Can you tune a string by weight?

Subject: Tech: Can you tune a string by weight?
From: DonMeixner
Date: 28 Dec 04 - 01:04 PM

Given a known length and a known diameter and a torque wrench can you tune a string to pitch without hearing the string as you go?

Don

Subject: RE: Tech: Can you tune a string by weight?
From: Pauline L
Date: 28 Dec 04 - 01:13 PM

My ex-husband, who was more mechanical than musical, had the same idea. He believed that the way an orchestra tunes up, each musician tuning his/her own instrument, was "inefficient." I told him that tuning a stringed instrument by the tension in its strings would not work. Other variables include the materials of which the strings are made, the age and history of use of the strings, and presence or absence of fine tuners, which would alter the length of the strings. As I've said many times, I believe it's best to learn to tune by ear.

Subject: RE: Tech: Can you tune a string by weight?
From: Pauline L
Date: 28 Dec 04 - 01:15 PM

I think you're asking whether you can tune a string by its tension, not its weight.

Subject: RE: Tech: Can you tune a string by weight?
From: GUEST,Auldtimer
Date: 28 Dec 04 - 01:47 PM

Some years back Folk-Legacy released an LP "The Hammered Dulcimer and How To Make It And Play It" by Howard W Mitchell Folk-Legacy FS-43,which may be of interest. This album came with a totaly absorbing illustrated book of instructions which recounted Howard W Mitchell's attempts at building a hammered dulcimer and included much information on stringing and tuneing and explaining why the lower notes should be thicker strings and the higher notes should be thiner strings. The note a string will be tuned to will depend on the length, diameter and tension. Have you plans to "invent" some form of automatic constant string tension device ? Then you realy could say "...it was in tune when I bought it".

Subject: RE: Tech: Can you tune a string by weight?
From: dick greenhaus
Date: 28 Dec 04 - 01:48 PM

You need to know mass and tension. Torque wrenches just aren't precise enough, in my experience.

Back in the days of coin-operated musical instruments (before recorded music made jukeboxes possible) they used actual fiddles, "bowed" woth a rosin-covered wheel (like a hurdy-gurdy). There were no tuning pegs, and pitch was maintained by using a roller for a nut and hanging different weights at the end of each string.

Subject: RE: Tech: Can you tune a string by weight?
From: PoppaGator
Date: 28 Dec 04 - 02:09 PM

When new, anyway, strings tend to stretch and tension needs to be periodically increased to stay in tune.

I doubt that one could work "aging" into an algorithm that would guarantee that a certain degree of tension on a string of a given diameter would result in a given pitch.

Subject: RE: Tech: Can you tune a string by weight?
From: McGrath of Harlow
Date: 28 Dec 04 - 02:15 PM

It's quite possible to have instruments looking like stringed instruments, in which the note would be produced electronically according to where you placed your fingers, and where a flick of a switch would shift you to a different key, or a different instrument, like electronic keyboards - in fact I think they already exist.

But a playable instrument with real strings, tuned by little electric motors, controlled by some kind of electronic tuner - I think that's some time off, though I imagine it'd be technically possible.

Subject: RE: Tech: Can you tune a string by weight?
From: Songster Bob
Date: 28 Dec 04 - 02:36 PM

No.

Bob

Subject: RE: Tech: Can you tune a string by weight?
From: DonMeixner
Date: 28 Dec 04 - 02:37 PM

Lets assume that all things being equal and that tension is equal to weight.

A string held at 20 lbs. by a physical weight will always be at 20lbs because the weight hasn't changed and nothing mechanical is locking the string at any point. As the string ages due to use or to constant tension the weight with gravity will continue to moderate the tension and pull the string so there is always 20lbs. on the string.

A string at 20lbs. and held there by a tuning machine will only stay at 20 lbs. just so long and then begin to lose tentsion because of use. The tuning machine being a fixed means of adding tension.

This discussion isn't going anywhere or has any deep purpose, it is just a "Wonder Me" kind of question.

Don

Subject: RE: Tech: Can you tune a string by weight?
From: McGrath of Harlow
Date: 28 Dec 04 - 03:14 PM

"Lets assume...that tension is equal to weight.

Is that necessarily a valid assumption?

Subject: RE: Tech: Can you tune a string by weight?
From: DonMeixner
Date: 28 Dec 04 - 03:25 PM

Of course it is Mac, I'm making the rules.

Subject: RE: Tech: Can you tune a string by weight?
From: Cluin
Date: 28 Dec 04 - 03:44 PM

Then you can do any damn thing you want.

I think Pauline L. has it. Too many other variables.

Subject: RE: Tech: Can you tune a string by weight?
From: DonMeixner
Date: 28 Dec 04 - 03:57 PM

Cluin,

You are right. I have actually confused the question haven't I? Tension caused by a tuner or tensioned caused by wieght is still tension. And tension on a wire equals a tone

There are no variables stated here other than the weight and the action of gravity or the tuner = mechanically created weight.

What follows I mistakenly assume would be understood.
Let us assume that we have two wire strings that are the same material, length, and diameter and attached to the same vibrating surface, soundboard.

