String length & tension.

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bugeyed

Posts: 56
Joined: Aug. 24 2009
From: Conroe, Texas

String length & tension.

In response to the following post, n85ae stated;
RE: Bass strings on opposite rollers (in reply to ToddK)

"It's a simple mechanical engineering question. A cable of a given tension will
deflect more at a longer length, than it will at a shorter length. You have
effectively lengthened the 6th String and shortened the 4th string. The Nut
is only the end of the cable with regard to the vibratory length. The roller
is the end of the cable with regard to tensile length.

The drawback is that you've likely increased the mechanical force on the
neck since the heavier cable has more of a lever to pull on now :)

Jeff"

My response was that the 6th string, having been lengthened, is now at a higher tension. It requires more tension for a longer string to be tuned to the same pitch. Is this correct, or is the distance from the saddle to the nut the important measurement? I just wanted to get this settled before the thread gets buried.
Thanks,
kev

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REPORT THIS POST AS INAPPROPRIATE | Date Nov. 2 2009 9:20:35

Ron.M

Posts: 7051
Joined: Jul. 7 2003
From: Scotland

RE: String length & tension. (in reply to bugeyed)

quote:

My response was that the 6th string, having been lengthened, is now at a higher tension. It requires more tension for a longer string to be tuned to the same pitch. Is this correct, or is the distance from the saddle to the nut the important measurement? I just wanted to get this settled before the thread gets buried.
Thanks,
kev

I can tell this is bugging you!

I'm not a mechanical engineer, but I would tend to reckon that tension=tension=tension.

(ie..there is no "long" tension or "short" tension...)

But as I said, I'm no mechanical engineer.

Dammit!!...You've got me intrigued now...

Perhaps n85ae will know the answer?

cheers,

Ron

REPORT THIS POST AS INAPPROPRIATE | Date Nov. 2 2009 10:22:29

bugeyed

Posts: 56
Joined: Aug. 24 2009
From: Conroe, Texas

RE: String length & tension. (in reply to bugeyed)

I am basing my statement on the fact that short scale steel string guitars have lower tension on the strings & long scale are higher. Here's a quote from the D'Addario site, "The longer the scale, the higher the tension is for the same string tuned to the same pitch – for example, a standard Fender™ guitar at 25½” scale has more string tension and will feel stiffer than a standard Gibson™ 24¾” scale guitar, even if both are tuned to the same standard pitch." I know this to be true & I suspect that the whole string, from bridge to roller sees this tension, not just from saddle to nut. Therefore, in our exercise, the 6th string would be tighter & 4th looser relative to the normal setup. I have no idea how much the string tension will differ, but it is noticeable when playing an extremely short scale guitar, like a travel style.
Cheers,
kev

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REPORT THIS POST AS INAPPROPRIATE | Date Nov. 2 2009 12:31:38

Ricardo

Posts: 14822
Joined: Dec. 14 2004
From: Washington DC

RE: String length & tension. (in reply to bugeyed)

Simple thing to think about. Imagine a little baby sized guitar. You put your strings on, up to pitch of a regular guitar, and they will be floppy. That is why little guitars are often tuned to higher pitches. Think Violins and Cellos too.

Regarding the milimeters involved with flamenco guitars, standard sized, as a player I have not noticed a significant difference. The MAIN difference is not break angle, string length scale length, nut, etc etc....it is simple the action. A low action over the fingerboard feels looser and easier plain and simple. High action always feels stiff. The actual bridge is something else, you can set up a low bridge with almost ZERO break angle, that still has a high stiff action over the fingerboard. And vice versa, you can have a mile high bridge (like humphry) and the action on the neck COULD BE super low....and no orders of magnitude high volume or any such nonsense, just a loose floppy buzzy guitar.

Ideal guitar for flamenco will always be...low bridge as possible....low action on fingerboard but not TOO low. Some buzz and looseness is allowed for snap, but you need to play hard with out loosing all tone. That is pretty simple concept to me as a player. Why so many different types of set ups for flamenco guitars is a mystery to me still.

