Thiele/Small (T/S) parameters are a set of electromechanical parameters that define the specified low frequency performance of a loudspeaker driver. They are named after their developers, A.N. Thiele and R.H. Small, who published their work in 1961.
T/S parameters are essential for subwoofer design, as they allow engineers to predict how a driver will perform in a given enclosure. This information can be used to optimize the subwoofer for maximum bass output, efficiency, and extension.
The following are some of the most important T/S parameters for subwoofer design:
- Fs (resonant frequency): The frequency at which the driver cone will resonate freely in air.
- Qts (total Q): A measure of the driver’s damping. Lower Qts values indicate more damping, while higher Qts values indicate less damping.
- Vas (air compliance): The volume of air that has the same compliance as the driver suspension.
- Sd (cone surface area): The effective surface area of the driver cone.
- Xmax (maximum linear excursion): The maximum distance that the driver cone can move in either direction.
Significance of T/S parameters in subwoofer design
The T/S parameters can be used to predict a subwoofer’s performance in a given enclosure in a number of ways. For example, the resonant frequency (Fs) and total Q (Qts) can be used to calculate the subwoofer’s low-frequency roll-off and cutoff frequency. The air compliance (Vas) can be used to design an enclosure that will provide the optimal amount of damping for the driver. The cone surface area (Sd) can be used to calculate the subwoofer’s maximum acoustic output. And the maximum linear excursion (Xmax) can be used to ensure that the driver does not over-excursion and damage itself.
In addition to the above, T/S parameters can also be used to design subwoofer enclosures with specific characteristics, such as those that are maximally flat or have a high Qts for maximum bass output.
How to use T/S parameters to design a subwoofer enclosure
Once you have the T/S parameters for the subwoofer driver you want to use, you can use them to design an enclosure using a variety of online tools and software programs. These programs will take the T/S parameters as input and calculate the enclosure dimensions and tuning frequency required to achieve the desired performance.
It is important to note that T/S parameters are only as good as the measurements used to calculate them. It is important to use accurate T/S parameters from a reputable source when designing a subwoofer enclosure.
Conclusion
T/S parameters are an essential tool for subwoofer design. By understanding the significance of these parameters and how to use them, audio enthusiasts can design and build subwoofer enclosures that deliver the best possible performance.