If 20 lbs through application of a torque wrench is put on one string
and a 20lbs. weight is hung on the other will the strings have the same tones?

Don

Subject: RE: Tech: Can you tune a string by weight?
From: Bert
Date: 28 Dec 04 - 04:14 PM

Songbob is right.

It sounds possible in theory but in practise there are so many variables and tolerances that it would not work.

Subject: RE: Tech: Can you tune a string by weight?
From: dick greenhaus
Date: 28 Dec 04 - 04:19 PM

Don-
The answer is "Yes"--unil the string stretches, which may be in an extremely short time. The weight will maintain tension regardless; the preset achieved by the torque wrench won't.

Subject: RE: Tech: Can you tune a string by weight?
From: DonMeixner
Date: 28 Dec 04 - 04:27 PM

Dick, that is my belief as well.

Lets ask this then: For any given string material and the equation;

d (diameter) + l (length) + w/t (Weight or Tension) = T (Tone)

Are the values in the formula known values any where?

(I'm on vacation, no jewelry to make and I'm bored)

Don

Subject: RE: Tech: Can you tune a string by weight?
From: Big Al Whittle
Date: 28 Dec 04 - 04:30 PM

Look sometimes its really difficult to get it in tune. Other times not , but sometimes horrendous...!

Give yourself every advantage. Listen to it. get digital readouts. tuning forks, if you think a torque wrench will help... you get one mate!

Subject: RE: Can you tune a string by weight?
From: Bert
Date: 28 Dec 04 - 04:54 PM

Other things that make it impractical are,

1. The material that the instrument is made of. Most instruments are not made of the same material as music wire. So that leads us to item 2.
2. Temperature. The thermal expansion properties of the instrument are different to those of music wire.
3. Manufacturing tolerance on the diameter of the string. It will be pretty good but then again the diameter is small so the percentage may be larger on thinner strings.
4. Manufacturing variables in the constituents of the steel. These determine the modulus of elasticity of the steel. Music wire used to be high carbon steel but I suspect that modern strings are made from various alloys which could be different for each manufacturer.
5. Is the string plain or wound.
6. if it is wound, what is the weight, size and material of the winding and what are their respective tolerances.
7. How are you applying the tension? If through a regular tuning machine then you would get variables such as gearing and friction. These again would make a determination of the string tension difficult.
8. How accurate do you want your tuning to be?

Take all these things into account and the best of flippin'

Subject: RE: Can you tune a string by weight?
From: Bill D
Date: 28 Dec 04 - 05:42 PM

here is a little program that will help choose and decide string tensions. All you can really know about an individual string is the basic 'range' that it can be safely tuned within and still maintain a reaonable tone.

Subject: RE: Can you tune a string by weight?
From: Bill D
Date: 28 Dec 04 - 05:50 PM

and here is another http://www.kennaquhair.com/ustc.htm

I did a search on "string tension" + calculate and got many hits. Those who play guitars and other stringed instrumens will have to decide if some of these are better than others. Some of them work online, some can be downloaded.

Subject: RE: Can you tune a string by weight?
From: Murray MacLeod
Date: 28 Dec 04 - 06:02 PM

I know exactly what Don is getting at and it is a valid question.

It would be perfectly feasible, though not commercially viable, to construct a pedal steel guitar which was tuned by hanging weights on the end of the strings. It would be interesting to know by how many cents a one ounce weight varied the pitch ...

Subject: RE: Can you tune a string by weight?
From: dick greenhaus
Date: 28 Dec 04 - 06:06 PM

As I said before, it's been done. Not particularly practical for hand-held instruments, though.

Subject: RE: Can you tune a string by weight?
From: Big Al Whittle
Date: 28 Dec 04 - 07:12 PM

well I still don't understand.....

Subject: RE: Can you tune a string by weight?
From: DonMeixner
Date: 28 Dec 04 - 07:20 PM

Ge whiz Wee

Haven't you ever just wondered something?

Don

Subject: RE: Can you tune a string by weight?
From: Pauline L
Date: 28 Dec 04 - 08:33 PM

I concur with all of Bert's reasons.

Subject: RE: Can you tune a string by weight?
From: DonMeixner
Date: 28 Dec 04 - 08:59 PM

And I never asked if it was practical. I just wondered if it was possible.

Subject: RE: Can you tune a string by weight?
From: JohnInKansas
Date: 28 Dec 04 - 09:06 PM

The formulas for calculating the frequency that a simple string of a given length, wire density, and tension are well known, and are sufficiently accurate to do what is asked. The difficulties arise from the application of the formaulas to any real physical system.

If you suspend a weight on the end of a wire, so that the tension is constant, the wire is stretched so that it's length is increased. When the wire stretches, it's diameter is reduced since there's still the same amount of "stuff" in the wire and the wire is now a little longer. If the diameter is reduced, then the critical parameter of "mass per unit length" is changed since the mass/weight of the string is now "stretched" over a longer length. This relationship is slightly non-linear for real materials, but is accurately described by the "Poisson contraction" that is well documented in elementary level mechanics (strength of materials) handbooks. For accuracy comparable to what is "detectable" with common tuning methods, the specific "Poisson ratio" for each material used in the string will be required, rather than the "about x for most materials" assumptions commonly used for strenght calculations.

