Patrick KREIT

The well-known impulse response or "tap-tone" method is widely used 30 years in instrument construction to adjust violin plates. Hold a top plate by a point on the nodal line (where there is no vibration) and with the other hand, tap on a "belly" (where vibration is present) to hear the fundamental note (mode 5) of the plate. The use of the free software "AUDACITY ©" made it possible to popularize this method and to tune the backgrounds and tables of the stringed instruments very easily.

By striking a violin body at given points, the noise heard can be analyzed as a "response curve", which indicates the resonance peaks specific to this particular body. When the sounding box is activated by a violin string, the sound produced is richer and more intense, to the extent that the string’s sound and its components coincide with the body’s response curve.

Methods and technologies for studying physical vibrations have led to that facilitate our understanding of the behavior of musical instruments.

Exceptional sound is achieved by tuning modes A0, B1- and B1+ and the delta between the latter, and by optimizing the arching for minimal weight of the materials, as well as obtaining appropriate thicknesses at the center and in the C-bouts of the back plates so as to limit deformation.

When all the modes of the sounding box are tuned to their respective frequencies, according to the criteria defined by the finest Stradivari and Guarneri violins, is the guarantee of a modern instrument with high-quality, stable sound.what is heard is the resonance of the wood. A reverberation of the sound within the sounding box should also be heard. Therein lies the particularity of the sound of Italian violins.

Easy emission, pure sound, and easy vibrato are determined by the delta between the B1- and B1+. A delta of 85 Hz between these two modes yields a bright, pure sound and firm playing.

Depending on their personal experience, some violinists prefer a dark timbre; others, clear. No matter what the tone color, a violin’s superiority lies in the facility of emission on the entire length of the fingerboard, perfect balance between high and low registers, an appropriate response to rapid bow-strokes, full warm low notes and bright high notes. The instrument must respond to the slightest solicitation of the bow and withstand its pressure. Most important of all is the purity of sound.

A pure sound will always be heard better because it carries better. This purity will also enable the soloist to play loudly enough and stand out above all the others instruments without saturation of the strings.

The difficulty encountered in violin acoustics has always been to understand and acknowledge the difference between the old masters' technology and that available to us today.

Over the course of two centuries, many explanations and hypotheses have been proposed, and in particular, the recipe for a varnish with wondrous properties, forever lost. In fact, it is simply a matter of understanding the laws of acoustics applicable to the violin, as well as the laws of physics concerning the structure of the constituent materials.

Violins available. Betts model. These instruments are powerful, perfectly balanced, and easy to play.

These violins can be seen and played in Reims, France, by appointment only.

Contact Patrick KREIT

The violin maker can implement the same procedure as Ernst Chladni’s method by using a frequency generator linked to a loudspeaker, instead of bowing against the edge of the plate.

When the loudspeaker’s frequency is identical to the vibrational mode frequency of a violin top or back, fine sand sprinkled onto the plate will naturally move towards the regions which vibrate less, i.e., the nodal lines, which will become clearly defined, and between which the "bellies" are located (see above photo - mode 5).

The back and top plates of the violin have their own frequencies and resonances. If these frequencies are badly tuned, the instrument will produce sound of bad quality.

As violin makers become familiar with the basic concepts of acoustics, and the cost of computer analysis decreases, modal animations reveal the hidden movements of the violin.

Violin body vibrations have been studied for more than 150 years, but the majority of our understanding of
the phenomenon has been acquired in the last 30 years with the development of optical holography and computer science, as well as the sophistication of digital measurements.

Today, we know how to analyze sound from the point of view of a "response curve" thanks to FFT (fast Fourier transform) software, and how to use spectral computer analysis to find the modes, as well as the overall response of an instrument.

The principle of spectral decomposition can be illustrated by that of light: a beam of white light directed onto a prism separates into a spectrum of different colors.

We can trace the spectrum of a sound, which will be strictly analogous to the spectrum of light. A sound breaks down into a sum of pure frequencies, so we will examine the intensity of each frequency.

The A0, B1-, B1+ modes of these violins have been tuned according to the frequencies of Stradivari’s finest

violins, by applying the acoustical laws described in the book

The Sound of Stradivari

Violin maker & researcher