Frank Benner

piano technician

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All pianos are different

All pianos are different, all the people that play the piano are different and the restorations we perform are different every time:

Sometimes we work on a grand piano
for a firm that lovingly restores old instruments.
We take the keyboard and the action back to our workshop, where we do a complete repinning and replace what’s worn or moth-eaten.
We can also repair worn or broken ivory keytops and make sure the keyboard runs smoothly.
If necessary we can renew the worn out hammers, or put new felt on the dampers.
When everything is returned to it’s place and regulated, the grand piano feels like a new one when you play it, but the character of the old instrument has not changed.

Sometimes a tuner asks us to work a few days on a piano in a music- school.
Work he finds too time-consuming or intricate to do himself.
We do the very necessary repairs and cure ailments like squeaking pedals.

Sometimes we restore a very well loved piano that has been in the family for years.
The cost can surpass the actual value of the piano, but it’s worth it because the instrument is of course irreplaceable.
We can do a total overhaul of the instrument.
In some cases that means for instance repair of any existing cracks in the soundboard, a newly calculated set of strings, and usually the revision of the action and keyboard.

Every time we shall discuss it
when we think an instrument is not worth the repair.

Sometimes we work a full week in a conservatoire
to retain and regulate the many pianos and grand pianos.

Sometimes you can find us in a lonely dark corner, under the stage of a concert hall, to take care of the intensively used grand pianos.

Sometimes we use a day to regulate
an already beautiful grand piano in an even better shape.

Every time we enjoy the challenge
to finish all those different jobs to perfection.

If you look further down, you can find more information concerning the different kinds of repair.

Topics, click:

> The touch
> Voicing
> Inharmonicity
> The restauration of ivory keytops
> What's inside my old piano?
> How does a player piano work?
> Vibrating strings
> Moving pianos is a specialist job
> Repinning
> Variation in sound
> The freedom of the piano restorer

The touch

The touch of an instrument is in a huge way responsible for the pleasure the pianist gets from his piano.
The music that is being played needs to sound the way the pianist wants it to sound.
When the regulation of the action is not finished rightly, the best quality instrument will be a disappointment to the player and a disappointment to listen to.

Voicing

Regarding the sound , the voicing is the finishing touch of a piano or grand piano. After the tuning and fine-tuning of a piano, the heads of the hammers are being treated with a voicing needle.

In the factory the wooden mouldings of the heads are wrapped tightly around with a thick layer of pressed felt. The tension and the choice of material determine the hardness and elasticity of the head.

By using voicing needles on certain places in the felt, the hardness and elasticity can be changed.

Using this method not only makes it possible to even out internal differences in tone, one can also alter the complete sound of the instrument.

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When the felt on the head of the hammer is cut through , you can see clearly how big the tension is on the felt.

Inharmonicity

Every note we play on a piano exists of a fundamental and a few partial sounds.
In short the inharmonicity of a string is the deviation of the different partial sounds according to each other and according to the fundamental of the string..

If for instance the fundamental is 440Hz, the first partial is 880Hz.
When that first partial is not exactly 880Hz but for example 880.4Hz we call this difference the inharmonicity.

The inharmonicity is determined by the stiffness of the string.

The stiffer the string, the higher the inharmonicity.
A short thick string is much stiffer than a long thin one producing the same sound.
The inharmonicity of the bass strings of a concert grand piano is much lower, because the strings are much longer and thinner, sounding much lower than those of a baby grand.

Usually one cannot hear the fundamentals of the lowest bass strings. Partially due to the tones sounding on the limit of the human sense of hearing, but mainly because the soundboard is not capable to transmit these tones well.

Even listening to a small transistor radio, that does not give low frequencies at all, we can tell the difference between a small and a big instrument.
The human ear is used to construct a fundamental from the different partials.
The inharmonicity is perceptible with great ease.
The level of inharmonicity can tell us if we are listening to a grand piano or a small upright.

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What do we perceive as a sound being  'beautiful'?

That, of course, is a matter of taste, but maybe habituation takes a part too.
Very small instruments (high inharmonicity) have a sound we usually don't like so much.
But do we like the sound of an enormous instrument like the Klavins 370?
This instrument has an extreme low inharmonicity and a enormous big soundboard too.
Thanks to that colossal soundboard it should be able to radiate the lower sounds.
Still we have to get used to this sound.

