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C37 Theory English
by Dieter Ennemoser (July 1998)

All attempts by science to explain the secrets of the character of sound have so far been unsuccessful.
On other hand, there is the immensely rich store of experience accumulated by instrument makers, who,
in earlier centuries before science had any impact, had their greatest successes.
There must be, therefore, some property of acoustics that has been overlooked by science.
The object of my research was to seek the missing link.

My technical training, my earlier passion for High Fidelity sound, and my profession as sound technician
were the building blocks of my work. The more important part of training came later: a violin maker´s
apprenticeship with master violin maker Carl Sandner in Mittenwald, Germany and further studies in violin
playing and singing. That was followed by the the long hard search for sound quality in violins.
Many years of innumerable experiments finally resulted in an important clue:

The imperative selection of the right materials (wood and varnish quality) raised the question about
the existence of a
reference property.

I eventually discovered that human bones and tissue to possess similar qualities.
A more detailed analysis showed that carbon is the decisive element in sound quality, and since the
sound is also coloured by body temperature, I chose to call this property the

C37 structure        

Where C = Carbon and 37° = body temperature in degrees Centigrade.         

Further analysis showed that C37 frequencies lie very close together (at least 10 frequencies per octave)
and this structure reoccurs in each octave. Another important feature of the C37 structure is that the
decay-pattern is the dominant feature rather than merely the amplitudes on a frequency response curve.
It is precisely the C37 structure that enables our ear to discern the quality of sound.

The ear consists of several interacting elements, eardrum, hammer, anvil, stirrup auditory hairs), each of
which has its own C37 property, so that at the end of the chain, the C37 properties are transmitted in preference to others.

Consequently the C37 structure is extremely sharp and clear at the end of this chain and gives humans
a marvelously sensitive measuring instrument.It is analogous to an electrical bridge circuit in that it compares
its own stimulated C37 structure with the incoming sound at the eardrum. The different interface patterns produced by this comparison are recognised as differences in timbre, sound colour and shading.
This occurs with such precision that, to paraphrase a HiFi test report for example, "an amplifier plays more freely and effortlessly, produces more spatial depth than width and with a light timbre".

Technically, however, it is not possible to evaluate such sound qualities. Naturally this ability of the ear was not refined by evolution for the purpose of judging HiFi-components, but to identify emotional differences in voice timbre. The development of speech was also enhanced by it.

Because the C37 sounds can stimulate a palette of pleasant, exciting, and subtle emotions while non-C37 sounds are hard on the ear, there was an (unconscious) development towards C37 sound quality by instrument makers.
The fruits of these developments are in the wide variety of instruments from church bells to orchestral instruments, and valve-amplified electric guitars.

In my profession as a violin maker, the C37 theory is put to daily use and constantly proves itself in the
selection of woods, varnish mixtures and design.

A further development is a new type of loudspeaker- cone (Patent EP 0491139).
Literature: The Character of Sound ISBN 3-907073-32-0 by Dieter Ennemoser.

Dieter Ennemoser (apprentice) and Carl Sandner (master) in Mittenwald in 1977        

Violin making apprenticeship at Carl Sandner's         

Materials possess their own specific tonal signatures, independently of shape or size, but directly related
 to temperature. The mechanism of our ears, made of bone and tissue, has its own unique signature:

Carbon at body temperature = C37structure, where        
C = carbon and 37 = temperature in °Centigrade.      

These material-specific resonances of our ears would drastically distort our perception of other sounds,
but they are filtered out by the brain, leaving an accurate and apparently objective image of our
acoustic environment. However, this objectivity is deceptive. Although the timbre of our own hearing
mechanism is no longer audible, our subconscious senses transmitted energy. The sound then has a
subjective strength and warmth.

A comparison can help make this clear: Glass bottles thrown into a metal container produce a lot of noise but little energy, since the sound
signatures of glass and metal have no similarity to
C37. On the other hand, sounds made by wooden
objects (close to
C37) or similar materials have high energy but without great loudness.
Loudness is used here subjectively and represents the total stress on our ears.
Stress is highest with
non-C37 sounds where, due to the lack of acoustic impedance (adjustment),
the inner mechanism of the ear remains virtually in neutral, resulting in large, painful displacements
of the moving parts and eventually, damage.

It is obviously desirable in music-making, where energy is produced and transmitted, to have a ‘healthy’
energy-rich sound with little loudness.
If a violin is made of wood which, although having good mechanical properties, has no
C37 structure,
it will have a hard tone with thicker wood and thinner wood will produce a hollow, weak sound.
Tinkering with the thickness of the wood and resonance frequencies will be in vain.
As a technical college graduate in physical sciences, I know what I am talking about.
I once held the sincere belief and devout hope that a full and pure sound could be achieved simply
by working wood into an ideal thickness. After I had dismantled, altered and rebuilt my first two violins
some seventy(!) times each, I realized what was not attainable in tone quality with
classical mechanics

Of course the laws of classical mechanics play a part; the balance of tone and good response are a result
of these natural laws, but the sound character, the tone, the depth and warmth of the sound are determined
by another criteria, namely
C37. Although this may sound simple, it is the result of 14 years of research while
building many violins, each being rebuilt up to ten times. But let’s return from this diversion to the applications. The bronze used in church bells is a metal alloy that simulates
C37, which is why bronze church bells sound
so clear and strong, whereas those of steel sound hard and cold.

The C37 theory can also explain the legendary qualities of the classical Cremonese violin varnish.
Due to the lack of understanding of the character of sound, scientists consigned the „Stradivarius varnish“
to the realms of mythology. Craftsmen on the other hand, recognize the effect a good varnish can have on
tone and only those who produce or work with poor quality varnishes would dispute this.

The entire history of instrument making has been a continuous effort to harness that energy outlined
by the theory. Since the sound signatures of materials cannot be explained by Newtonian mechanics,
they are, to the best of my knowledge, simply ignored; classical physics holds shape and size to be relevant
but not temperature, although according to my research, temperature directly influences material tones.
I found by measurement that these rise as much as 0.1% - 0.2% per °C, depending on the material.
That sound signatures of materials exist is well known by every child. They learn that wood, iron, plastic,
ceramics, cardboard and silver produce recognizably different sounds.

These material sound signatures are fundamental sound parameters. Our hearing has
developed an amazing sensitivity to them

How else could we differentiate between different types of wood and different voices? The accuracy of recognizing materials increases the nearer they are to C37, which is why such different timbres are
discernible in wood and why its selection is so critical in violin making.

There is good reason for using pine (spruce) and maple in violin making; both of these woods have
characteristics similar to that of our bones. In human voices we recognize a great variety due to
their inherent C37structure. Metallic (iron) and nasal sounds seldom exhibit such a diversity.

This phenomenon also explains why expensive sound reproduction systems can sound so different,
whereas the less expensive systems usually have a similar „cheap“ sound characteristic.
It also explains why HiFi enthusiasts tenaciously push their hobby to such a peak. Peak is perhaps not the correct metaphor; it is more like a tree that constantly grows more and more branches.