can someone explain this to me ~ scale length question

[Kuroyume]

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.

 

Cites, please?

[LAracer]

Mind Riot, I liked your explanation, thanks. It implies that the saddle offset should be adjusted if the action is changed. Is this correct? (I don't usually adjust my action much, so I don't have any experience with this).

[SuproSuper Man]

Mind Riot, I liked your explanation, thanks. It implies that the saddle offset should be adjusted if the action is changed. Is this correct? (I don't usually adjust my action much, so I don't have any experience with this).

 

its absolutely correct....just like i said in my two previous posts...

 

raise string height = move bridge back... ....

Lower string height = move bridge forward...

 

why - Because the higher the sting height the more it will stretch and go sharp on you when you press it...so to correct that sharpness and lower the pitch back down to normal you can lengthen the string by moving back the bridge ,,,that will bring your sharp note back down to normal pitch......

 

two things determine where saddle offeset is placed -

- one is sting height

- the other is mass size thickness of the string, , combined with material string is made of ....

 

[Mind Riot]

 

Mind Riot, I liked your explanation, thanks. It implies that the saddle offset should be adjusted if the action is changed. Is this correct? (I don't usually adjust my action much, so I don't have any experience with this).

 

 

Correct, in theory. As a guitar is an even tempered instrument, any note is only going to be so close to perfectly in tune. So if you raise the action a tad and check the intonation you may find it didn't impact the pitch enough to adjust. But in general, raising the action will make the string stretch more when fretted, so more compensation will be needed.

[Davo17]

 

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.

 

 

I.e.-speaking length, vs physical lenth.

[Mind Riot]

 

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

 

 

"When we discuss a string length, or scale, we're referring to the distance from the nut to the center of the saddle, measured in a direct line down the center of the fingerboard and body. A Strat, for example, has a scale length of 25 1/2". But the bridge saddles may actually measure as much as 1/8" to 3/16" more than that, depending string height, string gauge, etc. This addition to the string's length at the saddle is known as compensation. A basic understanding of compensation is necessary before the guitar's intonation can be properly set.

 

Compensation is the adjustment that changes the mathematical (measured) scale of a guitar by altering the string length-almost always at the bridge. This procedure sets the intonation, and is crucial for proper noting."

 

"When setting intonation, we try to get a string to play the same note when fretted at the 12th fret as when played open, only an octave higher. In theory, the distance from the nut to the 12th fret is the as the 12th fret to the saddle, since the 12th fret is the octave and halfway point of the scale (scale length equals the measurement from the nut to the 12th fret, times two).

 

In practice, the string length must be increased to offset the sharpness that results when the string is pressed down during playing (remember, the mathematical distance of the scale runs in a straight line from the front edge of the nut to the saddle's center). The string, however, runs up and away at an angle to this line. When pressed to the frets during playing, it becomes stretched, which causes it to go sharp." Italics added.

 

"The closer the strings are to the fingerboard, the less compensation is needed, since the strings go sharp less when pressed. However, guitars with lighter strings generally need more compensation than heavier ones, since as string tension decreases (going from heavier-gauge strings to lighter), the compensation need increases."

 

"Wound strings need more compensation than plain ones. Because of their extra weight an slower, lower pitched vibrations, wound strings need more clearance from the fingerboard to avoid buzzing. The extra clearance is gained by raising the string height from the fingerboard for wound strings. This increase in height causes the strings to go sharp more than the unwounds when depressed. This is why bridge saddles slant toward the bass side on steel-string acoustics or electrics."

 

"Notice that classical guitars have saddles with no slant. Why? The wound strings have a stranded core rather than a solid one, and sharp out at a rate similar to that of the solid nylon treble strings. Classical strings have a more even tension across the fingerboard than steel strings. Therefore, they require close to the same amount of compensation per string, and in general are more uniformly spaced from the fingerboard in terms of height." Italics added.

 

"Instruments with longer scales need less compensation that shorter scaled ones, because the longer string must be tighter to reach the same pitch. Thus the longer string is less apt to be sharp when fretted and needs less compensation (the higher the tension, the less a string goes sharp). Italics added.

 

-All above quotes from The Guitar Player Repair Guide 2nd Edition, By Dan Erlewine, pages 19, 20, and 21. Published by BackBeat books. http://www.stewmac.com/shop/Books,_plans/Building_and_repair:_Guitar,_electric/Guitar_Player_Repair_Guide.html

 

"Intonation- Having an instrument "in tune" throughout the scale is the goal of every player and luthier. Different string gauges, scale lengths, set ups, fret sizes, playing techniques and other variables can effect your instruments intonation. While it is true that there is a certain amount of compromise on equal tempered instruments, my goal is to have the best possible intonation."