Ricardo

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REPORT THIS POST AS INAPPROPRIATE | Date Nov. 2 2009 20:31:25

Anders Eliasson

Posts: 5780
Joined: Oct. 18 2006

RE: String length & tension. (in reply to bugeyed)

Just want to add one thing to Ricardos post.

In my opinion, the pulsation of the guitar is what mostly determines if a guitar is stiff of soft.
You can change break angle, setup height, string gauge, whatever. A stiff guitar will remain a stiff guitar and will require strenght to play.

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REPORT THIS POST AS INAPPROPRIATE | Date Nov. 3 2009 0:20:11

Anders Eliasson

Posts: 5780
Joined: Oct. 18 2006

RE: String length & tension. (in reply to Ricardo)

quote:

Ideal guitar for flamenco will always be...low bridge as possible....low action on fingerboard but not TOO low. Some buzz and looseness is allowed for snap, but you need to play hard with out loosing all tone. That is pretty simple concept to me as a player. Why so many different types of set ups for flamenco guitars is a mystery to me still.

You´re right, but its so easy to write and a lot more difficult to realize.
One of the most difficult things in constructing a good flamenco guitar (besides controlling pulsation) is to set the neck angle. Especially if you work the traditional Spanish way. The guitars always have some difference in neckangle when they come out of the assembly jig. With experience you learn to control this more, but there´ll always be some difference, meaning you have to leave some margin for this.

Another thing is that most new guitars move a bit in the neck the first year or so and besides they all change a bit with humidity changes.
So if you make a new guitar to your description, with 7mm stringheight at the bridge, you can end up with a very poor setup after a while with the strings to close to the soundboard, meaning poor break angle and fingers hitting the soundboard when doing a hard picado.... Its not so easy.

Besides, there are players who dont care so much about stringheight at the bridge. If the guitar has the right pulsation and sounds good and has no more than 9 - 10mm stringheight at the bridge, they like it.

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REPORT THIS POST AS INAPPROPRIATE | Date Nov. 3 2009 0:29:08

Ron.M

Posts: 7051
Joined: Jul. 7 2003
From: Scotland

RE: String length & tension. (in reply to Ron.M)

quote:

but I would tend to reckon that tension=tension=tension.

I suppose what I'm trying to say is...

Take 2 guitars with EXACTLY the same scale length (hence "vibratory" length, nut to bridge), but DIFFERENT distances between tie blocks and rollers.

The corresponding strings on each guitar would have IDENTICAL tension, for the same pitch, regardless of string length.

No?

cheers,

Ron

REPORT THIS POST AS INAPPROPRIATE | Date Nov. 3 2009 1:37:37

bugeyed

Posts: 56
Joined: Aug. 24 2009
From: Conroe, Texas

RE: String length & tension. (in reply to Ron.M)

quote:

ORIGINAL: Ron.M

quote:

but I would tend to reckon that tension=tension=tension.

I suppose what I'm trying to say is...

Take 2 guitars with EXACTLY the same scale length (hence "vibratory" length, nut to bridge), but DIFFERENT distances between tie blocks and rollers.

The corresponding strings on each guitar would have IDENTICAL tension, for the same pitch, regardless of string length.

No?

cheers,

Ron

Thanks, Ron, for getting back to the original issue. I see what you are saying & I am leaning the other way. The way I see it, the whole string, from tie-block to roller, sees the tension. The vibration pattern of the string is between the saddle & nut, but the tension on the string is felt between it's anchors at each end (tie-block & roller). Anyway, it's an interesting question. BTW Have you tried the alternate string set-up yet? I have not.

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REPORT THIS POST AS INAPPROPRIATE | Date Nov. 3 2009 4:22:51

Anders Eliasson

Posts: 5780
Joined: Oct. 18 2006

RE: String length & tension. (in reply to bugeyed)

Yeah, I agree.

