instruments drift sharp

Subject: instruments drift sharp
From: GUEST,Jim
Date: 31 May 06 - 06:18 PM

One of my students asked me a question tonight that stumped me. She noticed that when she went to tune her banjo to a tuner, that it was more often sharp than flat. I've often noticed this with Autoharps as well. What would cause an instrument to go sharp rather than flat?

Subject: RE: instruments drift sharp
From: Willie-O
Date: 31 May 06 - 06:27 PM

hammered dulcimers too. nightmare situation when you haven't taken it out for a year or so! it's a wonder it didn't explode.

Subject: RE: instruments drift sharp
From: Leadfingers
Date: 31 May 06 - 06:47 PM

Air Conditioning ??

Subject: RE: instruments drift sharp
From: Midchuck
Date: 31 May 06 - 07:03 PM

Air Conditioning ??

As Descartes said, just before he disappeared into thin air, I think not.

We have no air conditioning and it happens to my guitars, even in hot weather.

Peter

Subject: RE: instruments drift sharp
From: The Fooles Troupe
Date: 31 May 06 - 07:06 PM

Metal strings contract with the cold, sharpening pitch. In summer the reverse occurs.

Subject: RE: instruments drift sharp
From: The Fooles Troupe
Date: 31 May 06 - 07:11 PM

If the length of the instrument expands due to heat, that will increase tension on the string. But the relative expansion rates of wood and metal are such that the metal moves far more.

Subject: RE: instruments drift sharp
From: MaineDog
Date: 31 May 06 - 07:54 PM

When it gets cold, my recorders go flat, and my fiddle goes sharp.
MD

Subject: RE: instruments drift sharp
From: The Fooles Troupe
Date: 31 May 06 - 08:08 PM

ooooooooo, so does mine....

Subject: RE: instruments drift sharp
From: GUEST,Pete Sumner
Date: 31 May 06 - 08:31 PM

You might want to consider humidity more that the temperature...
In the piano field, which is my forte (pardon the pun), it is that factor above all others that has an effect on pitch.
Bridges lengthen and soundboards expand in humid weather thus sending the instrument sharp..I loved it in LA when the Santa Anna winds blew..sent all the pianos flat as the humidity dropped....Ooooops.....

Hope that helps

Pete

Subject: RE: instruments drift sharp
From: McGrath of Harlow
Date: 31 May 06 - 09:23 PM

I always find when I bring my guitar into the pub from the car that the strings tend to be a little sharp rather than flat.

The other thing is that sometimes you find in a noisy session that you are hammering away, and when you check the tuning it's gone up rather than down. I assume all this is something to do with changes of temperature or humidity.

On the other hand when I take an instrument up at home which I haven't played for some time the strings tend to be a little flat. So I don't think there is too much to worry about instruments getting sharper and sharper till they explode...

Subject: RE: instruments drift sharp
From: harpmolly
Date: 31 May 06 - 09:37 PM

I often find that the tendency to drift sharp or flat has a lot to do with the humidity. Nylon harp strings in general, being very stretchy, almost always go flat, but on a harp that has both nylon and bronze strings, they'll often drift in different directions. That's quite a shock when you sit down and are merrily playing along when you suddenly hit a bass string and all the hair on the back of your neck stands up at once...*shudder*

M

Subject: RE: instruments drift sharp
From: JohnInKansas
Date: 31 May 06 - 09:42 PM

A large part of the shift that's seen when an instrument has been idle for a while is from the redistribution of tension on the strings.

Most people "tune up" when getting ready to play. The string is turned down to a bit below pitch and then "raised to pitch." On most instruments it's easier to "find the pitch" this way than if you start sharp and tune down, because friction of the string on the nut makes the pitch of the main part of the string follow the adjustments to the tuner in a "jerky" step-slip way when you "tune down."

When you "tune up," the bit of "stiction" at the nut, aided by the bend in string direction, leaves tension of the bit of string between the nut and the tuner always a bit higher than the tension in the "playing part" of the string. Left in the case, and with any temperature and/or humidity change, the tension in the two parts of the string will equalize, lowering the tension in the bit between tuner and nut, and slightly raising the tension in the "playing part" of the string.

On some instruments, there's a similar effect from the "dead" string between bridge and tailpiece, but the flexibility of the bridge makes the observed effect smaller (usually).

If you have an accurate tuner with sufficient range, you can test this out by checking the tuning of the string, and separately checking the pitch of the nut-to-tuner bit of string before you put the instrument aside, and then checking both pitches before adjusting anything the next time you pick it up. You should find that the pitch of the nut-to-tuner segment has dropped significantly, and the main string has come up slightly.

