Abstract:
An apparatus for the amplification and projection of the sound of a musical instrument, such as an acoustic guitar, adapted to mount within the guitar itself. The apparatus may mount within the sound hole of the guitar, with an outward facing speaker within the sound hole adapted to project the sound of the instrument. The apparatus may have an amplifier attached to the speaker in a unitary design. The apparatus may be battery powered.

Description:
BACKGROUND 
   1. Field of the Invention 
   This invention relates to music, and more specifically to a system for amplifying an acoustic instrument, such as a guitar, using an internally mounted amplifier and speaker system that may be battery operated. 
   2. Description of Related Art 
   Musical instrument amplifiers are used to increase the acoustic volume of a performance of a musical instrument in a manner that produces sound faithful to the original instrument for the purpose of enabling the performance to be better heard. 
   Generally, a plucked string instrument such as a guitar is structured so that both ends of a plurality of strings are fixed to an instrument main body constituted of a body and a neck, and a bridge is sandwiched by the strings and a top of the instrument main body. A plucking operation of plucking the strings between the bridge and a nut on the neck with fingers produces musical sound. The bridge, in the case of a guitar, if fixedly attached to the top of the main body. 
   With an electric guitar, a magnetic pickup device that electrically detects the vibration of the steel strings by an induction effect allows for sensing, and then the amplification of, the vibration of the strings. With an acoustic instrument, the amplification typically is based upon the use of a microphone. With acoustic electric guitars, the guitar appears to be an acoustic instrument, but is wired with a pickup, typically within the bridge, that translates the vibrations into an electrical signal, often using a piezo effect. 
   Electric guitars and acoustic guitars and the music they produce are well known. Electric guitars are used with external speakers and amplifiers. When used in live performances in relatively large areas, the sound of an acoustic guitar is also amplified. Recent years have seen a demand for the faithful detection of the raw sound particular to acoustic instruments. In addition, often the need for amplification falls into a lower category that does not require large speakers and high power amplifiers. 
   What is called for is an amplification system for acoustic electric instruments that allows for increased volume and amplification without the use of large external amplifiers and speakers. What is also called for is such a device that can be as easily installed as guitar strings. What is also called for is such a system that does not constrain the user without physical connection to a stationary amplifier system. 
   SUMMARY 
   An apparatus for the amplification and projection of the sound of a musical instrument, such as an acoustic guitar, adapted to mount within the guitar itself. The apparatus may mount within the sound hole of the guitar, with an outward facing speaker within the sound hole adapted to project the sound of the instrument. The apparatus may have an amplifier attached to the speaker in a unitary design. The apparatus may be operated by a battery pack. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a sketch of guitar with an internally mounted system according to some embodiments of the present invention. 
       FIG. 2  is a side view of an amplification system according to some embodiments of the present invention. 
       FIG. 3  is a front view of an amplification system according to some embodiments of the present invention. 
       FIG. 4  is a cross-sectional view of an amplification system according to some embodiments of the present invention. 
       FIG. 5  is a bottom view of an amplification system according to some embodiments of the present invention. 
       FIG. 6  is a bottom-side perspective view of an amplification system according to some embodiments of the present invention. 
       FIG. 7  is a side perspective view of an amplification system according to some embodiments of the present invention. 
       FIG. 8  is a top perspective view of an amplification system according to some embodiments of the present invention. 
       FIG. 9  is a view of an amplification system battery pack according to some embodiments of the present invention. 
       FIG. 10  is a view of an amplification system battery pack according to some embodiments of the present invention. 
       FIGS. 11A-B  are views of a battery pack according to some embodiments of the present invention. 
       FIGS. 12A-C  are views of a cord for use with the amplification system according to some embodiments of the present invention. 
       FIGS. 13A-B  are perspective and cutaway view of a system according to some embodiments of the present invention. 
       FIGS. 14A-B  are an exploded and perspective view of a system according to some embodiments of the present invention. 