The string is tensioned from one anchor to the other. Its easy to test. Pluck the sting above the nut, tune the string up half a note and pluck it again.

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REPORT THIS POST AS INAPPROPRIATE | Date Nov. 3 2009 4:41:19

bugeyed

Posts: 56
Joined: Aug. 24 2009
From: Conroe, Texas

RE: String length & tension. (in reply to Anders Eliasson)

quote:

ORIGINAL: Anders Eliasson

Yeah, I agree.

The string is tensioned from one anchor to the other. Its easy to test. Pluck the sting above the nut, tune the string up half a note and pluck it again.

Thanks Anders. Are you aware of the origin of this discussion? It started with a recommendation to swap the 6th & 4th strings at the rollers, in order to lengthen the 6th. See "Bass strings on opposite rollers". The poster felt that the 6th felt looser & the 4th firmer. Do you have an opinion on, first, whether this configuration is beneficial &, second, if this length change would feel different? Thanks & keep up the good work.
kev

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REPORT THIS POST AS INAPPROPRIATE | Date Nov. 3 2009 4:58:32

Ron.M

Posts: 7051
Joined: Jul. 7 2003
From: Scotland

RE: String length & tension. (in reply to bugeyed)

quote:

I see what you are saying & I am leaning the other way. The way I see it, the whole string, from tie-block to roller, sees the tension. The vibration pattern of the string is between the saddle & nut, but the tension on the string is felt between it's anchors at each end (tie-block & roller).

Yeah Bugeyed....but are you saying the tension is different?

If that's the case, then it would also be different along the scale length, making a different pitch.

Tension is just tension and must be the same along the whole length of the string.

(This is not actually practically the case immediately after tuning, because of slight friction causing gripping the string at the nut and the bridge but it will eventually "creep" to equalize over time).

But assuming free movement at the bridge and the nut, the string tension MUST be the same in both guitars to have the same pitch for the same scale length surely?

It surely can't be different from the roller to the nut, then the same from the nut to the saddle, then different from the saddle to the tieblock.

That's a single string with 3 different tensions!

I've never heard of that!

cheers,

Ron

REPORT THIS POST AS INAPPROPRIATE | Date Nov. 3 2009 6:20:47

n85ae

Posts: 877
Joined: Sep. 7 2006

RE: String length & tension. (in reply to bugeyed)

Ron -

Think about it like this the tension is constant. Now put a capo on at the
second fret. Still the same tension, but the vibrating length has shortened.

Let's see if I can simplify it.

When you pluck a string it stretches (yes it does), and that stretch is felt
across the entire length of the string. So say each 10mm of string (length) has
X mm of stretch for a given force Now by changing the roller you have added
70mm Length to the sixth string. So while the tension is the same, you now
have more deflection with the same pluck. Because the pluck is felt across
a longer length of string, and therefore more stretching.

Does that help?

Regards,
Jeff

Jeff

REPORT THIS POST AS INAPPROPRIATE | Date Nov. 3 2009 6:25:23

Ron.M

Posts: 7051
Joined: Jul. 7 2003
From: Scotland

RE: String length & tension. (in reply to n85ae)

Yeah Jeff...I agree that the sideways string displacement force will be different the shorter the scale length, but not the "resting" string tension along the axis of the string.
That's what I understand the meaning of tension to be.
String displacement force, or "stiffness" is something else.

cheers,

Ron

REPORT THIS POST AS INAPPROPRIATE | Date Nov. 3 2009 6:30:41

n85ae

Posts: 877
Joined: Sep. 7 2006

RE: String length & tension. (in reply to bugeyed)

Well, in any case, it seems to me that the difference would be very negligeble
in any case, so I'm personally a skeptic. However, I know my car drives
better when it's washed, and waxed. Has MUCH more power, better handling,
etc. So ...

