You will find the German version of the interview here.
The classical guitar is usually used as a solo instrument. If you play a guitar together with other instruments, she can not compete. Where can your guitars in a musical environment be used appropriately? Where are the limits?
There is clear limit if you want to play a guitar in an orchestra or with a greater chamber orchestra. But this problem can easily be solved: With good pickups and the right audio system the guitar can be adapted to the level of the other instruments. Audio engineering possibilities have developed so far, so you can use them
in solo live performances, without committing a breach of style. But even the best technology can not do more than the one who is sitting behind the guitar
The guitar is subject to a further limiting factor: It is depending on the “assistance” of many other factors:
The intonation, the strings, the mechanics of stroking e.g. In this regard the work of a simple piano maker is much more easy. He can determine nearly all components of its system. Thus, the pianist can concentrate more on the interpretation. The guitarist on the other hand has to deal not only with the interpretation. He has to master at the same time the craftsmanship of the sound production.
The sound of the guitar is thus determined by three substantial factors: the sounding device/guitar, the guitar player and the acoustics of the room.
And even in the latter, the guitar does not provide much power of its own. She is dependent on the "assistance" of an optimal environment. Thus I often regret, that soloists play everywhere and are not more critical with the selection of the hall or ambiance. What good are concerts with famous soloist for, when the acoustic conditions make it impossible to seize the full sound of the instrument. In such a case it would be better to play with a proven amplification adapted to the room.
Asked pointedly: Who is essentially responsible for the sound: the guitar or the player?
Both - the guitar and the player - each part for itself has its area and thus its borders in which it can move freely. The guitar has its own characteristics: the sounding body, the timbre, the character of the instrument. The guitar cannot produce things, which must be done by the player. On the other side the player can still strive so much for a good tone and play as fine as he intimately can: He will never be able to change the character of the instrument. He will always stay in the given in the frame, but he can exploit.
But do not forget the listener in this interaction. He is usually not able to differentiate whether the sound was influenced by the guitar or the player. He hears holistically. If you hear "more professionally" you have to differentiate. As a luthier I must ask myself: Where is my constructive influence and what is the art of the player. And with that last point I have as a luthier unfortunately a problem: I have nearly no influence on the playing technique of the guitarist.
Does that mean that a very good guitar requires also a very good player, in order to tap the full potential of the guitar?
No, not really. But if a guitar has particularly good qualities, the player must have on the other side a special sensitivity for sounds. He must be able to produce this special sound characteristic in the instrument.
Let us imagine an extreme example: An amateurishly playing guitarist, who has however a very good sound feeling, is able to evoke much more for the demanding ear than a virtuoso who plays this instrument, because it was in the moment available and disrespects the tonal quality of the guitar.
During the sound production process: Which role does the guitar playing technique and the sound characteristics of the guitar play?
The stroke of the guitarist is an important component, which has a dominant role in the resulting sound. It should accordingly be perfected by the soloist. But he should be aware of the basic physical processes.
The guitar consists of two vibration systems: One is the corpus. The other one are the strings. The strings must be put in vibration so that they are as efficiently as possible coupled to the body .
The stroked string can vibrate in many directions (horizontal / vertical, etc.).The soundboard in contrast can only swing vertically. Therefore the playing technique must be optimized to produce a maximum degree of vertical oscillation.
Thus an optimal stroke is necessary, in order to use the full potentials of a guitar.
Which criteria determine the development of your instruments: Are there any scientific approaches, is it more empirical or do the playing techniques, characterize your building method?
I would call my approach empirical science. Basis for the optimization of the instrument is persistent and careful observation and evaluation of the different manifestations of sound .
After many years of experience, I was able to isolate the relevant parameters of sound production of the construction and to modify it. The systematic cycle: observe, judge, modify, monitor, evaluate .... is accomplished with each guitar and then produces also the appropriate results.
I had the chance to observe many guitars and also different luthiers: There are many connections between sound and structure that always repeat themselves. They are as quasi constants in the building of guitars. These are the starting points and the basics where I try to get to conclusions. They are based on physical laws.
My science is based to a large extent on qualitative knowledge. I know e.g. that a large sound hole or a thicker soundboard will increase the resonance frequency and vice verso. But I do not start to calculate with elasticity modules in order to determine the resonant frequency. In my opinion that is unreasonable. The work with empirical values and certain systematics, appears to me the more effective approach. So you have the chance to avoid coincidences.
To describe sounds with words, which will be interpreted by others in the same meaning is actually an impossibility. Anyway: Can you describe your sound ideas that you try to realize when building guitars?
