The speaker system usually consists of three parts: a cabinet, a crossover and one or more speaker units. The previous article covered many of their key characteristics and briefly explained how they work together to produce sound. This summary will focus on some of the more prominent points:
• A single-size electrodynamic speaker cannot accurately reproduce the entire 20Hz to 20kHz frequency range of human hearing, so most high-fidelity speakers use multiple-size speaker units.
• The low frequency response of the unit is usually limited by its resonance (Fs) and size.
• The high frequency response of the unit is usually limited by the size and quality of the diaphragm and the inductive reactance of the voice coil.
• The diaphragm of the unit is like a weight on a spring because it has mass and compliance. The suspension of the unit is compliant, similar to a spring, and the diaphragm of the unit has a mass, similar to a weight.
• The resonance frequency of the unit can be reduced by increasing the mass of the diaphragm or using a suitable suspension (folded ring and elastic wave).
• Divide the audio signal into separate frequency bands so that each unit receives its most reproducible part.
• There are two types: the more common passive crossover located after the amplifier and the more expensive active crossover located before the amplifier.
• The unit needs a box to prevent the sound waves emitted from the back of the diaphragm from mixing with the sound waves emitted from the front (to prevent acoustic short circuits). If there is no cabinet, the low frequency response will be reduced because the front and rear sound waves will cancel each other out.
• The cabinet will increase the resonance and total Q value of the unit.
• The cabinet can be used to shape the low frequency response.
• A well-structured airtight box should not resonate itself.
• For its part, a cabinet with an inverted tube or passive radiator is designed to generate resonance. This resonance is used to enhance and create low-frequency response.