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We’re still updating and improving these pages, they are intended as general guidelines to help with the understanding of T&S Parameters and their relevance to speaker design. In some cases, a simplified explanation or example is used to illustrate a point, and may not be 100% accurate in all circumstances., BL – Motor Strength or […]

What Is Sd? Sd (Effective Diaphragm Area) is the active surface area of a speaker cone that moves air to produce sound. It’s usually measured in square meters (m²), but sometimes also specified in square centimeters (cm²). Sd is most often used for calculating other TS parameters, and its fairly common for all woofers with […]

Qms represents the mechanical damping of a speaker driver, determined by the losses in the suspension system (spider & surround). It indicates how well the driver’s mechanical components control cone movement at resonant frequency (Fs). What Qms Tells Us About a Driver How Qms Affects Speaker Design Qms works alongside Qes (electrical damping) to determine […]

Pe – Power Handling Capacity Pe represents the thermal power handling capacity of a speaker driver, measured in watts (W). It indicates how much continuous power the voice coil can handle without overheating or suffering permanent damage. The test is done in a controlled environment with specific cabinet volume and controlled room temperature. The test […]

Nominal impedance (Z) is the simplified, rounded value used to describe a speaker’s average impedance across its frequency range. Unlike DC resistance (Re), which is a fixed value, impedance varies with frequency, often rising at resonance and at higher frequencies due to voice coil inductance (Le). Because impedance isn’t constant, manufacturers round it to standard […]

Qes – Electrical Quality Factor Qes represents the electrical damping of a driver at its resonant frequency (Fs). It describes how efficiently the voice coil and magnet system control cone movement, with lower values indicating stronger motor control and higher values indicating weaker electrical damping. How Qes Affects Speaker Performance Qes and Its Relationship to […]

Efficiency Bandwidth Product (EBP) is a useful guideline to determine whether a speaker driver is better suited for a sealed, ported (bass reflex), or even horn-loaded enclosure. It provides a quick way to assess how the balance between resonant frequency (Fs) and electrical damping (Qes) influences enclosure suitability. How to Calculate EBP Where: A higher […]

Re is the DC resistance of the loudspeaker’s voice coil, you should not confuse this with impedance, although related, the two are different. Measuring the resistance of a speaker with a multi-meter, the reading you get across the terminals should be close to the manufacturer’s specified Re, it’s not unusual to get a minor variation […]