In designing your own guitar personal preferences may play an important role. Do you want to play the guitar yourself? Do you (intent to) play just for yourself or do you need extra volume to cope with other instruments of the band or ensemble you are playing with? During the design of a guitar hundreds of large and small decisions have to be made. Sometimes related, sometimes not. (I have "counted" more than 200 different "decision points"!). To shed light on this complex decision process it is good to be aware of 5 main construction principles you have to take into account:
|Playing the guitar should be as easy as can be
|In constructing the different parts no unnecessary difficulties should be encountered
|The volume and sound should fulfill your specific and highest expectations
|The performance has to last for at least 50 years
|The guitar should be a piece of art and wonderful to look at
Sometimes these principles may lead to contradicting decisions and compromises have to be found. However most of the time it is easy to distinguish between "hard" and "soft" demands and to let prevail one principle above other ones. It is part of the design process and fun to make your own balanced decision on conflicting principles. A well-known example of conflicting principles comes up in the design of the soundboard. For a large volume and rich basses you will choose for a light, thin top. That may lead to an instrument with a wonderful sound, a sound however that will last for not more than some weeks because of the deformation due to the pulling forces of the strings. The "balanced" decision that has to be taken on this point and on many others as well will be discussed in the relevant chapters.
Nevertheless, decision points will remain which cannot be resolved by calculations, trying to be smart or whatever trick you should have in mind. For this group of "unsolved mysteries" we still have to look to the experience of others (in the past). This is fortunately only in exceptional cases and I will surely draw your attention to it.
The design process as described on this website is based on the design of a classical guitar. However, designers and builders of other acoustic string instruments may also benefit from the information in the relevant chapters. This holds especially for the design of harp guitars.
In chapter The harp guitar a detailed description is given on these wonderful instruments. This description also deals with the differences with a (common !) classical guitar.
Because it is sometimes easier to discuss the design process in terms of specific measurements, I will give from time to time specific examples of a realistic design. These examples are taken from some guitars designed and constructed by the author Bert Eendebak.
EB-2015 harp guitar
Whenever measurements are given in italics they are taken from that design. So keep in mind that those numbers are just examples and can or should be adapted to your own initial choices.
In the design process as described on this website, I have not used computer-based calculations or inside knowledge of mathematics, physics or acoustics. "Design of a classical guitar" is mostly based on the use of common sense, simple logic, experiments and of course a lot of reading.