Mandolin detunes sharp

[Narayan Kersak]

Here is something interesting. #I've got a Mowry. #When I leave it in the case or after I've been playing it for a while,the strings don't go flat, they go sharp. #So I always have to let some slack off and then retune (when tuning is necessary) #Any ideas why this is the case? #Seems counterintuitive to me. #None of my other instruments do that.

[Bertram Henze]

String stuck in the nut slot? When this happens, tuning to sharp leads to higher tension between nut and tuner than between nut and saddle at first, the latter following slowly until tension is equal - kind of retarded tuning.
If that is the reason, lube the nut slots with graphite or nut souce.

Bertram

[Bill Snyder]

Your situation is not that unusual. It is most likely as Bertram says. The string is tight in the nut slots.

[Mark Walker]

I don't think this is unusual. #My cousin has a 1923 Gibson A3 that goes sharp all the time; he 'holds' it in his arms for a while to 'warm it up' and that reduces the change in pitch somewhat. #My A strings on my Silver Angel seem to go a bit sharp after playing too, as does my cheapie PacRim Lotus. #

I live in Michigan - where climate and atmospheric changes happen nearly hourly in the summer. #(For example, yesterday about noon it was hot and 85 degrees. An hour later we had thunderstorms and the temps went into the 60's during the rain. #Yet another hour later it was in the upper 80's again and extremely humid.)

Anyway, my point is I've seen mandolins change pitch, and often they seem to go sharp. #I'm sure there is some scientific and/or physics law behind it all.

[fredfrank]

My mando does the same thing. I always thought it was a temperature issue. In the mornings when I get it out, it's usually cooler than when I put it away for the evening.

I know it's not the nut slots, because we're talking about the whole instrument going sharp, not just a couple of strings.

[Tim2723]

I've allways assumed it was temperature related. All my instuments, including zithers and psalteries that have neither nuts nor slots, do that.

[fredfrank]

Th easiest thing to do is to make everyone else tune to you.


http://www.mandolincafe.net/iB_html/non-cgi/emoticons/biggrin.gif

[MikeEdgerton]

I'd be more inclined to think it's environmental. Tight nut slots are passive. I can understand a tight nut slot letting an instrument go flat as the string tension pulls against it, the opposite defies logic.

[Bertram Henze]

If it's not the nut slots, it might be a humidity thing. Higher temperatures often mean drier air. Since the top is varnished or laquered on the outside but not on the inside, a jump to dry air shrinks the inside faster than the outside, thus causing the top to arch a little bit more => higher string tension; the same way, a jump to humid air tends to flatten the top. At least that is my explanation - luthiers, please feel free to correct me.

Bertram

[Narayan Kersak]

I think I'm going to go with the environmental issue. #Now that I think about it, it tends to do it more so in hot and humid environments. #Outdoor gigs, pubs with no AC.

Hmmm...I would think humidity would make the top swell. For example, in a guitar that has been dehydrated the top caves in a bit...I should say my mando is a flat top, not an arch top.

[Jason Kessler]

All of my stringed instruments detune sharp in the summer, and flat in the winter. It's a temperature/humidity thing.

[Jim Hilburn]

Instruments are made of wood and wood takes on or looses moisture depending on the humidity, swelling when it's more humid and making it go sharp.
My personal mandolin is both a mandolin and a hygrometer. Here in Colorado we can experience big swings in humidity. I run a swamp cooler in summer but if I go to someones house with AC the mandolin will go flat. Half the time I don't notice it till I go to band practice and realize how far it's drifted.
Roland White once told me how much his Randy Wood reacted to the weather conditions as he traveled around the country but it wasn't just the pitch, his action would dramatically change.
I have a theory that more lightly built instruments change more than heavy ones.

[Narayan Kersak]

Mine's pretty light. I've often had a friend pick up my case to put it in a car or move it somewhere and they'll always look at me funny and ask, "Is your mandolin in there?" It is!

[mandroid]

The player is a warm humid environment too, you know.

[Mattg]

My mandos and guitars do the same thing all the time. We get wild swings in humidity during the summer in the Denver area. I also run an evap cooler which causes big temp and humidity changes. I think that does it to mine.

Awhile back, a fellow luthier student braced up a set of tops on a very snowy day. A few days later when the storm passed and the climate dried up, the tops had actually cupped in the reverse direction very dramatically. It doesn't take much

[allenhopkins]

The "tight nut slot" hypothesis does explain a particular subset of the "going sharp" problem. When a string with a tight nut slot is tuned up to pitch, the increased tension isn't equally distributed through the length of the string. The portion of the string between the tuning peg and nut may be under more tension. Then, as the instrument is played, the vibration of the string "works" the string in the slot and the tension gets equalized -- i.e. the higher tension "behind" the nut gets distributed down the string, which can then go sharp.

This is different from an entire instrument changing pitch while being stored in the case. That I agree is attributable to changes in temperature and humidity affecting the instrument's wooden body and neck. Playing outdoors as much as I do, and keeping my instruments in a relatively humid basement room when they're stored, I've had many experiences of putting instruments away and finding them sharp when I took them out again.

My Dobro does have tight nut slots, and a fairly extreme angle between the raised nut and the 1st and 6th strings in their slotted headstock, so I've experienced strings "working" sharp as I play them. I think, however, this is a fairly rare phenomenon, but I know it can happen.

[MikeEdgerton]

OK, I see the logic behind that. If there is greater tension between the tuner and the nut than there is between the nut and the tailpiece I could see it going sharp. I also can't imagine it happening much but at least I understand the physics.

[TeleMark]

There were some interesting instrumental issues at Zoukfest this year (in Santa Fe, NM). Luke Plumb's Gil needed some significant work to adjust for the change of coming from Edinburgh to NM, and I don't think his mando ever quite figured out the climate changes. Virtually everyone experienced major action changes, buzzing, and several had cracked instruments (myself included).

[JGWoods]

I bet your mando not only detunes sharp but the action is getting higher too- humidity.
In the Fall/Winter it will go the other way.
I have a mandolin that is particularly sensitive to humidity and it changes with the weather more than the seasons- muggy, rainy, top raises and it goes sharp and the action gets higher.
Dry and clear- top settles down, action lowers, goes a little flat.
It sounds great most of the time and its been shifting around for 50 years without major damage. I do raise or lower the bridge with t he seasons to keep the action in a good range.

[Larry Simonson]

I, in agreement with several other posters, have seen both my mandolins detune sharp in the summer months and detune flat in the winter repeatedly over several years. #Since this mirrors the local relative humidity, I belive there is a correlation. #I know the pain of having to tune down all the strings and slowly bring them back to pitch.

[JeffD]

All of my stringed instruments detune sharp in the summer, and flat in the winter. #It's a temperature/humidity thing.
Same here

[Jason Holmes]

Mine do that too. I always just assumed it was climate changes happening and making the top rise or fall ever so slightly, hence the string tension changing. My nicer mandolin seems more susceptible to this, making me think it's got the thinner top of the two that I own.

[Tim2723]

Now that I've thought about it, mine are sharp in summer, flat in winter too. Even those without nuts.