Higher action on longer scale lengths?

Wiltonauer

SS.org Regular
Joined
Aug 6, 2022
Messages
213
Reaction score
177
I used to have a seven-string hollowbody with a 24.75” scale, and it wasn’t great. I had to use a 7th string that was a PITA to get in or out of the tailpiece and barely fit through the hole in the tuning peg. I’m much, much happier with this 26.5” arrangement and what is measuring as a .060” or .061”, probably a nominal .062” if you look at the specs.
 

Lopp

SS.org Regular
Joined
Mar 28, 2021
Messages
136
Reaction score
147
Location
Chicago
Even at just a 4% increase in nominal scale length, the difference in the fret spacing is pretty noticeable, especially near the nut. I’m surprised at how much deeper and richer this guitar sounds than the other sevens I’ve owned, as well as my normal sixes. Tonally, it’s somewhat baritone-esque.
That's interesting that the guitar sounds deeper. There must be other aspects of the guitar that cause that because a longer scale length gives a brighter tone and a shorter length gives a warmer tone.
Yeah this is correct. But it refers to a lower tuned string, not to the fact that a 7 string has an additional string tuned a fourth lower.

In my posts, 'feel' is 'perceived tension', which is mostly determined by 'actual tension' but also scale length and some other things. Basically 'how tight the string feels'.

Continuing from my first reply above ... this sounds like it might be a misunderstanding? A 7 string in standard BEADGBE is *not* tuned lower than a 6 in standard EADGBE, the top 6 strings are the same pitch. The 7 string just has an additional B string added.
The B tension is made a suitable value by using a larger gauge, a longer scale is not necessary to do that.
Are you saying the formula T = (f * 2 * L) ² * μ / g is incorrect? Please cite your sources that contradict physics.

The thread title is "Higher Action on Longer Scale Lengths."
The answer is longer scale lengths allow for lower action because, with everything else equal, a longer scale length causes more tension.
 

Wiltonauer

SS.org Regular
Joined
Aug 6, 2022
Messages
213
Reaction score
177
That's interesting that the guitar sounds deeper. There must be other aspects of the guitar that cause that because a longer scale length gives a brighter tone and a shorter length gives a warmer tone.
It seems like there is more to it than just bright vs. warm. The notes seem brighter and clearer, but there is also more enegy from the fundamentals, and the harmonics on ordinary fretted notes are very prominent. Everything sounds bigger, almost like when you play a baritone guitar, only the tuning is standard and the effects aren’t as extreme.
 

ixlramp

SS.org Regular
Joined
Mar 5, 2007
Messages
3,060
Reaction score
1,900
Location
UK
But it refers to a lower tuned string, not to the fact that a 7 string has an additional string tuned a fourth lower.
this sounds like it might be a misunderstanding? A 7 string in standard BEADGBE is *not* tuned lower than a 6 in standard EADGBE, the top 6 strings are the same pitch. The 7 string just has an additional B string added.
Sorry for the statements above, you can ignore them, i was partly misunderstanding your posts and also being overly fussy about the use of the phrases 'lower tuned' and 'lower tuning'.
A longer scale is of course beneficial for a guitar with a lower pitch string.
Are you saying the formula T = (f * 2 * L) ² * μ / g is incorrect?
No :) I think we just have miscommunication/misunderstanding
I did not realise the constant 386.4 stated on the original D'Addario tension pdf came from an imperial unit value for g, it is good to learn that.
The answer is longer scale lengths allow for lower action because, with everything else equal, a longer scale length causes more tension.
Here you are holding mass (gauge) and pitch constant, such that tension rises. You assume the same gauges are being used, which i think is not the general situation because the guitarist would not want a higher perceived tension, they would generally use slightly smaller gauges to maintain their preferred perceived tension.

My approach is to hold mass (gauge) and tension constant, because those both affect floppiness, pitch does not affect floppiness.
With mass (gauge) and tension constant, a longer scale certainly makes a string floppier and in need of a higher action.

Assuming the guitarist uses the same gauges and the same tuning when scale increases:
The longer scale makes the string floppier (with mass (gauge) and tension constant).
Then we add in the affect of increased tension, which is to make the string less floppy, which counteracts the above to some degree.
I am not sure if the tension increase would outweigh the effect of longer scale or not. I somewhat doubt it considering a bass guitar has twice the string tension but has similar or higher action (comparing the bass .040 G to the guitar .042 E to compare similar masses).