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Can we change the inharmonicity of an instrument?

Most piano manufacturers have started to determine the scale by trial-and-error. (the scale comprises the length and thickness of the strings)
Renowned manufacturers have had more possibilities to experiment themselves, but the small ones often copied the scale from others.

It was only in the fifties of the last century people have developed a formula which can be used to calculate the inharmonicity.



In a restoration project it is not possible to change the length of the strings, but by adapting the thickness of the steel and the copper of the windings, it is possible to greatly improve the sound and tuning of the instrument.



For the calculation of the strings we use a computer program written by mr.Hans Velo from Maartensdijk in Holland.

The restoration of ivory keytops

The first and most important contact between player and instrument runs through the keys.
The touching of these keys is the human movement that sets forth a series of technical actions in the inside of the piano, resulting into sound.
It's a delicate connection between hand and ear.

The keys should be almost as sensitive as the skin of the fingers of the pianist.
Careful attention to the surface of the keys is for that reason very important.

As key top, ivory has the primary quality of absorbing sweat. Therefore it feels much nicer than acrylic when you play.
There have been many experiments using different kind of acrylics or for instance bone. Regrettably there has not been found an alternative for ivory, with the same properties.

It is not possible to buy a new piano with ivory key tops, because of the ban on ivory trade.
An old piano can still have ivory key tops.
Unfortunately a lot of ivory has been replaced with acrylic key tops in the past.

A damaged ivory keyboard can be restored satisfactorily, unless the ivory has become too thin.
Using techniques from the dentistry we can repair broken pieces of ivory almost without a trace.
The damaged area is prepared with a dental drill to make further treatment possible (1)
The surface is treated with different chemicals (2)
A special composite is applied and hardened with Ultraviolet light (3)
The last action is the sanding and polishing of the ivory key top (4)

Loose ivory key tops are glued back with special glue. Missing key tops are carefully replaced with old reclaimed pieces. Following is the careful sanding, bleaching if necessary and polishing of the ivory key tops.

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My old piano

What's inside my old piano?

A frame ready to burst
Woodwork affected by mildew
The hammers with motty felt
The whippens are moving too slow
Loose ivory on the keys
The soundboard is cracked
The tuning pins are hanging
The pedals need lubrication
The wood on the back is infested by woodworm
A long lost key of the backdoor
Droppings from resident mice
A yellow sheet of music, never been played again Forgotten pound notes

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Strings

Although you'll find strings inside the piano, we don't call it a stringed instrument but a keyboard.

A finger touches a key
The key touches the action
The action sets the hammer into motion
The head of the hammer hits the string
The string is vibrating

The vibrating string touches the bridge
The bridge moves the soundboard
The sound reaches our ear

If all the strings would have the same thickness, the speaking length should be twice as long with each octave we go down.
If the highest A is 5cm long, the lowest A should be 640 cm long.
An instrument this size would not fit into our homes. That’s why we choose a shorter length and add to the thickness of the string.
The bass strings are wound with copper to get the sufficient mass we need for the right sound.

The division between length and thickness of the strings is called mensuration.

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How does a player piano work?

A pianola or player piano works on a pneumatic system where a vacuum is built up by bellows that are driven by pedals or an electric power.
A paper roll is pulled over a metal bar with a row of punch holes. In the paper roll you can find punch holes too; one little hole for each tone. Modern types also have holes for dynamics and pedal-use. Each punch-hole is connected with an ingenious system of valves and membranes. When air sucks through the hole in the paper, it lifts a corresponding membrane, which opens a valve, which closes a little bellow. This little bellow sets into motion the action of this particular tone and the hammer hits the string.
The speed, in which the paper roll passes the bar with the punch holes, indicates the tempo. There are special levers to adjust the tempo. The volume of the tone can be increased or decreased by the force in which the bellows are driven.

One can find special piano player rolls, played by famous artists and composers of old times. The pianola roll, when it was invented, made it possible to record complete pieces. The only alternative in those days: the record with 78 revolutions per minute had a limited playing time. The pianola gives us an opportunity to listen to the way a composer like Rachmaninov performed his Prélude in g minor.

