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| Why your piano goes out of tune |
There are five 5 main factors, why the piano goes out of tune.
To enumerate those factors by importance.
- Humidity changes (Controllable by us)
- Temperature changes (Controllable by us)
- Natural stretching of strings (Uncontrollable)
- Loose tuning pins (preventable sometimes not)
- How frequequently play it (Hard to say)
Factor 1 Humidity changes
According to my record and research.
An average pianos which is less than 30 years old
and maintained normanly ,the pitch goes 20cent (similar to percent) up from beginning of spring to end of summer and 40cent down from beginning of aurumn to end of winter.
Even though it was cutted for a long time ago and it's definitely dead.
The wood in the piano react like a live one.
For it's cell structure
(Imagine the grain of the cutting surface. It's wide in summer and narrow in winter)
Especially sound board(to simplify calculation I choose upright piano not grand), for it has such a wide area like
Height (1~1.4 M) * Width (1.4 M) * 2 (Double Side) = 2.8~4
Add more it has such a thin depth. Less then 1Cm
Under such a condition the quantity of the water which the soundboard absorb in the air is huge amount, as a result of interaction comes out without delay.
Problem is the lower end of the string and wire in the piano are linked to bridges.
And "bridge itself is bonded to soundboard” to deliver vibrate from strings and wires to soundboard.
Yes, this is the inevitable problem.
Bridge itself is bonded to soundboard
All the strings and wires are linked soundboard through bridges
As the soundboard shrink and expand, the tension on the string and wire are Changing.
As the tension changes the pitch changing.
Factor 2 Temperature changes
The humidity I mentioned before is the
Relative Humidity(RH)
RH = 100% Specific humidity
-----------------------
Water vapor capacity
The numerator, Specific humidity will be decided by raining
We can not control the raining. It's up to God's will
So let's just say it a constant.
"A denominator, Water vapor capacity will be decided by air pressure and temperature."
We can not control the air pressure either. It will be decided by Butterfly's wing.
So let's just say the air pressure as a “constant” to
simplify the explanation.
Now only "temperature" remains in the formula.
This is the only variable in my story.
Just imagine that you ordered one can of pop in a restaurent.
And waitress brings a glass with it.
So that you can pour it into the glass.
If the glass has a wide bottom area,then
the height of your coke looks shallow after pouring it.
Conversely if the glass has a narrow bottom area,then
the height of your coke looks deep after pouring it.
"The area of the glass" means "Temperature"
"The height of coke" means "Relative humidity"
During pouring coke in your cup, if the height became heigher than cup's capacity for its narrow area of the glass.
It overflows to the table.we call it "Condensatin or dew and frost in the sub zer
Without any supply actual water in the air.
(=constant Specific humidity)
As the Temperature gose high,
Relative hunidity goes down.
Let's see what happens in our house in winter.
Outside is Sub-zero enviroment,No raining or snowing during recent 7days.
Without raining no actual water supply in the air.
Also due to low temperature outside quantity of water in the air outside is very limited.
But you are running a heater without a humidifier.
So the humidity is arount 20% sometimes less than that.
Here's the web-service from Georgia State University
Atlanta, Georgia 30303-3088
Click Here for calculator
You can experience it's relation in this virtual laboratory work. (I'm pretty sure this site is like a treasure for your children's education.)
Click there and turn on the TV
set the channel to 24
on there you can see current "temperature and Relative humidity" Outside of the house.
If you have a hygrometre,please check the temperature and humidity inside of the house either.
- Put outside temp,RH on the calculator and writedown actual humidity in the calculator to know quantity of actual water contains in the air per M^3.
- and then put inside temp (normally 20~24C)
,and then change RH in the house until it became same actual humidity in the air from outside. That is your house RH without any humidifier if you only supply
water in the air from the natural surrounding.
- Now put temperature 25 and then set the Relative Humidity 45%.
Yes, that's our final goal to keep it safely.
Result on 3 - Result on 1 = Needs of actual water in the air to keep the piano perfectly.
Yesterday was 2006/12/14 and today is 2006/12/15.
In my case,I spend 11gallons of water
to keep 45% humidity in my house.
Follow this link if you are interested in all these informatioin, and make sure everything.
Click Here for information about EMC
(Equilibrium Moisture Content)
Canada Weather Centre
Summary: Don't change the temperature.
For it changes Relative humidity.
It's like a electromagnetic-interaction
Factor 3 Natural stretching of strings (Uncontrollable)
The average modern piano has over 230 strings under a combined tension of 15 to 20 tons.
A concert grand piano may have a combined string tension of up to 30 tons.
Although piano wire is made of steel, it does have some elasticity and does stretch.
A new piano, or one that has been restrung, will continue to stretch and go flat for quite some time.
If you have ever replaced a set of strings on your guitar, you know what I am talking about!
After a piano has been restrung retuned , it needs to be tuned a minimum of four times that first year and a minimum of twice a year thereafter.
Even after stabilized,actually stretching doesn't stop.
It only slows it's speed.
Also shortening the time spend until it stalized is the
genuine skill of each piano technician.
Factor 4 Loose tuning pins
Or maybe I can call it a cracked pinblock.
Usually that red area will wearout when ever you tune your piano.
But it's real small part of it so usually doesn't weaken the friction
between tuning pin and pinblock.
But if you fail to control the moisture
In the dryness. The pinblock shrink so there's no friction.
Unable to tune such a piano and it's called "Dry Out"
If the pinblock was soaken by the rain or dripped coffee.
It also weaken the friction.
Accordin to my record. Such a pinblock goes out of tune
3 to 5 times faster than normal.
You can see the result on such a defect from
following link in case 3
Click here
Although you kept it perfectly.
There's possibility the defect from the nature it self.
Eventhough it was firmly checked and selected woods before manufacturing.
The wood always has a node and it exist somewhere in the layer as a part of laminated thick block.
Sometimes it makes such a defect eventhough it was only 5 years old piano.
Pray before you buy the piano.
Factor 5 How frequequently it gets played
It's not a big factor but it still exist.
The reason why pianist tune their piano in every 6 months
is not only they have sensetive ears but also this reason.
They play it almost every day a lot of time and it accumulate
shock on the string sot that make the piano out of tune.
Hard to say objevtive percent but there's a tendency that
hard player's piano goes out of tune in short time.
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