If the string is simply hung vertically with a dead weight on the end, you don't really have a "string," you have a pendulum. Different (but still accurate) formulas apply. If you "fix" the length of the "active part of the string" using a bridge and nut as is common on instruments, the friction in the bearing between string and nut introduces an unpredictable difference between the "dead weight" tension and the "actual tension' in the active part of the string. Complex mechanisms have been designed to accomplish "frictionless" nuts, but such mechanisms add their own complications. If you use the common "roller" method, then the "edge" on which the string bears isn't a "sharp" one, and the "effective length" of the thread varies slightly with the amplitude of string vibration. (This probably affects the linearity of the string's harmonics more than it affects the fundamental pitch.)

With typical tuning machines, you tune the string by pulling part of the wire out of the "active length" between the bridge and nut. When you pull on the wire, you increase the tension; but you also reduce the "amount of string" - i.e. the mass of string between nut and bridge. The increase in pitch is caused partly by the increase in tension and partly by the reduction in the weight of the active part of the string. In many configurations the change in tension "dominates the equation" but in some configurations the effect of the reduction in string weight can become "large" compared to the effect of tension change. Typical acoustic string instruments, with modern metal strings, are usually tuned near the "80% of yield" point where the "mass effect" becomes comparable to the "tension effect." The "overtuned" point where twisting a tuning knob doesn't change the pitch happens when the effect of reducing string mass/weight equals the effect of increasing string tension and usually appears just about the time the string breaks.

While the basic equation relating pitch to string length, weight, and tension remains accurate, for a "real world" tuning, additional equations are needed to relate the change in weight and change in tension simultaneously to the change in length - which is what you really change with tuning machines. The needed relationships will be at least slightly different for each string, and possibly for each sample of a given kind of string. These "supplemental effects" will also be affected by temperature, and will change with "ageing" of the string(s). Aging effects can consist of work hardening from repeated stretching, changes in material due to surface and/or internal chemical reactions, changes in "material" due to addition of surface contaminants, etc.

Once the "analysis" for the string is done, the same analysis, with the same accuracy, must be done for the structure that supports the string and maintains the length/tension of the string.

The short answer to the original question is "Of course you can."
If one asks "Is it easy" the answer is NO.
If one asks "Is it useful" then one must revert to the old military "It depends on the tactical situation and the weather."

If one assumes a "musical instrument context," then the answer is that it's a lot easier to "twist the knob until it sounds right."

John

Subject: RE: Can you tune a string by weight?
From: DonMeixner
Date: 28 Dec 04 - 09:26 PM

Thanks John , thank you everyone,

I appreciate the info everyone has offered. This has certainly made for me a less boring day.


Don

Subject: RE: Can you tune a string by weight?
From: Bert
Date: 28 Dec 04 - 09:53 PM

here's some theory but that doesn't take into account the gearing and efficiency and lubrication of the tuning machines or the manufacturing tolerances of strings, material or of the instrument.

Subject: RE: Can you tune a string by weight?
From: Bert
Date: 28 Dec 04 - 09:59 PM

Oh! and I was forgetting backlash in the tuning machines and friction through the nut. That's what causes that wierd effect when you tune a string and then you can undo the tuning machine a little without changing the pitch of the string.

I doubt if calculations alone could produce meaningful results without introducing empirical data derived from the individual instrument.

Subject: RE: Can you tune a string by weight?
From: GUEST,punkfolkrocker
Date: 28 Dec 04 - 11:05 PM

ok.. i've suffered a life time of being crap at maths and physics..
and so not managed to read most of this thread..
so cant really say how relevant this is..
but in the practical world..

about 10 - 15 years ago Jimmy Page used a guitar prototype
which he demonstrated on TV [Tomorrows World..???]
..a converted les paul,
with body cavities containing electric motors, circuits, sensors,
and other technical stuff..
providing the guitar with auto tuning functionality..
it was supposed to be able to monitor and self correct fine tuning,
and also be switched immediately to pre-set alternative tunings..
This function was demoed convincingly on Tv..
providing otherwise impossible alt. tuning changes
at the flick of a switch at any time within a song performance..

anyone else remember..??

..i'm not making this up..

i guess the technology was too expensive and uneconomical to ever be developed commercially..

Subject: RE: Can you tune a string by weight?
From: Big Al Whittle
Date: 29 Dec 04 - 03:39 AM

the variax acoustic does alternative tunings at the flick of a switch.

Imagine that Jimmy page driving himself mad and all the time, the silicone chip was waiting offstage to make its entrance.

Of course being curious is a good idea Don, forgive my boorishness.

Subject: RE: Can you tune a string by weight?
From: Seamus Kennedy
Date: 29 Dec 04 - 04:03 AM

Don, go to bed!

Seamus