Regards,
Jeff

REPORT THIS POST AS INAPPROPRIATE | Date Nov. 3 2009 6:51:32

Ron.M

Posts: 7051
Joined: Jul. 7 2003
From: Scotland

RE: String length & tension. (in reply to n85ae)

Jeff,

Just to complicate things more...

I would say an instantaneous increase in tension (as caused by displacing the string before releasing) would NOT cause stretching throughout the WHOLE string, but would be confined mainly between the nut and the bridge, due to the friction caused by both these parts.
Just in the same way I said that when you play with a capo on, plucking will not cause the string to instantaneously stretch all the way back to the roller.

cheers,

Ron

PS: I also agree that my car always seems to have more power after I've pulled in at the petrol station and filled up,which makes it heavier! Crazy!

REPORT THIS POST AS INAPPROPRIATE | Date Nov. 3 2009 7:20:37

Anders Eliasson

Posts: 5780
Joined: Oct. 18 2006

RE: String length & tension. (in reply to bugeyed)

quote:

Thanks Anders. Are you aware of the origin of this discussion? It started with a recommendation to swap the 6th & 4th strings at the rollers, in order to lengthen the 6th. See "Bass strings on opposite rollers". The poster felt that the 6th felt looser & the 4th firmer. Do you have an opinion on, first, whether this configuration is beneficial &, second, if this length change would feel different? Thanks & keep up the good work.
kev

No, I havent yet. The problem is that if I string a guitar like that and post a photo or a video with it, I´ll have to answer 50 mails during the next couple of weeks, telling why I do so.

I´m not in the mood for this right now.

Another thing. Yes, theoretically the 4th string will be tenser and the 6th string looser. And so what? String sets are calibrated to equal out the tension. Also a tighter 4th string close to the 3rd string which is the loosest, is that something positive?

In some aspects I´m a straighthead. My car (24 year old Mercedes 190 diesel) drives the same way always. Its very slow.

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REPORT THIS POST AS INAPPROPRIATE | Date Nov. 3 2009 7:47:49

bugeyed

Posts: 56
Joined: Aug. 24 2009
From: Conroe, Texas

RE: String length & tension. (in reply to n85ae)

quote:

ORIGINAL: n85ae

Ron -

Think about it like this the tension is constant. Now put a capo on at the
second fret. Still the same tension, but the vibrating length has shortened.

snip

Regards,
Jeff

Jeff

You keep saying that the string tension of a longer string is constant. I maintain that, the longer the string is, the higher the tension required to tune it to the same pitch. Therefore the overall tension applied to that string is higher!

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REPORT THIS POST AS INAPPROPRIATE | Date Nov. 3 2009 9:42:15

n85ae

Posts: 877
Joined: Sep. 7 2006

RE: String length & tension. (in reply to bugeyed)

What you say is true, about a longer sting requiring a higher tension
BUT you're missing the vibrating length part.

It's the tension, AND the vibrating length.

Try this simple exercise.

Pluck the sixth string on the guitar. Now hold down the same string at the fifth
fret and - Wow, presto, like magic, the same tension BUT we magically changed
it into an A-String, how could this be???? Is this black magic? Sorcery?

Why No we changed the vibrating length of the string, yet the tension remains
the same.

Jeff

REPORT THIS POST AS INAPPROPRIATE | Date Nov. 3 2009 9:56:23

XXX

Posts: 4400
Joined: Apr. 14 2005

RE: String length & tension. (in reply to n85ae)

Capoed or fretted strings have a higher tension.

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REPORT THIS POST AS INAPPROPRIATE | Date Nov. 3 2009 10:06:50

bugeyed

Posts: 56
Joined: Aug. 24 2009
From: Conroe, Texas

RE: String length & tension. (in reply to n85ae)

I am glad we agree on the longer = higher tension & I have noticed that my guitar makes higher pitched notes as I fret up the neck???, but the original subject was regarding whether the 6th string would feel tighter or looser when lengthened, by moving it's anchor point to the 4th peg. I know it feels tighter with longer vs short scale guitars & assumed that this would be true in this case. I am not sure what point you are trying to make with the examples of the vibrating length of the string. You said that by lengthening the string you get more deflection, OK, but you also did not factor in the increase in tension for that string. You said that it remained the same.
BTW This discussion is good for my brain, as I am no longer employed in R&D, so I miss this type of exercise.