The central point for me is the aural experience of my own playing . My guitar studies, which I have concluded in Frankfurt, were in every respect very intense. During this period basic features of my playing technique and the associated sound conceptions were substantially engraved.
My personal ideal of sound is characterized by a very strong fundamental resonance. If you take for example a harpsichord. If you play it, you will notice that bass notes have very strong harmonics whereas the basic tone is in comparison relatively small. In contrast the piano has a much more fundamental resonance.
When we look at the guitar, the relation between the fundamental resonance and the harmonics varies from one guitar to another. An instrument tuned to a deep fundamental resonance will not only be defined by a strong bass. The deep fundamental tuning will be noticed also in the high registers. This means that also an instrument with a weak bass can be stronger in the fundamental resonance than an instrument with a strong bass register but whose sound is thin and nasal.
Stringed instruments are valued according to similar criteria. In use is the formant theory, which uses the complex tonal sound of vocals in order to classify an instrument. An instrument can sound like: "U", "O", "A", "E" and "I". With the tone color of the vocal a judgement is associated. Instruments, which sound after “E” or “I”, have a nasal character and will be set aside. Instruments, which sound after “O” or “A”, will be preferred. Instruments, which sound after “U”, sound dark and musty and will not be regarded as good instruments.
Within the violin building society you can find a well-defined and accepted value system. It can not be confused with questions of taste. I advocate to establish this system also for guitars .
Everyone can with simple technical means reconstruct this practically. If you run a musical performance through an equalizer, you can filter out the region of the formant. If you amplify or damp the special formant you will not only listen to a change of the sound, you will also get an evaluation. There is always a tonal change that is unpleasant or pleasant.
The dominance of the "E" and "I" register is unfortunately a characteristic of many guitars. This is strengthened by the habit of most players to play too close to the bridge, instead of compensating the sound by picking over the sound hole. The sound ideal of Spanish guitar in 1900 was probably quite different. I have the need to give to this “original " sound aesthetics new life.
Can you tell us something about the relationship between volume and sustain?
With these parameters you can observe two phenomena. One must distinguish two types of volume.
One could be called the power of projection. Instruments with great projection produce even with a light stroke a very penetrating sound advancing far into the hall. This property results from the fact that guitars emit in the frequency range for which the human ear is most sensitive. These instruments have a built-in "megaphone effect". Such a tone quality has the advantage that the pure tone information penetrates far into the room. It is an important characteristic for the rendition of language information. The aspect of sensual sound stays in this respect of miner importance.
On the other hand, there are instruments that have no special projection strength, but you can play them very loud. It is thus not the question: How loud is the instrument itself? But rather: How loud can I play the guitar without loss of sound quality? The volume is thus also always a question of quality. So I have made the experience that an old Hauser-guitar sounds beautiful when you play it pianissimo or mezzo forte. As soon as you drive such a guitar to the upper dynamic limits, the sound tilts. The tone color gets sharp and over driven. Turned around: Instruments, which are tuned to deep resonance, sound nearly muffled when played pianissimo. But when you play them fortissimo they will sound really brilliant and get precious.
Sustain is another phenomenon, which is connected to the psychology of hearing. The ear does not hear the actual tone duration. It hears the sound volume ratio of the transient to the decaying sound. An instrument is loud only after the transient oscillation. The decay is - even in the loudest guitar - always quiet. The ear perceives the at the beginning strong, then decaying curve of the sound volume and gets the impression that the sound is short and percussive. If one checks this however with measuring techniques, one can see that in a loud instrument, the sound is just as long, as in a quiet instrument, to which one attributes very much sustain. But the ear “feels” subjectively. A loud instrument is therefore felt more percussive with less sustain. The percussive element is for me an essential characteristic of the guitar sound.
Are there instruments or luthiers by which you have been influenced?
Yes! As the first I must mention Daniel Friedrich. I had a Friedrichs guitar with a spruce top (1968) on which I played and studied for about six years. She shaped also my playing technique of my right hand. The instrument had a very healthy bass and sounded with a deep fundamental resonance in relation to other guitars from this time.
This was followed by instruments which impressed me by their projection strength and simplicity. For example, a guitar from Robert Ruck, played by Manuel Barrueco, which you can still hear on his recordings. It took some time until I could make my own experiences with Torres guitars. I assumed that Torres guitars would sound similar as the instruments of Romanillos or Hauser. Both luthiers appointed themselves expressly on Torres. I had the opportunity to restore two guitars of Torres. Naturally I studied also the sound of these old instruments. The sound impression was however a completely different one. A very deep fundamental sound which had also in fortissimo a warm character. They were instruments that sounded strongly after "O" or "A" and had very little nasal portions. I had found the sound that I have unconsciously been looking for.
