can someone explain this to me ~ scale length question

[hondro]

so a guitars scale length is very important. It dictates where the frets will go and therefore if not done right could make it impossible to intonate a guitar.

 

 

So looking at bridges, shouldn't they're placement be CRUCIAL so that the scale length is EXACT for each string so they correspond with the fret placement

 

So...

 

 

Why is it that we have adjustable bridges? Shouldn't they all look like this?

 

 

and even then, shouldn't they be completely perpendicular to the end of the fretboard, not an an angle?

 

How can we have bridges like this, where the scale length is clearly not the same from string to string

 

 

and an extreme example

 

 

clearly the low E and high E don't have the same scale length.

 

My question is how does this work?

[PlectrumPete]

The stiffness and weight of the strings matters as to the placement of the bridge.

[mick8882003]

The different thickness (weight) of the strings means they need to be different lengths to vibrate at their respective frequencies.

[GCDEF]

 

The different thickness (weight) of the strings means they need to be different lengths to vibrate at their respective frequencies.

 

 

The tension determines the frequency, not the length.

 

It's a good question. I don't know the answer. Perhaps the thickness of the string determines how much the pitch changes when you bend it slightly by pressing it down onto the frets.

[joseflovesyou]

You seem to have answered your own question, within the question in question.

 

It is crucial to be exactly correct in each strings length to get the best intonation possible. Each string is going to intonate correctly at a slightly different length, so being adjustable is going to let you achieve that much more than a bar set all the way across for all the strings.

 

Wood also settles, so what was correct one day, probably wont be exactly correct a couple years later.

[Bad Chile]

 

The tension determines the frequency, not the length. It's a good question. I don't know the answer. Perhaps the thickness of the string determines how much the pitch changes when you bend it slightly by pressing it down onto the frets.

 

 

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.

[jrockbridge]

Fret placement, nut placement, and bridge placement as well as adjustment are all a compromise on a guitar. Nothing is exact it's just a compromise to meet the most common use of the guitar.

 

You should check out the Novax fanned fret guitars. They use a scale length approach to nut, fret and bridge placement. The frets are fanned out at angles (non-parallel). Many people report that these instruments sound more in tune on a wider range of chords and scales. Also, it allows them to manufacture a hybrid instrument with both bass and guitar strings.

 

http://www.novaxguitars.com/

 

http://www.novaxguitars.com/sales/index.html

 

http://www.novaxguitars.com/sales/serenade-acoustics.html

['s mel gibson]

Back in the early years of the 50's, there weren't a variety of string gauges. In the early 60's it was still wound G strings. With that in mind, the straight bar like on the 52 Les Paul was adequate I guess. Same with the 3 barrel Tele bridge and the compensated Gibson stop bar bridge.

 

Then light gauge string sets showed up in the mid to late 60's I think.

 

I had discovered in the early 60's that using a mandolin's hi G string for a hi E string worked for me and I would toss out the low E string. That really screwed up my intonation on my 59 LP Jr. but I had slinkier strings.

 

Adjustable bridge saddles are necessary in a world with a variety of string gauges.

[Help!I'maRock!]

Lotsa good answers in this thread.

 

I'm a guitarist, not a mathematician. So I can only relate to you what I saw last week when I restrung my PRS.

 

That guitar had really old string on it. Like 3 months old. When I finally got around to restringing it, the neck had settled to accommodate them. So the new strings had way lower action and were also very buzzy. I loosened the truss rod a quarter turn and solved the buzz issue.

 

But now that the truss rod was looser, that meant that the neck shifted and shortened the scale length. So I had to move the saddles back because the intonation was off. Same brand of strings, same gauge. But the neck moved, so the bridge needed to move back. Without adjustable saddles, or the ability to compensate, I would have had to re-drill the bridge posts, or play an out of tune guitar until such time the neck moved back to its previous position.

[ashasha]

You have to keep in mind that you are compensating for the length of the string when it is fretted (which is why the harmonic 12th fret intonation method is flawed in many people's eyes).

 

Here are just a few things off the top of my head that we are compensating for:

 

[GCDEF]

 

Nope. Length does affect frequency, as does mass and tension.

 

 

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.

[PlectrumPete]

 

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.

