resonant frequencies no where to go

[soundshooter]

I just closed my first box. It is a GS (small Jumbo) 14fret 25.4scale Cedar top walnut back. The back is not radial braced but is seems pretty mobile. I plotted the frequency and the box already is very close to target. 89.5 191 240 I don't have a neck or a bridge on, but with a 25gram bridge taped in place I got numbers of 87 172 235 . Not sure if I'm jumping the gun, but it seems that this may present problem if the T(1,1)1 (and every thing else for that matter) keeps going down. I'm hoping I didn't under build it.

I'm thinking that the sound hole is too small for the box even though it is right what the plans call for 95mm . I ,in my limited experience am thinking it is posable to push everything up with an adjustment to the sound hole, (which there is very little room for). Would a sound port help or just open a can of worms. How can i close a gap between the T(1,1)1 and the T(1,1)2 and what is that little hump around 110?

Any thoughts would be appreciated.

[luke_lee]

Hi sound shooter,

Are you building a classical or steel string? What are you target frequencies?

I’m am not an expert, I have only made one guitar using Gore/Gilet techniques.
It is a steel sting, x braced(sound similar specs. to yours, my sound hole 95mm) but these are my figures.
Boxed up with edges thinned:
91.5 191.3 224.8 293.8 319.6
Finished instrument:
90.1 173.6 215.3 298.4 310.9
The bridge was about 23g and the saddle added another 10g. I also shaved the back scallop to drop the back.

My target was 90, 170, 214.
I would not worry about changing anything an till you get stings on and have played it, then you will know where you really are at. You might have to reconsider you targets.

Hope this helps
Luke

[soundshooter]

thanks Luke.
Looks like you did pretty well with yours. But I notice it all started out higher.
My T(1,1)1 just seems low. I"ll be happy to land on anything that works. I guess that just might be a T(1,1)1 at 85 , with the T(11)2 at 160 to avoid landing right on an octave.
I think that I'm just think'n too much about it and it seems, like you say I should keep building and pay attention to how stuff develops.
Thanks again
Frank

[Trevor Gore]

Pretty much what Luke said.

Try to keep the bridge mass lower. It's possible to get down to 14grm for the bridge (no pins/saddle). Finish the build, and if you find a problem you can hear with the main air resonance consider enlarging the soundhole, but you can always come back and seek more advice if you have a problem.

[soundshooter]

Thanks Trevor.
I'll just keep building and see where it takes me.
Frank