Visual Analyser

[Jerry Mercer]

I am trying to use Visual Analyzer to test my tops as I go through the process of thicknessing, bracing, installation, voicing, etc.  I've set it up with a small amp which powers a coil, which in turn excites the top via a rare earth magnet stuck to the top.  The input signal is via a microphone.  I excite the top over a range of frequencies and am trying to capture the spectrum of response resonance from the top.  My problem is that I don't understand the jargon and acronyms used in this kind of analysis and have not been able to get a response curve that is intelligible.  When I do a capture of the spectrum, it seems to have no correlation to what I'm hearing and seeing on the oscilliscope window.  I feel like I need to go back to school and major in acoustics to be able to understand how to set this up to get what I want.  There are a bunch of settings to input in preparation, but they use acronyms and jargon that I don't understand.  Is anyone else doing this and can you help me with the setup?

 

Thanks.

[Chris Sisson]

Can you share a link to information about the "Visual Analyzer?"

[Paul Verticchio]

Read the instruction manual or contact the manufacturer?

[Jerry Mercer]

Just do a search for "visual analyser" and you can download the program for free.  You can also download an article and a manual.  The problem is the background definitions of the abbreviations and terminology is assumed and not well explained.  What I need to know is what are the initial settings, utilities and controls to get a smooth chart from a capture of a spectrum over the range of interest.

I think the originator of this program is in Italy.

 

[Jeff Highland]

I use VA but in a very different way

The settings I use for Tap testing of the finished guitar (and subsequent fine tuning) are on

http://www.goreguitars.com.au/attachments/Technical_note_on_collect...

I have a very strong belief however that testing of free plates is rather meaningless

Alan Carruth is the king of free plate tuning, however he uses Chladri patterns rather than analysis.

Trevor Gore's books are well worth the money if you want to explore this aspect of building.

[Jerry Mercer]

Thank you Jeff.  I think the article you referenced and the initial settings of the program will help.  The method I'm using to excite the top during its various stages of preparation and installation allow access to make adjustments right up until the back is glued on and finishing.  See Brian Burns's website lessonsinluthiery.com.  By taping the back on, it's possible to get a very close estimate of the final resonances of the guitar.  I'll report on my success (or not).

[Jeff Highland]

Actually it was Brian Burns who first put me on to Trevor Gore about 2 years ago ( he has hosted Trevor's workshop there)

I have had the books for about 6 months and a couple of weeks ago did a 3 day workshop with Trevor which was great.