Exploring Common DIY Terminology - Acoustic Phase Center

Acoustic Phase Center

The point in which sound emanates from a speaker element such as a tweeter, midrange, or woofer. A novice may assume this point is along the surface of a woofer dust cap, and while some may incorrectly use this as an estimate, the actual location varies from driver to driver. Unless marked on the individual component (as only a handful of manufacturers do, typically for pro audio equipment) the only way to determine this point is through frequency response measurements....

EBP (Effective Bandwidth Product)

EBP is a parameter used in loudspeaker design to evaluate the relationship between a loudspeaker driver's efficiency and its low-frequency extension. It provides insight into the suitability of a particular driver for different applications, particularly in determining whether it is better suited for vented (bass reflex) enclosures or sealed enclosures. To calculate the EBP value, you divide the driver's free-air resonance frequency (Fs) by its Qts...

Constrained Layer Damping (CLD)

Constrained Layer Damping (CLD) is a technique used in loudspeaker design to reduce unwanted vibrations and cabinet resonances that can degrade sound quality. It involves the addition of a damping material between two rigid layers which effectively dampens the vibrations and reduces their transmission. CLD construction typically consists of three layers: a central core layer, an adhesive layer, and two outer layers. The central core layer is usually a...

Frequency

Frequency, in the context of audio, refers to the rate at which sound waves vibrate or oscillate, resulting in the perception of pitch. It is measured in Hertz (Hz), which represents the number of complete cycles per second. The typical range of human hearing spans from approximately 20 Hz to 20,000 Hz, although this range can vary among individuals. The lower end of the range (20 Hz) represents very low-pitched sounds, such as the deep rumble of a subwoofer, while the upper...

Polarity

In loudspeaker design, polarity refers to the orientation of the electrical signals that drive the various drivers (such as woofers, tweeters, and midrange drivers) within the loudspeaker system. The polarity of a driver determines whether the cone or diaphragm of the driver moves inward (towards the magnet) or outward (away from the magnet) when a positive voltage is applied to the driver's positive terminal. Correct polarity is essential for achieving proper phase alignment...

Boundary Effects

Boundary effects, also known as boundary interference effects, refer to the interactions between sound waves emitted by a loudspeaker and the boundaries (surfaces) of the listening environment or loudspeaker enclosure. These boundaries can include walls, floors, ceilings, nearby objects, and the loudspeaker's own enclosure. Boundary effects are important considerations in loudspeaker design because they significantly impact the loudspeaker's radiation pattern, frequency...

Signal-to-Noise Ratio (SNR)

The signal-to-noise ratio (SNR) is an important parameter that helps evaluate the performance and quality of the audio output. In the context of audio, SNR refers specifically to the ratio of the desired audio signal (the sound produced by the loudspeaker driver) to the background noise generated by the speaker itself or the overall system.

The formula to calculate SNR in decibels is:

SNR (dB) = 10⋅log⁡₁₀(Power_Signal/Power_Noise)

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Bl (Thiele/Small Parameter)

Refers to the Bl product, also known as the force factor or motor strength of a loudspeaker driver. It is a key parameter used to describe the performance characteristics of a driver’s motor assembly. Bl is a measurement of the interaction between the magnetic field generated by the driver's permanent magnet and the current flowing through its voice coil. It determines the ability of the driver to convert electrical power into mechanical motion and produce...

Mms (Thiele/Small Parameter)

Mms is a Thiele/Small parameter that quantifies the mass of the loudspeaker's diaphragm and other associated components that move during the reproduction of sound. The moving mass of a loudspeaker is an important parameter that affects its overall performance in several ways:

• Resonant frequency: Mms is a key factor in determining the loudspeaker's resonant frequency (Fs). The relationship between Mms and Fs is governed by the equation Fs = 1/(2π√(Cms*Mms)),

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Damping

Damping in the context of loudspeakers can refer to two different aspects: damping related to the driver itself and damping of the loudspeaker cabinet.

• Damping of the driver: In loudspeaker driver design, damping refers to the control and resistance of the driver's diaphragm or voice coil movement. It is achieved by utilizing the driver's electrical and mechanical properties. The driver's electrical damping is primarily determined by its electrical impedance and the impedance

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