Ini aku iseng2 copy paste guideline lecture ku buat acoustics class 1 minggu lagi. Aku kira pasti ada orang yg tertarik baca2 ttg. konstruksi piano. Ini research ku yg ntar jadi bahan lecture di kelas. Ambil sana sini... Moga2 bisa lebih appreciate piano, ternyata rumit nya bukan maen >_<.
Di tengah ada tabel sebenernya, tapi kayaknya rusak, ngga bisa ke copy paste, tapi ada penjelasannya napa aku pasang tabel itu.
BTW, kalo inggris nya singkat2 n ngga jelas, harap maklum nya, ini BUKAN artikel yg aku buat, ini cuma guideline buat aku ceramah di kelas ntar .. setelah 8 jam research ama ngetik, aduh .. maen piano aja jadi neg setelah tau serumit ini barangnya. hahahahaha .. anyway .. cheers .. ! have fun with it ...
Piano Lecture on Musical Acoustics
History and Basic Construction
The physics of the piano sound can be described by reviewing the evolution of the modern piano and its principal components. As a “stroked” string instrument, it has similarities with string instruments. Started before the recorded history, string instruments are existed. Bible refers to an instrument called psaltery that was played by plucking strings stretched across a box as the resonator. As well in China thousands of years before the Christian era, a similar instruments are found.
Around 6th century, Pythagoras used a simple stringed instrument called monochord in his investigation of the mathematical relations of musical tones. It’s a single string stretched tightly across a wooden box with a movable bridge than can divide the string into various lengths and can vibrate differently at a different fundamental frequency.
Invented 1709 by Bartolomeo Cristofoti in Florence. More than 7 octaves (88 keys).
The main parts are the keyboard, the action, strings, soundboard and the frame. A typical concert grand piano has 243 strings, varying in length about 2m at the bass end and about 5cm at the treble end.
Read the part of the pianos on the print out!
The soundboard is usually made of spruce about 1cm thick (10mm) with its grain running the length of the piano. It’s the main source of the radiated sound just as is the top plate of a violin/cello.
3 pedals of piano:
1. Sustaining pedal (right pedal)
Raises all the dampers, letting the strings to continue vibrate after the key are released
2. Expression pedal (left pedal)
In the most grands it shifts the entire action sideways, causing the hammers to strike only 2 of 3 of their strings. In vertical/upright piano, it’s a soft pedal, which moves the hammers closer to the strings.
3. Sostenuto pedal (center/3rd pedal)
It sustains only those notes which are depressed prior to depressing the pedal and doesn’t sustain subsequent notes. On few pianos, it’s a bass sustaining pedal which lifts the bass dampers, and on a few upright pianos it’s a practice pedal, which lowers a piece of felt between the hammers and the strings, muffling the tone.
How Piano Works
Hammer mechanism = inner mechanism on piano (read the part of the piano). Frame, Soundboard, Strings, Action, Pedals, Case, Pinblock, bridge.
Strings of the piano convert kinetic energy of the moving hammers into vibrational energy and pass it on to the bridges and soundboard. They determine the sound quality of the piano a lot.
Piano has 3 strings for each note. The best piano sound results from tuning those strings 1 or 2 cents different from each other. If they are tuned to exactly same frequency, the transfer energy from the strings to the soundboard takes place rapidly and decay time of the sound is too short. If we tuned them too far apart, the beats are heard.
The hammer sets all 3 strings into a vibration with the same phase, and energy and rapidly transferred to the soundboard initially. The small difference in their frequency made the strings get out of phase soon and the rate of sound decay slows down, leading to a 2nd slope in the decay curve (aftersound).
The thickness of a piano varies, with bass strings thicker than treble. It’s about 1/30inch for the highest treble string to 1/3 inch for the lowest bass. The length of the strings also varies.
The longer strings are desirable because of the inharmonicity phenomenon. When stroked, every string vibrate on it’s natural pitch aka fundamental frequency and many overtones. Since the overtones match other notes on the piano (as in musical harmony), the strings vibrate sympathetically with one another whenever they are not covered by their dampers. This creates the characteristic rich tone of a piano.
An ideal string vibrates in a series of modes that are harmonics of a fundamental or what we called as a harmonic series. But in piano, the overtones do not quite coincide with harmonically related musical notes. The string’s thickness and length made its harmonics deviate from being multiples of the fundamental, and creates an unmusical sense. This is what we called as inharmonicity.
Inharmonicity depends on the string length, the longer the strings are, the more they approximate ideal theorical strings, and the more they’ll vibrate sympathetically with other, musically related notes.
Inharmonicity explains why the lowest strings of the piano are not made of plain steel, but rather of steel wrapped in copper. The wrapped construction adds the necessary mass to the string while minimizing the addition of stiffness (and the inharmonicity as well). They become more flexible than are solid strings of the same diameter. This reason applies to the lower strings on guitars and violins too).
The inharmonicity is desirable in piano. People as in musicians and nonmusicians prefer a synthesized piano with inharmonic partials in the tone. With the harmonic partials, the tone produced is lacking of warmth. Inharmonicity also helps to mask small tuning errors.
The chart shows the increased percentages of carbon and the greatly increased tensile strength of music wire from 1827 – 1913. Early piano was strung with iron or low-carbon steel wire, which was softer, more elastic and produced a different sound than a modern piano wire. The strength of the wire doesn’t determine the high quality sound of the piano. A high percentage of sulfur (over 0.03%) is usually considered as a metallurgical defect in the manufacture wire.
Wire Sources Diameter (mm) Min Load Cap. (Newtons) Tensile Strength (N/mm2) Carbon % Sulfur %
Graf fortepiano #1594 (Vienna, c. 1830) .772 / .777 560 1189 .3150 .015
Graf #1594 2nd test .911/.921 530/535 804/812 .095 .007
Graf #1594 3rd test .754/.769 440/445 967/978 .125 .010
Graf fortepiano #2627 (Vienna, c. 1838) .886/.885 530/540 882/898 .077 .008
Graf #2627 (brass wire) .995/.940 610 830 - -
Bösendorfer fortepiano #167 (Vienna, c.1840) .790/.802 580/590 1170/1190 .370 .045
B.G. Wire (Vienna, c. 1840) .730/.735 400 950 .0553 .0044
Broadwood square #15793 (London, 1850) .993/1.005 900/905 1148/1155 .45 .035
Chickering (Boston, c. 1850) 1.150/1.190 1815/1910 1690/1780 .72 .052
Bösendorfer #3881 (Vienna, 1851) .810/.814 1070 2066 .72 .010
J.B. Streicher grand #6493 (Vienna, 1863) .744/.749 890 2036 .46 .008
Bechstein grand #981 (Berlin, 1864) .945/.947 1610/1640 2291/2333 .81 .017
Steinway (NY) #89867 (1897) 1.130/1.148 2540/2560 2490/2510 .740 .032
Steinway (NY) #160445 (1913) .965/.969 1860/1925 2530/2620 .770 .034
Steinway (NY, 1959) .938/.943 1680/1700 2421/2450 .74 .010
Malcolm Rose Type B .693/.695 340/360 900/950 .12 .018
Malcolm Rose Type C .893/.900 720 1140 .45 .022
Malcolm Rose Type C (Control) .900 720 1132 .4380 .0240
Christopher Clark Cluny, France. Modern harpsichord wire .921/.929 1580 2351 .805 .011
Giese Wire Co. sample wire c. 1975 1.119/1.125 2410/2380 2437/2407 .915 .0135
Röslau wire - sample wire c. 1987 .900 1457 2290 c .85 ?