All Blüthner grand pianos (with the exception of the model 11, our smallest grand piano) are equipped with the famous Blüthner Aliquot string. In the last treble section of our grand pianos, each note is assigned a fourth string. This fourth string is slightly raised from the others and is not struck by the hammerhead. The aliquot string resonates in unison with the note played, therefore amplifying the note without producing an aggressive or metallic sound. The system was developed by Julius Blüthner over a century and a half ago and is considered one of the many features behind the famous Blüthner golden tone.
The Inner Rim Construction, along with the cast iron frame has to withstand huge tensions when an instrument is brought up to pitch. These enormous tensions are distributed from the inner rim assembly to the cross beams. These cross beams are manufactured with a solid centre of red beech with German pine laminated to each side. This makes it virtually impossible to allow movement caused by humidity changes. It also ensures a permanent and solid fit for the bolts of the iron frame. The fan like arrangement of the beams stiffens the rim and prevents any movement. The inner rim and beams on all Blüthner grand pianos are joined using the traditional dove-tail joint, which guarantees the durability of the Blüthner construction.
The iron frame is cast in a quartz sand mould using traditional methods. To withstand the enormous tension of nearly 20 tonnes the design of each frame is precisely calculated and manufactured. Each frame is seasoned outside for two years before being sprayed to a high quality finish and individual fitted to an instrument.
Only the finest white high mountain spruce from selected alpine stock is used for the production of Blüthner soundboards. The wood must have straight running grain and at least seven annual rings per cm. Our soundboards are seasoned for many years to ensure maximum resonance and durability. The shape of a Blüthner soundboard is unique – a cylindrical curve with a tension evenly matched to the strings. Before the soundboard can be installed, it is pre-tensioned and crowned in a process developed by Blüthner. The ribs are shaped to fit the curvature required and therefore the tensions of the soundboard remains in-tact over the decades. In fact, even under difficult climatic conditions, the curvature will remains 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 soundboards curve tension. As the soundboard is pre-stressed in this fashion, it can be fitted precisely and remain under tension permanently.
The bridge is adapted to the tension and curvature of the soundboard in its optimum position. This ensures the string vibrations in their full spectrum are transferred to the soundboard. Both the bass and treble bridges are constructed from European maple.
The pin block or wrest plank is made of 14 highly compressed hard wood layers cross-banded and glued at ninety degrees to the direction of the wood grain. This ensures that the tuning pins are held on all sides and that the tuning stability will be long lived. 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 of the pin.
The hammerheads consist of a core made of white beech on upright pianos or walnut on grand pianos. This core is covered with a dense, hard-woven felt. The head of the hammer hits the strings and makes them vibrate. Our felts are processed in a complex cold-pressing process that optimally protects and preserves their valuable properties. The bright blue underfelt is recognisable in all Blüthner instruments.
The keyboard is the component of the instrument through which the pianist expresses their musicality and connects with their Blüthner piano. With over five and a half thousand moving parts within the action and damper assembly alone, great precision is required to allow a sensitive touch – from fine pianissimo to vigorous fortissimo whilst the pianist retains full control.
The key frame is carefully fitted to the key bed to ensure optimal performance. The key bed is constructed of alternate layers of red beech and German pine resulting in a high degree of stability from humidity and temperature changes. The key frame is constructed from oak. The keys of our instruments are made of fine Bavarian mountain spruce and high density ebony wood. White key tops are made of acrylic. Each key is precisely weighted and adjusted in terms of height and depth of touch.