CHOOSING MUSICAL INSTRUMENT TIMBER by the TAP TONES SELECTION METHOD
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I have read publications by guitar manufacturers where they say something like; this season's harvest of exceptionally good "tonewood" is going to produce some very fine acoustic guitars. Other guitar makers claim that they have found some very old timber that's well harden, or they use a special hi tech process to age the timber so they don't have to wait too long till it becomes harden and able to be used. The claim here is that select species of old harden timber is the best wood to use and supposably is the main factor that determines the outcome, of the best sounding guitars. Wood cells, vessels and fibres made of cellulose are filled with gums and resins, the cell walls are cemented together with lignin, collectively these substances eventually tend to become harden with age. This aging process makes a timber soundboard stiffer and gives it a higher value of spring constant (k), tensile strength.
A piece of timber is primarily seasoned to remove the excess water content, which makes it stable enough to use for most jobs. If the timber is going to be used to make a musical instrument though, it will need further treatment. Luthiers use an old age method of choosing their own tone-wood. A thin wafer of soundboard timber is held loosely at one end and is allowed to hang in mid air, while it is tapped on by the knuckle. The ringing sound that is produced and heard is the deciding factor.
The person listening to the ringing sound of a soundboard is hoping to hear some good tone; ok generally what's heard is a long period of ringing or a short period of ringing. The soundboard will not ring for very long if all the cellulose fibre, lignin, and small amounts of gum and resins have not had enough curing time to solidify. Simply the vibrations will be absorbed by the softer state of these ingredients. On the other hand if it is in a cured solidified state with a higher value of tensile spring constant (k) it will have to ring for a longer period of time, to shake off the vibrations rather than absorb them, before returning back to a normal state of equilibrium.
So how does the tone come in to all this? If it rings for a longer period of time it has tone? Yes it does, tone specifically is a collection of diminishing higher frequencies included within the longer lasting first fundamental frequency, where the important word here is diminishing! You need a long period of vibration to hear as many higher frequency harmonics as you can, to build up a musical tone. To take this a little further it's not because it sounds a little louder initially when it's tapped on or that the soundboard rings at some lower or higher fundamental frequency but what comes after, the sustained ringing tone!
Ok so now with all the above in mind, even if you do choose the best timber soundboard you still have to put it altogether in some way to produce a musical stringed instrument. Simply placing an equivalent weighted mass load of 74 kg onto the central area of an x- braced soundboard, supported only by the thin side walls of the guitar body and crossing your fingers hoping the x-brace and the "tonewood" will take care of the rest; simply wont do and sounds like an uncalculated proposition to me.
OVERALL POINTS OF DISCUSSION
It's well known, that different species of timber produce different tones of sound, when we simply tap on a sample piece of timber to make it vibrate. Like all materials, the tonal sound we hear from a sample piece of timber when set to vibrate will largely be made up of a first natural fundamental frequency. But other weaker higher frequencies called overtones are also included and occur in the tonal sound we hear naturally.
These combined frequencies altogether simultaneously produce a collective tone called a complex tone, in accordance to the timber samples own set of natural resonance and fibre characteristics. All objects by their own set natural resonance and material characteristics' produce different tonal sounds. A string, stretched and made to vibrate a sound also demonstrates its own natural characteristic tone, according to its metal composition, mass and especially in regards to how well the string is held, while it vibrates! The subject of tone is complex to say the very least; an in-depth mathematical analysis of the subject is beyond the scope of this paper, and is not of my intention here. However, for the sake of clarity, a more general or qualitative outline of the subject will be made here. You may also find the drawings of figures 1-11 helpful, for any of the following concepts. If you would like to query any of the concepts outlined on the following pages, please feel free to contact me. We will look into:
A piece of timber is primarily seasoned to remove the excess water content, which makes it stable enough to use for most jobs. If the timber is going to be used to make a musical instrument though, it will need further treatment. Luthiers use an old age method of choosing their own tone-wood. A thin wafer of soundboard timber is held loosely at one end and is allowed to hang in mid air, while it is tapped on by the knuckle. The ringing sound that is produced and heard is the deciding factor.
