Higher action on longer scale lengths?

[Wiltonauer]

Is it normal for people to set up longer-scale guitars with higher string action than on a 25.5”?

I’ve been playing straight Strat-scale guitars for years, some with pretty low action, some not so low, but I just picked up a 26.5” 7-string, and I love it, but the action seems pretty high compared to what I’m used to.

Does anyone set up their longer-scale guitars with higher action than they would use on shorter scales? Or do you just get down in there and cozy up to the frets?

 

[CanserDYI]

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 seem to like lower action, no matter the scale. There are plenty of people that don't, but 99% of players I hang out with or use their instruments would rather have as low action as possible, and most of them play extended instruments.

 

[Matt08642]

All my stuff is set to 1.5mm at the 14th fret including my 29.4" M80M. The only exception on that guitar is the low F that's maybe 1.6mm, just a bit higher since it moves a lot.

 

[Wiltonauer]

It was meant to be more of a question than an assumption. I could see having the strings a little higher on the bass side so you could whack the hell out of them. More tension and higher action seems like it would be less fun playing in the second octave of the plain strings, but it also sounds really good, so I wondered if that was something people did on purpose or if my guitar was just set up like that to hide uneven frets.

 

[Winspear]

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.

 

[ixlramp]

^ I agree with Winspear.
At the same string tension, a longer scale requires a higher action.
Even a bass guitar which has twice the string tension of a guitar has higher action.
25.5" to 26.5" is only a small increase though, so the significant difference you notice is probably partly or mostly due to other factors.

 

[trem licking]

I haven't looked in a while but from what i remember, I'm running 3mm+ on my low 9th string tuned to C# with a .106 string... Healthy amount of tension there. This is to obtain zero buzz, i had a hell of a time adjusting to the scale length/tuning anomalies coming from 25.5" 6 and 7 strings that had no buzz at a much lower action. My 8 strings are north of 2mm on the low strings, so I'd agree that they need a little higher action even with higher tension strings. This all depends on your string noise tolerance too, of course

 

[NoodleFace]

I setup all my guitars with the lowest possible action they'll accept

 

[elkoki]

Set it up to be lower then, it could just be badly setup. Sometimes you buy a guitar regardless of how many strings it has, and they wont be set up at all. If you don't know how, learn how to, it's not hard.

 

[Wiltonauer]

I can certainly pursue setting it up differently. I kind of like it the way it is, though. It may be harder to play than my shreddy superstrats, but it’s also very rewarding because it sounds so frickin’ good. Every note seems worth the extra effort. I just can’t crank them out as fast.

 

[Lopp]

You should be able to achieve lower action on a longer scale length.

I think the way it works is the longer scale length requires more tension on the strings. More tension keeps the string from moving as much, so you can lower the action while still avoiding buzz.

Did you use the same gauge strings? Try a higher gauge, which should allow you to lower the action.

 

[ixlramp]

I just picked up a 26.5” 7-string, and I love it, but the action seems pretty high compared to what I’m used to.

Ok i misunderstood. You are commenting on someone else's setup.
Therefore, you cannot really conclude anything from this because different people just like different actions. It is not necessarily anything to do with scale length.

The scale length has been multiplied by only 1.04, so the necessary increase in action resulting from that would be barely noticeable.

Strings with higher mass (larger gauge) flop around more and require higher action, so we have to eliminate that effect when considering this. Therefore ...

How i understand it:
Assuming unchanged tension and approximately unchanged string mass, as the scale length of a string increases, the action needs to be higher.
This is because as the two end anchor points of the string become further apart it becomes easier for the middle part of the string to move sideways, the string becomes floppier, and the 'perceived tension' falls.

You can experience this on any guitar by grabbing the middle of the vibrating length of a string and moving it side to side ... try this with an unfretted string, then while firmly fretting the highest fret ('firmly' to avoid the string slipping sideways at the fret). The string will become less floppy as its vibrating length decreases.

So with a longer scale length, you need higher action, or a little more tension, or both. Tension needs to be increased slightly if you want the 'perceived tension' (feel) to be unchanged.

 

[Wiltonauer]

Okay, cool. This is the factory setup; I bought it new with no dealer setup. I’m always interested in at least understanding what the manufacturer was going for, before I change it.

 

[Lopp]

Ok i misunderstood. You are commenting on someone else's setup.
Therefore, you cannot really conclude anything from this because different people just like different actions. It is not necessarily anything to do with scale length.

Yes.

The scale length has been multiplied by only 1.04, so the necessary increase in action resulting from that would be barely noticeable.

There is no "necessary increase in action" when increasing scale length. See below.

Strings with higher mass (larger gauge) flop around more and require higher action, so we have to eliminate that effect when considering this. Therefore ...

With all due respect, no. Higher gauge strings require higher tension to keep them in tune. This is why the lower strings on your guitar are thicker. They would otherwise have too little tension without increasing the string gauge. I.e., the lower the tuning, the higher the gauge to get the correct pitch. For example, if you replaced your low e string with a high e string, you would have too little tension because the gauge is too low. (See the formula below).

How i understand it:
Assuming unchanged tension and approximately unchanged string mass, as the scale length of a string increases, the action needs to be higher.
This is because as the two end anchor points of the string become further apart it becomes easier for the middle part of the string to move sideways, the string becomes floppier, and the 'perceived tension' falls.

So with a longer scale length, you need higher action, or a little more tension, or both. Tension needs to be increased slightly if you want the 'perceived tension' (feel) to be unchanged.

