Abstract:
A tuning device receives the electrical output of an instrument that reflects sound at a first tone level. The tuning device digitizes electrical output. The user has switches operable to generate control signals that are processed to effect a bypass of the device or to digitally drop the tone level in half steps up to an octave and to selectively mix the drop tone level with the input tone level. The user may then broadcast one of the bypassed signal, the drop tone signal or a mixed signal of the drop tone and the input tone level.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. The Field of the Invention 
         [0002]    This invention relates to systems to modify the electrical output of an musical instrument that generates an electrical output reflective of sound at a particular tone level and more particularly to devices that modify the electrical output so that it can be broadcast unmodified or modified, or combined in multiple formats. 
         [0003]    2. The Relevant Technology 
         [0004]    In order to create a musical effect, it is sometimes desirable to present the music as written at a lower or different pitch or tune. The process has been referred to as drop tuning. Drop tuning is typically associated with guitars. Drop tuning is discussed on several web sites on the world wide web such as at www.learnclassicalguitar.com. To drop tune one or more strings, those one or more strings are tuned down or dropped the equivalent of one or two or more frets. Drop tuning involves modifying the tuning of the guitar and thus is something that is not lightly undertaken because when the use at the lower or dropped tune level is complete, one must retune to the normal level. Alternately, one must have multiple guitars all tuned differently. 
         [0005]    Electrical musical instruments like electrical guitars produce an electrical signal at a selected tone level. The electrical signal is typically amplified and sent to speakers which convert the electrical signal into sound. Users may wish to drop tune their electrical guitars or similar electrical musical instruments. However, the means to drop tune an electrical guitar are essentially the same as the non electrical instruments. Devices or systems to effect drop tuning easily without actually having to retune an electrical guitar are not known. 
       BRIEF SUMMARY OF THE INVENTION 
       [0006]    A device for modifying the electrical output of a musical instrument has an input configured to receive the electrical output of the musical instrument which is at a first pitch or tone level. A suitable electrical instrument includes, but is not limited to an electrical guitar or electrical bass guitar, acoustic guitars and even an electric bass fiddle. The device has change means to generate change signals for changing the first tone level to a second tone level. An analog to digital converter receives the analog electrical output at the first tone level and converts it to a first digital signal that is supplied to a digital signal processor. The digital signal processor is configured to change the first digital signal to a second digital signal that is the same as said first digital signal but modified to be at a second tone level that is different from the tone level of the first digital signal and to supply the second digital signal as the signal processor output. 
         [0007]    The device has a controller that is connected to receive the change signals. The controller is configured to generate and supply control signals reflective of the desired change communicated by the change signals to create a second tone level different from the first tone level. The controller supplies signals to the digital signal processor to cause the digital signal processor to use the first digital signal to make or create the second digital signal as the signal processor output. The second digital signal is then supplied to a digital to analog converter to convert the signal processor output into an analog electrical output. The analog electrical output is then supplied to an output device which receives the analog electrical output and then supplies it as the device output for connection to a system for converting the analog electrical output into sound at the second tone level. The device also includes a power supply connected to its components to supply power thereto. 
         [0008]    In a preferred arrangement, the change means is configured to generate a plurality of change signals to cause the electrical signals reflective of the sound at the first tone level to change to an electrical signal reflective of the sound at any one of a plurality of second tone levels. The change means may be a computer or other automatic device to generate the change signals in accordance with certain triggers which can be sounds or patterns of sound detected as music is being performed. Most preferably the change means is one or more manual switches positioned in a chassis or housing positioned for operating by the user. The housing or chassis is preferably of the type that can be positioned on the floor with switches being buttons operable by the feet of the user. 
         [0009]    In a more preferred configuration, the device includes display means connected to the controller to receive the control signals and to the power supply to receive power there from. The display means is arranged to generate a visually perceivable image of the selected tone level from the plurality of tone levels available for the device output. 
         [0010]    In a more preferred configuration, the device includes an output switch connected to receive the analog electrical output. The output switch is also connected to the device input to receive the electrical output of the musical instrument at the first tone level. The output switch is operable between a bypass position in which the electrical output of the musical instrument at the first tone level is supplied as the device output and a second position in which the analog electrical output is supplied as the device output. 
         [0011]    Preferably the output switch is controlled by the controller which is connected to said output switch. The controller supplies control signals to cause the output switch to move between the bypass position and the second position. The change signals supplied to the controller preferably include a bypass signal. The controller, in turn, generates control signals that are sent to the output switch to cause the output switch to move between the bypass position and the second position. 
