Guitar Design Research Articles

An Analysis of the Displacements in 3D-Printed PLA Acoustic Guitars.

This study focuses on the analysis of the displacements generated in 3D-printed acoustic guitar tops. Specifically, the influence of 3D printing direction parameters on the vibrational behavior of a guitar top designed for polylactic acid (PLA) by analyzing five points of the top surface at a reduced scale. For this purpose, finite element tests and laboratory experiments have been carried out to support the study. After analyzing the results, it can be affirmed that the vibrational response in reduced-scale top plates can be modified and controlled by varying the printing direction angle in additive manufacturing, providing relevant information about the displacement in the vibrational response of PLA acoustic guitars. Furthermore, this work shows that the behavior of a specific acoustic guitar design can be characterized according to a specific need.

Design for performability: a proposal for democratic redesign of the classical guitar

Mastery of a musical instrument, including an ability to reach virtuosity in expression and performance, is commonly achieved through a lifelong commitment to practise. The specific instrument played has a crucial role in this journey. This paper reports on design research that aimed to determine the potential for redesigning the classical guitar, whether iteratively or radically, from the perspective of key stakeholder groups: luthiers, composers, and performers. A total of 25 interviews were conducted and analysed to identify shared and unique concerns amongst the stakeholder groups. The findings are used to conceive and develop a new design-related musical term ‘performability’, which builds upon the established term ‘playability’ but has much stronger interactional and experiential dimensions. Furthermore, the paper provides insights into ways in which an industrial designer can contribute to classical guitar design as a fourth stakeholder. Industrial design expertise is proposed to provide a mediating and catalysing role for democratic (i.e. multi-stakeholder, multi-perspective) instrument design or redesign. The paper concludes with a proposal for a ‘design for performability’ framework suited to co-design sessions aiming to achieve a highly performable classical guitar.

Archtop guitar dynamics—Continuing research of archtop guitar acoustics

The contemporary archtop guitar, designed by Lloyd Loar of the Gibson Mandolin-Guitar Mfg. Co. Ltd., will be 100 years old in 2023. Since the first L5 shipped in 1923, the archtop guitar has taken on a life of its own, having been reinvented by luthiers worldwide. Research of the archtop guitar is a new field in instrument acoustics. Measurement techniques developed by the bowed instrument research community have been adapted for guitar to offer a glimpse into the acoustic behavior of a century old, yet timeless guitar design. This talk will focus on the ongoing research that has been conducted since the 2021 publication of Archtop Guitar Dynamics by the Violin Society of America Papers. The archtop guitar shares features of violin family instruments, including a carved top, ff-hole perforations, and raised bridge. Beyond aesthetics, the archtop shares acoustic similarities to both violin and guitar family instruments resulting in a unique acoustic signature. Continuing research includes analysis of historically significant instruments from Gibson Mandolin-Guitar Mfg. Co. Ltd and the works of New York luthier, John D'Angelico as part of the Archtop Project: New York sponsored by D'Addario & Co. and the Archtop Foundation.

Designing Mechatronic Musical Instruments: The Guitar

Since the earliest times, humans have sought the ability to produce rhythms and tones using devices external to the human body. As technology developed, so too did the desire for this sound production to become automated. Initially peaking around the Industrial Revolution, traditional automated musical production devices went into a steep decline with the arrival of the phonograph. However, factors such as the ubiquitous acceptance of the microcontroller led to a resurgent interest in this field. This paper investigates the design considerations and development of the stringed chordophone and specifically the guitar. The challenge is to produce a mechatronic device capable of speedy and reliable note selection, string actuation, string damping and expressiveness. In the same manner that there is not one best way to play a guitar and no best guitar design, so too is there no “best” chordophone design. Rather, the competing factors of speed, precision, reliability, portability, expressiveness and timbral variation can be given different weightings and result in different designs. Therefore, rather than presenting a single chordophone development, this paper provides a multitude of design options providing an interested reader with the background and suggestions to create their own bespoke design. This paper concludes with the presentation of the authors’ final design as an integration of the presented ideas and design techniques. We demonstrate that this chordophone introduces expressivity at a level not achieved before, is modular yet portable, is mechanically quiet and can play at a speed beyond that of even the best human player.

String theory--the physics of string-bending and other electric guitar techniques.

Electric guitar playing is ubiquitous in practically all modern music genres. In the hands of an experienced player, electric guitars can sound as expressive and distinct as a human voice. Unlike other more quantised instruments where pitch is a discrete function, guitarists can incorporate micro-tonality and, as a result, vibrato and sting-bending are idiosyncratic hallmarks of a player. Similarly, a wide variety of techniques unique to the electric guitar have emerged. While the mechano-acoustics of stringed instruments and vibrating strings are well studied, there has been comparatively little work dedicated to the underlying physics of unique electric guitar techniques and strings, nor the mechanical factors influencing vibrato, string-bending, fretting force and whammy-bar dynamics. In this work, models for these processes are derived and the implications for guitar and string design discussed. The string-bending model is experimentally validated using a variety of strings and vibrato dynamics are simulated. The implications of these findings on the configuration and design of guitars is also discussed.

