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Author Topic: string length behind nut effects on tone  (Read 11004 times)

ToneMonkey

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Re: string length behind nut effects on tone
« Reply #15 on: October 11, 2010, 12:01:15 PM »
The total length of the string is the length that determines the tension the string has to be brought to to attain a given pitch.

The bit behind the nut matters, as does the bit below the bridge if relevent on the guitar in quesion.

f=(1/2L).sqrt(T/d)

where f is frequency, L is the length of the string, T is its tension and d is the mass per unit length of the string, f is therefore inversely proportional to L (but we all knew that already, right?) and L has to be the total length. That means that if you increase the length behind the nut for the same pitch, tension as a funtion of length here is

T = 4df^2L^2

But we're keeping f constant d is also constant, and so was '4', last I checked, so may as well write

T~ L^2

= increase length, increase tension needed to attain the same pitch, so philly was right.

Sorry for the maths, but its a physics question, it gets a real physics answer :p.

I'm afraid that I can't sign up to this one mate.

What that formula doesn't take into account is the two MASSIVE dampers in the system (being the bridge and the nut).  As the length between these two points remains the same, then I would say that for any gauge string, the tension between these two points remains the same (and therefore the tension of the whole string).

I would model the string behind the nut and bridge as a further damper to the system which has the affect Feline talks about.

I'm not a physicist, but that's my engineering opinion  :lol:
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MDV

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Re: string length behind nut effects on tone
« Reply #16 on: October 11, 2010, 12:54:13 PM »
The total length of the string is the length that determines the tension the string has to be brought to to attain a given pitch.

The bit behind the nut matters, as does the bit below the bridge if relevent on the guitar in quesion.

f=(1/2L).sqrt(T/d)

where f is frequency, L is the length of the string, T is its tension and d is the mass per unit length of the string, f is therefore inversely proportional to L (but we all knew that already, right?) and L has to be the total length. That means that if you increase the length behind the nut for the same pitch, tension as a funtion of length here is

T = 4df^2L^2

But we're keeping f constant d is also constant, and so was '4', last I checked, so may as well write

T~ L^2

= increase length, increase tension needed to attain the same pitch, so philly was right.

Sorry for the maths, but its a physics question, it gets a real physics answer :p.

I'm afraid that I can't sign up to this one mate.

What that formula doesn't take into account is the two MASSIVE dampers in the system (being the bridge and the nut).  As the length between these two points remains the same, then I would say that for any gauge string, the tension between these two points remains the same (and therefore the tension of the whole string).

I would model the string behind the nut and bridge as a further damper to the system which has the affect Feline talks about.

I'm not a physicist, but that's my engineering opinion  :lol:

There are myriad dampers in the system, but the string length in question is definitely the full length, not the scale length.

Anyone that has a floyd rose equipped guitar should know this all too well, and if you've got one you can prove the above with it.

Engineers and physicists both appreciate experiments :)

Tune up the guitar, lock down the nut clamps.

Take the string with the longest total travel and use the fine tuners to change the tuning by a tone/as much as you can

Unlock the clamp for that string.

If you tuned it up, the pitch will drop when the clamp is released because your increase in tension between the nut and bridge is now distributed over the whole string, so the tension per unit length is lower

If you tuned down the pitch will raise when the clamp is released, because your reduction in tension per unit length from the nut and bridge is now over the whole string, and averaged with the higher tension per unit length that the section above the nut was held at by  the clamp.

The total load on the string doesnt change when you release the clamp, the distribution of load per unit length above and below the nut is is simply equalised. Ergo, the length of string in question as to what tension one must attain for a given pitch and gauge is the entire length of string, not just the length between the nut and bridge

Roobubba

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Re: string length behind nut effects on tone
« Reply #17 on: October 11, 2010, 03:51:22 PM »
Roo, if you really want a job as my online spellchecker, youre going to have your work cut out for you for very little reward or recognition ;)

Nope, absolutely no problem with this one, go ahead and publish!

Andrew W

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Re: string length behind nut effects on tone
« Reply #18 on: October 11, 2010, 04:31:03 PM »
Roo, if you really want a job as my online spellchecker, youre going to have your work cut out for you for very little reward or recognition ;)

Nope, absolutely no problem with this one, go ahead and publish!
If it were me, I'd put an apostrophe into the "youre".  Can I check the checking for little reward or recognition?

In all seriousness though is another consideration not the behaviour of the string as it comes out of the nut over the fretboard?  If you bend the string you're changing the angle on the string as it comes out of the nut on the fingerboard side which I'm guessing would cause some sort of friction and change in tension, no?  Whether it's a significant amount I don't know but if the string break angle over the nut and onto the headstock is a consideration then a string bend would also be a factor too or am I getting this hopelessly wrong?
« Last Edit: October 11, 2010, 04:39:23 PM by Andrew W »

ToneMonkey

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Re: string length behind nut effects on tone
« Reply #19 on: October 11, 2010, 05:08:12 PM »

The total load on the string doesnt change when you release the clamp

You sure?

