Big string bends on acoustic and staying in tune

[Jimmy Recard]

I'm playing some Lightnin' Hopkins on the acoustic which involves some big string bends. I'm wondering experiences people have had with acoustics staying in tune when doing string bends. I know electric guitar people talk about locking tuners (not sure what they are), and electric guitars hold the string differently at the bridge. Do open gear tuners and the Gotoh style closed back tuners,and bridge pins, provide enough anchorage to hold tune when bending on acoustic? Sometimes I seem to drop about an 1/8 to 1/4 step when bending and other times it holds tune.

[Silly Moustache]

As long as you aren't using electric gauge strings on an acoustic, but light enough (i,.e. standard lights - 12-53) AND you have Stretched your strings adequately after putting them on, then all should be OK.

But understand that strings perpetually go out of tune - heat, humidity, age, capos and just plain playing them means that most of us have to quickly and carefully check tuning during applause after every song anyway.

[fazool]

We use a slang term of "stretch" in the guitar world which is only partially accurate. To avoid confusion I am going to use the term "elongation" when referring to the metal of the string getting longer by (truly) stretching permanently. Sometimes we just say "stretch" meaning to pull a string, but for now I'll stick to "elongation" and refer only to metal changes.

It is very rare for a string to go higher in pitch. That can happen when tuning UP and the string binds at the nut, creating higher tension above the nut versus below. Then when it slips it yanks the string, increasing pitch. One other scenario is for the guitar body to swell slightly from environmental changes.

If you ever have to tune DOWN, then the above scenarios are for you.


Excluding the above , we can just talk about the string going flat. The only thing that causes a string to go flat (pitch going low) is if the string tension reduces. Only certain conditions will cause the string to lose tension.

The body shrinks slightly due to environmental conditions - doesn't need much explanation.

The tuner is "loose" and rotates. A lot of people think this is what happens but it's generally not. Other than friction pegs, any worm gear cannot be driven backward because of mechanical advantage so the posts don't "turn" from string tension. Also any backlash or slop in the gears is already taken up by the string tension. Generalizing - expensive tuners do not hold pitch better - they simply are more precise during tuning adjustments. You can agree or disagree but that's the way the mechanics of that system work.

So, it's not the tuners "moving".

The big one people like to point to is the string elongating. This actually can't happen. The string is operating entirely in the elastic region which, by definition, is the region where it never changes permanently. The transition for these materials is so abrupt that the plastic region is very brief. That's why strings snap - they went over that line.

Once the string elongates, the string necks down and the cross-section is smaller. The stress (force per cross-sectional area) goes up, causing more stress per unit-area. If you try to tune up to pitch you will have to apply the same tensile force across a smaller area (that already purportedly was in the plastic region). You physically cannot do this. It is not a physical possibility.

I know many of your experiences seem contradictory - What you are seeing is really happening, but its not caused by what you think. Just so you don't think I'm "blowing smoke" with my nonsense ramblings, understand my information: I taught Engineering Mechanics in college, I led a team metallurgy effort designing new tool steel and I'm currently "affiliated" with the world's leading metallurgy tensile testing equipment maker. I'm not just making up nonsense. I know it sounds contradictory to your experience. What I am saying is that the string metal is not getting longer. Something is truly happening, but it's not that.

Think about the logic of strings elongating: If that was true, then the string would elongate forever under tension - you would keep retuning and it would keep elongating, forever and ever. If the string elongates when tuned to pitch, then it will elongate next time as well. And next time. And next time.

That isn't what's happening.

So, what does that leave? The way the string is installed on the guitar!

So, when you yank or bend a string and it goes a little flat - you didn't deform/elongate the metal. What you did was pull it tighter against the post. I've tried referring back to my drum-hoist design days but I htink a shoelace might be a more relate-able analogy:

If you tie your shoes, the string is tight, if you grab the string and YANK it more, it pulls some more slack from where it winds through the eyelets and now its looser where you pulled the slack to. The lace itself did not get longer. There is a point where you can't tighten your shoelaces any more.

You're seeing the same phenomenon with guitar strings. When you yank/bend a string you are tugging the string and pulling slack out of the system. If it goes flat, that's because slack was removed from the system - usually at the post-windings, sometimes at the bridge pin.

If you are truly able to get all the slack out of a system (hypothetical perfect installation) - you could wail away on your guitar all day and never have to retune once (assuming environmental conditions and the body tec. stay the same).