You have very precise conceptions how your instrument should sound. How do you achieve your sound conception by constructional measures?
After a long time of observations and many experiments I try to manipulate the constructional variables of the guitar in such a way, that the guitar exactly functions, as I imagined. There are several factors affecting the instrument sound: The proportions of the guitar, the thickness and the characteristics of the soundboard are the most important parts defining the character of sound.
If you experiment with the guitar sound, there is a big problem: When I build two different instruments several months pass by. And I do not trust my ability to judge any longer. If I build several guitars at the same time and design them all differently, I have naturally different results. But these are not strictly comparable. Instruments with different soundboard thicknesses will sound different. But to conclude that the thickness of the soundboard is alone responsible for the timbre, falls short. The causes can lie also in the other material constants or slightly structural variants.
In order to receive meaningful results, I run my experiments only on the same instrument. These modifications are applied to the finished instrument. This method probably sets me apart from most other guitar makers. My actual work on the timbre of the instrument begins, when the guitar is after traditional understanding already finished. With a few simple steps I achieve the structural change and hear while playing immediately, which influence this part has to the overall sound. I have therefore a safer decision basis whether the change corresponds to my conceptions.
Because the guitar possesses one "pleasant characteristic": a sound hole. So you can perform through that hole a variety sound changing measurements. This can go as far as to remove the whole strutting system from a finished instrument and glue a modified system in again. Today you find quite sophisticated tools, which support this kind of work. The radicalism of the way I work, allows me to evaluate and compare changes very quickly.
Does your construction differs substantially from a “classical” Spanish guitar?
No, not at all. My instruments are absolutely built after the rules and traditional defaults, which were specified at that time by Torres and his successors. I have tried a lot and was ready to modify traditional defaults: the proportions, the location of the sound hole, extreme curvatures similar to the violin, changes of the string attachments, in order to avoid tension on the soundboard, bracing of the bottom in the longitudinal direction, reinforcements of the back or the neck etc.
It did not help at all. Meanwhile I am however convinced, that the traditional system works amazingly well and concerning the basics there is no need for further improvement.
Talking again about the sound characteristics. How do you evaluate the relationship between the soundboard and the rest of the guitar?
Back, ribs and neck do not have a substantial radiating function. That does not mean however that you can construct them as you like. For example, if a soundboard resonance occurs, there will always be the other half of that wave, which is activated in the back or at the neck.This second part of the oscillation does not contribute to the radiation, but is necessary so that the oscillation can be formed on the soundboard. If the back is very heavy or the neck is extremely stiff, the oscillation can not be well formed and thus the soundboard can not vibrate accordingly.
Let us talk about the construction of your soundboard, which differs substantially from "traditionally built" guitars.
It was again a matter of experience: guitars with light soundboard material have always sounded in my ears better than those with a heavier top. I continued my experiments with light material, which brought further improvements to the sound. In the consequence I looked for possibilities to become independent of the natural constants.
If I had thus a beautiful, but to heavy wood, I have tried systematically to make this plate lighter by suitable construction methods. This led me to the sandwich structure. This is a principle, which one can observe everywhere in technology and nature. The wood itself has the characteristics of sandwich construction. Viewed under a microscope one finds cavities which are enclosed in chambers. I have enlarged this quasi micro system integrated in a sandwich construction. The static structure is thus just as strong as solid wood, but much lighter. This technique is used consistently in the aircraft construction. I use meanwhile a honeycomb system, which is developed and used in this industry.
Your soundboard also differs in that it has no arch in the lower area. How do you justify this design feature?
I had seen guitars with arched soundboards, who developed a significant stronger bass than guitars with a flat soundboard. Then I thought: That is the way I have to do it! But I realized, that I just had not watched closely enough. Luthiers, who used strongly arched soundboards, dared at the same time to make their soundboards thinner. That is, the stronger bass sound was promoted by the thinner covers and not by the stronger curvature.
The curvature worsens the bass, because the soundboard cannot oscillate so well as a whole any longer. The division of the soundboard into different vibration areas remains, but the spectrum is smaller with a curved soundboard. The deep fundamental tone spectrum is raised, the harmonic spectrum, however remains the same. This is the reason why my guitar soundboards are completely flat.
How do you solve the problem of invasion of the soundboard in front of the bridge?