The person listening to the ringing sound of a soundboard is hoping to hear some good tone; ok generally what's heard is a long period of ringing or a short period of ringing. The soundboard will not ring for very long if all the cellulose fibre, lignin, and small amounts of gum and resins have not had enough curing time to solidify. Simply the vibrations will be absorbed by the softer state of these ingredients. On the other hand if it is in a cured solidified state with a higher value of tensile spring constant (k) it will have to ring for a longer period of time, to shake off the vibrations rather than absorb them, before returning back to a normal state of equilibrium.
So how does the tone come in to all this? If it rings for a longer period of time it has tone? Yes it does, tone specifically is a collection of diminishing higher frequencies included within the longer lasting first fundamental frequency, where the important word here is diminishing! You need a long period of vibration to hear as many higher frequency harmonics as you can, to build up a musical tone. To take this a little further it's not because it sounds a little louder initially when it's tapped on or that the soundboard rings at some lower or higher fundamental frequency but what comes after, the sustained ringing tone!
Ok so now with all the above in mind, even if you do choose the best timber soundboard you still have to put it altogether in some way to produce a musical stringed instrument. Simply placing an equivalent weighted mass load of 74 kg onto the central area of an x- braced soundboard, supported only by the thin side walls of the guitar body and crossing your fingers hoping the x-brace and the "tonewood" will take care of the rest; simply wont do and sounds like an uncalculated proposition to me.
OVERALL POINTS OF DISCUSSION
It's well known, that different species of timber produce different tones of sound, when we simply tap on a sample piece of timber to make it vibrate. Like all materials, the tonal sound we hear from a sample piece of timber when set to vibrate will largely be made up of a first natural fundamental frequency. But other weaker higher frequencies called overtones are also included and occur in the tonal sound we hear naturally.
These combined frequencies altogether simultaneously produce a collective tone called a complex tone, in accordance to the timber samples own set of natural resonance and fibre characteristics. All objects by their own set natural resonance and material characteristics' produce different tonal sounds. A string, stretched and made to vibrate a sound also demonstrates its own natural characteristic tone, according to its metal composition, mass and especially in regards to how well the string is held, while it vibrates! The subject of tone is complex to say the very least; an in-depth mathematical analysis of the subject is beyond the scope of this paper, and is not of my intention here. However, for the sake of clarity, a more general or qualitative outline of the subject will be made here. You may also find the drawings of figures 1-11 helpful, for any of the following concepts. If you would like to query any of the concepts outlined on the following pages, please feel free to contact me. We will look into:
- The building blocks of tone, the sine wave.
- How waves can affect each other and combine together to form a new complex wave, or complex musical tone (i.e. a "note" played on a guitar).
- The behaviour of Standing Wave Patterns on a vibrating string and their Elastic Energy levels, associated with each overtone pattern.
- Reflection of Travelling Wave Pulses on a vibrating string.
- How the overtones of a vibrating string are affected in more ways than one, when the string length is not held rigid and why overtones can sound either harmonious or discordant.
- Why does the X-braced acoustic guitar produce a discordant tone that degrades further with heavy strumming?
- What are the problematic causes, behind the often expressed terms that musicians make about their X-braced acoustic guitars? i.e.: A booming bass clouds or masks over diminishing treble notes? Lots of dead notes are found on the high end positions? The Treble range sounds tinny? Sympathetic string vibration occurs on some strings causing notes that are being played to sound dirty, not clean? There's no string range balance "when the guitar is unplugged".
- We will be looking at Forming a Suitable Indirect Bracing Structure (IBS) System for the Soundboard, to overcome the limitations of a direct bracing system, and at the same time resolve all the problems associated with the limited X-bracing system, by my novel approach.
- How THE BENEFITS of the IBS SYSTEM come about; as listed from Fig 1.
- Why the Soundwave Propagation from the sound hole of my IBS System is clear and projects further.
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