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...

Vas (Thiele/Small Parameter)

Vas stands for "equivalent compliance volume" or "effective volume of compliance". Vas represents the volume of air that has the same compliance (springiness) as a driver's suspension system. In other words, it measures the air volume that would produce the same acoustic compliance as the driver's mechanical suspension. Vas is typically expressed in liters (L) or cubic feet (ft³) and is an important parameter when designing loudspeaker...

Qes (Thiele/Small Parameter)

Qes (Electrical Q-factor) is a parameter used in loudspeaker design to quantify the electrical losses within the driver's voice coil and magnetic circuit. It provides insights into the efficiency and electrical characteristics of the loudspeaker. Qes is an important parameter and carries the following implications:

• Efficiency: Qes is an indicator of the driver's electrical efficiency. It represents the ratio of electrical energy stored in the voice coil

...

Directivity

Directivity refers to the intentional control of the sound dispersion pattern of a speaker system. It involves shaping the radiation characteristics to achieve specific coverage and performance goals. Directivity control is crucial in applications where precise sound targeting, uniform coverage, and controlled off-axis response are desired. Loudspeakers typically exhibit different directivity patterns depending on their application, which can be broadly categorized into...

Heat Sink

Heat sinks are components or structures used to dissipate heat generated by the voice coil during operation. Loudspeaker drivers, particularly high-power drivers, can generate significant heat due to electrical resistance and mechanical losses. Heat sinks help to transfer this heat away from the voice coil and other sensitive components, preventing overheating and potential damage. The primary function of a heat sink is to increase the surface area available for heat dissipation....

Nominal Impedance

Nominal impedance is a manufacturer specification commonly used to describe the average or approximate electrical impedance of a loudspeaker or individual driver. It is usually represented by a single value, such as 4 ohms or 8 ohms. For consumer audio, the nominal impedance indicates the most difficult average load a loudspeaker presents to an amplifier under normal operating conditions and is used to match the speaker to the amplifier's output impedance. For designing...

Pe (Thiele/Small Parameter)

In loudspeaker design, "Pe" stands for thermal power handling. It is one of the Thiele/Small parameters used to specify a loudspeaker driver's ability to handle electrical power without experiencing thermal overload or damage. When an audio signal is applied to the loudspeaker's voice coil, electrical energy is converted into mechanical motion, generating sound. However, some of the electrical power is converted into heat due to resistive losses...

Surround

In the context of loudspeaker drivers, the surround, also known as the "speaker surround" or "suspension surround," is a component that plays an important role in the driver's suspension system. The surround is typically a flexible ring or membrane that connects the outer edge of the loudspeaker diaphragm (cone/dome) to the driver's frame (basket). The primary function of the surround is to provide a compliant and flexible suspension for the diaphragm, allowing...

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.

...