Guitar scale lenght and tension

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tele

Posts: 1464
Joined: Aug. 17 2012

Guitar scale lenght and tension

If building two guitars with the same plans, except that one guitar uses 662mm scale and the other 655mm scale, would the difference in string tension be very noticeable if using the same strings?

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REPORT THIS POST AS INAPPROPRIATE | Date Dec. 18 2013 11:58:36

krichards

Posts: 597
Joined: Jan. 14 2007
From: York, England

RE: Guitar scale lenght and tension (in reply to tele)

Its not clear if you are using the same plan for each guitar and just building with two different scale lengths
OR
maybe you are using two different plans?

Anyway, all other things being equal then yes, you would notice a difference between the scale lengths.

662mm is considered fairly long, and 650mm is more or less an industry standard now. 655mm is a compromise and this is the scale I prefer myself

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REPORT THIS POST AS INAPPROPRIATE | Date Dec. 18 2013 12:40:56

tele

Posts: 1464
Joined: Aug. 17 2012

RE: Guitar scale lenght and tension (in reply to krichards)

Actually I'm not building but I would like to know a bit about the effect of scale lenght on string tension, so
my question in general would be about the feel for right and left hands on the string tension. Would the tension be so different that the same string set might feel like high tension on the longer guitar?`

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REPORT THIS POST AS INAPPROPRIATE | Date Dec. 18 2013 12:56:05

orsonw

Posts: 1941
Joined: Jul. 4 2009
From: London

RE: Guitar scale lenght and tension (in reply to tele)

quote:

I would like to know a bit about the effect of scale lenght on string tension

Search the foro, there have been very many threads about this. Also try searching for "pulsation"

e.g. http://www.foroflamenco.com/tm.asp?m=135815&appid=&p=&mpage=1&key=pulsation&tmode=&smode=&s=#135945

http://www.foroflamenco.com/tm.asp?m=106565&appid=&p=&mpage=1&key=tension%2Cscale&tmode=&smode=&s=#106568

http://www.foroflamenco.com/tm.asp?m=64518&appid=&p=&mpage=1&key=660&tmode=&smode=&s=#64905

REPORT THIS POST AS INAPPROPRIATE | Date Dec. 18 2013 13:14:21

tri7/5

Posts: 570
Joined: May 5 2012

RE: Guitar scale lenght and tension (in reply to tele)

quote:

ORIGINAL: tele
Would the tension be so different that the same string set might feel like high tension on the longer guitar?`

No one can answer that but you. The tension would be greater from a pure physics standpoint yes. To what extreme you'll feel it is subjective to the player. You may or may not even realize you're on a longer scale.

REPORT THIS POST AS INAPPROPRIATE | Date Dec. 18 2013 13:49:44

etta

Posts: 342
Joined: Jan. 20 2010

RE: Guitar scale lenght and tension (in reply to tele)

In theory and practice, for the most part, the tension would be greater with the longer scale all other factors being equal. But, the tension, pulsation, build into two identical guitars of the same scale length can differ even with the same action heights. I have several guitars by the same maker, all the same scale; tension is very similar on three of them; the fourth has much greater tension. I lowered the action on this guitar (already low) and managed to bring it into the same tension "feel" as the other three. I once owned a 664 scale, and with all I could do, it played stiff. Yes, I agree also that a 655 is a good compromise.

REPORT THIS POST AS INAPPROPRIATE | Date Dec. 18 2013 16:02:17

Anders Eliasson

Posts: 5780
Joined: Oct. 18 2006

RE: Guitar scale lenght and tension (in reply to tele)

quote:

Would the tension be so different that the same string set might feel like high tension on the longer guitar?`

no. There´s very little difference.

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REPORT THIS POST AS INAPPROPRIATE | Date Dec. 18 2013 16:03:13

jshelton5040

Posts: 1500
Joined: Jan. 17 2005

RE: Guitar scale lenght and tension (in reply to Anders Eliasson)

quote:

ORIGINAL: Anders Eliasson

quote:

Would the tension be so different that the same string set might feel like high tension on the longer guitar?`

no. There´s very little difference.

Anders is correct. There are too many variables to make a definitive statement about the effect of scale length.

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John Shelton - www.sheltonfarrettaguitars.com

REPORT THIS POST AS INAPPROPRIATE | Date Dec. 18 2013 18:05:48

El Burdo

Posts: 632
Joined: Sep. 8 2011

RE: Guitar scale lenght and tension (in reply to Anders Eliasson)

Using simple equations and comparing two scale lengths, one of 660mm and one 650mm...

Assuming the same string (i.e. same mass per unit length) and assuming the same note..the 660 string will be at a tension 103% of the 650 string.

So, there has to be more to it.

REPORT THIS POST AS INAPPROPRIATE | Date Dec. 18 2013 18:07:18

keith

Posts: 1108
Joined: Sep. 29 2009
From: Back in Boston

RE: Guitar scale lenght and tension (in reply to tele)

tele, here is the equation for changes in string tension due to a change in scale length. i provided an example using a string tension of 15.08 pounds. an engineer gave me the formula.

