An overview

Voicing the Guitar TopVoicing is the shaping and creating of the voice of an instrument. It is one of the most important and fundamental techniques for the luthier. Although a musical instrument may already fit the category of “arts and crafts” because of its artistic design and aesthetics, its true value is to be found in its voice, its sound. By shaping the voice (or discovering the voice that is already there), the instrument maker contributes his share to the artwork that is completed by the performance of the musician. In the following paragraphs some techniques of voicing are mentioned and described, especially the techniques that are used (in the higher-end models) of Vorreiter instruments.

Some background info:

The voicing of musical instruments is as old as the trade itself, and there are numerous techniques which differ from one instrument type to another. The instructions for voicing by makers such as Lundberg, Bourgeois, Carruth, Hill and Allan mainly deal with the tuning and voicing of free plates. For this technique, much research, experimentation and experience is necessary, since some time elapses between modifying the instrument part and judging the sound of the finished instrument. An interesting advantage is to be found in the voicing of a finished instrument. Such an instrument can be accessed through access ports (as is found in the instruments of Fleishman and Mueller, for example), and modifications can be made until the sound is “just right”. Another very interesting technique has been described in a report by Benfield, about the guitar maker Jim Norris. The spring edition of “American Lutherie”, 2007 describes how Norris assembles the guitar body without the back glued on in a contraption built for that purpose, puts strings on and voices the instrument, while being able to pluck the strings to evaluate the changes made on the sound.

Methods for acquiring information on the sound proprties of an instrument:

The measuring of deflection yields important information on the rigidity of the instrument top (or any other desired component of the instrument). It provides much more detailed information on the future vibrational behaviour of the top than the traditional thickness measurements, which tend to completely ignore the effect of varying material properties. – The composition of Chladni modes shows the luthier at which sound intensity and frequency an instrument displays a certain Chladni pattern. These Chladni patterns give the maker an understanding of the complex vibrational behaviour of an entire instrument. – The frequency analysis records the “fingerprint” of a musical instrument and shows the existence of double peaks, jaggedness, the shifting of main frequencies and coupling. – The playing of the instrument gives an immediate and subjective impression of the sound. In my opinion, this is one of the best methods to evaluate the sound and make adjustments.

The techniques of voicing used in my workshop:

Two fundamentally different techniques of voicing must be distinguished; – the voicing of a finished instrument and – the voicing of the components of an instrument during and before assembly. The voicing is mostly done by first tapping the instrument or plucking the strings, and then making changes to the instrument to modify the timbre. Chladni patterns, deflection measurements and FFT (all of which are objective evaluations of sound) are only used to supplement the highly subjective evaluation of sound by tapping or playing. Vorreiter instruments are mounted in a contraption with a neck and stringed during the building process. The instrument can therefore be played before the back is glued on the body. This makes it very easy to make changes to the top (bracing and composition of the top plate). The impact of these changes can be heard and evaluated immediately by playing the instrument. A finished instrument with a sideport also yields the great opportunity to make more modifications through the sideport, in order to make some final corrections and improvements to the instrument sound. Additionally to the playing and tapping of the instrument, a method learnt from Professor Mark (which is based on the research of Lundberg and Streu) is applied to evaluate instrument sound: One takes their knuckle or another object and presses it on the top punctually in several areas, and plays the strings at the same time. This creates forced knots on the oscillating top, which can change its timbre considerably. Then the luthier can either subtract or add material in that area until the sound of the instrument meets his expectations.

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