 

"Scale Length and String Length The strings scale length* begins at the nut and ends at the saddle. If you look at the saddles on your guitar or bass you will quickly realize that they do not sit parallel with the last fret (with the exception of some classical guitars) as they been adjusted to alter the strings length and intonate the instrument. Some additional string length is added to the actual scale length in order to off set the sharpening of the note which occurs when the string is stretched while being fretted."

 

"Factors That Can Cause Poor Intonation:

 

High action: An instrument with high action will of course cause the string to be stretched further before contacting the fret, this stretching sharpens the note slightly. High action at the nut is particularly troublesome as chords played in the 1st to 3rd position can sound terribly out of tune."

 

-Quotes from fretnotguitarrepair.com

http://www.fretnotguitarrepair.com/Electric_Guitar_Intonation.htm

 

 

 

I can find more I suppose. You're right about one thing, that the string not beginning to vibrate until a certain distance past the nut and saddle is a factor in intonation as it affects the speaking length of the string, thus making the bridge placement inherently off a tad. I reread your post, and I grasp better what you were saying. That's certainly an important factor in guitar design, and in the physics of string behavior.

 

But I also think I've pretty amply demonstrated that introducing the factors of the tension of the strings, their height, and their going sharp when fretted are the crucial factors involved in intonation compensation, and it seems to me that the physics of my explanations are not only quite clear but also widely embraced by professionals in the field.

[Kuroyume]

"When we discuss a string length, or scale, we're referring to the distance from the nut to the center of the saddle, measured in a direct line down the center of the fingerboard and body. A Strat, for example, has a scale length of 25 1/2". But the bridge saddles may actually measure as much as 1/8" to 3/16" more than that, depending string height, string gauge, etc. This addition to the string's length at the saddle is known as compensation. A basic understanding of compensation is necessary before the guitar's intonation can be properly set. Compensation is the adjustment that changes the mathematical (measured) scale of a guitar by altering the string length-almost always at the bridge. This procedure sets the intonation, and is crucial for proper noting." "When setting intonation, we try to get a string to play the same note when fretted at the 12th fret as when played open, only an octave higher. In theory, the distance from the nut to the 12th fret is the as the 12th fret to the saddle, since the 12th fret is the octave and halfway point of the scale (scale length equals the measurement from the nut to the 12th fret, times two). In practice, the string length must be increased to offset the sharpness that results when the string is pressed down during playing (remember, the mathematical distance of the scale runs in a straight line from the front edge of the nut to the saddle's center). The string, however, runs up and away at an angle to this line. When pressed to the frets during playing, it becomes stretched, which causes it to go sharp. " Italics added. "The closer the strings are to the fingerboard, the less compensation is needed, since the strings go sharp less when pressed. However, guitars with lighter strings generally need more compensation than heavier ones, since as string tension decreases (going from heavier-gauge strings to lighter), the compensation need increases." "Wound strings need more compensation than plain ones. Because of their extra weight an slower, lower pitched vibrations, wound strings need more clearance from the fingerboard to avoid buzzing. The extra clearance is gained by raising the string height from the fingerboard for wound strings. This increase in height causes the strings to go sharp more than the unwounds when depressed. This is why bridge saddles slant toward the bass side on steel-string acoustics or electrics." " Notice that classical guitars have saddles with no slant. Why? The wound strings have a stranded core rather than a solid one, and sharp out at a rate similar to that of the solid nylon treble strings. Classical strings have a more even tension across the fingerboard than steel strings. Therefore, they require close to the same amount of compensation per string, and in general are more uniformly spaced from the fingerboard in terms of height. " Italics added. "Instruments with longer scales need less compensation that shorter scaled ones, because the longer string must be tighter to reach the same pitch. Thus the longer string is less apt to be sharp when fretted and needs less compensation (the higher the tension, the less a string goes sharp). Italics added. -All above quotes from The Guitar Player Repair Guide 2nd Edition, By Dan Erlewine, pages 19, 20, and 21. Published by BackBeat books. http://www.stewmac.com/shop/Books,_plans/Building_and_repair:_Guitar,_electric/Guitar_Player_Repair_Guide.html "Intonation- Having an instrument "in tune" throughout the scale is the goal of every player and luthier. Different string gauges, scale lengths, set ups, fret sizes, playing techniques and other variables can effect your instruments intonation. While it is true that there is a certain amount of compromise on equal tempered instruments, my goal is to have the best possible intonation." "Scale Length and String Length The strings scale length* begins at the nut and ends at the saddle. If you look at the saddles on your guitar or bass you will quickly realize that they do not sit parallel with the last fret (with the exception of some classical guitars) as they been adjusted to alter the strings length and intonate the instrument. Some additional string length is added to the actual scale length in order to off set the sharpening of the note which occurs when the string is stretched while being fretted. " "Factors That Can Cause Poor Intonation: High action: An instrument with high action will of course cause the string to be stretched further before contacting the fret, this stretching sharpens the note slightly. High action at the nut is particularly troublesome as chords played in the 1st to 3rd position can sound terribly out of tune. " -Quotes from fretnotguitarrepair.com http://www.fretnotguitarrepair.com/Electric_Guitar_Intonation.htm I can find more I suppose. You're right about one thing, that the string not beginning to vibrate until a certain distance past the nut and saddle is a factor in intonation as it affects the speaking length of the string, thus making the bridge placement inherently off a tad. I reread your post, and I grasp better what you were saying. That's certainly an important factor in guitar design, and in the physics of string behavior. But I also think I've pretty amply demonstrated that introducing the factors of the tension of the strings, their height, and their going sharp when fretted are the crucial factors involved in intonation compensation, and it seems to me that the physics of my explanations are not only quite clear but also widely embraced by professionals in the field.

