Wiring

In modern times, a primary concern for musicians is the volume output of their instruments. Initially, this depends on the instrument’s acoustic construction. When the instrument reaches its natural acoustic limits and more volume is required, electric amplification comes into play. Electrical systems are also used to shape or alter the tonal character of an instrument.

This is why we design electronic amplification systems, based on the principles of electromechanics and physics. The first stage is the conversion of mechanical energy into electrical energy, which is performed by transducers—commonly referred to as pickups. A transducer is any device that converts one form of energy into another. For musical instruments, transducers operate on either piezoelectric or electromagnetic principles. The type of transducer determines the overall design of the instrument’s electronics.

Piezoelectric systems typically involve the placement of a pickup under the bridge or inside the soundboard. They exploit the mechanical energy from vibrations propagating through solid materials (bridge, soundboard) generated by the strings, converting it into an electrical signal. Piezo elements are made from ceramic or crystalline materials, which generate voltage when subjected to pressure.

• Piezo rods capture string vibrations directly, emphasizing the strings’ sound over the body resonance.

• Piezo saddles or soundboard-mounted pickups capture the body’s vibrations, emphasizing tonewood resonance and soundboard coloration more than the strings.

In general, piezo systems produce a more natural acoustic tone.

Electromagnetic systems operate via magnetic pickups (commonly called “pickups,” not to be confused with the magnets inside them). These function as small generators: vibrating metal strings induce a voltage across the coil, producing an electrical signal. Consequently, magnetic pickups only work with metal strings.

To process and shape the signal from a transducer, an electronics circuit is required. This can be either passive or active:

• A passive circuit relies solely on the voltage produced by the pickup to operate all circuit elements. Common passive components include potentiometers, capacitors, resistors, and diodes.

• An active circuit includes a power source, usually a battery, primarily to operate preamplifiers for active pickups or piezo systems, providing higher output and tone-shaping flexibility.