Sunday, February 13, 2011

Voicing the Top - Intuition and Technology

Shaving the soundboard braces to bring out the guitar's tonal potential is one of the more intuitive and mysterious aspects of guitar construction.  For me, it's also one of the more tactile and enjoyable stages when the use of hand tools is mandatory and the senses come strongly into play.  A cycle of tapping, flexing and brace shaving is involved, with a somewhat nebulous goal in mind despite having read everything I can on the subject!

Unfortunately, my hobby builder status dictates that it's often many months after voicing a top then going on to complete and evaluate the instrument before I'm able to repeat the exercise - hardly an ideal situation in terms of being able to build any sort of muscle memory or draw meaningful conclusions. The pertinent questions whose answers seem elusive in terms of being able to adequately articulate them are:
  • What did the top feel like as I flexed it, i.e., how much resistance was there when bending it across the grain and with the grain?
  • How did the top ring as I tapped it and how was the response influenced by the way the top was held or suspended and where it was tapped?
  • What was the correlation between those very subjective assessments and the success of the completed instrument from a tonal perspective?  
  • To what extent did the materials, density and stiffness of the guitar's other components combine with those of the top and contribute to the outcome?
As I review that list of questions, it strikes me that the challenges they pose seem almost insurmountable.  It's obvious that relying on my memory from one instrument to the next isn't a satisfactory approach given the subjective nature of the assessments involved and how infrequently I'm able to repeat this part of the process.

Perhaps the use of technology offers a way forward and can lend a degree of objectivity to what would otherwise be limited to some vague, transient sensory experience. Measuring top deflection both parallel to and across the grain prior to gluing the braces, photographing the top bracing and noting brace heights, recording tap tones with a decent microphone (or perhaps one of the hand-held Zoom recorders) or even videoing myself as I hold the top and tap it seem likely candidates as I seek to minimise the guesswork involved in the voicing process and develop a baseline for subsequent instruments.  Or perhaps I should learn to trust my senses and develop a greater appreciation for the delightful uncertainties inherent in wooden instrument construction!