The difficulty in defining the sound properties of Old Italian instruments is that there are at least two distinct groups of instruments based on their sound characteristics. One group is characterized by a low, mellow tone apparently lacking the higher end of the sound spectrum, and seemingly subdued volume. The other group is marked by a highly intense sound with a penetrating ringing tone, but not without the low end. We can only speculate about the reason for such difference.
The first group is greatly admired by chamber music performers, whereas the second group is most prized and sought after by soloists.

Another aspect that confuses the issue is the fact that musical recordings have made by far the biggest impact on how the sound of Old Italian instruments is perceived. The majority of distinguished classical recordings belong to an era when recording technology was inadequate to reflect the full spectrum of a violin, thus, creating the impression that Old Italian violins played by the old virtuosos had a very narrow tonal range. Whole generations of musicians grew up listening to these recordings and consequently could not escape their influence.
Modern recordings of the same instruments prove that these violins had in fact an extremely wide harmonic spectrum and possessed an intense powerful sound, and thus undoubtedly belong to the second group.

Though the tonal spectrum of these two groups appears to be different from up close, there are certain sound properties that are common to both, setting them apart from all the rest of the violins. One such property is referred to as projection of sound or just projection. This sound property belongs exclusively to the Old Italian instruments (all claims to the contrary confuse this unique property with simple loudness or volume of the sound) .
Armed with this unique sound quality, Old Italian instruments deliver a clear, voice-like sound image, void of shrillness but strong and distinctive far into the largest concert halls.

Another exceptional quality of Old Italian instruments is their exceptional tone. As opposed to the sound of all other violins, which are basically an acoustically amplified sound of strings, these instruments respond to the touch of the bow with their own unique voice. This distinctive tone with unusually strong overtones (can be heard by an un-augmented ear from up close) helps Old Italian violins to stand out from the rest of the orchestra, and facilitates unique to these instruments playable characteristics such as treble sustain and slotting

Aesthetic components of the BelCanto sound:

1. Clarity a). no extraneous noises(hiss, wheeze, grit etc.)
b). compactness or simplicity of the sound spectrum
2. Focus absence of extraneous overtones (harmonics of a different main frequency)
3. Inner Strength sound contains overtones with unusually high amplitude
4. Content
(Acoustic Appeal)		 combination of high amplitude overtonesthat's pleasing to the ear

 

The sound characteristics of a violin

1. TONE main tone (harmonic spectrum).
2. TONE DYNAMICS tone variation in response to different bow pressure/technique.
3. BALANCE (volume balance)balance of the strings (G,D,A,E) ;
(tonal balance)evenness of tone while changing from one string to another.
4. RESPONSE Amati vs. Guarneri (the ease of sound production).
5. FOCUS the clarity of the pitch, the absence of 'stray' overtones.
6. TREBLE SUSTAIN brightness of tone while moving to higher positions.
7. SLOTTING the active separation of one note from the other (syn. Articulation).
8. VOLUME maximum sound power of the instrument.
9. PROJECTION carrying power, the definitive presence of tone from the far end of a hall ('opaqueness' of tone, the ability to stand out from the orchestra).