Search found 7 matches

by dwsdolce
Sat May 06, 2017 3:06 pm
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Redraw of 4 Degree of Freedom Model
Replies: 9
Views: 10692

Re: Redraw of 4 Degree of Freedom Model

I am putting together a package for some of the people on Robbie's forum that includes the design, models, and some instructions to get started. I will send it to you once it is ready (Monday at the latest).
by dwsdolce
Sat May 06, 2017 12:28 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Redraw of 4 Degree of Freedom Model
Replies: 9
Views: 10692

Re: Redraw of 4 Degree of Freedom Model

Hi Trevor, First let me apologize. You were absolutely correct. The difference in my formulation was that I did not realize that the back difference and back pressure from the Helmholtz resonator needed to be inverted. I went back to the "Four mass coupled oscillator guitar model" article by John Po...
by dwsdolce
Wed May 03, 2017 12:51 pm
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Redraw of 4 Degree of Freedom Model
Replies: 9
Views: 10692

Re: Redraw of 4 Degree of Freedom Model

I do not think the problem is in the model. The directions are all relative to ground. Consider that the ground is in the middle of the guitar and in that case all directions are positive in a direction from inside the body outward. That is how the equations are formed and the models within the equa...
by dwsdolce
Wed May 03, 2017 2:29 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Redraw of 4 Degree of Freedom Model
Replies: 9
Views: 10692

Re: Redraw of 4 Degree of Freedom Model

The DAE that this picture represents is identical to the model you have in the book. The back is not connected directly to the sides. There is a spring on the back whose force is equal to Kb times the sum of the motion of the back and sides and there is another spring on the sides whose force is equ...
by dwsdolce
Tue May 02, 2017 5:12 pm
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Redraw of 4 Degree of Freedom Model
Replies: 9
Views: 10692

Redraw of 4 Degree of Freedom Model

I have reworked the 4 DOF model into SaberRD Student Edition. The model looks like the image below. It contains all of the elements that are in the equations in the book or in the Matlab/Octave model available on the Australian/New Zealand Luthiers forum. I get the same resonant frequencies with sli...
by dwsdolce
Tue May 02, 2017 3:04 pm
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Inertial Force in 4 DOF model
Replies: 3
Views: 5961

Re: Inertial Force in 4 DOF model

I do see that the restoring force on the back and sides are both related to the sum of the movements times Kb. I guess I do not see why it is done this way instead of: 2.42 having Ks*ys and 2.44 having Kb*yb I guess it is the rationale for why the restoring force is the same on both the back and sid...
by dwsdolce
Tue May 02, 2017 6:09 am
Forum: Contemporary Acoustic Guitar Design and Build - Trevor Gore
Topic: Inertial Force in 4 DOF model
Replies: 3
Views: 5961

Inertial Force in 4 DOF model

Hi, I am new to the forum and just completed a course that Trevor Gore gave in the US on Modal Plate Tuning. In reviewing equation 2.4-3 and 2.4-3 in the Contemporary Acoustic Guitar Design and Build book I am trying to understand where the term Kb(ys+yb) for both the side and back oscillator comes ...