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REPORT THIS POST AS INAPPROPRIATE | Date Nov. 3 2009 10:11:58

Ron.M

Posts: 7051
Joined: Jul. 7 2003
From: Scotland

RE: String length & tension. (in reply to bugeyed)

Yes to tune the WHOLE string length to the same pitch.

To tune 2 strings of different lengths to the same pitch, you need different tensions.

But you're not doing that.

The only thing that control the pitch is the saddle-nut distance, string mass and string tension.

Which MUST be identical in guitars with the same saddle-nut distance... which in turn determines the scale length.

So it wouldn't matter if the roller was on a stick extending out to TWICE the length of the guitar itself, or even more.
The actual tension measured by an in-line tension guage or fishing scale, would be EXACTLY the same, regardless of nut to roller distance.

As ne85a said, this would possibly change the feel of the deflection force, which would be less, the greater the string length, since the WHOLE string stretches, not just the nut-saddle part.
(However, this would be more noticable if you pulled the string as in a bow and arrow, but less significant when actually playing IMO, as I have stated earlier.)

But NOT the axial tension of the string itself.

The thing that is confusing the debate further is that some folk are using the term "string tension" when they mean "stiffness" or "deflection force", which is not the same thing.

Hey Deniz is a physics guy...has he got something to add here?

Edit: OK I see Deniz has just added that caped or fretted strings have "more tension".

Wow.. really?

Like the axial string tension gets higher?

In that case you have invented a "force amplifier" and a possible solution to the World's energy problems!

Or does it just feel "stiffer"?

cheers,

Ron

REPORT THIS POST AS INAPPROPRIATE | Date Nov. 3 2009 10:13:37

hamia

Posts: 403
Joined: Jun. 25 2004

RE: String length & tension. (in reply to bugeyed)

quote:

ORIGINAL: bugeyed

quote:

ORIGINAL: n85ae

Ron -

Think about it like this the tension is constant. Now put a capo on at the
second fret. Still the same tension, but the vibrating length has shortened.

snip

Regards,
Jeff

Jeff

You keep saying that the string tension of a longer string is constant. I maintain that, the longer the string is, the higher the tension required to tune it to the same pitch. Therefore the overall tension applied to that string is higher!

http://en.wikipedia.org/wiki/Vibrating_string

The physics is contained in the 1D wave equation. Velocity of the wave is equal to square root of string tension divided by mass of string (per unit length). The frequency is related to the velocity:
vel = wavelength times frequency. The link shows the relevant equation for frequency of fundamental mode.
Freq = (1/2L)*SQRT(T/m) where L is string length, T is tension, m is mass of string per unit length.
So increasing string length will result in lower frequency,
increasing tension will raise frequency
increasing string mass will lower frequency.

So this explains why the strings all get progressively heavier from 1st to 6th (necessitating the heavy metal winding on the lower strings) - otherwise they'd be too floppy. And moving to a longer scale length will mean that the tension will have to be higher than that of a shorter scale length in order to compensate.

l

REPORT THIS POST AS INAPPROPRIATE | Date Nov. 4 2009 2:29:14

Ron.M

Posts: 7051
Joined: Jul. 7 2003
From: Scotland

RE: String length & tension. (in reply to hamia)

Usually these scientific examples use the resonant frequency of the WHOLE string vibrating under tension, not just PART of the string, as in a musical instrument.

Anyway...all this stuff is doing my head in now!