   

   DETAILED DESCRIPTION 
   In some embodiments of the present invention, as seen in  FIG. 1 , an amplified guitar system  10  with a sound enhancing unit  16  is mounted within the sound hole of a guitar  12 . The guitar may be an acoustic electric guitar, with strings  14  extending along the neck  15  and across the main body  11  of the guitar  12  to the bridge  13 . In the example of an acoustic electric guitar, the guitar may not use pickups mounted into the guitar under the strings in the middle of the main body  11 , but instead may have a pickup mounted within the bridge  13 . The pickups may be of a piezoelectric type. Typically, the acoustic electric guitar will have wiring within the guitar body running from the pickups to a jack somewhere on the main body  11  adapted to provide input to an amplifier. With the example of an acoustic electric guitar, the guitar is adapted to play with or without external amplification, as the instrument has a hollow body and a sound hole in the main body, and is adapted to project sound to some extent. The system provides a self-contained guitar and amplifier system. The sound enhancing unit is adapted not to effect the acoustic performance of the guitar. The system need not be mounted in any permanent fashion and allows for easy removal as well as easy installation. 
     FIG. 2  illustrates a side view of a sound enhancing unit  30  adapted to mount within the sound hole of the guitar with its front surface  31  just below the strings of the guitar and the unit itself mounted inward into the main body of the guitar according to some embodiments of the present invention. An electric plug  36  is mounted to the sound enhancing unit  30  such that the plug is accessible from the outside of the guitar when the sound enhancing unit  30  is mounted within the guitar. The electric plug may interface with an external power supply in some embodiments. The external plug may interface with the output of the guitar in some embodiments. A power on/off switch  33  is seen which is used to turn on the sound enhancing unit  30 . A volume knob  34  is seen. The control features are adapted to keep a low profile to minimize the likelihood of interference with the guitar strings or the hands of the player. 
     FIG. 3  illustrates a front view of a sound enhancing unit according to some embodiments of the present invention. The outer periphery  30  of the front surface  31  is designed to be somewhat larger than the typical range of guitar sound hole diameters such that when the sound enhancing unit is placed into the sound hole of the guitar, the outer periphery  30  of the front surface  31  prevents the sound enhancing unit from fully entering into the guitar and dropping into the main body. The typical range of sound hole diameters is 97-104 mm. A flat surface  60  along the top of the front surface  31  of the sound enhancing unit is adapted to fit guitars where the neck and fret board have a straight end that projects somewhat into the sound hole, or into the area that a circular sound hole would have taken. A treble level knob  35  and a bass level knob  36  may be present in some embodiments. A unit on indication light may be present in some embodiments. 
   In some embodiments, the unit may also be adapted to allow the user to select an amplification level based upon whether the guitar has a pre-amplifier. The unit may have a switch on its front face that allows the user to switch between a pre-amp mode or a bypass mode. 
     FIG. 4  is a cross-sectional view of a sound enhancing unit  30  according to some embodiments of the present invention. The front surface  31  of the sound enhancing unit will be facing outwards from the guitar when the sound enhancing unit  30  is installed within the guitar. The lip  32  underneath the outer periphery of the front surface  32  will be engaged with or close to the surface of the guitar main body. 
   A grip ring  88  is mounted onto the body of the unit just below the lip  32 . The grip ring  88  may of a rubberized material and is ductile to allow the tighter fit of the unit into the sound hole as the unit  30  is pushed down into the sound hole. The grip ring  88  allows for the unit to be snugly fit into sound holes of varying diameters. The unit  30  may be firmly pressed into the sound hole until the grip ring is under compression, which will allow both a snug fit and also good hold and retention of the unit  30  by the guitar sound hole. Although the grip ring  88  has a function to enhance the fit and the snugness of the fit of the sound enhancing unit in sound holes of different diameters, the ductile nature of the grip ring also enhances the acoustic isolation of the speaker within the unit and the pickups of the guitar. 
   Within the sound enhancing unit  30 , a speaker  37  is mounted at a distance below the front surface of the guitar. An intermediate area  89  is seen wherein there may be openings  45 ,  46  within the unit which may allow the natural acoustic noise of the guitar to exit through the unit  30  and out of the sound hole. The openings create a pathway from outside the main unit, within the guitar body, to an area over the speaker. In some embodiments, there may be six such openings  45 . The spacer of the intermediate area  89  places the speaker deeper into the guitar and allows for the location of these openings. The depth of the intermediate area  89  may vary between 10 mm and 25 mm in some embodiments. 
