A new grand action



At the beginning of the new millenium we introduced a new innovation in the grand piano action. This new action design is called the Magnetic Balanced Action or MBA for short. This innovation was designed by Evert Snel and Hans Velo and has been incorporated in a number of grand pianos built by some of the top piano manufacturers. The MBA system is also available as retrofit-kit in Europe and the USA to retrofit conventional grand pianos actions. In our opinion and the opinion of a number of pianists and technicians this new balancing mechanism has numerous advan­tages over the conventional grand piano action. Almost any conventional grand action can be retrofitted into the Magnetic Balanced Action.

The conventional grand action

In the course of the development of the piano in the 19th and 20th centuries, the weight of the hammers has been increased, in order to augment the volume of sound the instrument can produce. This was made possible, by the introduction of the iron frame, which allowed for the use of higher tension strings.

To keep the touch weight of the keys the same as it was in the instrument with light hammers, the practice developed of inserting lead weights into the piano keys .

The force which the hammer operating mechanism of the modern grand pianos exerts on the rear end of the key is often so great, that without speci­al measures, the touch force or weight at the front end of the key, would become too great and would vary from key to key over the scale of the piano.

The most commonly used method to date, to equalise the key touch, has been to insert cylindrical lead weights into the piano key. These are placed in the front-end of the key when the touch weight is too large and in the rear-end of the key, if the touch weight is too small.

For example in the bass section of the modern grand piano the touch weight, without lead in the key, can be 95 grams. In order to get a touch weight of 52 grams, which is normal for the bass section, a considerable amount of lead weights must be placed in the front end of the key.

An example of such an action is shown in the next figure.

                                                                                                           


This method has several disadvantages for the technician as well as for the pianist:

1) It is time consuming to determine the number and optimum position of the weights, for each key individually.

2) Due to the increased weight of the key's, the moment of inertia of increases, which is especially detrimen­tal to the key's dynamic response, in the bass section of the piano.

3) This method only equalises the static touch-weight of the key.

4) As the instrument is used, the hammers become grooved. It then becomes necessary to file away some of the outer felt from the hammers to compensate for this wear. This of course destroys the original accuracy of the weigh­ting.

In conventional piano technology there is no practical way to compensate for such changes, or for the change in touch-weight that may sometimes arise from changes in relative humidity.

5) Using this method, it is practically impossible to adjust the touch-weight to the wishes of the individual pianist. That means that when the instrument is used in the concert hall, the pianist has to accept the touch weight of that instrument.


As noted above, it is important to remember, that the addition of weights to the keys only equalises the static weight of the keys, i.e. only for keys in rest position or which are depressed very slowly. When the piano is played loudly or quickly, the force required to accelerate the hammers from a state of rest to a relatively high velocity, requires a much more dynamic input force than is the case when the keys are depressed slowly.

Although the static force, required to raise the hammer, may be in the range of approximately 48 to 52 grams, the dynamic key force by loud and/or fast playing is considerably greater.

At these key speeds, the result of adding key weights, to give additional touch-weight to the key, makes the touch sensa­tion of finger against key different, for a piano key with a large number of weights than to one which has no weights or only a small number of weights.

The amount of key inertia apparent to the pianist also depends on the distance of the weights from the fulcrum of the key. As a result, the feeling of the action for the pianist may differ from key to key. So static equalising of the touch weight does not always mean an equal touch feeling for the piano player.

The new Magnetic Balanced Action

The present new MBA action uses a system with magnets to equalise the touch weight of the piano keys. In short, there are two opposite polarity (attracting) magnets at the front end of the key, counter-balanced by two same polarity (repelling) magnets at the rear end of the key. This is made possible by the development of modern magnet materials. This modern magnet material will not lose it magnetic properties during the lifetime of the piano.


This method described, in short, has several advantages.

5) It is very easy to adapt the touch-weight quickly to the personal preferences of the pianist. In fact, the pianist can do it themselves, by manipulating a number of adjustment controls at the front of the instrument. The touch-weight can be adjusted from +5 grams in relation to the nominal weight, to –10 grams in relation to the nominal weight. In the latter case, the touch-weight is reduced by about 20 per cent.

