Positioning, Free-Field | Tannoy B475 specs

9. Positioning

When a bass loudspeaker is used in an environment with boundary surfaces, its placement affects its frequency response. When such effects are properly understood, they can be used to great effect in producing the desired sound quality without the aid of additional amplification.

Consider Figure 9a in the diagram below, here we see a loudspeaker in free field or anechoic conditions. We measure its sound pressure level at a distance D, and refer to this as our reference level, or 0 dB SPL.

If we now place a large reflective surface (i.e., a wall, ceiling or floor) next to the loudspeaker, see Figure 9b, the sound that is radiated towards the boundary is reflected. As a result, the sound pressure level can increase by as much as 3 dB (effectively doubling the available amplifier power). The loudspeaker is radiating its power into half as much space, this is known as half space loading. For each additional boundary the SPL can increase by 3dB. Corner placement or eighth space (Figure 9d) loading can increase a bass speaker’s efficiency by up to 9dB.

This effect is not the same at all frequencies. Loudspeakers are only essentially omni directional at low frequencies (where the wavelength is large in comparison to the loudspeaker). At high frequencies sound radiates in a more directional manner. We can position full range loudspeakers next to a boundary in order to boost the lower frequencies while the highs remain unchanged.

Coupling, or placing bass cabinets together will also increase bass output.

Figure 9a. Free-Field

Figure 9b. Half Space

Figure 9c. Quarter Space

Figure 9d. Eighth Space

B475 specifications

The Tannoy B475 is a high-performance loudspeaker that showcases the brand's commitment to excellence in sound reproduction. Designed primarily for professional audio applications, the B475 embodies a rich heritage of audio engineering, making it an ideal choice for musicians, sound engineers, and event organizers who demand clarity and power.

One of the defining features of the B475 is its robust construction. Built to withstand the rigors of touring and live performances, the cabinet is crafted from high-quality materials that ensure durability without compromising sound quality. The enclosure is designed to minimize resonances, allowing the speaker to deliver a clean and accurate sound across a wide frequency range.

At the heart of the B475 is Tannoy's proprietary Dual Concentric driver technology. This innovative design integrates the woofer and tweeter into a single point source, providing a coherent sound that enhances the listener's experience. The Dual Concentric design ensures that high and low frequencies are produced from the same location, resulting in improved phase coherence and a more natural soundstage.

Another significant aspect of the B475 is its exceptional power handling capabilities. With a high sensitivity rating, the speaker can efficiently convert input power into sound output, allowing it to deliver impressive levels of volume without distortion. This makes the B475 suitable for large venues where high sound pressure levels are required.

The B475 also features advanced crossover networks that are finely tuned to optimize performance across various frequencies. These crossovers ensure that each driver operates within its optimal range, resulting in a smooth frequency response and precise imaging. The use of high-quality components in the crossover design further enhances the overall sound quality.

Versatility is another hallmark of the Tannoy B475. It can be used in a variety of setups, whether as a standalone speaker, part of a larger PA system, or in combination with subwoofers for enhanced low-end response. With multiple input options, including XLR and 1/4-inch jacks, the B475 can easily integrate into different audio systems.

In summary, the Tannoy B475 stands out as a powerful and versatile loudspeaker, thanks to its rugged build, innovative Dual Concentric driver technology, and robust performance characteristics. Whether used for live sound reinforcement or studio monitoring, the B475 delivers audio quality that truly reflects Tannoy's legacy of excellence in the world of professional audio.