So that was a long-winded reply, but the answer is :

As SillyMoustache said you might see this happen all the time, but it's not the tuning machines nor the string metal - it's simply how the strings are installed.

Originally Posted by Jimmy Recard

I'm playing some Lightnin' Hopkins on the acoustic which involves some big string bends. I'm wondering experiences people have had with acoustics staying in tune when doing string bends. I know electric guitar people talk about locking tuners (not sure what they are), and electric guitars hold the string differently at the bridge. Do open gear tuners and the Gotoh style closed back tuners,and bridge pins, provide enough anchorage to hold tune when bending on acoustic? Sometimes I seem to drop about an 1/8 to 1/4 step when bending and other times it holds tune.

On my Gibson and Epi acoustics (both Grover Rotomatics) they do not go out of tune with string bending.

[DenverSteve]

I play a lot of Clapton and Bob Seger type songs with a lot of bends. I never have a problem with staying in tune. String and tuning machine vary with every guitar and no difference between guitar.

[Wyllys]

The probable cause is the string hanging up in the nut. The probable cure is to put a little graphite in the slots.

[Kerbie]

I've never had a tuning problem from bending strings. Most of my bends in the blues are pretty small, maybe a 1/4-tone or so. How much are you bending the tone?

Like Silly said, I would think sufficiently-stretched strings should handle bending just fine.

[earri]

Originally Posted by fazool

The way the string is installed on the guitar!

So, when you yank or bend a string and it goes a little flat - you didn't deform/elongate the metal. What you did was pull it tighter against the post. I've tried referring back to my drum-hoist design days but I htink a shoelace might be a more relate-able analogy:

If you tie your shoes, the string is tight, if you grab the string and YANK it more, it pulls some more slack from where it winds through the eyelets and now its looser where you pulled the slack to. The lace itself did not get longer. There is a point where you can't tighten your shoelaces any more.

You're seeing the same phenomenon with guitar strings. When you yank/bend a string you are tugging the string and pulling slack out of the system. If it goes flat, that's because slack was removed from the system - usually at the post-windings, sometimes at the bridge pin.

If you are truly able to get all the slack out of a system (hypothetical perfect installation) - you could wail away on your guitar all day and never have to retune once (assuming environmental conditions and the body tec. stay the same).

So that was a long-winded reply, but the answer is :

As SillyMoustache said you might see this happen all the time, but it's not the tuning machines nor the string metal - it's simply how the strings are installed.

This is exactly correct. In my experience, after some time I reach an equilibrium (for lack of a better word) where most, if not nearly all of the slack has been reduced from the system. My guitar solidly stays in tune (bends and all), absent environmental changes. The thing is, I only reach that point after having had the strings on for some weeks (usually 4, or more), so it requires long lasting strings (currently Monel Retros).

My E10SS is currently in that state. I played in a jam circle last week and wailed on it for 3+ hours.; never strayed (at all). Still in tune the next day, and for 3 days thereafter until a change in the weather required a slight retune some days later.

My question Fazool is why do the strings begin to not hold tune when they have aged significantly? That's one indication for me that it may be time for a change.

[fazool]

Originally Posted by earri

...after some time I reach an equilibrium (for lack of a better word) where most, if not nearly all of the slack has been reduced from the system. My guitar solidly stays in tune (bends and all), absent environmental changes. The thing is, I only reach that point after having had the strings on for some weeks (usually 4, or more)....

One thing I did was start using an exaggerated "Taylor method" as shown in their video. After stringing and tuning to pitch, I then firmly pull the string away from the sound hole, slide up, tug again at 12th fret, slide up and tug again at 5th fret. Tug-tug-tug. Pretty strongly, too. I do this on every single string.

Then I recheck tuning, retune and repeat.

Each iteration gets closer to pitch so the process looks like this


string, tune, check 50 cents low, tune-up
tug-tug-tug, check 30 cents low, tune-up
tug-tug-tug, check 10 cents low, tune-up
tug-tug-tug, check 6 cents low, tune-up
tug-tug-tug, check 2 cents low, tune-up
tug-tug-tug, check 0 cents low, tune-up
tug-tug-tug, check 0 cents low, tune-up

I can do this super fast now so its not a long process. tug-slide-tug-slide-tug, literally takes 3 seconds per string.

After I do this, my guitars are super stable and, at most, will require maybe one more tune-up the next day.

