PSA: The Preeminent Authority on Acoustic Sound

[varve]

I commend Breedlove/Bedell.

They are testing their wood with well established technology, measuring the actual acoustic properties of the top, and applying that information to optimize tone, instead of simply relying upon visual grading and hoping for the best. Kudos!

This type of approach works -- really well! The following link scrolls down to a study that is not Breedlove, but one done with Taylor guitars and our partners at the Technical University in Dresden. It was published Oct 2019 in the Journal of the Acoustical Society of America.

https://www.researchgate.net/profile/David_Olson13

Here is the abstract - if it is of interest, please do read the whole thing. Although we use a slightly different technique than Breedlove/Galloup, it validates the approach of using acoustic characteristics to optimize tone:

"The wood of the spruce tree (Picea spp.) has been valued for centuries as an ideal soundboard for stringed instruments due to its material acoustic properties. There is large variability in these properties between individual trees of the same species and even within an individual log. It stands to reason that this variability would produce audible differences in the sound quality of otherwise identical musical instruments. Furthermore, there may be a suite of physical characteristics of the soundboard that would result in optimal sound quality for a given design. Nine steel-string guitars of the same model were produced. The guitars varied only in two parameters: the density and Young's modulus of the soundboard and bracewood. This variability was representative of the range of wood currently produced by Pacific Rim Tonewoods. A short music sequence was used for a pairwise preference evaluation in a listening test. The results suggested that, for this particular model (the Taylor 814ce Grand Auditorium), the low density and Young's modulus of the soundboard and bracewood had a positive impact on the sound quality. More generally, these results underscore the importance of integrating a given design with the physical characteristics of the component wood."

Cheers, Dave Olson

[frankmcr]

Originally Posted by varve

I commend Breedlove/Bedell.
They are testing their wood with well established technology, measuring the actual acoustic properties of the top, and applying that information to optimize tone, instead of simply relying upon visual grading and hoping for the best. Kudos!
This type of approach works -- really well! The following link scrolls down to a study that is not Breedlove, but one done with Taylor guitars and our partners at the Technical University in Dresden. It was published Oct 2019 in the Journal of the Acoustical Society of America.
https://www.researchgate.net/profile/David_Olson13
Here is the abstract - if it is of interest, please do read the whole thig. Although we use a slightly different technique than Breedlove/Galloup, it validates the approach of using acoustic characteristics to optimize tone:

"The wood of the spruce tree (Picea spp.) has been valued for centuries as an ideal soundboard for stringed instruments due to its material acoustic properties. There is large variability in these properties between individual trees of the same species and even within an individual log. It stands to reason that this variability would produce audible differences in the sound quality of otherwise identical musical instruments. Furthermore, there may be a suite of physical characteristics of the soundboard that would result in optimal sound quality for a given design. Nine steel-string guitars of the same model were produced. The guitars varied only in two parameters: the density and Young's modulus of the soundboard and bracewood. This variability was representative of the range of wood currently produced by Pacific Rim Tonewoods. A short music sequence was used for a pairwise preference evaluation in a listening test. The results suggested that, for this particular model (the Taylor 814ce Grand Auditorium), the low density and Young's modulus of the soundboard and bracewood had a positive impact on the sound quality. More generally, these results underscore the importance of integrating a given design with the physical characteristics of the component wood."

Cheers, Dave Olson

The last sentence appears to be saying that, although the tonewood type is important, what the builder does with that particular example of tonewood is equally important?

[bufflehead]

When I look at the charts in the OP, what I see is a huge plug for myrtlewood.

[merlin666]

Originally Posted by varve

I commend Breedlove/Bedell.

They are testing their wood with well established technology, measuring the actual acoustic properties of the top, and applying that information to optimize tone, instead of simply relying upon visual grading and hoping for the best. Kudos!

This type of approach works -- really well! The following link scrolls down to a study that is not Breedlove, but one done with Taylor guitars and our partners at the Technical University in Dresden. It was published Oct 2019 in the Journal of the Acoustical Society of America.

https://www.researchgate.net/profile/David_Olson13

Very interesting. There are many threads on the AGF where studies like this were discussed. It reminds me a bit of the pioneering work of C. Kaman in the early 70s who used a vibrometer to measure guitar top characteristics. His ultimate goal was to use this approach to design a top that had the "perfect" sound (using the top guitar players at the time as test subjects), and was also independent of the natural variability inherent to wood. The result were the first carbon-fibre topped guitars which are still in production now, almost 50 years later.

BTW I like your early papers on paleolimnology. I wanted to do similar work based on stable isotopes in the early 90s but alas my advisor pushed me into the carbon-hydrogeochemistry field. Oh well ...

[varve]

Originally Posted by frankmcr

The last sentence appears to be saying that, although the tonewood type is important, what the builder does with that particular example of tonewood is equally important?

The type of tonewood is less important than the underlying acoustical properties of each piece of wood. There is such variability in, e.g., stiffness and density of spruce wood (check out the two graphs in the paper - a total of 1200 pieces of wood sampled), that one species will grade into another and erase the importance of species designation for a given guitar. This paper just looked at Sitka, but each species used as topwood will have an average property, and a LOT of variability around that average.

Each guitar design, it would stand to reason, has an ideal set of physical characteristics in the top wood and bracing that will give rise, predictably, to a desired tonal quality. This paper gives one such example, for a popular steel string guitar model (the Taylor 814) -- but it would not be expected that other designs would necessarily have that same optimal set of characteristics.

The key message , though, is that once that optimum is determined, for any given design,we can use acoustic testing to reliably deliver very similar wood for the next guitar, or the next thousand....

DO

[lar]

I couldn't find the full text, but the abstract says:

"the low density and Young's modulus...had a positive impact"

So this means low density and low Young's modulus (i.e., low stiffness)?

[varve]

Originally Posted by lar

I couldn't find the full text, but the abstract says:

"the low density and Young's modulus...had a positive impact"

So this means low density and low Young's modulus (i.e., low stiffness)?

The title, found in the midst of a few other papers on torrefaction, etc:
"Perceptual evaluation of bracewood and soundboard wood variations on the preference of a steel-string acoustic guitar"

Yes, for this particular model and design of guitar, the best top wood, in two separate and independent runs of the experiment, was the lower density and lower stiffness Sitka spruce. The high density/high stiffness wood showed a signifcantly lower preference score, based on pairwise comparisons in listening tests with 23 guitarists, both pro and amateur.