Of course, if the instrument has been through large temperature and/or humidity changes while idle, there are other effects on the tuning; but the typical "case-shift" is largely due to the difference in tension in the separate sections of the string when tuned in the normal fashion just averaging out their differences.

Of course individual instruments may have their own idiocyncrasies, and there are other effects that can affect tuning; but on my instruments this effect is clearly demonstrable.

John

Subject: RE: instruments drift sharp
From: Al
Date: 01 Jun 06 - 12:35 AM

John's note displays sharp logic with the ring of truth.
Al

Subject: RE: instruments drift sharp
From: Bill D
Date: 01 Jun 06 - 03:51 PM

and with autoharps, the large difference in length between many of the (usually)36 strings makes especially interesting changes. The shorter, tighter, thinner strings move less than the long thicker ones....so add this to temperature & humidity changes in the wood, and the need to 'adjust' for the way the ear hears higher & lower notes, and it is often more art than technology getting an autoharp to sound 'just right'.

Bryan Bowers refuses to use an electronic tuner, as he claims that the ideal tuning is slightly off what the tuner shows...plus, he tunes a G note a little different in a G chord than in a C chord, so he uses several 'harps, each adjusted for a couple of specific keys. ..Me, I can't hear the difference, so I just use my Korg and assume it's tolerable...*grin*

Subject: RE: instruments drift sharp
From: JohnInKansas
Date: 01 Jun 06 - 04:18 PM

Bill D -

Bowers obviously prefers "just" tuning, and most electronic tuners only indicate equal tempered tuning. Quite a few gittar-whangers I know use the electronic tuner to get one or two strings close to what everybody's using, then tune the other strings to "harmonics."

As long as you stick to a few keys close to what you tuned for, it works okay either way (to my ear) but if you jump off into odd keys, the "harmonically tuned" ones often spend half the number re-tuning.

If you get the top-of-line Korg tuner (OT120 - the newest, or OT-12 - the classsic one), you can tune to about a dozen different theoretically perfect "temperaments," some of which I can't even pronounce, much less have any idea why one would want to use them. The difference between $19 for the tuner I bought her, or even the ~$100 for the old one I usually use, and the $400+ for the "good one" inclines me to settle for simplicity.

If your ear is good enough, just tuning works great; but someone frequently tuning lots of instruments with a whole lot of strings could, in principle, use the tuner to get what they want - perhaps a little more easily, even if they prefer something other than equal tempered.

John

Subject: RE: instruments drift sharp
From: wysiwyg
Date: 01 Jun 06 - 04:24 PM

Because they're ALIVE and have moods!

~Susan

Subject: RE: instruments drift sharp
From: GUEST
Date: 01 Jun 06 - 05:18 PM

a

Subject: RE: instruments drift sharp
From: McGrath of Harlow
Date: 01 Jun 06 - 05:55 PM

If I'm tuning at home I try to give the string a wee lift in the process, so as to even out that difference between the tuner-nut section and the main length of the string. It just seems neater to even things out that way. I've never tried checking if that helps it keep in tune, but in principle it ought to.

Subject: RE: instruments drift sharp
From: SharonA
Date: 01 Jun 06 - 07:01 PM

I have a friend who uses graphite on his guitar strings at the nut, in order to lessen the "redistribution of tension" of which JohninKansas speaks (it supposedly makes the string move across the nut more easily while being tuned).

Subject: RE: instruments drift sharp
From: The Fooles Troupe
Date: 01 Jun 06 - 07:17 PM

"Left in the case, and with any temperature and/or humidity change, the tension in the two parts of the string will equalize"

So John, are you trying to say that you would stay better in tune if you had Teflon Nuts?

.....

Subject: RE: instruments drift sharp
From: The Fooles Troupe
Date: 01 Jun 06 - 07:18 PM

... or just rub graphite on them?

Subject: RE: instruments drift sharp
From: McGrath of Harlow
Date: 01 Jun 06 - 07:35 PM

Graphite, otherwise known as "pencil lead"...

Subject: RE: instruments drift sharp
From: JohnInKansas
Date: 01 Jun 06 - 07:38 PM

SharonA

A bit of graphite doesn't hurt a thing, but the real reason for using it is that if the string doesn't slip smoothly in the notches of the nut, the strings will more rapidly deepen (i.e. wear out) the grooves and spoil your carefully prepared set up. If the notches in the nut get too deep, the action is affected, the string tone is "dampened," and the amount of "grab" on the strings can make tuning more difficult.

