Acoustic-electric stringed instrument with improved body, electric pickup placement, pickup switching and electronic circuit

An improvement to the body of a stringed instrument, comprising:

• a. a plate-like and removable acoustic soundboard, also known as a top or top cover, mounted on the top surface of said body of said instrument, with the upper surface of said soundboard, away from said body, being a decorated surface, with a bridge assembly on said upper surface of said soundboard, which said mounting of said soundboard on said body allows acoustic vibrations across the entire surface of said soundboard, from interior to edges, except where said soundboard is fixed to said body,
• i. being fixed to said body with removable connectors and adjustable in height above said body at two points adjacent to the neck of said instrument,
• ii. being fixed to said body at and under a tailpiece,
• iii. being fixed to said body with connectors in approximate line with said bridge at the sides of said body, said line called the bridge line or intonation line, an average of positions on said strings from said neck and the nut of said instrument to assure nearly correct intonation,
• iv. having incorporated into said soundboard an electrostatic shield, over most of its extent, connected to the output ground of said instrument, for the purpose of shielding any sensors or electronics incorporated into said instrument,
• v. with said bridge fixed to said soundboard between said soundboard and said strings for the purpose of adjusting the height of said strings above said soundboard, adjusting the intonation of said strings, and transferring the vibrations of said strings to said soundboard,
• b. a tailpiece, with slots in the surface facing said bridge through which said strings of said instrument may pass, but the buttons on the ends of said strings may not, so that said strings are captured and positioned vertically and horizontally with respect to said bridge at the points where they exit said tailpiece, and with an electronic connection between said strings and said output ground of said instrument,
• c. a decorated plate-like and removable bottom cover or back, fixed to said body with removable connectors, incorporating electrostatic shielding being electrically connected to said output ground of said instrument,
• wherein said soundboard vibrates independently from said body over much of its surface free of restrictions due to lack of connection at its edges to said body, allowing said body to vibrate at lower modes, wherein said soundboard and said bottom cover may be removed to gain access to any said sensors or electronics in said body, wherein said sensors and electronics may be mounted out of sight beneath said soundboard for the purpose of unobstructed decoration and improving or changing the timbre of said soundboard by removing the inertia and movement of said sensors or electronics.

A pickup switching system for electric stringed instruments that use electromagnetic coil sensors to sense the vibrations of ferrous-like metal strings, also known as pickups, so as to reduce the pickup of external electromagnetic noise from other sources, also known as humbucking, with two or more switched tone capacitors in parallel with the pickup output, comprising:

• a. a pickup switching system that connects K single-coil pickups, all with equal numbers of turns in their coils, two at a time, such that when two of said connected pickups have opposite magnetic poles upwards, their signal outputs are connected together in phase, and when two of said connected pickups have the same magnetic poles upwards their signal outputs are connected together out of phase, producing (K*(K−1)/2) parallel-connected humbucking pair outputs and (K*(K−1)/2) series-connected humbucking pair outputs, for a total of (K*(K−1)) humbucking pair outputs, and for K greater than 3, a number of humbucking quad outputs from humbucking combinations of four of said single-coil pickups,
• b. a switch of one or more poles and two or more positions, connected to two or more of said capacitors with one or more resistors of high value, typically one MegOhm or more, also known as bleeder resistors, across one or more of said capacitors, typically with the highest values of capacitance, to provide slow discharge of said capacitors to avoid switching noise, with one position which is not connected to any of said capacitors, with a potentiometer connected in series with said switched capacitance, to damp its effect, the resulting capacitance of said switched capacitance and potentiometer connected in parallel with said humbucking output of said pickup switching system,
• whereby said pickup switching system provides the instrument player at least (K*(K−1)) choices of humbucking outputs, such that in the instance of three of said matched single-coil pickups, it provides six humbucking pair outputs, such that in the instance of four of said matched single-coil pickups, it provides 12 humbucking pair, multiplied by the number of capacitor switch positions, wherein three of said single-coil pickups and a 3-position capacitor switch provide at least 18 choices of tone and timbre, and wherein four of said single-coil pickups and a 12-position capacitor switch, provide at least 144 choices of tone and timbre, plus the optional action of said tone potentiometer.

A system for amplifying, distorting or analog predistortion in an electrified acoustic and string instrument, comprising:

• a. an anti-parallel diode pair for shaping the input signal, Vs, into an input-output signal transfer function, similar to an italic-f, which can be shifted with respect to the input with a bias voltage, Vb, providing a distorted output signal, Vd, with respect to said Vs and said Vb, Vd(Vs, Vb), such that an unshifted version of said Vd, Vd(Vs,0), approximates a combination of said linear signal, Vs, plus the approximate cubic of said linear signal, Vs3, and such that for non-zero values of said Vb, said Vd varies from said linear and cubic combination to a signal that approximates a combination of said linear signal, Vs, and its square, Vs2,
• b. a mixer circuit which linearly and continuously combines said distorted signal, Vd, with the negative of said linear input signal, -Vs, so as to provide a predistorted output signal, Vdist, which varies continuously from a near-second harmonic of said Vs, Vs2, and to a near-third harmonic of said Vs, Vs3, with said Vs2 and said Vs3 respectively created by the cancellation of said Vs in said Vd, as it varies from said combination of said Vs and said Vs2 to said combination of said Vs and said Vs3, which Vdist is then combined with said Vs to create an output signal, Vo, which is a linear combination of said signals Vs, Vs2 and Vs3, which varies continuously in tonal character through said linear combination of said Vs, and its near-second and near-third harmonics, Vs2 and Vs3.