[earri]

I do the Taylor method also with a good set of tugs then tune. I wil try you method to try to reach "equilibrium" sooner.

[fazool]

Originally Posted by earri

...My question Fazool is why do the strings begin to not hold tune when they have aged significantly? That's one indication for me that it may be time for a change.

My strings don't really get very old or corroded so I don't have this experience too much. I use coated strings and change them when I see some corrosion and they sound a little 'dead", but I don't really have a lot of experience with really "old" strings.


One thing that's changing is the chemistry of the metal - some surface corrosion is happening. I'm not sure of how the effect of "dead" strings happens but I can imagine maybe three mechanisms:

1) the surface corrosion actually has some dampening characteristics. The corrosion actually absorbs and muffles some vibration

2) the different material has different mechanical properties and vibrates differently so the vibrations cancel between the two materials (similar effect to the above but coming from a slightly different cause)

3) the corrosion is very non-homogenuous and there are "boundaries" between the pure material and the corrosion layer and the vibration energy has to cross these boundaries from one material into another. Because these boundaries are splotchy and randomly all over, there a chaos pattern in the vibrations where some vibration waves are in pure material, others are bouncing through layers and changing. Sort of like a drop of oil on the surface of a huge pool. The light refracts at the boundary and changes colors. Well imagine that oil is splatter sprayed around the pool and you look at the light from a distance - its all splotchy and non-uniform.

(totally different mechanism but that's a visual of the concept)

Anyway, I think the strings can go dead but I haven't noticed them lose ability to hold pitch.


If that does happen, I think the string's modulus of elasticity must be changing. That could be happening from work hardening where repeated stresses are causing "slippage" between the metals crystalline structure - these create basically create obstacles so the boundaries can't slip more. This would make the material harder and possibly change its properties but I'm struggling to think this one through.

[robj144]

Originally Posted by earri

This is exactly correct. In my experience, after some time I reach an equilibrium (for lack of a better word) where most, if not nearly all of the slack has been reduced from the system. My guitar solidly stays in tune (bends and all), absent environmental changes. The thing is, I only reach that point after having had the strings on for some weeks (usually 4, or more), so it requires long lasting strings (currently Monel Retros).

My E10SS is currently in that state. I played in a jam circle last week and wailed on it for 3+ hours.; never strayed (at all). Still in tune the next day, and for 3 days thereafter until a change in the weather required a slight retune some days later.

My question Fazool is why do the strings begin to not hold tune when they have aged significantly? That's one indication for me that it may be time for a change.

I've never noticed my strings not holding tune when they are getting old. It's never happened once to me and I can go a very long time without changing strings. They just sound dead.

[JeffreyAK]

I don't bend much on acoustic guitar, but lots of deep bends on many electrics over the years, and in my experience it's not the tuners or how the strings are locked at the bridge. Mostly it's new or new-ish strings, and after that it's the nut and/or saddle points not allowing the string to move smoothly and then return to exactly where it was before the bend.

Note my experience contradicts the idea that all the string "settling" after installation is due to slack being taken up by tuners. The fact that this isn't the whole story is evidenced by the fact that you can take a string off the guitar completely, then put it back on and tune it up and it will stay in tune - or at least require only a little tugging to set it properly before it will stay in tune. A real string is a complicated thing, and a new string has internal "slack" at the microscopic level that you take up by stretching it after you install it.

[Toby Walker]

I bend ALL of my strings from time to time during my performances, from a 1/4 step up to a whole step. The strings are always new and even with the best stringing methods and 'tugs' before playing, every now and then I'll have to slightly re-tune, but not too drastically.

[Earl49]

Originally Posted by fazool

.....One thing that's changing is the chemistry of the metal - some surface corrosion is happening..... <snip> .... could be happening from work hardening where repeated stresses are causing "slippage" between the metals crystalline structure......

A very detailed and correct technical analysis, if I remember my materials science classes correctly. However, IMO the corrosion aspect is pretty minor. Uneven corrosion will change the propagation of vibration through the clean and corroded portions of the strings.

But old strings with a lot of play hours on them tend to get unstable in tuning mostly because of wear points on the windings against the frets. This has been my experience with older corroded strings (long term storage in humidified cases, but not much play time on them) versus mildly corroded strings that have many play hours and wear divots on the underside. Yes, I have a heavy left hand touch. I am trying to work on that.....