 

 

If that were true then fretting the string in different places would not change the note.

[joseflovesyou]

 

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.

 

 

a 20 inch strings with 15 pounds of tension will not sound like a 15 inch string with 15 pounds of tension. The length changes, and tension stays the same, changing the pitch

[MahaloVision]

It's called "compensation". When you fret the string, you change both the length and the tension of the string at that fret. Adding a little length to the scale at the bridge end compensates for that. Thicker strings need more compensation. Classical bridges are perpendicular to the scale.

[hondro]

interesting. What about accounting for different scale lengths? Are the frets simply closer together on a Gibson than on a Strat or Tele?

[Bert-O-325]

 

interesting. What about accounting for different scale lengths? Are the frets simply closer together on a Gibson than on a Strat or Tele?

 

 

Right.

 

the placement of the frets is figured as specific fractional divisions of the overall scale length.

 

ie: the 12th fret is half the length of the total scale length

[tim gueguen]

There's also the fact that before the riise of computer controlled manufacturing equipment a bridge wouldn't likely be precisely in place for automatic intonation. Read enough guitar descriptions and sooner or later you'll run into someone who found a guitar where the bridge was off position so much it was impossible to intonate no matter how much adjustment range the saddles had.

[GCDEF]

 

If that were true then fretting the string in different places would not change the note.

 

 

Try and follow along. The individual string lengths aren't adjusted at the bridge to get them "vibrate at their respective frequencies.". That's what the tuners are fore.

[Slaymoar]

Also, there is humidity levels, heat and cold - which you know variates the tension on the neck... these things all play into the reasons why adjustments are available.

[SuproSuper Man]

some of the older early guitars were built very basically with not a lot of concern put into intonation accuracy,...if intonation was in the ball park they were content back then...

 

and individual compensated bridges didnt start to appear and become popular till much later in the guitars evolution....so thats why you see alot of old or acoustic guitars with a simple one piece bridge they just were happy if intonation was just in the ball park,,,

 

now a days we tend to be tuning and intonation crazy,,,,which is good or bad depending on your perspective...yet still some people actually do like the quirkiness of a guitar thats not perfectly intonatable...(that out of tune chorusy effect thing happening)

 

if all you play is three chord songs in the first position then you may not really notice or give a rats butt about intonation...where as some other styles of music may require extremely precise tuning to accomplish their sonic objectives...and of course theirs everything in between those two extremes of the spectrum.. ... it all depends on your expectations and what you find acceptable for your particular use...and thats probably why you can still buy tele's with only three adjustable saddles, or gibbys with just a solid one piece saddle , it just depends on the individuals needs for their particular style of music...

 

As for the physics of string saddle placement , things such as , density, physical thickness, stretching when the string is pressed all have to be compensated for if what you want is a guitar with extremely high tolerances in regard to intonation.....but if you just wanna belt out a few tunes, or have a bit of guitar acompanyment while you sing a song around the camp fire then you really dont have to worry too much about intonation being dead on to have alot of fun playing guitar....

 

being aware of intonation is very important IMO, so that you are educated to its benefits, but at the end of the day how far or to what extremes you want to pursue the intonation of your guitar is entirely up to you the individual and your musical comfort zone....

 

some of my axes are highly tuned precision instruments that would put NASA engineers to shame ...lol...while others that i have are the furthest thing from ever being able to be in tune acurately, but I like their tone and there fun to just beat out the tunes on, so i dont get too anal about their intonation issues ,, their fun axes with their own unque personality shall we say ,,,,

[Caleb B]

Wow, this is a really informative thread. I'm glad someone asked this question.

[PlectrumPete]

Try and follow along. The individual string lengths aren't adjusted at the bridge to get them "vibrate at their respective frequencies.". That's what the tuners are fore.

 

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

[mondaymonkey]

 

The tension determines the frequency, not the length. It's a good question. I don't know the answer. Perhaps the thickness of the string determines how much the pitch changes when you bend it slightly by pressing it down onto the frets.

 

 

Lolz @ this

 

They both affect tension. If length didn't affect frequency, how can you make different tonez with difference frets?

[hondro]

my question isn't so much about intonation, but about why the bridge is set at an angle instead of straight

[PlectrumPete]

 

 

 

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