general, lighter strings will require more intonation compensation than heavier ones. They stretch easier, have more give, and go out of tune easier when hit hard. Heavier strings generally require less compensation, all else being equal. They have less give being at a higher tension. That higher tension means the action can often be set lower, requiring less pulling off center when fretted. The variability in tensions is particularly pronounced with electric guitars, because they use strings with much less tension in general than other instruments, including acoustic guitars. Bending and ease of play take priority with electric guitars, as well as the fact that their being an amplified instrument means that big, tight, powerful strings aren't needed to produce their sound like they are with acoustic instruments. This is also why adjustable bridges aren't often seen on acoustic instruments; they require tighter strings to excite their soundboards and create resonance in their chambers, and so their bridges are usually set when they're built in anticipation of the strings that will be required to produce optimal sound. And if anyone is wondering why classical guitars don't have angled bridges, it's because nylon and gut strings behave differently than steel ones. They have a more even tension with each other, whether wound or unwound, they have the same action across the board with a flat bridge and flat fretboard radius, and they are much more elastic than steel strings. They can stretch more without it affecting pitch as much, because it doesn't affect their tension as much. I hope this helps. I know it can be a bit of a confusing subject, but once you get down to it it's all just physics, mechanics, and math.

 

 

 

Actually I think this is mostly wrong. The compensation is not about making the string longer so it has more "mechanical give" (whatever that is) and it is only partially related to the tension. It is actually compensating for the fact that the bend where the string goes over the nut means that the bridge is not acting as a perfect node - the stiffness of the bent string means that the virtual length of the vibrating string is slightly less than the actual length of the string. That's also why nylon strings need less compensation - they are less stiff.

[mick8882003]

I know, I just didn't want to overly complicate my response. I was just trying to point out in response to mick8882003 that when talking about one string at a time, you don't vary its length to change its frequency, you change its tension.

 

 

Yes but to get it to vibrate at the correct frequency you need to change the string length, you cannot change the mass of the string, so you need to adjust the other variables around this.

And yes I do realise that changing the tension changes the frequency, but also changing the length does to, basically its a compromise.

[Mind Riot]

Actually I think this is mostly wrong. The compensation is not about making the string longer so it has more "mechanical give" (whatever that is) and it is only partially related to the tension. It is actually compensating for the fact that the bend where the string goes over the nut means that the bridge is not acting as a perfect node - the stiffness of the bent string means that the virtual length of the vibrating string is slightly less than the actual length of the string. That's also why nylon strings need less compensation - they are less stiff.

 

 

 

Ahhh, I get it. I wasn't totally sure in the other thread alone, but now I see. You're trolling, just being contrary, or are just one of the most confused people I've ever seen.

 

I'm not going to take any more of my time; I've already answered the question the OP posed.

 

I hope I helped with the information I posted, but if folks don't believe me please go find a good book on guitar design and set up and see for yourself.

[PlectrumPete]

Ahhh, I get it. I wasn't totally sure in the other thread alone, but now I see. You're trolling, just being contrary, or are just one of the most confused people I've ever seen.

 

 

None of those things. Just trying to point out that your explanations are wrong from a physics perspective. But heh, believe what you like.