   The main assembly of the sound enhancing unit  30  may be attached to the front portion of the unit with fasteners  44 . A speaker mount  38  may be mounted to the spacer of the intermediate area and may hold the speaker in place. A rear box portion  40  may be attached to the main assembly with fasteners  41 . An amplifier  39  may be mounted into the rear box portion  40  with fasteners  42  and spacer mounts  43 . 
     FIGS. 6-8  are partial see-through perspective views of a sound enhancing unit according to some embodiments of the present invention and are included to further illustrate these embodiments. 
   In some embodiments, the speaker and amplifier are part of an integral unit mounted within the sound hole, with an external power source outside the guitar.  FIGS. 9 and 10  illustrate and external power supply  50  according to some embodiments of the present invention. The external power source  50  may be fashioned to be worn on the guitar strap, or on the belt of the user, using a strap clip  53  on the unit. External plugs  54 ,  55  may be used to provide power via a cable to the sound enhancing unit. One plug may also be used to recharge the batteries  51 ,  52  within the unit. In some embodiments, two 9 volt transistor style batteries may be used.  FIGS. 11A-B  illustrate another embodiment of the external power supply. 
     FIGS. 12A-C  illustrate a patch cord  101  adapted to be used with the sound enhancing unit. With the unit mounted in the guitar, the guitar side plug  102  is adapted to plug into the unit at its interface plug  36 . The second end of the patch cord  101  has a jack  103  adapted to receive a small stereo plug which is part of a cord coming from the standard exit jack of the guitar. In some embodiments, the center portion  104  of the cord  101  is flexible. In other embodiments, the center portion may be more rigid, and may be pre-shaped into a dog leg, or bent, orientation which may reduce the likelihood of the patch cord and its mating cord from interfering with the user. 
   In some embodiments, the power source may be mounted on or within the guitar body. In some embodiments, the power source may be integrated into the sound enhancing unit itself. In some embodiments, the speaker may be affixed to the sound hole as in other embodiments, but the amplifier may reside at another location. 
   The installation of the sound enhancing unit may be as follows. The strings, if installed on the guitar, would be removed. In some applications, the wire leads from the pickups of the acoustic electric guitar would be disconnected from the external jack on the guitar body and instead attached to the sound enhancing unit. This direct connection is not required and the user may instead use the patch cord as discussed above. The sound enhancing unit would then be placed down into the sound hole of the guitar until snug. The strings would then be replaced onto the guitar. The power supply is then connected to the sound enhancing unit using a wire cable to the flush mounted jack on the sound enhancing unit. The unit may then be turned on and played. 
   A sound enhancing unit according to the embodiments of this disclosure may allow for a 3-6 dB enhancement of the volume of the guitar. This may be ideal for situations wherein that guitar is to be played and a somewhat enhanced volume is desired. 
     FIGS. 13A-B  and  14 A-B illustrate a sound enhancing unit  150  according to some embodiments of the present invention. A central support portion  155  is attached to a mounting portion  152  adapted to mount the unit to the circular rim of the sound hole of a guitar. The mounting portion  152  may have a lip  151  adapted to reside on the outer portion of the rim of the sound hole of a guitar. The mounting portion  152  may have a ring  153  of ductile material to enhance the grip on the unit to the sound hole of the guitar. The speaker  156  may be attached to the central support portion  155  using a standoff  157  as an isolator. In some embodiments, the standoff  157  is of an EVA foam. In some embodiments, the standoff  157  is a circular element which has holes or slots within it that allow for mounting, or grabbing, of elements mounted to central support portion. 
     FIG. 14A  illustrates a rear cover  160  adapted to cover the rear of the unit. The rear cover  160  may have rear openings  161  which may enhance the sound resonance within the guitar. In some embodiments, the unit may have both the openings  45 ,  46  and the rear openings  161 . In some embodiments, there may be only the rear openings  161 . In some embodiments, there may be only the openings  45 ,  46 . 
   As evident from the above description, a wide variety of embodiments may be configured from the description given herein and additional advantages and modifications will readily occur to those skilled in the art. The invention in its broader aspects is, therefore, not limited to the specific details and illustrative examples shown and described. Accordingly, departures from such details may be made without departing from the spirit or scope of the applicant&#39;s general invention.