barnesviolins

String tension and afterlength

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Given a set bridge height, what is the relationship of the string tension with the afterlength? Does a longer afterlength have less or more tension?  I have heard it said both ways enough to make me look at the physics of it.  
I am thinking about both linear tension as well as tension down on the bridge which I would assume both increase and decrease relative to each other although not in direct proportion.  
 
If anyone has seen this discussion in the past, then thank you in advance if you are able to find the thread!
 
Dorian
 
 

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For a string of a given weight to play a given tone, the tension is a function of the other two. Since that means that the tension of the playing part of the string is fixed (assuming the string is tuned), it follows that the tension on the other side of the bridge is also fixed, or the string would move and the bridge fall over.

When you stop the string with a finger to play a higher note, the string tension does not change (well -it dies, but very very little) - only the vibrating length.

That again means that the tension in the afterlength is independent of the actual length - assuming string weight, tuning, and bridge height are kept unchanged.

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2 hours ago, barnesviolins said:

 

Given a set bridge height, what is the relationship of the string tension with the afterlength? Does a longer afterlength have less or more tension? 
 

Tension and bridge downforce remain the same.

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3 minutes ago, David Burgess said:

Tension and bridge downforce remain the same.

Yup.

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Yes, because a longer afterlength would need a higher tension to get to the same pitch.  If you made it shorter, it would be like stopping the playing length.  The pitch goes up, but the tension doesn't change.

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31 minutes ago, barnesviolins said:

So when I lengthen the afterlength the pitch of the afterlength lowers.......

But the tension is the same?

Yes. For a given string, a shorter vibrating length at the same tension has a higher pitch, and a longer vibrating length at the same tension has a lower pitch.

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At a given pitch the longer the string the higher the tension if all other factors are constant.

at a given pitch the thicker the string the higher the tension if all other factors are constant.

 

If there are strings with identical characteristics other than the after length including identical vibrating string length the string with longer after length should be under higher tension.

 

DLB

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Got it.

Thanks for helping me keep my sanity,

Sometimes I just need to hear something said a different way to reinforce what I though I understood.

I had a violist tell me that when someone put a violin length tailpiece on their instrument that it dramatically increased the"sound"... and the tension.  So much so that the tailgut snapped.  I was trying to understand how putting a shorter tailpiece on and increasing the afterlength had an increase in tension causing the tailcord to fail........

And then there is the whole explanation of why a violin tailpiece made a huge perceived impact on the sound of the viola.........

Ugh.

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2 minutes ago, Dwight Brown said:

If there strings with identical characteristics other than the after length including identical vibrating string length the string with longer after length should be under higher tension.

 

DLB

Wait......

Isn't that the opposite of what has been said?

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2 minutes ago, barnesviolins said:

Wait......

Isn't that the opposite of what has been said?

Given that the whole string is under tension and can slide freely over the bridge a string at a given pitch with a longer total length should be under a greater tension. 

DLB

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4 minutes ago, Dwight Brown said:

Given that the whole string is under tension and can slide freely over the bridge a string at a given pitch with a longer total length should be under a greater tension. 

DLB

I think I understand what you are saying.  

I'm considering the string to be tuned to the same pitch with the longer afterlength.

 

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Yes that’s it. If you have two identical strings with identical vibrating lengths but one has an afterlength of 50mm and the other has an afterlength of 100mm the vibrating portion would have to have the same tension to be at the same pitch. The whole string including afterlength might have a higher tension. It is a puzzlement!

like I said I think we need a rig.

DLB

or a physicist!

 

 

physicist !

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24 minutes ago, barnesviolins said:

I had a violist tell me that when someone put a violin length tailpiece on their instrument that it dramatically increased the"sound"... and the tension.  So much so that the tailgut snapped.  I was trying to understand how putting a shorter tailpiece on and increasing the afterlength had an increase in tension causing the tailcord to fail........

Durn violists, she probably tuned an octave high without realizing it. :lol:   (Sorry Dwight) ;)

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2 minutes ago, Dwight Brown said:

Yes that’s it. If you have two identical strings with identical vibrating lengths but one has an afterlength of 50mm and the other has an afterlength of 100mm the vibrating portion would have to have the same tension to be at the same pitch. The whole string including afterlength might have a higher tension. It is a puzzlement!

 

I dont think that last part is right, both string tensions are determined by pitch and vibrating string length. Tension on both sides of the bridge will be the same..

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6 minutes ago, Dwight Brown said:

Would the afterlength behave as a separate system?  Now I'm really interested and not a bit sure!

DLB

Both afterlenghts have the same tension but the longer one will have lower pitch.

Edit: they are connected to the vibrating string: so same tension but the afterlength can be separately varied.

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Would the tailpiece and the tail gut be part of the same system?  If you had the same instrument with shorter or longer tailpieces the length of the whole thing under tension would be the same just more or less afterlength and less tailpiece or less afterlength and more tailpiece.

Sorry about my typing, my eyes are really acting up.  I go see the surgeon next friday!

DLB

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