I'll have a think about this when I haven't just put out a cigarette of the Bob Marley variety PDT_009

We really should have a beer at some point MDV  :D
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MDV

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Re: string length behind nut effects on tone
« Reply #20 on: October 11, 2010, 10:43:39 PM »

The total load on the string doesnt change when you release the clamp

You sure?

I'll have a think about this when I haven't just put out a cigarette of the Bob Marley variety PDT_009

We really should have a beer at some point MDV  :D

Reasonably. I've thought about it quite a bit, tested it on 2 FR gutiars with blocked trems, and still sort of expect someone to go 'errr, mark, no, because _insert obvious thing that I should have thought of here_' :lol:

But yeah, by my best estimation, the locking nut gives us a scale length Vs full length variable controlled direct comparison that you can make the testable predictions that I did about when you exclude or include the section of string above the nut where the load, most importanly doesnt change, its just the proportional division of the load above and below the nut

And, yes, we should!

And a week after quitting sellafield, no more random drugs tests, and a bob marley cigarette was one of the first things I wa going to indulge in and I cant find any :(

Roobubba

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Re: string length behind nut effects on tone
« Reply #21 on: October 13, 2010, 09:45:58 AM »
Roo, if you really want a job as my online spellchecker, youre going to have your work cut out for you for very little reward or recognition ;)

Nope, absolutely no problem with this one, go ahead and publish!
If it were me, I'd put an apostrophe into the "youre".  Can I check the checking for little reward or recognition?


My sarcasm didn't come over very well there, I take it!

Andrew W

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Re: string length behind nut effects on tone
« Reply #22 on: October 13, 2010, 10:10:55 AM »
Roo, if you really want a job as my online spellchecker, youre going to have your work cut out for you for very little reward or recognition ;)

Nope, absolutely no problem with this one, go ahead and publish!
If it were me, I'd put an apostrophe into the "youre".  Can I check the checking for little reward or recognition?


My sarcasm didn't come over very well there, I take it!
No I getcha but I couldn't resist a little recursion.  It's a weakness. :)

Kamin

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Re: string length behind nut effects on tone
« Reply #23 on: October 17, 2010, 04:40:53 AM »
I think the bending of the string isn't affected by the change in tension some are talking about.  I think it has more to do with the total amount of free string.  Whenever you bend a string, you change the total length of the string.  When you bend a string with a theoretically perfect locking nut the total length of the string is from nut to bridge.  When you bend a note with a non-locking nut the total length of string is from tuning peg to bridge.  So for a set amount of bend (a half-step for example), the force it takes to complete the bend decreases as the length of the string increases.  This length is different than the length that is resonating the pitch.

Bob Johnson

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Re: string length behind nut effects on tone
« Reply #24 on: October 18, 2010, 07:47:00 PM »
If there's a lot of string either above the nut or below the bridge you're going to have to bend the string a lot further to raise the pitch by a tone (for instance) because it takes a great deflection to tension a longer overall string length.

If there's any friction in the system then, obviously, any extension in the string length will cause tuning stability issues simply because more string has to pass over the nut or bridge either when tuning or string bending.

Extra string at either end of the scale length will, as Jonathan said, resonate and add extaneous noise. Depending on the guitar, this will either compliment or detract from the overall sound. Some guitars with extended lengths of string and particularly unique tones have benefited from the additional "overtones" (some jazz archtops, fender jazzmaster/jaguar) but I doubt that there is a hard and fast rule that stipulates how this actually occurs. My feeling is that when you actually look at all the variables in play here it's a case of if it works, great and if it doesn't; well tough, try something else.

My own observations / experience would suggest that the smallest amount of string either side of the nut or bridge is the preferable route. certainly a small stiff headstock will help with sustain and attack and that's why I designed my MG range with only 30mm between tuners and fairly straight string pull.

Inverted headstocks on six-in-a-row layouts probably help to damp extraneous noise in the form of unwanted harmonics and other derivatives of the base frequency from the lighter strings which will be more prone to give off unwanted noise than the bass strings would be.


Regards,
Bob Johnson
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gwEm

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Re: string length behind nut effects on tone
« Reply #25 on: October 24, 2010, 12:47:48 PM »
I notice clear differences. My Steinbergers are a piece of piss to bend strings on - headless design, so only a few mm behind the 'nut'. My WezV 23 fret strat has no string trees, which may increase the length behind the nut (?) and its tough to bend strings on - its the only guitar I run as low as 10s on. 25.5" scale alround

was dicking around with my fenders this morning, and i've figured it out..!

nothing todo with the string trees at all i think - seems like my strats with trems need more effort to bend the strings than my hardtails
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