Seeing the thread title "Higher action on longer scale lengths?", a scientifically trained person (me) will interpret that with 'all else being equal'. The other factors that affect floppiness/action are tension and mass (gauge), so those are assumed to be the things 'being equal'.
To consider the effect of scale length on floppiness/action, we have to keep the other factors that affect floppiness/action equal.

So just the result of my physicist brain :lol:
*Emerges from rabbit hole*
 

Wiltonauer

SS.org Regular
Joined
Aug 6, 2022
Messages
213
Reaction score
177
If you increase the scale length of a string and keep the same gauge, the vibrating mass of the string increases because it is longer.

You can’t have the same string gauge, tuning, and tension on different scale lengths. At least one of the three has to change.

I’m making no assumptions in my original comparison other than tuning and string gauge remaining the same. I’m thinking more about the string oscillations and the shapes outlined as deviations from the strings’ resting positions, and their propensities for clanging against frets in an undesirable fashion.

If you keep the same string gauge and tuning and increase the scale length, the tension must increase to maintain the same pitch. I’m not going to change my pitch to accommodate a desired tension, scale, or string gauge; it’s the other way around.

Pitch, intonation accuracy, tone, playing comfort, freedom from buzzing — these are my goals. In the service of these goals, I’m up for experimenting with different scale lengths, string gauges, tensions, and setups. I’m up for tension changing if it serves the goals. One of the reasons I was excited about getting a longer-scale seven is that I thought it would be fun to play with this stuff. Are we having fun yet? 🤣
 

Lopp

SS.org Regular
Joined
Mar 28, 2021
Messages
136
Reaction score
147
Location
Chicago
Oh cool. It looks like we are obtaining a meeting of your physicist's mind and my engineer's mind.

Sorry for the statements above, you can ignore them, i was partly misunderstanding your posts and also being overly fussy about the use of the phrases 'lower tuned' and 'lower tuning'.
A longer scale is of course beneficial for a guitar with a lower pitch string.

No :) I think we just have miscommunication/misunderstanding
I did not realise the constant 386.4 stated on the original D'Addario tension pdf came from an imperial unit value for g, it is good to learn that.
👍:cool:
Here you are holding mass (gauge) and pitch constant, such that tension rises. You assume the same gauges are being used, which i think is not the general situation because the guitarist would not want a higher perceived tension, they would generally use slightly smaller gauges to maintain their preferred perceived tension.
Exactly. "Everything else equal" including mass/gauge.

That is actually the challenge I have with my 25.5" 7-string. I like lighter gauges as I frequently work on minimizing pick travel distance and the pick has to travel more over the thicker lower-tuned/higher gauge strings. This means I have to deal with more floppiness on the low B because that is a relatively low scale length for the B. A bit of a trade-off because the looser strings also affect pick travel distance.
My approach is to hold mass (gauge) and tension constant, because those both affect floppiness, pitch does not affect floppiness.
I'm confused about the statement "pitch does not affect floppiness." To keep gauge and tension constant, changing the pitch will affect the floppiness unless you change the scale length.
With mass (gauge) and tension constant, a longer scale certainly makes a string floppier and in need of a higher action.
This is only true if you decrease the pitch/frequency. If the frequency is the same, a longer scale will increase the tension and decrease the flop.
Assuming the guitarist uses the same gauges and the same tuning when scale increases:
The longer scale makes the string floppier (with mass (gauge) and tension constant).
Then we add in the affect of increased tension, which is to make the string less floppy, which counteracts the above to some degree.
I am not sure if the tension increase would outweigh the effect of longer scale or not. I somewhat doubt it considering a bass guitar has twice the string tension but has similar or higher action (comparing the bass .040 G to the guitar .042 E to compare similar masses).
Hmmm... That might be where our communication styles are diverging. I view "floppiness" as effectively synonymous with tension. I am also viewing everything in a guitar context where tension is always positively correlated with frequency, length, and weight. Change any of frequency, length, and weight while maintaining the others constant results in a correlated change in tension. That is possibly the result of the difference between a engineering practical application mind and a physicist theoretical mind.
Seeing the thread title "Higher action on longer scale lengths?", a scientifically trained person (me) will interpret that with 'all else being equal'. The other factors that affect floppiness/action are tension and mass (gauge), so those are assumed to be the things 'being equal'.
To consider the effect of scale length on floppiness/action, we have to keep the other factors that affect floppiness/action equal.
Yeah. If scale length is increased when frequency and gauge are kept equal, the tension increases, which allows lower action.
So just the result of my physicist brain :lol:
*Emerges from rabbit hole*
And the result of my engineering brain. :lol:
*Starting to poke head out of rabbit hole*
 

Wiltonauer

SS.org Regular
Joined
Aug 6, 2022
Messages
213
Reaction score
177
What about basses and baritones? Bigger strings, longer scales… higher action, usually, but is this inevitable or just how they usually come from the factory? I’m not a bass player or a baritone player, so I don’t see that many examples. Do some people set theirs up significantly lower? Not to disregard plain strings at guitar tunings, as that was kind of my main point of inquiry originally.
 