6) Maintenance is also improved. If grooved hammers have to be filed down, or even replaced, it is very easy to adjust the touch weight of the piano keys individually. This adjustment is also possible if changes in relative humidity caused touch w

 

The operation of the Magnetic Balanced Action

The following diagram shows the MBA installed in a bass key.



At the front-end of the key about 5 cms. from the balance point, a magnet attached to a screw is mounted. Oppo­site this magnet a second magnet is mounted on a fixed rail. The polarisation of these magnets is set to attract each other. The force of attraction can be adjusted by altering the air gap between these two magnets, which is done by adjusting the screw at the front-end of the key.

As can be seen when the key is depressed, the gap between these magnets decreases and the force of attraction increases.

To compensate for this effect a second pair of magnets is mounted, one in the rear-end of the key, in the same fashion as the magnet in the front-end of the key, opposite of this one, another magnet is mounted on a vertical movable rail. The polarisation of these two magnets is set to repel each other. This force can be adjusted, by altering the gap between the magnets, which is done by adjusting the screw at the rear end of the key.

If the key is in the rest position, the gap between the repelling magnets is relatively narrow and the gap between the attracting magnets is relatively wide. If the key is depressed the force of attraction at the front end of the key increases and the repelling force at the rear end of the key decreases. Consequently, an increase in the attracting force is compensated for by a decrease in the repelling force. If the magnets in the key are adjusted so that the gap between the repelling and the attracting magnets is equal at the point where the key is depressed half-way, then the compensating force is almost equal during the depressing of the key.

If the gap between the repelling and attracting magnets is equal when the key is fully depressed, then the compensating force will be higher when the key is at the rest position, than when the key is fully depressed. This has the effect that the key has a lower starting touch-weight than the average touch-weight . At the practical level, we have established that this kind of adjustment facilitates playing, especially pianissimo playing.


It should be clear from the above that, because of the adjustments which are possible, the new magnet-assisted compensating mechanism offers great flexibility in the key touch.


By virtue of the fact that half of the compensating force is supplied by a mechanism which has the effect of lifting the key (i.e. the repelling magnets at the rear end of the key), the amount of friction at the point of balance is reduced, in comparison with a mechanism which supplies compensating force by means of a couple of lead-weights.


As mentioned above, the magnets which are located opposite the magnets in the rear end of the key are mounted on a vertical rail. This rail can be moved up and down from the front of the piano, making it possible to adjust the touch-weight of a group of keys simultaneously. Consequently, the pianist can adapt the touch-weight of the entire keyboard according to his or her preference within half a minute.


A simplified version of the MBA is also possible by leaving out the controls at the front of the instrument. Also in this version it is still possible to adjust the touch weight to the preference of the pianist, but this has to be done by a piano technician by adjusting the magnets in each key individually.


Some reactions of pianists

(In random order)

Martijn van den Hoek:

This action showed an ,,easy-to deal-with" quality, with the possibility of a direct adaptation within shortest possible time. When I was informed about the details and additional possibilities, that can be derived from these, i.e. the quick adjustment of the key weight and the easy maintaining of it, I truly felt that this might be a real contribution to the, more or less perfectioned piano as we know it today.

Paul Komen:

The complete absence of inertia, especially in the bass register, is quite spectacular. This gives a lightness and directness that I have never before encountered in a piano. The sensitivity of response makes possible the finest nuances, making this action the ideal tool for one to approach one’s ideal sound. In my opinion, this is the most important invention in the piano action since Erard’s double repetition action. It merits wide-spread application.”

Carlos Moerdijk:

On Tuesday 23 March (1999), together with Emmy Verhey, I made a recording with your Fazioli. I was very surprised at the touch. How you have made pianists happy!  I think this invention is of equal importance to the invention of the double repetition action over a century ago. I hope that many grands will be equipped with this action.”

Rian de Waal:

With this letter I would like to express my enthusiasm with the magnet action. The magnet action is a fantastic improvement as it allows the pianist literally to play with the touch-weight of the keys. On days when you have to practice for eight hours, the touch is as light as possible; on days when Brahms’ First, or Rachmanninov’s Third is on the music reading desk, a touch-weight as heavy as possible is there to train the muscles. Its ideal!

Bert van den Brink:

From now on, easy or light playing is no longer the same as weak and unpredictable playing; on the contrary, the keys stick to your fingers regardless of the chosen touch-weight.


If you are interested in a demonstration or on further information, please contact me.

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