[El Duque]

thanks for that explanation.

So..if there is too much backbow it would affect the action as in too high? But the action could be high and the relief correct - a result of a high saddle or nut. I'm guessing there is more to it - like why there is relief in the first place.

is there a standard measurement for relief?

I do admit to thinkin the truss rod was there for the action. Still learning...