Patent CA-2683587-A1 (CA)
Title: A structurally balanced, frame supported, mathematically tuned, acoustically amplified instrument
Inventor: BAXTER DONALD STANLEY
IPC: G10D1/08
Filed: 2009-10-29
Abstract: In an acoustic guitar, it is known to have strings suspended over and attached to or rested on a piece of wood that is tensioned by those strings, causing the wood to vibrate when the tensioned strings are plucked. That wood becomes the top of and is permanently attached to a wooden chamber that is intended to give volume and direction to the strings' vibrations. That chamber is permanently or non permanently attached to a solid wood neck. The neck is to allow the human hand to temporarily change string length and therefore frequency of string vibrations.  Permanently attached to the neck is a fret board which regulates changes with stops known as frets. There are, as far as is practicably measurable, an infinite number of groups, known as octaves, each comprised of twelve equally tempered divisions, in the harmonic musical scale, and the terminus of the first octave, along with the location of the twelfth fret, is the middle of the string. This is the harmonic centre of the string and where most stringed instruments join the neck to the chamber. Strings must be tensioned to vibrate at the specific frequencies associated with guitars and that tension originates at adjustable tuners located at the outboard end of the neck and terminates either at the end of the chamber or at some point on the top of it. The vibrating element, the amplifying element, the structural element that opposes string tension and the shape and size of the instrument are all integral to each other structurally, cosmetically and acoustically.    In this invention, the neck of the guitar is hollow and runs the length of the instrument. It is structurally in balance, has total control of opposition to string tension and is the primary means of introducing vibrations into the instrument.  The ends of the neck are identical except for an inverse arrangement of string purchase, equalizing string lengths and leverages and focusing the forces opposing string tension at the twelfth fret. On steel string guitars, steel reinforcement runs the length of the neck and is tuned, in the hollow chamber, to string length, string pull and harmonic center. The neck is not integral to the shape of the guitar or the amplifier and is permanently attached to a frame, a back and a top by being built integral to them. The top, other than where it contacts the frame and the neck and the small portion between the inboard end of the neck and the inboard end of the frame, is largely decorative and can be removed in large or small quantities to allow for acoustical balance between the vibrations being sent into the amplifier and those being sent back out and for decoration. The frame alone is built structurally integral to the shape of the guitar. Non-permanently attached to the frame and opening at the twelfth fret, is an acoustically diffusive amplifier, mathematically tuned to the harmonic centre of the instrument and fractal in three planes.     It is also known that an acoustic guitar is made of wood and it is accepted that solid wood is superior to plywood in the construction of acoustic guitars. In instances where some product other than wood is used, an acoustic guitar is built in the same manner as one made with wood, in that the resonating chamber consists of sides, a back and a top, in a clearly recognizable and accepted configuration. The top and back are usually arched to some degree. The neck of the guitar is made separately and attached to the body with glue or screws.     In this invention, the guitar is made of one eighth inch no void Birch plywood, similar to the type used to construct some aircraft. It is possible that no product in the world has better strength to flexibility to weight to price ratios than high quality no void Birch plywood. It is arranged in layers, staggered as to grain orientation and, through alterations made to each layer, forms three elements:  The neck, integral to the structural control of string tension and acoustical control of string vibrations; the frame, integral to the structural and cosmetic shape of the guitar and permanently attached to the neck and, together with the top and back, comprise the frame/neck assembly. The top and back are structurally and cosmetically integral to the frame, structurally integral to the neck and acoustically integral to both the generation and the amplification of vibrations; and the amplifier, which is built separately from, then non-permanently attached to the frame and is acoustically integral with the neck, the top and the back on its inner surface and cosmetically integral to the frame on its outer surface.     It is also known that a hollow body guitar can be tensioned by either nylon or steel strings and that a hollow body guitar with steel strings cannot be built without reinforcing the wood as the tension required to make steel strings vibrate at usable frequencies exceeds the limits of a wooden neck and top to oppose that tension and that those reinforcements were not built integral to the guitar but were added on to an existing design.     In this invention, the neck runs the length of the instrument, is hollow, is structurally in balance, is the main element transferring vibrations into the amplifier and in total control of string tension. On steel string guitars, a steel rod runs the length of the guitar inside the hollow chamber, which is on the same plane as string attachment and, through the use of shims, divides opposition to string tension between each end of the neck and the twelfth fret.     It is also known that a hollow body guitar is assembled permanently and that assembly, disassembly and repairs require high skill levels and specialized equipment.     In this invention, the fret board, which is the wear element, and the amplifier, are attached non-permanently. Assembly, disassembly, external and internal repairs or modifications do not require high skill levels or specialized equipment.