Lopp

SS.org Regular
Joined
Mar 28, 2021
Messages
136
Reaction score
147
Location
Chicago
What about basses and baritones? Bigger strings, longer scales… higher action, usually, but is this inevitable or just how they usually come from the factory? I’m not a bass player or a baritone player, so I don’t see that many examples. Do some people set theirs up significantly lower? Not to disregard plain strings at guitar tunings, as that was kind of my main point of inquiry originally.
A couple of reasons I can think of:

1. Even with the higher gauge and longer length, the tension may still be lower.

T = (f * 2 * L) ² * μ / g

With a bass, the frequency (f) is dropped an octave below a guitar. That is drastic and would be terrible to play if other parameters were not changed. Thus, the parameters of length (L) and string weight (μ, which is correlated to gauge) are increased to account for the reduction in frequency. Even with increasing the length and gauge, you still may have reduced tension, which would require higher action to avoid buzzing.

2. Preference and playing style

I personally have my bass set up with fairly low action. Other bassists prefer higher action. Higher action does make it easier to slap and pop.
 

ixlramp

SS.org Regular
Joined
Mar 5, 2007
Messages
3,060
Reaction score
1,900
Location
UK
I'm confused about the statement "pitch does not affect floppiness."
What i mean is:
Pitch itself does not directly affect floppiness.
Pitch can only affect floppiness indirectly by altering something else, such as string unit mass, tension, or scale length.
1. Even with the higher gauge and longer length, the tension may still be lower.

T = (f * 2 * L) ² * μ / g

With a bass, the frequency (f) is dropped an octave below a guitar. That is drastic and would be terrible to play if other parameters were not changed. Thus, the parameters of length (L) and string weight (μ, which is correlated to gauge) are increased to account for the reduction in frequency. Even with increasing the length and gauge, you still may have reduced tension, which would require higher action to avoid buzzing.
Since you are referring to a bass guitar here ...
A typical 'medium' tension for bass guitar strings is 40-50 pounds, more than twice that of typical guitar string tension. You can see this in D'Addario's published tension values for their string sets.
So the tension is not lower for a bass guitar.

The reasons bass guitar strings have similar or higher action compared to a guitar, despite typically having twice the tension, are:
1. A longer scale length makes the strings more floppy.
2. The higher string masses make the strings much more floppy.
 

Lopp

SS.org Regular
Joined
Mar 28, 2021
Messages
136
Reaction score
147
Location
Chicago
What i mean is:
Pitch itself does not directly affect floppiness.
Pitch can only affect floppiness indirectly by altering something else, such as string unit mass, tension, or scale length.
Ah. I see now where you are coming from. It appears you view floppy and tension as different. Indeed they are different, at least in that they are inversely proportional when a modifier is added (less tension=less tight=more floppy). Based on my understanding, the two terms are equivalent for the purposes of whether they are "directly" affected by pitch. Pitch does directly affect floppiness because it directly affects tension in an inversely proportional manner: tune down a string, it gets more floppy.

Based on your reasoning, pitch alters tension, which results in altering floppiness. Since they are inversely proportional, I see where you are coming from. Either way, we get the same result of pitch affecting floppiness.

Pitch does not alter string mass or scale length. Those things would have to be changed on their own if you want to keep all the other variables constant, which is what you seemed to have meant by stating it indirectly affects floppiness. For example, if you keep the tension constant when changing pitch, you would need to alter string mass or scale length. Otherwise, pitch does directly affect tension/floppiness: tune down a string, it gets more floppy.

Since you are referring to a bass guitar here ...
A typical 'medium' tension for bass guitar strings is 40-50 pounds, more than twice that of typical guitar string tension. You can see this in D'Addario's published tension values for their string sets.
So the tension is not lower for a bass guitar.

The reasons bass guitar strings have similar or higher action compared to a guitar, despite typically having twice the tension, are:
1. A longer scale length makes the strings more floppy.
2. The higher string masses make the strings much more floppy.
I forgot referring to bass. I primarily play 6 and 7-string guitar, but must have mentioned my bass earlier. Either way, any guitar-based instrument works for me.

