Boomy B

[Crusader]

The most recent guitar I've made is like a large Les Paul in shape and is fully chambered. While not being an accoustic it has a lot of accoustic properties. It has f-holes, a Bone Saddle with an LR Baggs piezo under it, but also has two humbuckers, so a bit of a hybrid. The question I have is more to do with the accoustic side of things

It has quite a boomy sound when I play around B or C, whether its single notes anywhere on the fretboard or chords. It feeds back like crazy when playing any of those notes or chords

One of the things I have experimented with on guitars is their "Tap Tone" and this thing tap tones at B1+40 cents. So my conclusion is that's what causes the boominess when playing those notes

HOWEVER

It occurs to me that because it's hollow that the problem may also lie in its accoustic resonance. What if the accoustic resonance is also B? How could I determine what it is. Blow over the f-holes like a bottle?

[curtisa]

I would've thought you've already found the best way to determine its acoustic resonance - plugging it in and seeing which notes it wants to feed back on the most.

I also would've thought that any acoustic resonance will far outweigh the inherent 'tap tone' the solid parts of the guitar may have, in which case it will always appear to resonate at B1. The chambers you've created are providing some acoustic amplification and will impart their own resonances (in this case, B1) to the overall sound when excited by the strings vibrational energy. Taking your beer bottle example, blowing across the top to excite the resonance inside the caivty gives its own distinctive pitch, but very little of the high-pitched 'ting' you get when hitting the side of the bottle with a hard object gets imparted into the tone you hear when exciting the acoustic resonance of the bottle's chamber.

[Crusader]

11 hours ago, curtisa said:

I would've thought you've already found the best way to determine its acoustic resonance - plugging it in and seeing which notes it wants to feed back on the most

Yes I was thinking that. I Googled around and found a similar question and it was suggested to sing into the sound hole. And the feedback should achieve the same result. So if that is the case then it seems that the accoustic resonance is the same as the tap tone

Thanks for your reply Curtisa

[ScottR]

When I was building Sarah's mandolin I learned that the tuning of the tone bars in the arched top was intended to combat that very effect. Your description is the best I've ever run across of what that effect actually does.

SR