Hmpf

[Matt Atkinson]

Cut binding channels today. I haven’t worked on this guitar for a while and the closed body has been sitting around. Shop humidity is under control. I gave the top a tap as I usually like to do and it sounds tight as a drum. The plates rang nicely before assembly. Dead as a door nail. I have an old beater I made years ago somewhat disassembled, and that one booms when I tap it. Hmpf...
The top is .110”, back is .105
Bracing is fairly light.
Will thinning the top help perhaps? Scraping the tone bars?
Thoughts?

[Barry Daniels]

Cutting the binding channels will make the body sound dead. Glue in the bindings and you will get your tap tone back.

[Matt Atkinson]

That's good to hear and interesting. I guess solidly gluing the bindings is important for tone? Does this mean wood bindings and plastic bindings have different effects on tone?

[Barry Daniels]

I don't know about that. There are so many other factors that influence tone. You would have to build two identical guitars except for the binding to see if it makes any difference. And that probably even wouldn't be definitive.

[Alan Carruth]

Cutting the binding rabbets does two things; it loosens up the edge a bit, and opens a lot of air holes. I'm pretty sure its the leakage that has the most effect on the tap tone sustain, and the pitch, particularly for the 'main top' and 'main back' modes does drop. The 'main air' mode should rise in pitch with all the air leaks. Putting the bindings on stops up all the leaks, and replaces most of the lost stiffness, so you pretty much get back to where you were. I'm not sure there's any difference between plastic and wood binding: I only use wood.

[Clay Schaeffer]

I've read that violin purflings are lightly glued in place so the top acts as a "hinged" plate rather than one that is solidly glued. I'm not sure that having a well defined tap tone is what makes an instrument sound good. I made a guitar whose back tapped like tupperware. The finished guitar sounded very good. I would be curious to know what other people's thoughts are on this.

[Alan Carruth]

I think a well defined top tap tone is probably a good thing. Maybe not so necessary on the back: the top and back have different jobs, after all. A lot probably depends on why the tap tone is 'tight' or not.