The reason bass guitars typically have higher action is to avoid fret buzz caused by the lower tuning, not because of the longer length or higher string mass. The longer length and higher string mass are used to increase the tension to compensate for the lower tuning. For example, try tuning down your guitar towards bass frequencies with its shorter scale length and the same gauge strings: the strings will become more floppy. They will have more fret buzz when using the same neck relief.

A longer scale length and a higher string mass makes the strings less floppy. This is why you use longer scale and higher string mass on a lower tuned instrument, like bass: to make the strings less floppy.

Keeping all of the other variables constant, longer length and higher string mass does not make strings more floppy. Increased length and mass give the strings more tension, which results in less floppy strings.

T = (f * 2 * L) ² * μ / g

Based on math, raising one variable of either f (frequency/pitch) or L (scale length) on the right side of the equation raises tension (T).

Based on practical application, if all you are considering is trying a different scale length for a particular guitar, you will want the same pitch (f) because you are only concerned with different scale length. Thus, a longer length causes more tension, which results in less floppy strings when you keep the same tuning and use the same string gauge.
 

Oscar Stern

SS.org Regular
Joined
Dec 1, 2020
Messages
121
Reaction score
9
Longer scales do have more noticeable string movement (which is what makes them sound clearer).
Thus the perceived tension is lower.
They could indeed be noisier at the same tension and action. Tune a bass to guitar tension and it will play, feel, and sound, like spaghetti.
I find however if you take care of that, by running slightly higher tension, then equally low action is just fine :)
Good rule of thumb is to increase the tension by the % increase in scale length.

For example if you like a 46 E at 25.5" (~17.5lbs), you might assume 28" will allow you to use a 42 in the same tuning (~17.8lbs). However, it will likely feel looser. The scale length increase is almost 10% - so try for a 10% increase in tension which results in a choice of 44 gauge (~19.4lbs).

I do tend to find this little bump up is only necessary on the wound strings, btw.
Actually the Longer Scale Length means you're increasing the tension cause the longer the string has to travel from the nut to the bridge the tighter it's going to be. However w/ a shorter scale length the string is traveling at a lesser distance so the tension is lower. Lighter gauge strings seem to work better on a longer scale length cause it compensates for the reduced tension. That's according to my guitar string calculator.
 

Andromalia

Pardon my french
Joined
Dec 24, 2009
Messages
8,512
Reaction score
2,806
Location
Le Mans, France
I mean with a sample size of one, that seems like a pretty radical assumption that all people with longer scale guitars prefer higher action.
Most people who pick longer scale guitars do it for clarity in the rythm section. Which also gets helped by higher action. So the assumption isn't stupid. Even if playing on it is a chore, a high action (quality) baritone will sound good. Then it's a matter of finding a decent middle ground between tone and playability. For recording you'll favor the earlier, for live play probably the latter.
 

penguin_316

SS.org Regular
Joined
Sep 1, 2006
Messages
1,029
Reaction score
195
Location
TX
Maybe I’m in the minority, but having played 25.5” to 30” scale guitars for over 20 years…and having a mechanical engineering background. One thing is certain, a simple formula cannot account for the variation of tuning and tension. The longer the scale and the lower you wish to tune, the gauge must increase almost exponentially to accommodate a similar feel.

At the same time, even if the tension feels good and the gauge is acceptable. The string height might need to be a great deal higher due to the movement of the strings on a longer scale.

You won’t want the same tension on a 25.5” scale that you would run on a 28” scale or above. You will generally run more tension to get a similar feel, while using slightly higher action.

If you have an Evertune, you can alter this a lot…using much thinner strings on a baritone and having the best of both worlds. Minus a tremolo…..
 

Oscar Stern

SS.org Regular
Joined
Dec 1, 2020
Messages
121
Reaction score
9
Maybe I’m in the minority, but having played 25.5” to 30” scale guitars for over 20 years…and having a mechanical engineering background. One thing is certain, a simple formula cannot account for the variation of tuning and tension. The longer the scale and the lower you wish to tune, the gauge must increase almost exponentially to accommodate a similar feel.

At the same time, even if the tension feels good and the gauge is acceptable. The string height might need to be a great deal higher due to the movement of the strings on a longer scale.

You won’t want the same tension on a 25.5” scale that you would run on a 28” scale or above. You will generally run more tension to get a similar feel, while using slightly higher action.

If you have an Evertune, you can alter this a lot…using much thinner strings on a baritone and having the best of both worlds. Minus a tremolo…..
They now have an Evertune Whammy
 


Top