Connect the frequency generator to the independent ampli, then connect the amplifier output to the loudspeaker inside the box. Or connect the frequency generator directly to a guitar amplifier.
Tapping the bridge on the bass side with a small simple hammer (wood), used in conjunction with free Audacity® software, enables readings of the principal modes of the violin. The microphone must be placed facing the lower left eye.
The book is accompanied by a CD including software (Windows®) to:
·calculate the A0 cavity mode,
·calculate density of the tonewood,
·calculate moisture content in the wood.
·An 8 minute video demonstrates how to monitor the A0, A1, C2, B0, B1-, B1+, mode frequencies and how to read frequency peaks using Audacity.
·Stradivari and Guarneri forms.
·Spreadsheet with mode frequencies B1- and B1+ of 18 Stradivari and 13 Guaneri violins.
This book answers several questions:
- How to tune the frequency of mode 5 of the back and top plates violin ?
- How to select a bass bar in order to raise the top plate's frequency after cutting the f-holes?
- How to tune the frequency of modes B1- and B1+ ?
- How to tune the A0 cavity frequency "without sound post," on which the A1 mode frequency also depends?
- How to tune the B0 mode frequency with the A0 cavity frequency "with sound post"?
Several chapters are dedicated to the choice of materials and surface treatments, followed by a synthesis
on heating wood and varnish.
The Italian violin makers at the beginning of the 18th century knew how to recognize a frequency (a beat or a cycle, according to the terms of that era) and knew that the materials’ frequencies followed the moisture content in the wood, which itself followed the ambient humidity. All it takes to realize this is to tap a free violin plate (in the white or varnished) under different conditions of ambient humidity.
Such research constituted the “secret” that has fascinated violin makers and scientists for generations.
It is purely a matter of acoustics, since the aim is to reproduce the sonority of the finest Italian violins.
305 photographs show the nodal lines for modes 2 and 5 Page 3facilitating their tuning on a top
and back plate, both free and assembled separately on the ribs, as well as the tuning
of modes A0, A1, B0, C2, B1- and B1+of a violin in the white. Page 4
Each photo is accompanied by the explanations necessary to understand the technique for tuning
free top and back plates, as well as the various modes of the sounding box,
through the final stringing of the violin in the white.
35 chapters and 44 tables are included in this book.
Recipes for sizing and varnish with explanations concerning the modification of modes B1- and B1+. P. 6
Viola and Cello
One chapter is dedicated to the mode 5 frequency of the free back and top plates, as well as modes A0,
B1-, and B1+ of these instruments. The tuning technique for these modes is identical to that of the violin.
The regions that raise or lower the mode 5 frequency of the extrados indicated on the book
are the same for both the viola and the cello.
The method of violin plate construction detailed in this book, “The Sound of Stradivari”
is the one used by most contemporary violin makers. It consists in entirely finishing
the free top and back plates before gluing them onto the rib garland,
irrespective of the form used (inside or outside mold).
Two examples explain the procedure for tuning free back and top plates, whatever the violin model.
It is conceived for violin makers (no formulas) in accordance with traditional violin making.
It answers all the essential questions about violin acoustics that a violin maker needs to know.
This very simple tuning technique makes it possible to naturally reproduce arching
in the "Italian" style and to understand the genius of Stradivari.
However, designing the outline of a violin model based on perfect geometry and reproducing one of the finest Stradivari or Guarneri instruments will not suffice to obtain excellent sound.
All is vibration; all vibration is a law of physics or acoustics, from the violin to the secret melody
of atoms; hence the need to tune the free top and back plates, as well as all of the body modes,
to their respective frequencies.
The bow makes the string vibrate, the string makes the violin’s materials vibrate, which in turn sets into motion the air molecules within the body, making it a sound resonator and amplifier.
To replicate the sonority of a classic Italian violin, the violin maker must know these same laws that enabled the creation and perfection of such masterpieces.
Dedicated to the acoustics of the violin, it is accessible to all:
professionals, amateurs or beginners.
Generator or software:
both techniques, each with its advantages and drawbacks, can be used concurrently.
Computer (desktop, portable, tablet, or phone) equipped with sound analysis software.
Back plate and top plate can all be tap-tuned by using audio-capture software such as Audacity (free)
All of the inside of the box should be lined with aluminum foil for the UV rays to be diffused in all directions.
Four neon fixtures are needed: either
60 cm or 120 cm (23.62 or 47.24 inches).
UV or black light tubes and fixtures are available in many stores.
