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Old 01-25-2021, 09:20 AM
redir redir is offline
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Join Date: Aug 2011
Location: Mountains of Virginia
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Originally Posted by ArchtopLover View Post
Excellent post, this is exactly how I understand neck angle geometry for a flattop.

However, for archtops (which I prefer), neck-set geometry is not as critical a concern for the structural integrity of the instrument. Although, where tone and volume is concerned, the neck-set geometries importance comes into play when the builder is determining the string break angle at the bridge. This break angle parameter has enormous ramifications in the overall tone and volume of the instrument, and the builder can actually "voice" the guitar by simply raising or lowering the string break angle for a particular sound to be achieved. Of note, James L. D'Acquisto made his ebony tailpieces adjustable, so that the customer could play his instrument and have the tailpiece adjusted for optimal tonal preference. What is most interesting, in this regard, is that the tonal differences are well understood; a low break angle gives a warmer more plush tone with less volume, conversely a higher break angle increases volume, and brightens the overall tonal character, but adds some harshness and acoustic artifacts, that many archtop players find annoying or disagreeable, so, finding that perfect Goldilocks sweet spot is really tricky .
I don't have any experience with archies yet but the same could be said for flat top instruments too. In fact part of the reason I went to a bolt on neck is so that I could make very fine adjustments to the neck angle not for action and playability but for tone. It doesn't have so much to do with the break angle though. And if Alan Carruth comes in he can explain some of the research he did that shows that string break angle is not very important if at all on a flat top guitar in terms of tone, but what is, is bridge rotation. So if the bridge is rotated too far forward it can choke the tone. By lowering the neck angle the bridge rotates less and the guitar tone opens up. From many different experiments and measurements that rotation is accepted to be about 2deg.

So that's why this 1/2in string height at the bridge is not really a golden rule but an average. If a guitar I just built had a perfect 1/2in at the bridge but with 2.5deg rotation then I would adjust the neck angle to get back to 2deg rotation which would lower the string height at the bridge a bit. But I would rather have proper rotation which is actually meaningful then the 1/2in height which is not.
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