Measuring the frequency response of the acoustic guitar
The frequency response of the acoustic guitar is the single most important piece of technical information of an acoustic guitar. It gives insights about:
– Tonal balance
– Low frequency extension
– Midrange character
– Sound Projection
– Back activity
– Wolf notes predisposition
The frequency response of the Orchestra model.
85% of the sound of the acoustic guitar is produced by the first six resonances of its body:
– the acoustic resonance: T(1,1)1
– the soundboard monopole: T(1,1)2
– the back monopole, if active: T(1,1)3
– the soundboard dipoles: T(2,1), T(1,2)
– the soundboard troipoles: T(3,1), T(1,3)
The amplitude and frequency distribution of these modes is largely responsible for the timbre of the instrument, its tonal balance, and the bracing of the soundboard is largely responsible for the amplitude and frequency of the main resonance modes.
The frequency response of the Orchestra model.
The measurement of the frequency response is quite simple. An appropriate impact hammer is used to supply mechanical energy to the soundboard and excite its resonances; a microphone captures these impulses, and a FFT analysis software translate these sounds into a curve, in the frequency domain.
Reading a curve of frequency response is not very difficult, but it requires a bit of competence and experience. If you are interested in these topics, please go to my research page or to my Youtube channel, where you will lot of info.
Each Iulius Guitar model is offered with an individual specification sheet that also reports the frequency response. This data allows you to track the evolution and aging of the instrument over the years, and the ETS system will enable you to fine-tune the main resonances if necessary, to always maintain the guitar at its maximum acoustic potential.
