Q: I loved a latest column by which you talked about how headstock repairs can have an effect on guitar tone. Web boards abound with anecdotes of swapping out heavy tuners with lighter machines to enhance the tone on sure guitars. Is there any reality in that? Having a PhD in physics, I additionally appreciated the physics taste sprinkled all through the article. I spend lots of time fascinated about why totally different guitars have totally different sounds. In idea evidently one might predict the tonal properties of an acoustic guitar simply by realizing the entire materials properties and particulars of development. However in observe I’ve realized that there’s as least as a lot artwork concerned as there may be science. It’s fascinating to me!
—Stephen Johnson

A: Thanks for the type phrases. With out query, the physics of stringed devices is an intriguing and complicated subject, filled with extremely interactive variables and completely subjective evaluations. Individuals can spend—and have spent—entire lifetimes making an attempt to orient themselves on why devices work the way in which they do, and methods to predict or management the outcomes prematurely. Earlier than we take a look at your particular query, I’d prefer to recommend just a few rabbit holes for anybody keen to leap into the world of physics-based instrument constructing and analysis.

The fashionable method to scientific research of instrument conduct started primarily on this planet of violins, with the extremely influential work of Carleen Hutchins and Norman Pickering. From there, violin analysts comparable to George Stoppani have carried the torch ahead, creating high-tech analytical instruments utilizing custom-written software program, accelerometers, and laser holographic imaging to visualise plate conduct. Guitar luthier Alan Carruth was one of many main bridges between the violin and guitar fields, and continues to be on the forefront of analysis on guitar efficiency.

One other necessary faculty of guitar analysis originated in Australia. Luthiers Graham Caldersmith and Trevor Gore introduced new ranges of rigor and scientific methodology to their constructing method and revealed fairly just a few papers documenting their outcomes each empirically and mathematically.

Lastly, in america, numerous builders have begun utilizing FFT (Quick Fourier Remodel) software program to judge and tune their devices, each throughout and after development. Specialised gear such because the LucchiMeter is used to measure transmission velocity of vibration via supplies, permitting wooden suppliers to type wooden in response to sonic efficiency in addition to mechanical and aesthetic properties.

Though many of those methods have begun to point out actual outcomes, I believe it is very important point out that the gold commonplace of tone and efficiency for a lot of makers stays the classic guitars of the Nineteen Thirties and ’40s, all constructed lengthy earlier than such scientific strategies have been developed. Instrument tone is inherently a subjective and consistently shifting goal, and analytical instruments can solely inform us a lot, simply as no scientific analysis of a portray can precisely measure its emotional affect on the viewer.

Shifting on to your particular query: altering the load of tuning machines can completely have an effect on the tone of the guitar, and I’ve encountered this fairly just a few instances in my restore work. The neck and headpiece are fairly a bit extra versatile than many guitarists understand, and I’ll generally shock my shoppers by clamping the physique in a vise and displaying them simply how simply the neck will flex with mild hand strain. On some guitars, it’s doable to yank on a single string and watch the others stand up larger above the fretboard as the entire neck bends ahead.

This flexibility is among the primary culprits in subtracting vitality from the vibrating string. The neck/headpiece system oscillates when excited by the string, and the speed of that oscillation can be affected by each the stiffness and weight of the neck. Loading the tip of this oscillator is a very direct strategy to management its charge. Heavier tuners will sluggish the speed, which has two results—it could actually contribute to maintain by including inertia, however it could actually additionally probably push the neck’s oscillation down into the musical vary of the guitar. When this occurs, some notes can sound weak and even lifeless, because the guitar will lose vitality to the neck far more rapidly at these particular frequencies. It’s fairly straightforward to experiment with including mass to the headpiece to gauge its impact—a easy C-clamp will do (padded, after all!), or one of many commercially obtainable aftermarket merchandise such because the Fatfinger maintain enhancer. For notably versatile necks, these merchandise can generally be useful in shifting the problematic frequencies to a much less problematic vary.

Lighter tuning machines, against this, will present much less inertia, which raises the native frequency of the neck/headpiece system. For this reason some gamers understand an improved tone after switching to lighter machines. The lifeless spots typically shift larger into a variety that doesn’t compete with generally performed notes. It accomplishes an identical impact to creating the neck extra inflexible, however a lot much less invasively. Lighter tuners additionally noticeably enhance the steadiness of an acoustic guitar, decreasing “neck dive” and total weight.

Each guitar have to be thought-about in its entirety as a bodily system, and totally different makers have totally different priorities and preferences of their work. The late Rick Turner typically expressed a choice for heavier, extra inflexible necks in his devices, whereas different builders, comparable to Ken Parker, have engineered sensible programs to construct necks which might be each lighter and stiffer than the normal strong mahogany and maple. Each approaches have their adherents—and each can yield outstanding devices.

Received a Query?
Unsure about guitar care and upkeep? The ins-and-outs of guitar constructing? Or one other subject associated to your gear? Ask Acoustic Guitar’s restore skilled Martin Keith by sending an e mail titled “Restore Knowledgeable” to [email protected] and we’ll ahead it to Keith. In case your query is chosen for publication, you’ll obtain a complimentary copy of AG’s Acoustic Guitar Proprietor’s Guide.

This text initially appeared within the July/August 2023 situation of Acoustic Guitar journal.