KST x (NSL / OSL) ^2 = NT

where:
KST = Known String Tension
NSL = New Scale Length
OSL= Old Scale Length
^2 = Squared
NT = New String Tension

example: the string was rated at 15.08 pounds on a 655mm scale length and it is now placed on a guitar with a 662mm scale length

(15.08 pounds X( 662mm / 655mm) ^2 = 15.38 pounds. whether or not the new number is significant depends on the player and the guitar.

REPORT THIS POST AS INAPPROPRIATE | Date Dec. 18 2013 22:57:20

tele

Posts: 1464
Joined: Aug. 17 2012

RE: Guitar scale lenght and tension (in reply to keith)

quote:

ORIGINAL: keith

tele, here is the equation for changes in string tension due to a change in scale length. i provided an example using a string tension of 15.08 pounds. an engineer gave me the formula.

KST x (NSL / OSL) ^2 = NT

where:
KST = Known String Tension
NSL = New Scale Length
OSL= Old Scale Length
^2 = Squared
NT = New String Tension

example: the string was rated at 15.08 pounds on a 655mm scale length and it is now placed on a guitar with a 662mm scale length

(15.08 pounds X( 662mm / 655mm) ^2 = 15.38 pounds. whether or not the new number is significant depends on the player and the guitar.

Cool, that's pretty useful info

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REPORT THIS POST AS INAPPROPRIATE | Date Dec. 19 2013 11:29:56

orsonw

Posts: 1941
Joined: Jul. 4 2009
From: London

RE: Guitar scale lenght and tension (in reply to etta)

quote:

I once owned a 664 scale, and with all I could do, it played stiff.

I have owned low pulsation guitars (including 670 scale) that certainly get stiffer with the highest tension strings but never really have a pulsation that suits me. I assume that you tried low tension strings on the 664 scale? If so doesn't this suggest that string tension is only one of several factors influencing 'stiffness'?

My understanding is that how the guitar itself (mainly the top?) responds to the string is most significant, scale length is a side issue?

Isn't the engineering calculation meaningless because it's based on the false assumption that the string is attached to two fixed points. I think the guitar moves that's how it makes a noise (and no two guitars move quite the same)? And I presume the incalculable mysteries of how they move is what inspires the luthiers? In my experience, the only way I know to judge a guitar's 'stiffness' is to play it.

Or maybe I'm no good at maths? Please educate me (gently!)

REPORT THIS POST AS INAPPROPRIATE | Date Dec. 19 2013 12:43:54

tele

Posts: 1464
Joined: Aug. 17 2012

RE: Guitar scale lenght and tension (in reply to orsonw)

quote:

ORIGINAL: orsonw

My understanding is that how the guitar itself (mainly the top?) responds to the string is most significant, scale length is a side issue?

Isn't the engineering calculation meaningless because it's based on the false assumption that the string is attached to two fixed points. I think the guitar moves that's how it makes a noise (and no two guitars are quite the same)? .

Stiffness of the top certainly can make same scale guitar with same strings feel different(so if you have two guitars with two different top tensions/pulsation)

However I think the calculation is useful when thinking about situation when you make two guitars with the same stiffness and think how much added scale lenght would add to the string tension. Am I right?

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REPORT THIS POST AS INAPPROPRIATE | Date Dec. 19 2013 12:51:01

keith

Posts: 1108
Joined: Sep. 29 2009
From: Back in Boston

RE: Guitar scale lenght and tension (in reply to tele)

the string calculation is a measurement with all other variables held constant and the only variable that changes is the length between the nut and saddle. since a guitar is more than nut and saddle other factors have to be taken into account to make a judgement how a given tension will work. that said, the equation does allow one to know how a string's tension will change. the number only has relevancy when there is a framework to make a judgement.

REPORT THIS POST AS INAPPROPRIATE | Date Dec. 19 2013 13:49:23

Anders Eliasson

Posts: 5780
Joined: Oct. 18 2006

RE: Guitar scale lenght and tension (in reply to orsonw)

quote:

My understanding is that how the guitar itself (mainly the top?) responds to the string is most significant, scale length is a side issue?

My experience, and this is based on building and trying and not on crebral calculations, is that stiffness of a guitar is 5% scalelength, 25% stringtension and 70% how the soundboard and braces have been balanced.

besides, in my hands, a stiff guitar always feels stiff never mind the other two factors, A soft guitar and a sloppy guitar the same.

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REPORT THIS POST AS INAPPROPRIATE | Date Dec. 19 2013 15:31:18

beno

Posts: 881
Joined: Nov. 3 2006
From: Hungary

RE: Guitar scale lenght and tension (in reply to tele)

I went from a 660 guitar to a 650, and the strings I used the most didn't worked anymore, at least not in the same tension, as it was too low.

I'm sure there are plenty of factors, but I significally felt the difference.

REPORT THIS POST AS INAPPROPRIATE | Date Dec. 20 2013 6:28:22