Australian/New Zealand Luthiers Forum

Hi Trevor, I finally got to check this one again: I hadn´t been able to reproduce the spectrum. This time I stuck the coins from the outside to the back as I was a bit lazy to loosen the strings so that I could put them inside the guitar. I hope that doesn´t make a big difference otherwise I can rep...

Did the test with the added mass to the back and ended up with a drop of 2Hz in T(1,1)2 when I adjusted the T(1,1)3 to 214Hz. So I think the lighter bridge could do the work. With the x-brace I´m a bit confused. I get a value that seems too high. The deflection is quite high according to my jig. As ...

Thanks Trevor. I will have a look at the two bridges and see if I can get the weight a bit further down. The density of the walnut I used is around 655 kg/m3. Somewhere you posted a range of 550-650kg/m3 for the walnut you are using, so that would be at the upper end. But at the moment I don´t have ...

ohh. Correction: x-braced OOO: T(1,1)1 = 99.5Hz T(1,1)2= 202.7Hz T(1,1)3= 226.4Hz I forgot to say that the binding data was taken before scraping the binding and before sanding. After the final sanding there are further changes in the spectra of both guitars. I put in a graph which shows the changes...

Ok, I finished the binding yesterday during the night. Hmm actually it had been morning when I finished (1:30am). I should really think about doing something else instead of tinkering with guitars... Ok, here are the results for the x-braced OOO: binding x-brace OOO.JPG T(1,1)1 = 99.5Hz T(1,1)2= 193...

Ok, finally closed the x-braced OOO as well. As I promised here´s the next spectrum: closed box x-brace OOO.JPG Actually I had to shave the braces because the top frequency had been quite high. I think I miscalculated the height of the braces. Next time I should take more care to check the wood prop...

Hi, it´s me again. This time again some frequency spectra. I finally managed to close the box of my falcate steelstring OOO version, trimmed the back and top and couldn´t wait to see the spectrum. Here it is: closed box falcate OOO.JPG My peak detection excel sheet finds 7 peaks in the range from 10...

Ok, I have some pictures to show. First Chladni experiments in my life and most probably not very helpful. I actually checked with all three cases: without mass mass at the sides mass at the back at and around the resonance frequencies from the spectra 52gr at sides: 106Hz: 52gr at side 106Hz.jpg 19...

As soon as I´m back from my business trip I´ll try to put something together. Up to now I don´t have anything to do a chladni analysis. So it may take a while.

I forgot to include a picture. As you can see nothing fancy but still ...

As at the moment the humidity rose by 10% to 56% I am at the moment blocked. with my two experimental builds I´m at the stage where I could start closing the box but looks like I have to wait a few more days. This led to a situation where I had too much time while being in guitar mode. So I started ...

Hi again, I finally started with my two experimental builds. One will be a falcate braced OOO and the other one a x-braced OOO where I aim for the frequency response of a guitar I built earlier. Here I will change from the original scalloped bracing to straight braces as they are used for the J45 in...

Hi Trevor, I fear I might get annoying but I´m a bit confused so I need to ask to get the spectrum interpretation the next time right: You write that when you talk about characteristic frequencies T(1,1)1, T(1,1)2 and T(1,1)3 you mean the fully coupled frequencies. So I have to look at the unplugged...

Ok, finally back form work. If Trevor always refers to the fully coupled frequencies the numbers actually are no longer as good... the unplugged spectrum with the peak positions: top_va_spec_pos.JPG In this case I´m not only a few Hz too low. 162.5Hz for T(1,1)2 and 215Hz for T(1,1)3 doesn´t sound s...

Cladni testing could be a possibility but I have already given the guitar back to its owner
In addition I would have to start putting the equipment together as I didn´t start into this direction

Hmm, but that means I aleady have a T(1,1)3 with 214Hz as this is the peak which vanishes from the spectrum when the soundhole is plugged. So I have to raise the top frequency? Ok, I will check the peak positions of the unplugged spectrum as soon as I´m back form work and post the values. The top an...

Hi Dave, I saw that you didn´t get an answer. I can give just give you my opinion: Actually I´m quite new to the books of Trevor and Gerard but I never heard about a simple summary. The thing is that you have to work through the math. You don´t have to understand all derivations for the different fo...

Hey Trevor, thanks a lot for the confirmation of my data. It does sound nice, but that doesn´t mean there´s nor space for improvement :) As I wanted to use this guitar as a test object I can try to aim for a back frequency you suggested. Btw. just to be sure: when you talk about the target frequenci...

Hi, it´s me again. I finally got my old guitar back from it´s new owner to do some frequency analysis and to check the values for the specific mobility. This was my second steel string build where everyone had been totally surprised when they heard I built it myself. And I never came near the sound ...

Thanks for your comments Trevor. This helps to get further. Concerning the braces with and without carbon fibre... yeah, I should have checked that first instead of just guesssing. According to my spreadsheet it´s around 0.6mm I would have to remove. With the MOR would guess one needs a good statist...

Hi. I´ve got a question concerning flexural rigidity for falcate steel strings and classical. But first quite a long text to show that I most probably managed to get my spreadsheets working After a quite long break due to my job I continued work through the Book to start with the excel sheets for ta...

Hi, I need some advice: When I started building guitars, a few years ago, I somehow managed to build a really nice sounding guitar. Spruce top, maple back and sides, walnut binding. At that time I didn´t write down any dimensions, I just used the OOO plans from stewmac and added a scoop cutaway. Eve...

Sorry, somehow I kind of forgot that I read this chapter :) I was so stuck with the rest of 4.7 ... And already the obligatory spreadsheet done. Actually I was quite surprised that a variation of the scale length by 35mm didn´t change the solution for the compensation. I used the example data in tab...

Hi Trevor, thanks for your input. Sounds promising. I´ll start with the new spreadsheet over christmas and use as reference for the neck my already existing guitars. Btw. how would you determine the nut and saddle compensation on an already finished guitar? For input we have now the intonation error...

Hi, I´m building guitars as a hobby for some years. Actually these guitars have never been really bad but from 11 builds lets say 3 are really good sounding but I never really knew why. When I read about the "BOOK" I organized a copy in a library (actually I could find just one book in whole Germany...