         [0012]    In a more preferred configuration, the digital signal processor includes shift means for changing the first digital signal to any one of a plurality of second digital signals each being the first digital signal modified or shifted to be at any one of a plurality of tone levels each different from each other and from the first tone level. The controller supplies control signals to the digital signal processor. The control signals include a shift signal to cause the shift means to change the first digital signal to the second digital signal. Even more preferably, digital signal processor includes a mixer to cause said first digital and the second digital signal to be mixed and supplied as the signal processor output. The mixer being is operable between a non mix position in which the signal process output is the second digital signal and a mix position in which the signal processor output is the sum of the first digital signal and the second digital signal. Even more preferably, the first digital signal is mixed with a second digital signal that is an octave below the first digital signal. This is called an octaver. 
         [0013]    In a more desired arrangement, the change means is configured to supply a mixing signal to the controller to cause the controller to supply a mix signal to the mixer in the digital signal processor to cause it to operate between the non mix position and the mix position. 
         [0014]    In a preferred assembly, the display means includes an array of light emitting diodes each reflective of a tone level. The display means includes a driver to operate each of the light emitting diodes of the array in accordance with the control signals. 
         [0015]    In a more preferred assembly, the device includes an input amplifier connected to receive the electrical output at said first tone level. It is configured to and to amplify the electrical output at said first tone level and to supply the amplified electrical output at said first tone level to the digital signal processor. Similarly, an output amplifier is connected to receive the analog electrical output and to supply the amplified analog electrical output to the output and more particularly to the output switch. Most preferably, the input amplifier and the output amplifier are each variable amplifiers operable by the user by any suitable means such as a knob. 
         [0016]    The device in any of the above arrangements and configurations is part of a sound system that includes an instrument of the type that generates electrical signals reflective of sound at a first tone level upon operation by a player. Electrical guitars, electrical bass guitars, acoustic guitars, violins, and similar instruments are contemplated. The system includes a speaker system connected to the device to receive the device output and to broadcast sound reflective of one of the musical instruments&#39; output at the first tone level and at said second tone level and at the mixture of the first tone level and the second tone level. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    To further clarify the above and other advantages and features of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. It is appreciated that these drawings depict only typical embodiments of the invention and are therefore, not to be considered limiting of its scope. The invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which: 
           [0018]      FIG. 1  is a simplified block and line diagram of a drop tune device of the present invention; 
           [0019]      FIG. 2  is a simplified block and line diagram of a drop tune system of the present invention; 
           [0020]      FIG. 3  is a perspective view of a chassis of a drop tune device of the present invention; 
           [0021]      FIG. 4  is a rear view of a chassis of a drop tune device of the present invention; and 
           [0022]      FIG. 5  is a perspective of an alternate form of a chassis of a drop tune device of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0023]    Music is typically written to be performed in a key that may range over several octaves depending on the particular music. The music being performed can be said to be performed at the sound level or tone level desired by the writer. On occasion, the performer may wish to play the music at a different level or tone level than as originally contemplated by the writer. As an example, one could play music an octave lower than as written by the writer of the music. For music to be performed by certain instruments like a guitar, the performer may wish to drop tune or change the sound level or tone of the music being performed for artistic reasons. Guitars and similar instruments may be specifically adapted or tuned to a different sound level or tone level that is typically below or at a lower tone level that the music as written. The practice of drop tuning instruments like a guitar has become accepted so that procedures for drop tuning are available from a number of sources. See, for example, HOW TO TUNE A GUITAR at www.howtotuneaguitar.org/tuning/drop-c on the world wide web. 
         [0024]      FIG. 1  is a line diagram of a device for selectively drop tuning the output of an electrical instrument like an electric guitar. That is, the instrument involved may be any one in a wide category of instruments that produce an electrical output for further amplification and broadcasting into audible sound over speakers. While electric guitars and bass guitars are specifically contemplated, other stringed electrical instruments including a string upright bass, and other various electric violins, violas, cellos, zithers, ukuleles, and the like, may susceptible to drop tuning. 
         [0025]    The output of the electrical instrument is supplied to the input  12  of the device  10 . The input  12  is a suitable receptacle sized to receive a connector at the end of a suitable wire or lead coming from the electrical instrument. The input  12  may be hard wired; but it is typically a female receptacle sized to receive a standard male connector. The input  12  may also be an array of receptacles to receive one male connector that may be one of several different sizes. The input  12  may also be configured with a fuse circuit (not shown) to protect the device  10  as well as appropriate line filters as may be desired to filter out undesired electronic signals that may be acquired (e.g., electromagnetic interference). The input  12  as shown has a node  14  to which a bypass conductor  16  is connected to transmit an incoming electrical output at a first tone level directly to the output  18  as more fully discussed hereinafter. 
