Grand and vertical pianos consist of a number of essential sub-assemblies. Blüthner coordinates them with one another in mutual harmony to guarantee the legendary Blüthner sound.

The back and cast iron frame have to take up the enormous tension of the strings that comes up to almost 20 tons when the piano is tuned to 440Hz.

The pre-crowned soundboard is solidly glued in place on the back assembly with the iron frame positioned directly above. Circumferential supports or a frame liner of red beech fit exactly to the curvature of the soundboard and fix the frame at the proper height (Figure 2).

This strong design, quite unique to Blüthner, captures the soundboard, giving it the freedom to develop the full spectrum of the string vibrations and not be absorbed by the load bearing components.

Such a system ensures a more complete transmission of the string vibration without interference or tonal loss.

The iron frame takes on the force from the strings under tension and must be firmly connected with the inner casing under structure.

Blüthner has developed an iron frame that is reinforced along the main tensile lines of force. It is not only important to have an appealing and timeless design; the frame also has to be able to affect the instrument's acoustics.

Blüthner's many years of experience and knowledge in iron frame design ensure that no audible amount of the tonal spectrum is lost. In fact, the iron frame does indeed contribute to the tonal development of the Blüthner piano.

All fitting of the iron frame is done in house. This means that over 600 holes for pins, tuning pins, and bolts are drilled by hand using a number of control measures to ensure preciseness.

A full mirror finish is the final touch to this work of art.

Many control measurements and quality checks of materials and fittings are necessary in order to build a piano that is worthy of joining the ranks of the Blüthner tradition.

At the beginning of piano making the soundboard consisted solely of a thin wooden board, stiffened with bars glued on the underside and the bridges on the upper side.

Further development was derived from the soundboard of a violin with its spherical crown. However the soundboard of a violin is made of a thick piece of wood being shaped by grinding, chipping and sanding into its final form.

A piano soundboard is made from a thin board being bent by force into this form. this method however produces disadvantages comparable to those which one will experience when you try to put a sheet of paper atop a ball.

Studies made by Blüthner's research and development department have proven that tensions and compressions develop on the edges that are inhomogeneous and not controllable.

In contrast, the soundboard that Blüthner has developed has a cylindrical curvature so that the tension of the soundboard can be exactly defined. The ribs are planed to fit the curvature needed and therefore the tension of the soundboard remains intact over the decades.

In fact, even under difficult climatic conditions the curvature will remain in a constant form since not only the rib structure will hold it in place but also the red beech inner rim is pre-formed to the correct angle to receive and retain the soundboard's curve tension. Because the soundboard is pre-stressed in this fashion it can be fitted exactly and remain under curve tension permanently.

The bridge, of course, is adapted to the tension and curvature of the soundboard in its optimum position. This ensures that string vibrations in their full spectrum are transferred to the soundboard.

By utilizing the resonating surface, the special design of the Blüthner soundboard generates tone significantly better. This guarantees every Blüthner piano its legendary sound.

The bridge is constructed from European maple. This material is strong and conducts the string vibrations well. In the upper section the bridge is capped with cross-laminated European maple. This ensures solidly fixed pins for many years to come.

Generations of piano makers have been constantly attempting to improve the quality of their instruments.

Julius Blüthner made an important contribution with the development of the Aliquot System. Patented for the first time in 1872, it was one more step that provided Blüthner's well known warm and romantic sound.

Currently, the Patented Aliquot System employs and additional fourth string in the treble section attached directly to the bridge that is not struck by the hammers (Figure 6).

The fourth string is stimulated to vibrate through sympathetic resonance when the other three strings are struck, which results in an acoustical system enriching the overtone spectrum. It produces a very dynamic sound, which is audible over a wide range. This unique effect conveys the resonant treble of the Blüthner piano.

As an example, it is possible to experience this special effect with many of Beethoven's compositions giving an added dimension in tone colour and dynamics.

Another factor that is a great advantage is that all Blüthner strings are individually hitched.
This allows for the Aliquot System to develop to its optimum as well as guaranteeing that the strings are tuned exactly.

For optimum effect, precise tuning is essential. In today's instruments the 'aliquot strings' are tuned in unison with the trichords.

The Renner Action, including the action and damper mechanism, is the component of the piano through which the pianist can physically connect with his or her Blüthner piano. Therefore it is not surprising that Blüthner has gone to great lengths to design this very sensitive part of the instrument to withstand enormous amounts of use and stress.

The keyframe is carefully fitted to the key bed to ensure optimum performance.

The key bed is constructed with alternate layers of red beech and pine resulting in a high degree of stability from humidity changes and use. Naturally tanned high quality calfskin trim on the lodge points of the key frame ensure a quiet movement. such solid construction also results in long lasting regulation of the Renner action and keys.

Blüthner's technicians skillfully regulate the action to exacting specifications that ensure the highest degree of precision, adjustment and regulation. It is also important that sensitive key balancing is performed to exacting specifications that ensure ease of repetition and control since this is the basis for long and constant play.

Again, it is good to stress that it is an old tradition at Blüthner to regulate their instruments at least three times or more before leaving the factory. For best intonation of the hammers, the elasticity of the felt is adjusted to the needs of the instrument. This is accomplished in several steps with the ideal to develop the Blüthner tone to its full beauty and resonance.

Blüthner's voicing specialists perform this task using special techniques to adjust the hardness and elasticity of each hammer. The density and size of the hammer is an important factor the voice must deal with also in this process. The larger hammers are made with the traditional inner and outer layers of felt which help to stabilize the elasticity of the hammer and aid in producing the full rich tone of the Blüthner piano. All of these factors combine to form a basis for long lived and finely modulated hammers.

The Pin Block or Wrest Plank has the special task of acting as a receptacle for the tuning pins and to keep them very tight, to hold the string tension and still allow the piano to be tuned.

Blüthner gives an additional support of a hardwood bushing where the tuning pin passes through the iron frame, which aids in reducing the bending load on the pin.

The wrest plank is made of 36 highly compressed hardwood layers cross-banded and displaced at 22.5 degrees to the direction of the wood fibre. This ensures that the tuning pin is solidly held on all sides and that tuning stability will be long lived.

Blüthner continues to set the pace in this area with the latest results of research that are combined with traditional production techniques and methods.