The transformers in the neon fixtures emit heat, which is advantageous
in dehydrating the wood of materials
in the white.
One month of UV exposure on materials in the white yields very good results.
The plates remain more stable under conditions of variable ambient humidity once the instruments have been varnished.
TEMPERATURE & AMBIENT HUMIDITY
Outdoor temperatures in Cremona can fall below freezing in the winter (-4 °C to -5 °C = 24.8/23 °F) with 10% moisture in the air. Moisture content in the wood drops naturally to between 2% and 1.5%. Ambient humidity can also drop to 10% in the summer or during a drought, or rise to 95% during periods of high humidity. The moisture content in the wood can increase to as much as 13.5%. The same is true for North America and Europe, with 0% moisture content in the wood when the temperature outside drops to -15 °C
(5 °F) and even lower, as for example, in Finland (-25 °C = -13 °F).
The same holds true for North America and Europe, with 0% moisture content in the wood when the outdoor temperature falls to -15 °C (5 °F), or even lower, as in Finland, for example.
A personal electronic weather station will make you aware of significant, rapid changes in ambient humidity and allow you to anticipate a significant, rapid change in the moisture content in the wood during the tuning process.
The frequency problems related to the wood’s hygroscopic instability could not have been unknown to the Italian craftsmen. Without modern technical means, they nevertheless had the possibility of using a simple method, consisting in tuning: a) without hollowing the intrados, the starting volume of a back plate and a top plate to a specific note, corresponding to a determined moisture content in the wood; and b) “model plates” (i.e., a pre-finished free top and back plate before cutting the f-holes). As moisture content in the wood follows the curve tracing ambient humidity, the frequency of these “model plates” lowers or rises, following this same curve.
HUMIDITY METER WITH SCANNER
A humidity meter is necessary, for it reveals the changes in moisture content of the wood, and is particularly useful during the months when the workshop is unheated, a period when rapid changes in moisture content are likely to occur, leading to variations in frequencies during violin construction, as well as in the body mode frequencies of an instrument.
The density of the wood depends on its moisture content.
There are different types of moisture meters for wood :
Scanner, with or without removable pins.
Tester with pins type GANN H35 à H70 (usable with or without the pins).
When using a moisture tester with a scanner, do not lay the plate on top of your hand, or else the reading will be higher than the true value (due to the skin’s humidity). Hold the plate in the air to take readings, or else the scanner may measure the moisture in the wood of your workbench.
Equipment to tune the mode 5 frequency of free back and top plates and body modes:
- tone generator with frequency meter (USD 60/90 on eBay)
-computer (PC, portable, tablet, or phone)
-software: Audacity® (free) or Visual Analyser® or Spectrum Lab (free real-time sound analysis)
-computer microphone (USD 15)
-moisture meter with scanner and tops (USD 50/100)
-moisture meter for wood GANN H35 à H70 (295 to 650 euros ).
To implement this technique, neither an elasticity tester nor knowledge of the wood’s celerity and elasticity by another means is required. Nevertheless, because the success of a violin depends above all on the choice of materials, select half-plates with the highest tap-tone frequencies (see tables of book).
This solution is simpler and more reliable than a tester, because a high frequency indicates that the wood has high overall characteristics (celerity and elasticity, irrespective of the density). However, moisture content in all the materials must be identical in order to enable comparison.
For the maker who wishes to conduct research, an elasticity tester provides the means to explain and understand the behavior of the materials according to their characteristics and moisture content.
Celerity and Young’s modulus should be measured simultaneously with the moisture content of the moment.
If the moisture content in the wood rises or falls, celerity, Young’s modulus (both longitudinal and transverse), and the material’s frequency will follow the same curve.
All scientific data in “The Sound of Stradivari” regarding the frequency heights for violin modes B1- and B1+, the deltas between modes A1, B1-, B1+, coupling frequencies, as well as the tuning technique for the starting volumes of violin, viola, and cello back and top plates, results from the personal research and experimentation by Patrick Kreit.
Reproduction in any form of any content from this site or from the book “The Sound of Stradivari” without my express written permission is prohibited. Only the owners of the sites www.platetuning.organdwww.thestradsound.comare authorized to reproduce certain items originating from my work.
This book is the result of 42 years of research on the acoustics of the violin, viola, cello, and on varnish. This work provides all the necessary explanations regarding the behavior of the materials, according to their characteristics and moisture content, in order to properly tune the mode 5 of the free materials, with optimized weight.
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