The Scientific Process Behind It

The development process behind the Tone Magnet Sustainer began with the hypothesis that adding weight to a guitar will increase sustain and improve tone. This is a largely anecdotal position, and any scientific testing that has taken place on string vibration and tonal qualities affected by mass or other variables, have made reference to acoustic stringed instruments – particularly the violin – rather than the electro-magnetically powered electric guitar. (See, for example: J. McLennan “The violin: Music acoustics from Baroque to Romantic”, (PhD thesis) NSW 2008; H. T. Nia, A. D. Jain, Y. Liu, M-R Alam, R. Barnas, and N. C. Makris, “The evolution of air resonance power efficiency in the violin and its ancestors,” Proceedings of the Royal Society of London A: Mathematical, Physical and Engineering Sciences, 471(2175):20140905, 2015; the excellent resource at New South Wales’ department of Physics is exclusively concerned with acoustic guitars; K.R. Zappas “The Science of Sound: Examining the Role of Materials in Musical Instruments” JOM, 59.8 13-17 is a quick introduction across the orchestra.)

Even the largely-debunked ‘tonewood’ theory – where certain varietals of tree produce provide better acoustic properties than other similar woods – has always been more a feature of the non-electric, rather than electric scene. Although the present author takes the position that ‘tonewoods’ are likely to be part-myth, part-confirmation bias, this has yet to be shown in a peer-reviewed paper. In the absence of that, there are a number of excellent anecdotal treatments of the subject ( on the myth-busting side, and on the counter-argument). Certainly, if there is a case for wood making a noticeable impact on the sound of an electric guitar, it is to made in reference to the density and weight of the instrument rather than any ethereal properties of – to give an extreme example – lyme vs basswood.

Whence the hypothesis that additional density, including the fixings of the guitar, would materially affect tone. The hypothesis was tested in non-lab conditions over the course of some 30 live performances using a Fender USA Standard Stratocaster made in 1995, under varying conditions, usually with a Fender Hot Rod Deluxe amplifier, this being the closest to the idea of ‘standard equipment’ to the enthusiast/semi-professional guitarist practically available. The experiments consisted of the application and removal of weights at different points of the guitar. Namely, the processes tested were: a) taping coins to the headstock, a ‘home remedy’ dating from the 1950s; b) the application of a 180g ferrite magnet to the bridge of the guitar; c) the Fat Finger, a device sold by Fender Music. Of these, b), the magnet, came out of the tests as the most effective modifier: again, not under lab conditions. The hypothesis was therefore progressed, on the evidence that the magnet solution provided the greatest change in mass of the three options. Further to this, the fact that the guitar relies on electromagnetism to produce audible sound was noted, alongside the fact that the mass of the magnet, and therefore the flux, was in contact with the bridge and therefore the strings.

The next step was to approach an academic partner to investigate further. Through the grant of an Innovation Vouncher from the Scottish Funding Council, a partnership was established with the University of Strathclyde in Glasgow and a budget of just under £10,000 to test the magnet was set. The department of Design Manufacture and Engineering Management under Dr Andrew Wodehouse was selected as the best place to undertake the study and refine findings into a commercial product.

The initial lab-based experiments were tasked with determining whether the weight of the magnet had an effect on the sound produced. The work involved the design and build of a string-plucking robot, christened Jimi, that could, as far as possible, exact identical and replicable force on a given string over the timeline of tests. The guitar used for these tests was not the 1995 Stratocaster used in the initial non-lab experimentations, but a cheaper model, with a body of plywood, but of similar density to most production electric guitars.

The results were positive, showing a clear difference in sound wave production resulting from the application of the ferrite magnet to the guitar’s bridge. However, a control was made for a) a higher-powered, lighter bar magnet and b) fixed weight without magnetic fixings, resulting in the outcomes below:2016-11-13

As can be seen, both the weight and the magnetism have an effect on the sound wave, with the bar magnets specifically according longer sustain than the medium (180g) weight. This led the team to modify the initial hypothesis that the mass added by the ferrite magnet to the guitar would affect tone and sustain and instead propose the theory that both the mass and the flux of the magnet had a significant, measurable effect on the sound of the instrument.

As part of the brief under the terms of the Innovation Voucher, the team went on to propose an effective and efficient design for the fixing, which has recently been the subject of UK Patent Application number GB1619014.2 (10th November, 2016) and UK Registered Design Application number 6002755 (10th November, 2016). Copies of these filings will be available in due course.