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Moving Pianos is a specialist job

The story by Anna Enquist is a perfect example of the way pianos and grand pianos are moved.
Luckily nowadays, we have the right equipment to do that.
In the old days it was a different matter, pianos and grand pianos were carried up the stairs by four men using special webs.
This must have been very heavy work. The Bechstein grand piano on the picture weighs about 500 kg.
Moving pianos is a special skill; piano movers could and can only do it because they know exactly what they are doing.

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Variation in sound

Everyone knows the traditional part of the piano in a concerto.
To avoid this role-reinforcing part and looking for new ways to colour the relation between the piano and the orchestra, the composer is confronted with things that are not possible using the piano: making a crescendo within a single note: a note which is sounded and which thereupon grows in vollume.
This was the inspiration for a concerto for piano. The crescendo, following the first note, is realised by six horns, which take over the tone of the piano and so in this way replace the soundboard of the piano. This idea of soundboard replacing is taken over by the whole orchestra in a next stage.
The use of the piano as a rhythm instrument is not avoided, except in the more contemplating middle part. In the Piano concerto a principle can be found: the exploration and crossing of borders.
This is even made visual at the end of the concerto when the last tone a c is tuned into an f sharp with a tuning hammer.
The tension builds up by this stretching of the string and the perception of the music is culminates into a very sudden ending of the concerto with a single ‘whiplash’

Some composers write down even more variations in their score than even the piano or grand piano can offer.
In such cases a lot of adjustments have to be made into the instrument, such as the placing of screws, clothes pegs and pieces of rubber on strategical places in between the strings.
Sometimes the sound is made by hitting the strings with sticks instead of hitting the keyboard, or by strumming the strings by hand like on a guitar or harp.
The tuner or piano technician watches this with mixed feelings…

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from: Bildatlas zum Lehrbuch des Pianofortebaues. Verlag E.Bochinsky, Frankfurt/Main.

Using Passion and good Sense

Everyone playing the keys of the keyboard with passion, expects to hear the same passion expressed into the sound.
The player should not need to worry about the functioning of the action inside the piano to produce that sound.

How do the action parts move?

In this picture you can see the action of a grand piano with its hinge points.

The action of a piano or grand piano has a great number of moving parts. When we press a key, it puts into action: a whippen, a hammer and a damper! All these moving parts have their own hinge points.

One part of the hinge point, the so-called flange, is screwed on its rail.
The other part must be able to move.
The hinge point, the center pin, is locked into the wood of one part and is able to turn in the other part.
The little hole in that part is lined with cloth to make this possible. This is called the bushing.

This is a blown up picture of a part of the flange.
Very clearly one can see the bushing with red cloth and the center pin.
The hole in the wood is only 2.5 mm Ø, the center pin 1.3 mmØ

This technique has the advantage of a very small scale and a great durability.
The disadvantages are: wear and tear causing unwanted slacking of the parts. The bushing can become to loose causing the action part to tick.

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High humidity is a greater enemy: damp, but also the use of lubricants, causes the center pins to get stuck in the long run, with a slow reaction of the action as a result.
It will get more and more heavy to play the piano and in the end it will be impossible, when different parts get completely stuck.

A piano should always be in the right climate and the hinge points should never be lubricated. Lubrication causes the hinge points to get rigid.
When the action parts tick or get rigid they need to be repinned. The action must be disassembled and the old pins are one by one pushed out of the wood.
The bushing cloth needs to be reamed with a special reamer and after that a new, one size thicker pin, will be pushed into the flange.
Repinning is a very meticulous job because the new pin is only 0,025 mm thicker than the old one.
If the bushing has become greasy, through the use of lubricants, it has to be replaced: a very time-consuming, expensive job.

To give you an idea of the size of the of the hinge points: a match is put beside it!

One needs to take away exactly the right amount of bushing cloth with the reamer.
It takes a lot of time because a modern piano contains over 330 pins and a grand piano even almost 500!

centerpin

To play the piano well is a matter of passion.
To treat a piano well is a matter of good sense.
We think of all the people using their good sense to do this: People building, renovating, restoring, innovating, and preserving pianos.

Freedom

How much freedom does a piano restorer have?
We believe the original design needs to be respected and maintained.
As a matter of course original materials, like for example bone glue, need to be used as much as possible.
Only if necessary one can use an alternative, avoiding irreversible changes to the instrument.

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