Exploring Common DIY Terminology (work in progress)

Preface

I started this article with the intention of offering a guide to DIYers, mostly those new to the field, that defines and explains the terminology you often see in discussions on the topic of DIY loudspeakers. Now, I have plenty of learning to do myself, and am under no illusion that what I do know is complete and correct. Because of this, I want these articles to be living documents. By that I mean, I'd like the DIY community to offer input on each definition to expand and clarify...

AMT (Air Motion Transformer)

An AMT is a type of driver (often a tweeter) that is based on a principle called the “Heil Air Motion Transformer” developed by Dr. Oskar Heil in the 1970s. An AMT is constructed from a diaphragm - a thin structure made of a lightweight material such as polyester film or metal foil - driven by a magnet and voice coil assembly positioned around it. The diaphragm is typically pleated like an accordion or folded like a fan to increase its effective surface...

Qms (Thiele/Small Parameter)

Qms (Mechanical Q-factor) is a parameter used in loudspeaker design to quantify the mechanical losses within the driver's moving system, which includes the diaphragm, voice coil, and suspension components. It provides insights into the damping characteristics and mechanical performance of the driver. The following are areas that are directly impacted by Qms:

• Damping and transient response: Qms is an indicator of the mechanical damping within the driver.

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Distortion

Distortion refers to any unwanted alteration or modification of the original audio signal as it is reproduced by the loudspeaker. It manifests as changes in the waveform or frequency response of the reproduced sound, leading to a degradation in audio quality and accuracy. There are various causes of distortion in loudspeakers, including:

• Nonlinearities in Driver Response: Loudspeaker drivers, such as woofers, tweeters, or mid-range drivers, may exhibit nonlinear behavior

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Horn

A horn refers to a type of acoustic device used to improve the efficiency and directivity of sound reproduction. It is designed to efficiently couple the sound energy from a loudspeaker driver and effectively project it into the listening space. A horn can enhance the overall performance of a loudspeaker system by increasing sensitivity, controlling dispersion, and extending the low-frequency response. The primary function of a horn is to transform the relatively small diaphragm...

Power Compression

Power compression is a phenomenon that occurs when the voice coil and other components of a loudspeaker driver heat up due to increased power input. As the voice coil temperature rises, its resistance also increases, leading to a decrease in the electrical power converted into acoustic output. This reduction in acoustic output for a given electrical power input is known as power compression. The concept of power compression is essential to understand because it can...

Acoustic Phase

Acoustic phase is a concept used to describe the relationship in time between two or more sound waves at a specific point in space. It represents the relative timing or alignment of the crests and troughs of the sound waves as they propagate through the air. In simple terms, the phase of a sound wave indicates where it is in its cycle at a given moment. A sound wave is a repeating pattern of compressions (areas of higher pressure) and rarefactions (areas of lower pressure)...

Suspension

The suspension refers to the mechanical system that provides support and control for the diaphragm (cone/dome) and voice coil within the driver's magnetic structure. The suspension is an important component that allows the diaphragm to move back and forth in response to the electrical audio signal while maintaining stability and linearity. The suspension system typically consists of two key components: the spider and the surround.

• Spider: The spider, also known as the "speaker

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Anechoic Chamber

A space or area (often a large room for industrial applications) that is designed to eliminate reflected sound, as well as eliminate sound from outside the chamber. The noise floor inside an anechoic chamber is very low, typically close to the threshold of human hearing in the 10–20 dBA range, and sometimes much lower (the noise floor of a typical home is approximately 40 dBA). In acoustics, such a room is used to measure loudspeakers and individual loudspeaker elements....

Alnico (magnet)

An alnico magnet is a type of permanent magnet known for its strong magnetic properties and high-temperature stability. The name "alnico" is derived from its components: aluminum (Al), nickel (Ni), and cobalt (Co). Alnico magnets were first developed in the 1930s and have been widely used in various applications, including loudspeakers, guitar pickups, sensors, and industrial machinery. Key characteristics and features of alnico magnets include:

1. Magnetic

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