My personal observation has been that those who are devoted to and vocal about their conviction that "lubricating" is necessary tend to be those who've let their nuts get gouged to the point where some "slickum" really is needed just to be able to get in tune.

Using a pencil lead as a "graphite" source is not recommended, since most leads are more clay than graphite, and what you get may be more abrasive and more damaging to the nut than the bare string. The powdered graphite sold for use in locks and such is much preferred. Some people recommend using a silicone grease, but any excess amount can migrate to other places and can be very difficult to remove. Some prefer wax, but anything used there should be applied in the smallest amounts possible, if only for the sake of neatness.

John

Subject: RE: instruments drift sharp
From: Kaleea
Date: 01 Jun 06 - 07:54 PM

Equal or nonequal temperament aside, U do not understand why some instruments will go sharp when another instrument in right next to them in the same room will go flat. Or why a certain section of strings on my Autoharp (or harp) will go sharp--even in the winter.
I prefer to have a Pianoforte which is tuned "Brilliant" meaning that the higher notes are slightly sharp. Then there is the way some folks-such as Brian-will tune certain notes "sweet" so that they are slightly flat.

Subject: RE: instruments drift sharp
From: GUEST,Jim
Date: 02 Jun 06 - 10:55 AM

Kaleea,
The way Brian Bowers and some others tune their Autoharps works only if you have a diatonic Autoharp. If your harp plays in more than one key, it will not sound "Sweet" in the any keys other than the one it was tuned to. In fact it will sound just plain bad in the other keys. That's why you see Brian come on stage with a pile of Autoharps, one for each key in which he intends to play. I've also found that an instrument tuned to sweet tuning doesn't sound as sweet when it is playing with instruments with equal tempered tuning.

Subject: RE: instruments drift sharp
From: JohnInKansas
Date: 02 Jun 06 - 11:33 AM

Kaleea -

I'm afraid you're leaping to conclusions based on your own confusions. "We," or at least some of us, do understand why some instruments go sharp and some go flat, and why different strings on the same instrument may go in different directions. The question asked was specifically about why some instruments go sharp, so that was the only one addressed in replies. If you want the full course, it can be provided; but I'm not sure it's appropriate now, in this thread.

Most of us also are aware of the influence of "personal preferences" on tunings, and whether Bowers is tuning accurately to a particular "just temperament" is immaterial, since he's tuning to what suits his own performance. He likes it, the way he does it, and that's all that matters. As Guest Jim notes, he needs to do it that way primarily because of peculiarities of his favored instruments, and he can get by with doing it that way because he's primarily a solo performer - and has lots of harps.

Many performers with whom I'm acquainted favor "slightly deviant" tunings, and it makes little difference to those of us who play with them. An advantage in group play is that stringed instruments, and especially long-string instruments like guitars, will pick up the pitch of nearby other instruments, so the "magic tweaks" that many players use simply disappear in a group; and nobody argues with them because it only matters to their imagination; but that's lecture number 397, for another time too.

John

Subject: RE: instruments drift sharp
From: s&r
Date: 02 Jun 06 - 01:00 PM

The original question was from a banjo player. Real skin or synthetic? Now that should make a difference with humidity changes.

Stu

Subject: RE: instruments drift sharp
From: JohnInKansas
Date: 02 Jun 06 - 01:44 PM

Stu -

Isn't the effect with banjos part of an international agreement, that they'll never stay in tune since the more time spent tuning the less time spent playing - which makes every one happier?

Kidding of course.

Banjos are perhaps more susceptible to humidity changes, especially with natural heads; but that was mentioned in one of the first replies. General answers for banjo are difficult because individual instruments may behave differently, depending on head material, tension, bridge height, strings, neck set, etc. An increase in humidity usually will cause a lowering of the tuning if changes in the head are the cause, but restoring an original lower humidity level seldom brings it back up quite as much, at least with short term exposure.

Banjo strings are often at lower tension, and sometimes different materials/construction than other common instruments, so the differential expansion with temperature of the instrument vs the strings may have more effect than for other instruments. Without talking about a specific banjo, with a known setup and known storage conditions, it's hard to say whether the changes will be consistently up or down for many of the things that can contribute to a change in tuning. With any instrument there are some effects that tend toward going down, and others that tend to go up; so it's a matter of which wins the race.

A related phenomenon: In a "session" with a large percentage of "ear tuners" the group-tuning invariably goes up as the evening goes on, especially if several players have a tendency to "tweak a string" frequently during play. A player who uses a tuner at the beginning of a session, but tweaks by ear during the session, is likely to put the instrument away with a higher tuning than when it was set up at the beginning of the session. I tell my buddies who do this it's "ear fatigue" but I think it's really the search for a continually "brighter" sound. Some players have an easier task keeping track of their own instrument if it's "bright" (perhaps 2 to 5 cents sharp?) compared to the rest of the group, so this probably has an effect as well.