Incorrect if you are maintaining the same tuning. I am surprised at how many people on a 7-string guitar site are getting this wrong because 7-string guitars often have longer lengths to provide more tension for the lower tuned strings.

The basic formula for the relationship is:
T = (f * 2 * L) ² * μ / g
T=tension
f=frequency (pitch)
L=length
μ=string weight (related to gauge)
g=gravitational acceleration (approximately constant at around 386 in/s^2)

Increase any of the frequency, length, or gauge will result in higher tension.

With the same tuning, the longer scale length results in higher tension. You are correct that the anchor points become further apart. However, this means you need more tension to keep any given string tuned to the same pitch as the shorter length. The same string gauge tuned to the same pitch will require more tension when you increase the scale length.

Think about it. Why bass do guitars have longer scale lengths and 7-string guitars often have longer scale lengths? This is because the lower tuning of the lower strings would otherwise have too little tension on a shorter scale length.

Okay, cool. This is the factory setup; I bought it new with no dealer setup. I’m always interested in at least understanding what the manufacturer was going for, before I change it.

Yeah. It was just originally set up with higher action. The longer scale length will provide more tension and allow you to have lower action without buzzing.

 

[Winspear]

^ You seem to be disagreeing with ixlramps points and then confirming what he said backing them up and agreeing with him?

 

[ixlramp]

With all due respect, no. Higher gauge strings require higher tension to keep them in tune.

Only if the pitch is held constant, which is not what i am considering.

That statement of mine assumes the strings compared have equal tension.
It is widely experienced that if you have an 'equal tensions set' with a tiny plain steel string on the top and a huge wound on the bottom, the huge wound will be much more floppy and require a much higher action.
You need an extended range instrument to experience this clearly though.

I wrote that statement because, to consider the effect of scale length on floppiness, we need to eliminate the effect of string mass, which is why my primary statement contains "Assuming [...] unchanged string mass".

Incorrect if you are maintaining the same tuning.

I am not maintaining the same tuning. My primary statement says "Assuming unchanged tension and approximately unchanged string mass,", so pitch decreases.

I am surprised at how many people on a 7-string guitar site are getting this wrong because 7-string guitars often have longer lengths to provide more tension for the lower tuned strings.

No. Longer scale lengths are not for raising tension (as stated by dumbed-down marketing), because although this might be helpful for the typically low tension lowest string in traditional sets, it will also make all the other strings too tight.

Guitarists have a 'preferred feel' (by 'feel' i mean 'perceived tension') that they use.
If they move to a longer scale length they often cannot use the same string set because it becomes too tight, so they slightly reduce the gauges to return to their 'preferred feel'.

Longer scale lengths are actually for maintaining the same 'feel' while allowing slightly smaller gauges to be used, which improves tone, intonation etc. on the lowest strings.

Increase any of the frequency, length, or gauge will result in higher tension.

With the same tuning, the longer scale length results in higher tension. You are correct that the anchor points become further apart. However, this means you need more tension to keep any given string tuned to the same pitch as the shorter length. The same string gauge tuned to the same pitch will require more tension when you increase the scale length.

Correct.
But my primary statement says "Assuming unchanged tension and approximately unchanged string mass,".
My first post also stated unchanged tension.

To understand the effect of a longer scale, i am considering the effect with 'all else equal', therefore unchanged tension and unchanged gauge (mass). This means pitch decreases.

Your approach in your posts above is to assume the same gauges and the same tuning (which i would consider a mistake made by the guitarist), in which case tension increases, counteracting the effect of increased scale length to some degree.

So on this point we do not necessarily disagree.

 

[Lopp]

@ixlramp Thank you for taking the time to share your thoughtful comments.

ELI5:

I am confused because based on the formula: T = (f * 2 * L) ² * μ / g, if you decrease the frequency for a lower tuned guitar, you would only need to increase the gauge to maintain the same tension and "feel." Is "feel" something more than tension?

(I was recently talking to my guitar tech, who indicated he prefers scale lengths longer than 25.5" for a 7-string to keep the tension while having the lower tuning. I personally prefer the "feel" of the shorter length 25.5" fret spacing and am willing to put up with less tension).

 

[Wiltonauer]

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.

 

[ixlramp]

Your approach in your posts above is to assume the same gauges and the same tuning (which i would consider a mistake made by the guitarist)

Thought i should add ... my comment about "a mistake" refers to a general approach to scale length.
I can understand a guitarist choosing to use the same gauges in some situations. For example: If the scale length increase is small (25.5" -> 26.5"/27") and the next lighter string set is a big decrease in gauges such that it results in a lower tension that is more of a problem than a slightly higher tension.
Another example would be wanting a higher tension on the longer guitar.

The tension jumps between traditional .008, .009, .010 sets is quite big, so i expect many guitarists use the same gauges on a slightly longer scale length. But this is a result of the small number of string set choices that the big traditional manufacturers provide, due to their business model making every additional pre-packaged string set a huge investment.
There should really also be .0075, .0085, .0095, .0105 etc. sets. The small 'custom set/mail order' type companies like Kalium, Stringjoy, Winspear etc. with .0005-step plain steel strings are the right way to do string sets.

 

[ixlramp]

I am confused because based on the formula: T = (f * 2 * L) ² * μ / g, if you decrease the frequency for a lower tuned guitar, you would only need to increase the gauge to maintain the same tension

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.

Is "feel" something more than tension?

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'.

I was recently talking to my guitar tech, who indicated he prefers scale lengths longer than 25.5" for a 7-string to keep the tension while having the lower tuning.

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.