I see therein no problem. The dip is not the consequence of the flatness of the soundboard. There are many guitars that have flat soundboards which do not sink in so much. It is rather a consequence of the elasticity of the material. If I tune an instrument to a deep fundamental resonance, then it must be much more flexible. In this case not only the oscillations of the soundboard communicate themselves more strongly, but also the static tensions. The tension of the strings lets the bridge tilt forward. The string length becomes shorter thereby in the course of the time. My problem solution consists in the fact, that I take this amount also into account.. The saddle slot, in which the saddle is positioned, will be inclined by about 5 degrees to the rear. After a year when the soundboard has reached a stable condition and has come down, the saddle is still upright and tilted slightly backward.
On the subject of compensation: The string must always be a little bit longer, than the scale prescribes. So you add normally to a 65 cm scale another 1-2 mm. Caused by the tilting of the saddle these 1-2 mm will disappear and the guitar is not any longer tuned to a perfect octave. The height of the bridge is also of importance. The pitching moment is dependant from the distance between the string and the soundboard. So I add to the calculated string length another 3-3.5 mm. This leads to the fact that the 1st octave of the string at the beginning of the 12. fret is somewhat tuned too low. But after one year the equilibrium is reached and the timbre is correct.
Are not you afraid that your delicate soundboard collapses once? Or: Is your guitar still in tune after 20 years?
I am building guitars since 1985 and in 1990 I built a 10-string guitar in sandwich technology. But I have never heard that my guitars are broken. But wait: the 10-string guitar is broken. She managed to get under some wheels during transport.
The negative curvature of the soundboard does not break the guitar. I saw a great many defective guitars, but not one of them burst through a sunken bridge. Interestingly, cracks do not appear in the transverse direction, but always in the longitudinal direction. These cracks are mostly caused by aridity. And if timbre problems occur caused e.g. by a wrong position of the bridge, this can be easily corrected. The dip of the soundboard is not a process without end. It reaches an equilibrium state after one to two years. I can confirm this also with Torres guitars, which are about 120 years old. The flexible soundboards partially broke in / deformed strongly, but still are completely stable.
How do you adjust the timbre of your instrument ?
My focus is to bring the two resonance systems, the strings and the body into harmony. These systems have to be matched in two relations:
First of all: The basic fundamental resonance tuning needs to be adjusted. The strings are in a bass / tenor tuning comparable to the mood of the cello. The corpus however can of course have different moods, but should exactly correspond to the tuning of the strings.
With many guitars, which were built in the 70's, 80's and especially the Spanish guitars from this period, you get the impression, that strings for a Cello have been mounted on the body of a violin. They had a nasal character. The overtone was resonated very strong, but not the fundamental tone. When talking about guitars you can not correctly speak about one resonance frequency. It is not a particular tone. A musical instrument is a very broad-band resonator. This broad band can be in a low, middle or higher range. For this reason, a cello body is larger than a violin body. The corpus must correspond to the tuning of the strings.
The second point is the mass: The string mass is relatively low. There is no point in having a small mass (like a guitar string) drive a body that as the mass e.g. of a cello. The cello corpus concerning the fundamental tuning would be quite suitable, but the mass which would have to be energized into oscillation would be too great.
That implies for our instrument: The mass of the vibrating soundboard must be in a precise relationship to the mass of the strings. Is the mass of the soundboard too high, the tone of the guitar will be lasting long, but without intensity. If the mass is too small, the sound will be very percussive, but loses the reverberation. It seems to me that most guitars have a soundboard which is too heavy, so that there is no the sound intensity.
In physics, this mass is known as impedance. This plays a key role in any power transmission, including those of the string vibration to the soundboard. Regardless of its importance this aspect is within instrument builders unexplored or unknown.
How do you see the potential of future developments of the guitar?
Actually everything was has been tested. I actually recognize no large development potential in the building of guitars.
Another point are the people involved:
Luthiers might consider to invest time in musical training. The possibility to discover and develop oneself the potential of the instrument, should be an integral part of their training. Maybe even a music degree would be advisable. The sonic and musical training causes concrete sound conceptions that improves the construction process.
The guitar players too have a potential for development. I think that luthiers mostly do "their thing" already quite good. The guitar players: Their contribution to the sound of the guitar, the keystroke mechanism, is on average unfortunately not given enough priority to. This of course has also to do with a nerving problem: fingernails.
I believe that the potential of development lies in the cooperation of player and luthier. This should be the task for the future.
This article appeared in "Gitarre Aktuell"