Rob Armstrong – over 40 years of outstanding guitar making in England’s heartland

Abstract This ‘portrait’ provides a timely look at the work and thoughts of Rob Armstrong, one of the United Kingdom’s most prolific and well-known acoustic guitar makers. For over 40 years, Rob has been hand crafting exceptional musical instruments from the modest facilities of his garden shed at the end of his Coventry garden. With a reputation as a formidable innovator rather than being satisfied with reproducing standardized instruments, this article seeks to understand Rob’s approach to his trade, the nuances in his making activities, and his unending motivation and curiosity to keep pushing the boundaries of acoustic guitar design and construction. On 23 July 2013, the authors made a special visit to Rob’s premises to witness his latest work and to engage in a revealing conversation about his love of guitars and his passion for crafting outstanding instruments.

A platform for manipulation and examination of the acoustic guitar: The Chameleon Guitar

A platform for manipulation and examination the acoustic guitar is presented, based on a novel guitar design – the Chameleon Guitar – featuring a replaceable acoustic resonator functioning as the soundboard of the instrument. The goal of the design process is to create a tone as sonically close to that of a traditional guitar as possible, while maintaining an easily replaceable soundboard. An iterative, data driven approach was used, each design step coming under examination from one or more measurement tools: finite-element method, acoustic impulse testing, and laser vibrometry. Ideal resonator geometry, bridge location, and piezoelectric sensor positions were determined. The finished instrument was then examined with laser vibrometry to confirm earlier results, evaluate the behavior and chosen sensor positions for various tonewoods, and examine the acoustic effects of adding sensors and wax finish. The conclusions drawn are diverse and point to the significance of attention to detail in each step of instrument construction. For example, when changing instrument material from one softwood to another, ideal locations for piezoelectric sensors are subject to change. We conclude that detailed acoustic analysis can significantly aid in the construction of new instruments by quantifying the impact of instrument geometry and material properties.

Modal analysis and computer aided design studies of acoustic guitar structural designs

This study seeks to systematically identify modern Computer Aided Design (CAD) techniques to optimize acoustic guitar design. The study uses traditional design as a starting point for analysis of variations in materials and bracing structures of the front sound plate. CAD techniques are used to model the guitar and provide a broadband input that allows analysis of its modal response. Design optimization occurs in creating the most favorable modal response of the instrument while still maintaining structural integrity through effective support of the forces created by the strings’ tension in the bridge and neck. The measures chosen to help identify the most favorable response are modal density, magnitude of the response at each mode, and the locations of the largest magnitudes. Increased modal density provides a richer timbre while the amplitude of the response determines the relative intensity of the sound projected. Increased modal response in the upper bout of the instrument can improve the timbre of pitches in the upper frequency range of the instrument. After analyzing these measures for multiple variations and iterations of a selected set of structural parameters, an optimal design is suggested. The results show good agreement between experimental modal measurements and computer-aided design modeling.

On the structural‐acoustic design of guitars

A structural‐acoustic model of a guitar top plate backed by a rigid cavity has been built. Acoustic coupling between the interior and exterior acoustic fields is accomplished with a simple model of the soundhole. Acoustic power spectra are calculated in 1/12 octave intervals from 55 to 440 Hz. The soundboard is modeled as an orthotropic damped plate with reinforcing beams and a circular cutout forced by harmonic point loads representing the strings. The model requires the plate outline to be axisymmetric. There are no limitations on the number or orientation of the reinforcing beams. Material property variations, brace cross section, brace pattern layouts, individual brace tapers, plate thickness, and varnish and glue line effects can be studied with this model. A suitable database of material properties and guitar geometry parameters, string lengths, bridge placements, etc. has been built to support the model.

Characterizing guitar sound using time-evolving spectra

The sound of a guitar or similar instrument can be characterized by the time evolution of its partials and its noiselike sound components. This includes the establishment or generation of noise, families of partials, and formants and resonances by the nature of the plucking and the characteristics of the instrument. It particularly includes the decay and interchange of energy among all the sound components. The investigation of these components is facilitated by using linear and logarithmic-frequency spectral analysis and by using variable-length time windows in acquiring data to be analyzed. Displays of time-evolving spectra demonstrate the different characteristics of classes of guitars such as classical and steel string and the differences between members of each class. The relationships among measurable sound parameters and guitar quality and guitar design and construction will be discussed.

The craftsman's and the concert performer's evaluations of new classical guitar designs

The luthier must set standards of construction based on both the choices of woods available for guitar construction and the criteria of instrumental mechanical integrity in coping with a new guitar design. The concert musician must re‐evaluate his own approach to guitar dynamics in performance, as well as instrumental balance, when a new instrument is used in ensemble and concert hall performance. A demonstration of the characteristics of a new classical guitar with and without internal microphone amplification will be given.