Bass Reflex Frequency Calculator

Formula

The formula to calculate the tuning frequency of a bass reflex speaker is:

\[ Fb = \frac{v}{2 \pi \sqrt{\frac{Vb \rho}{A}}} \]

Where:

\(Fb\) is the tuning frequency of the bass reflex speaker
\(v\) is the speed of sound in air (approximately 343 m/s)
\(\pi\) is a mathematical constant whose value is approximately 3.14159
\(Vb\) is the volume of the speaker box in m³
\(\rho\) is the density of air (approximately 1.2 kg/m³)
\(A\) is the cross-sectional area of the port in m²

What is a Bass Reflex?

A Bass Reflex is a type of speaker system design that uses a port or vent cut into the speaker cabinet, leading to an internal resonance chamber. This design enhances the speaker’s efficiency at low frequencies, allowing it to produce deeper bass sounds than a similar speaker in a sealed enclosure. The port redirects sound from the rear of the speaker cone and combines it with the sound from the front, reinforcing lower frequency response and improving the overall sound quality.

Example Calculations

Example 1:

Volume of the Speaker Box (Vb) = 0.05 m³
Cross-sectional Area of the Port (A) = 0.01 m²

Using the formula:

\[ Fb = \frac{343}{2 \times 3.14159 \times \sqrt{\frac{0.05 \times 1.2}{0.01}}} \approx 22.29 \, \text{Hz} \]

The tuning frequency is approximately 22.29 Hz.

Example 2:

Volume of the Speaker Box (Vb) = 0.1 m³
Cross-sectional Area of the Port (A) = 0.02 m²

Using the formula:

\[ Fb = \frac{343}{2 \times 3.14159 \times \sqrt{\frac{0.1 \times 1.2}{0.02}}} \approx 22.29 \, \text{Hz} \]

The tuning frequency is approximately 22.29 Hz.