In confined spaces, a TV speaker box's bass performance is often limited by insufficient cabinet volume. However, this issue can be significantly improved through appropriate structural design. Cabinet volume is a key factor affecting bass performance. When the cabinet volume is too small, the bass response is insufficient, resulting in a harsh and lacking sound. However, when the cabinet volume is too large, the bass response is blunt and may even induce reverberation within the cabinet, affecting sound clarity. Therefore, the design process requires striking a balance between bass response and transient response. For example, by calculating the TV speaker box's Q factor (typically designed between 0.7 and 1.2), this balance can be achieved between bass depth and sound clarity.
The vented TV speaker box structure is an effective solution for enhancing bass performance. Its principle is to use a ported port to invert the phase of the sound waves at the back of the speaker and radiate them forward, where they are superimposed on the front sound waves, thereby enhancing the low-frequency energy. Compared to sealed TV speaker boxes, vented designs achieve deeper bass performance within a smaller cabinet volume and offer higher radiation efficiency. During design, the length and diameter of the bass resonant tube must be precisely calculated in relation to the enclosure volume to ensure accurate low-frequency resonant frequency. Improper bass resonant tube design can result in exaggerated low-frequency sound or make the tapering pattern of the tube diameter difficult to grasp, negatively impacting sound quality.
The labyrinthine structure of a TV speaker box uses a zigzag acoustic channel within the enclosure to extend the propagation path of low-frequency sound waves, allowing sound waves at the rear of the speaker to overlap in phase with those at the front, thereby extending the low-frequency range. This design significantly enhances the low frequencies of full-range speakers and is particularly suitable for space-constrained environments. However, the complex acoustic channel of the labyrinth structure can increase sound wave reflections, leading to high-frequency interference. Therefore, sound-absorbing materials are required within the channel to attenuate high- and mid-frequency waves and enhance low-frequency clarity. Furthermore, labyrinthine TV speaker boxes are generally less sensitive than bass resonant boxes and require a higher-power amplifier to fully realize their potential.
Passive radiator (empty cone) technology is another low-frequency enhancement solution suitable for small spaces. The principle is to replace the ported tube with a passive diaphragm. The elasticity of the air inside the speaker box drives the passive diaphragm to vibrate, radiating low-frequency sound waves. The passive diaphragm's vibration frequency is aligned with the speaker, fully utilizing sound energy and broadening the low-frequency response. This technology requires sophisticated installation techniques, but it effectively extends the depth of low-frequency sound while avoiding airflow noise that can be introduced by the ported tube.
The rigidity of the enclosure material is also crucial for low-frequency performance. Thin steel or plastic enclosures are prone to resonance due to speaker vibration, resulting in low-frequency distortion. Thick, high-density materials (such as medium-density fiberboard) can reduce enclosure vibration and improve low-frequency purity. Furthermore, internal ribs can further enhance structural stability and prevent low-frequency energy from being absorbed by the enclosure.
The appropriate use of sound-absorbing materials can optimize the acoustic environment within the enclosure. In sealed TV speaker boxes, sound-absorbing foam can increase the effective volume while also increasing damping and reducing low-frequency reverberation. However, it is important to control the amount of sound-absorbing foam used to avoid excessive absorption that can lead to dry bass. In a bass-reflex TV speaker box, sound-absorbing materials should be primarily placed in the non-bass-reflex area to prevent high-frequency interference.
The virtual bass enhancement algorithm offers a new approach to optimizing low-frequency sound in small spaces. By analyzing the harmonic components of the audio signal, the algorithm simulates low-frequency information below the physical limit of the speaker, enhancing the bass's depth and impact. This technology requires no additional hardware; it can be implemented simply by embedding a specific algorithm within the audio processing chip, making it particularly suitable for compact TV speaker box designs.