         [0026]    The input  12  is connected by conductor  20  to supply the incoming electrical output at a first tone level to an analog to digital converter  22  through an optional amplifier  24 . The incoming electrical output is a first tone level that is an analog signal in that it may be viewed as a complex wave form that is varying in amplitude. The analog to digital converter  22  converts the incoming electrical output to a first digital signal for transmission via conductor  26  to a digital signal processor  28 . An AK5358 ETP 24 bit converter available from AKM Semiconductor, Inc. of San Jose, Calif. is believed to be a suitable device for electrical guitars. Of course, other suitable analog to digital converts (A/D) should be available from other manufacturers. 
         [0027]    The digital signal processor  28  receives control signals from a micro controller  30 . The control signals supplied by the microcontroller  30  include a shift signal via conductor  32  and a mix signal via conductor  34 . The digital signal processor  28  includes a shifter  36  that is configured to shift the first digital signal at the first tone to a second digital signal at a second tone level selected or determined by the shift signal supplied to shifter  36  from the microcontroller  30  over conductor  32 . The second digital signal is the same as the first digital signal but at a tone level that is different. More specifically, the tone level can be lower than the tone level of the first digital signal. Indeed, the tone level can be lowered in acoustic ½ steps up to and including 7 half steps or 3½ tone levels plus one step that is an octave and another that is an octaver. 
         [0028]    The mixer  38  in the digital signal processor  28  is a summing circuit that can combine the second digital signal as the output of the shifter  36  with the first digital signal received via conductor  40  to produce a signal processor output that is supplied to a digital to analog converter  42  via conductor  44 . The mixer  38  is operable between a non mix position in which the second digital signal is supplied as the signal processor output and a mix position in which the signal processor output is the combination of the first digital signal at the first tone level and a the second digital signal at the second tone level. A TMS  32006745  from Texas Instruments is believed to be a suitable digital signal processor  28 . Other possible digital signal processors are discussed at http://en.wikipeida.org/wiki/Digital_signal_processor. 
         [0029]    The microcontroller  30  is a small computer that is specifically configured to generate digital control signals for the digital signal processor  28  and, more particularly, the mix signal that is sent via conductor  34  and the shift signal sent via conductor  32 . Microcontrollers of the type used are discussed at http://en.wikipedia.org/wiki/Mircrocomputer. A C 8051F335GM made by Silicon Laboratories, Inc. of Austin, Tex. has been found to be a suitable microcontroller  30 . The microcontroller  30  also supplies a digital control signal or bypass signal that is also supplied via conductor  46  to the output  18  to control a relay switch  48  which moves between a by pass position in which the electrical output at the firs tone level is received via conductor  16  and supplied as the device output via conductor  49  and connector  50  and a second or drop tune position in which the device output is received from the digital to analog converter (D/A)  42  via optional amplifier  52  via conductors  54  and  56 . The connector  50  is a male receptacle sized to receive a standard female connector. It may also be an array of receptacles to receive a connector of a different size. 
         [0030]    Change means  64  are provided to supply change signals to the microcontroller  30  to cause the microcontroller  30  to supply the control signals via conductors  32 ,  34  and  46 . The change means  64  can be any structure configured to supply signals to cause change. Thus, a computer system or any other automatic or semiautomatic device may be configured to supply change signals in accordance with instructions provided to the computer. However, the change means  64  as shown and as presently preferred includes a decrement switch  58  which supplies an electrical signal to the microcomputer to cause it to generate a shift signal to, in turn, cause the shifter  36  to shift the first digital signal down or decrement the first digital signal to create the second digital signal. Of course, the second digital signal is then supplied to the mixer  38  which is connected to and supplies the signal processor output to the digital to analog converter  42  via conductor  44 . Similarly, an increment switch  60  is connected to supply an electrical signal to the microcontroller  30  to generate a shift signal to cause the shifter  36  to shift the first digital signal up an increment upward. Thus, the shifter  36  may be at a level to cause the first digital signal to be lowered 2 and ½ steps. By operating the increment switch  60 , the shifter  36  is configured (e.g., moved to a desired ½ step) to step the second digital signal toward or to the first digital signal. The decrement switch  58  can be operated (e.g., depressed) to cause the shifter  36  to decrement down up to 3½ steps or 7 half tones plus one octave and to an octaver position. The increment switch  60  can be operated to cause the shifter  36  to move up from the octaver position to the octave and through the 7 half step positions as desired by the user/operator. The increment switch  60  and the decrement switch  58  may preferably be spring loaded push button switches. Suitable switches are available from NKK switches on the world wide web at http://www.nkksswitches.com. 