Just in case this latter effect might have bearing, the student who asked should be encouraged to put the tuner on his/her banjo at the end of the session. The suggestion could be put in terms of "is it staying in tune" but with a banjo that might sound fascetious... (kidding agin).

John

Subject: RE: instruments drift sharp
From: Kaleea
Date: 02 Jun 06 - 05:13 PM

Sorry!!-- that uppercase "U" was a mis-type, & should have
been an "I" !!
It is I, me & myself, who makes typos & does not understand why certain sections of strings tend to float sharp.
Yes, I know many folks with diatonic Autoharps who use the sweet tuning. My Fladmark is chromatic so as to be able to me the most versatile with other Musicians, & tuned according to A=440, unless my eyes are too elderly to see when my tuner plays tricks on me the way my fingers sometimes do when I type.

Subject: RE: instruments drift sharp
From: GUEST,Jim
Date: 02 Jun 06 - 06:07 PM

Stu,
I was the original poster and the heads on my and my student's banjo are both mylar. Mine is a fiberskin and hers is a frosted skin that comes on a Deering Good Time.
Thanks to all for your answers and theories. I don't know if this'll help me explain it to her, but I'll let her read all this herself and hope she's satisfied. I know that I sure don't need to know any more.
I'm always amazed at the neat responses people receive on this site.

Subject: RE: instruments drift sharp
From: JohnInKansas
Date: 02 Jun 06 - 07:02 PM

An autoharp is actually a pretty complex instrument to try to make general statements about. While it's somewhat true of most instruments, an autoharp really represents "a great bundle of compromises" when viewed as a "vibrating mechanical system," even omitting that it's intended to be musical.

Each string has a tail section that runs from a pin to a "lower nut." The nut usually consists of a more or less straight bar. A center section of the string does the musical vibrating. Each string also has a nose end that runs from an "upper nut" to the tuning peg. The upper nut usually is also a more or less straight bar.

One may quibble about whether one or the other of the bars should be called a "bridge" or by some other name, but that's not too important here.

Because of the multiplicity of strings, the pin and peg usually are in staggered rows, so the "nose end" and "tail end" for a given string can be any of two or three lengths.

The longer the nose end is, relative to the active middle section where you do the playing, the more effect it can produce if a difference in tension between the two parts of the string is produced during tuning, generally raising the pitch if the tension difference evens out - hence there are at least two or three possible conditions within any group of adjacent strings due to the regular alternating of nose lengths.

The longer the tail end is, relative to the active middle section where you do the playing, the more effect it can produce if a difference in tension is produced by tuning, but relaxation of the difference over the lower nut usually will lower the pitch. Again, with two or three lengths due to the staggered rows of pins.

It's common to use strings of a single weight and composition over a range of notes, and the distance between the two bars decreases as you go to higher pitch; but straight bars (with evenly spaced strings) can't give you the pitch intervals needed, so the tension on individual strings must increase/decrease in some regular fashion across the set of "same weight strings." When you go to the next string weight, a similar progression of tension increments will repeat for the next set of strings. Higher string tension usually increases the likelihood that tuning will leave differences in tension between the three sections of the string when you first tune.

Within a group of strings all of the same size, you're likely to notice that it's the strings at one end or the other of the group that's most likely to need retuning, simply because of the progressive change in tension within the group of strings with the same weight. The ones with "long tails" may have more tendency to go down in pitch if the strings don't slip on the lower bar during tuning, but they're likely to be the same ones that have the long noses, and equalizing of the tension in the "nose end" when the instrument sits a while is likely to produce a larger upward shift in pitch for the strings with longer ends at the tuning pegs.

Small to moderate changes in humidity are unlikely to cause much shift in an autoharp, simply because the wooden (usually) structure has to be "massive" to hold the tension of all the strings, and it takes fairly long times for the moisture content of "thick" wood to change by much in response to reasonable changes in humidity. Whether a given instrument is more or less than usually affected by small changes in temperature depends on how rigidly the framework is built.

The short end of the story is that each autoharp is likely to have its own personality, and while each can be analyzed individually, it's unlikely that any of them can be ¹cured.

¹Think teenage children. Love 'em and live with 'em; but remember that each kid will have its own dirty tricks that you have to learn and deal with - usually repeatedly. Sometimes one can look forward to teenagers growing up and leaving home, but an autoharp is probably forever.

John