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REPORT THIS POST AS INAPPROPRIATE | Date Nov. 4 2009 2:36:45

n85ae

Posts: 877
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RE: String length & tension. (in reply to bugeyed)

Ron -

It still says exactly the same thing, it's just in an alien language

Jeff

REPORT THIS POST AS INAPPROPRIATE | Date Nov. 4 2009 8:35:38

domzo

Posts: 64
Joined: Jan. 10 2007

RE: String length & tension. (in reply to bugeyed)

quote:

I am not sure what point you are trying to make with the examples of the vibrating length of the string. You said that by lengthening the string you get more deflection, OK, but you also did not factor in the increase in tension for that string. You said that it remained the same.

I agree with Ron, the tension is the same.

Try going backwards:

Take 2 E strings, one tied at the normal place (6th string roller) and one on the 4th roller - then tune them both to E.

Both strings are now at the same pitch and the vibrating length of both strings is the same and the mass per unit length is the same. Therefore the tension in both strings is the same.

If you then remove the nut, then they will be at different pitches (because now they are different vibrating lengths), but still at the same tension.

REPORT THIS POST AS INAPPROPRIATE | Date Nov. 4 2009 11:02:48

Ramon Amira

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From: New York City

RE: String length & tension. (in reply to bugeyed)

Not yet having earned a PhD in Theoretical Physics and Acoustics from the Massachusetts Institute of Technology, I'm not sure I understand any of this, but am I correct that the original idea was to give the fourth string more tension. If so, why would anyone want to do that. Slurs are probably played more on the fourth string than any other. Why make them more difficult. And what inherent advantage is there in having more tension on the fourth string in particular, as opposed to say having more tension on the fifth string.

REPORT THIS POST AS INAPPROPRIATE | Date Dec. 3 2009 19:30:56

Ron.M

Posts: 7051
Joined: Jul. 7 2003
From: Scotland

RE: String length & tension. (in reply to Ramon Amira)

Playing the guitar loudly also adds to Global Warming, since more energy is expended and needs to be replaced by food, leading to higher CO2 and methane emissions generally.

(This assumes you believe the theory in the first place of course.)

To be eco-friendly, one must play very quietly and NEVER use any kind of amplification which is very demanding on energy.

Or better still, we should not play at all, but just lie down or go to bed...or just bloody well die..

cheers,

Ron

REPORT THIS POST AS INAPPROPRIATE | Date Dec. 4 2009 5:17:03

mark indigo

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Joined: Dec. 5 2007

RE: String length & tension. (in reply to Ramon Amira)

quote:

am I correct that the original idea was to give the fourth string more tension

i don't understand it all myself, but i think this discussion is following on from another thread ;

http://www.foroflamenco.com/tm.asp?m=118362&p=1&tmode=1&smode=1

which was a discussion of the idea presented here;

REPORT THIS POST AS INAPPROPRIATE | Date Dec. 4 2009 7:41:26

edguerin

Posts: 1589
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From: Siegburg, Alemania

RE: String length & tension. (in reply to bugeyed)

quote:

or just bloody well die..

Now I'm not sure that would be eco-friendly: decomposition gases surely are as bad as methane?

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REPORT THIS POST AS INAPPROPRIATE | Date Dec. 4 2009 8:47:36

Ron.M

Posts: 7051
Joined: Jul. 7 2003
From: Scotland

RE: String length & tension. (in reply to edguerin)

Very good point there, Ed!

It makes you wonder if our Leaders truly have a grasp of the big questions like the possible man-made effect on Climate Change?

Or where the Taliban are going to go after the West's "obvious" victory in Afghanistan in 18 months time?

Maybe the Talibs will say "OK..fair game, old chap...you win."

(Sheesh...The entire British Army were at war with the "terrorist" IRA for over 40 years..and that's just a small, English-speaking province on our doorstep... not an entire foreign country in another continent!)

(And it's still not even settled in N. Ireland yet!)

Stroll on!

Better putting your spare time and energy (in your limited time on Earth) into appreciating and understanding Flamenco Guitar IMO.. and let them get on with it.

cheers,

Ron

REPORT THIS POST AS INAPPROPRIATE | Date Dec. 4 2009 11:21:48