Testing Pacific Rim Tonewoods sonic graded tops

[johnparchem]

I am starting a new classical guitar. At the Guild of American Luthier convention I bought some Pacific Rim Tonewoods sonic graded tops with the Density and young modulus and Q provided. How well do they match up? Actually pretty well: Density 422 kg/m3 vs 411 and elong of 13.67 GPa vs 13.8 GPa. When I plugged the values I got from Pacific Rim Toonwoods vs my tested values the target thickness changed .024 mm. (I used my Ecross)

Here is a 10 minute video showing me going through the process.


youtu.be/SoG0iopzKfw

[kiwigeo]

Great stuff thanks John!

[GregHolmberg]

Nice to know they're doing a good job at PRT.

I had seen one piece on their website that was measured when it was 21 mm thick. If they then slice it up to thinner pieces and put the same label on all of them, I suppose there could be small variations within the larger slab, which would explain the small differences you are seeing. Also, I suppose the moisture content could have changed.

I think it's a great service. You actually know before you buy it how thick you will be able to make it, and what the mass will be. All the other places just grade the appearance (in a non-standard way). Having a low-mass top is how you get exceptional monopole mobility. Well, that and how stiff the bracing is.

Greg