 

Don't forget Hideo Kamimoto's "Complete Guitar Repair"! Some say it is dated but except for a couple new things like double-locking tremolo systems, this is from 18 years of guitar repair experience (1960-1978 as of date of publication).

 

Also, you might want to include "How To Make Your Electric Guitar Play Great!" (pg. 92).

 

Should I just continue adding to your list?

[Mind Riot]

Don't forget Hideo Kamimoto's "Complete Guitar Repair"! Some say it is dated but except for a couple new things like double-locking tremolo systems, this is from 18 years of guitar repair experience (1960-1978 as of date of publication). Also, you might want to include "How To Make Your Electric Guitar Play Great!" (pg. 92). Should I just continue adding to your list?

 

I don't have a copy of Kamimoto's book, but I've heard nothing but good things about it. If I had one I'd quote from it too.

 

"How to Make Your Electric Guitar Play Great" is a condensed version of the Guitar Player Repair Guide, from what I understand.

 

I also have Melvyn Hiscock's "Make Your Own Electric Guitar", which is practically required reading for builders, it's a great book.

 

I don't know how much more information will be needed. I kind of thought I had it with my first post here, but apparently...

[MahaloVision]

 

Correct, in theory. As a guitar is an even tempered instrument, any note is only going to be so close to perfectly in tune. So if you raise the action a tad and check the intonation you may find it didn't impact the pitch enough to adjust. But in general, raising the action will make the string stretch more when fretted, so more compensation will be needed.

 

 

So, since this has been brought up before, and you're handing out good answers, why even mention temperament? If the guitar were designed for a natural/non-tempered tuning, wouldn't that only effect the fret placement? The saddle would still require some compensation with either one. You would still need to ensure that the open note and the fretted note an octave above would still be an octave.

[Mind Riot]

So, since this has been brought up before, and you're handing out good answers, why even mention temperament? If the guitar were designed for a natural/non-tempered tuning, wouldn't that only effect the fret placement? The saddle would still require some compensation with either one. You would still need to ensure that the open note and the fretted note an octave above would still be an octave.

 

Even tempered isn't the same thing as true temperament. Even tempered refers to an instrument like a guitar using a fixed scale for all strings, which makes it play close to in tune all over the board but not perfectly.

 

True temperament is a fret placement system someone came up with that supposedly compensates for the even tempered nature of the guitar to make it play more in tune.

 

I wasn't trying to introduce anything about fret placement theory or anything involving true temperament.

 

I only mentioned guitars being even tempered instruments to provide context for my saying that raising the action might not always require an intonation adjustment. Any note on a guitar will only be close to perfectly in tune due to it's being an even tempered instrument, and I just thought it would be helpful to note that X amount of adjustment in action height won't necessarily require a precisely corresponding adjustment in intonation.

 

If you're just raising the action a smidge, it's entirely possible that it won't affect the intonation enough for your ears to tell the difference because we're all used to things only being so close. Of course, sometimes it will require an adjustment; the post I was responding to was asking if there needed to be corresponding adjustment with raising the action a small amount.

 

Basically, a novel's worth of words to say sometimes yes, sometimes no, each case on it's own.

[PlectrumPete]

 

But I also think I've pretty amply demonstrated that introducing the factors of the tension of the strings, their height, and their going sharp when fretted are the crucial factors involved in intonation compensation, and it seems to me that the physics of my explanations are not only quite clear but also widely embraced by professionals in the field.

 

 

They do go sharp when fretted, but the compensation does not work in the way you explained. It does not increase the "mechanical give" by increasing the length, it merely increases the length of the fretted string thereby flattening the note. This is also clear from what Erlewine is saying.