         [0031]    The change means  64  may also include a bypass switch  62  that is operable to supply the bypass signal via conductor  46  to the output  18  and in turn cause the relay switch  48  to move between the by pass position and the second or drop tune position. 
         [0032]    Returning to the digital signal processor  28 , the signal processor output is supplied to a digital to analog converter  44  such as 24 bit AK4388ETP offered by AKM. The second digital signal or the combination of the second digital signal and the first digital signal is supplied as the digital signal output of the digital signal processor  28  to an analog signal that is optionally amplified by an amplifier like a NJM 4580E that, in turn, is provided as the device output through the relay switch (such as a SC1C-5HS that is offered by World Products) when the relay is in the second or drop tune position shown in  FIG. 1 . The analog signal is of the type that drives or operates suitable speakers of a sound system to provide audible sound that the player or musician seeks to present to the listener. 
         [0033]    In  FIG. 1 , the microcontroller  30  is shown supplying control signals via conductor  72  to display  68  that includes an LED driver  66  and an LED display  70 . The LED driver  66  may by any suitable circuit configured to drive an array of light emitting diodes (LED). Various circuits may be used such as those offered by LINEAR Technology at www/linear.com/pc/view/Category on the world wide web. The LED display  70  includes visual or perceivable images  74 - 83  of the steps or levels that have been selected by operating the decrement and the increment switches  58  and  60  of the change means  64 . 
         [0034]    The LED Driver  66  also receives a signal from the mixer  38  via conductor  34  and microcontroller  30  reflective of the level of the acoustic signal being supplied as the signal processor output. The level or volume of the signal is then displayed in a multicolor level indicator  84 . 
         [0035]    The device  10  of  FIG. 1 . also has a source of power or a power supply  86  that is connected to supply power to the display  68  and the other components over conductors  88 - 95  as seen in  FIG. 1 . The power supply may be any source of electrical power including 115 V outlet power that is suitably reduced and isolated with fuses to provide the desired power for the desired circuits. 
         [0036]    It may also be noted that the input amplifier  24  and the output amplifier  52  are each operable by suitable means to vary the amplification level. As shown, the amplifiers have a variable resistor that is operable by a dial, knob or slide  98  that are ganged together to move both up and down  100  so they are operated in tandem or together. Thus, the amplifiers  24  and  52  are operated at substantially equal levels. 
         [0037]    A system is shown in  FIG. 2  that includes an instrument  102  that supplies an electrical output via conductor  104  to a drop tune device  106  comparable to drop tune device  10 . The output of the drop tune device  106  is supplied via a suitable conductor  108  that is suitably connected to a speaker system  110  which converts the device output into sound energy that is audible. The instrument  102  shown is a guitar  112  that includes a standard output amplifier  114  that receives power from a conventional outlet. The speaker system  110  includes a suitable amplifier  116  and a speaker arrangement  118 . Power may be supplied from any suitable source such as an outlet. 
         [0038]    In  FIGS. 3 and 4  shows a suitable chassis  120  that contains all the components of  FIG. 1  with suitable push button switches  122 ,  124  and  126  that are comparable to the decrement switch  58 , increment switch  60  and a bypass switch  62 . The visually perceivable display  128  is comparable to visual LED display  68  and the array of LED&#39;s  74 - 83 . The input connector receptacle  130  that connects to and is part of the input such as input  12  is also visible as is the output connector  132  that is comparable to output connector receptacle  50 . Power may be supplied to the device  120  by a suitable transformer to the device via connector receptacle  134 . The level of the input amplifier and the output amplifier may be controlled by the knob  136  that is comparable to the control  98  of  FIG. 1 . 
         [0039]    An alternate chassis  138  is shown in  FIG. 5  that is comparable to the chassis  120  of  FIG. 4  with the amplifier control knob  140  on the face or top  142  of the chassis  138  in lieu of the sound level indicator  84  seen in  FIG. 1  and the sound level indicator  137  seen in  FIG. 4 . 
         [0040]    In operation the device  10  of  FIG. 1  and the system of  FIG. 2  can be operated to drop tune an electrical instrument like a guitar in ½ tone steps up to 3 and ½ steps. Thus, an guitarist playing an E chord can use the device  10  to decrement to an E flat, D, D flat, C, B, B flat or A by pushing the decrement button. Once decremented down, the device can increment up through the same chords by operating the increment switch such as switch  60 . The BYPASS switch like switch  62  can be depressed to switch the relay between the bypass position and the drop tune position at the level previously selected. The LED Display will show the drop tune level selected by illuminating the appropriate LED for that which has been selected. Notably, the user can continue to depress the decrement switch to select a full octave drop and also an octaver in the tuning. 
         [0041]    The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.