 

Also, the reason different strings need different compensation is almost entirely down to the stiffness (and the point I made about the way the end is constrained) and only in part related to the tension or weight of the string. Nylon string guitars are compensated (to allow for the fretting effect), but each string is compensated by the same amount since the strings are not stiff. In fact some nylon string guitars have a compensated saddle to allow for the G string being thicker and stiffer than the others. Erlewine has this a little wrong.

[ashasha]

Jeez, I love it when internet discussions evolve into hair splitting.

 

I think that we can all agree that compensation at the saddle is important for being as close to in tune as possible on an electric guitar. We all know that if it's flat then move the saddle towards the nut and if it's sharp move it away from the saddle.

 

Trying to discuss physics and {censored} is kind of silly for something so simple. It's not like the use or technique of compensation is going to change based on who wins the argument...which by the way is really starting to sound like arguing the same point; just in different terms and from a different POV.

[PlectrumPete]

 

Jeez, I love it when internet discussions evolve into hair splitting. I think that we can all agree that compensation at the saddle is important for being as close to in tune as possible on an electric guitar. We all know that if it's flat then move the saddle towards the nut and if it's sharp move it away from the saddle. Trying to discuss physics and {censored} is kind of silly for something so simple. It's not like the use or technique of compensation is going to change based on who wins the argument...which by the way is really starting to sound like arguing the same point; just in different terms and from a different POV.

 

 

Is everything you don't understand called hairsplitting?

[MahaloVision]

 

I only mentioned guitars being even tempered instruments to provide context for my saying that raising the action might not always require an intonation adjustment.

 

 

Fair enough.

[Mind Riot]

 

They do go sharp when fretted, but the compensation does not work in the way you explained. It does not increase the "mechanical give" by increasing the length, it merely increases the length of the fretted string thereby flattening the note. This is also clear from what Erlewine is saying. Also, the reason different strings need different compensation is almost entirely down to the stiffness (and the point I made about the way the end is constrained) and only in part related to the tension or weight of the string. Nylon string guitars are compensated (to allow for the fretting effect), but each string is compensated by the same amount since the strings are not stiff. In fact some nylon string guitars have a compensated saddle to allow for the G string being thicker and stiffer than the others. Erlewine has this a little wrong.

 

 

I see your point about increasing the length and it's well taken.

 

But what I mean by mechanical give is elasticity (I don't know why I started calling it that). Intonation compensation has to take into account many factors, and I feel your take on it is downplaying the practical, real world side of the equation.

 

Each string will have a certain amount of elasticity to it, and it will vary depending on the construction and materials. The elasticity will also lessen as the string is tightened, the closer the string comes to it's breaking point the less give the material will have.

 

Meaning at higher tensions, moving the string from it's resting position will affect it's pitch primarily by increasing it's tension. The string doesn't have much give as it's tuned so tight, so the movement off resting position causes a fairly predictable, equivalent increase in tension. Higher tension also means the string will deviate less from it's fundamental pitch when struck, as the vibrational arc will be tighter.

 

But with a string that is tuned at a lower tension, when it's pulled from it's resting position by fretting it's not only the increase in tension that must be compensated for but the elasticity of the material. A looser tuned string may actually deviate in pitch slightly less when fretted due to it's elasticity offsetting being pulled off center slightly, but it's also much easier to fret too hard, raising the pitch further. It's looser tension and greater elasticity will also make it much more prone to sounding sharp when struck, as the vibrational arc will be wider and the same amount of picking force will produce a greater arc, meaning more variation from the fundamental, all else being equal. This will often require more compensation to counteract.

 

These factors have to be taken into consideration, and are a large part of why electric guitar bridges have such wide range of adjustment. If simply increasing the length by a corresponding amount based on deviation from center when fretted was the crux of the matter, then there wouldn't be need for such a wide range of adjustments with string gauges. A few basic settings based on string height would be all that was needed.

 

However, all that being said, you're absolutely right about increasing the string length not increasing elasticity or give. I see more clearly from your explanation above the physics involved, and I was clearly mistaken. Any increase in elasticity in a string from an extra millimeter of length would be meaningless. My apologies.

 

I'm not quite sure what you mean about stiffness in relation to classical strings. Is it just referring to how much the tension is raised when the string is moved off center? As in, a stiffer string will require more compensation due to being less elastic, while a less stiff string will require less because the pitch will change less when the string is stretched?

 

I'm just not clear on what specific properties you're referring to with stiffness.

 

Thank you for your take on things, I've gained some valuable new perspective.

[Kuroyume]

Stiffness involves the property of the solid object being deflected, stretched, or compressed.

 

Elasticity involves the property of the material itself.

 

http://www.absoluteastronomy.com/topics/Stiffness