Comparison KEF Reference 8b vs JBL VRX 918SP

— Behind. It is recommended to install subwoofers with a rear bass reflex so that the back of the case, where the bass reflex is located, is away from the wall. If you put such a subwoofer right next to the wall, then the sound quality will be noticeably reduced. Bass reflex subwoofers on the back of the cabinet are usually placed in the centre of the room. If it is not possible to put acoustics in the centre, then they try to place this type of subwoofers away from the wall that the bass reflex is looking at.

— Front. Front-facing bass reflex subwoofers are good if the acoustics need to deeply reveal the image of low-frequency sound. Acoustics of this type are recommended for music in which there is a lot of bass. The front location of the phase inverter allows you to put the subwoofer almost close to the wall.

— From below. Bass reflex subwoofers are designed to be hung at a height. In this case, there will be no interference in the path of low-frequency sound, that is, the bass will be revealed as fully as possible. If it is not possible to hang such a subwoofer, then it is permissible to put the acoustics on a high stand. But the stand should not overlap the phase inverter.

— Sideways. Subwoofers with a side bass reflex can be placed close to the wall and in the corner, but if the corner wall does...not block the bass reflex. The lateral location of the phase inverter allows acoustics to focus on mid-frequency and high-frequency sound. The low frequency sound will become moderate. This is the optimal acoustic scheme for watching movies.

Rated power of the subwoofer. Technically, this is the highest average (rms) sound power at which the device can work normally (without sound distortion and damage to components) for an unlimited time. Simply put, the more powerful the subwoofer, the louder it is. The choice for this parameter depends primarily on the size of the space / room that is planned to be covered; detailed recommendations for different situations can be found in special sources.

Also, the power is directly related to the characteristics of the amplifier used with the subwoofer. For active subwoofers (see "Type"), this item actually indicates the nominal power of the built-in amplifier; the speaker itself can be more powerful, but it doesn't matter anymore. For passive models, the power rating corresponds to the highest amplifier power that can be connected to the speaker without the risk of damaging it at high volume.

The sensitivity value determines the volume of the subwoofer when an external signal of a certain power is connected to it. The higher the sensitivity, the louder the sound will be, with equal signal power and impedance.

The highest sound pressure level that a subwoofer can create, in other words, the volume that it produces at its maximum power level. This parameter is measured in the same way as any noise level - in decibels; since the decibel is a non-linear quantity, it is easiest to evaluate loudness using comparative tables. So, the most modest modern subwoofers are capable of delivering up to 95 – 100 dB, this is comparable to the volume of a subway car or a chainsaw. In the most powerful ones, it can exceed 130 dB - this is louder than an airplane on takeoff, a long stay near a subwoofer operating at full power can lead to hearing damage.

Note that sound pressure and sensitivity (see above) are fundamentally different characteristics, although they are measured by the same units.

Subwoofer AC impedance. This parameter matters primarily when connected to an external amplifier: if the impedance is lower than that of the amplifier, sound distortion is possible, if the impedance is higher, the subwoofer may sound quieter than we would like.

The range of audio frequencies reproduced by the subwoofer. As a general rule, the wider the frequency range, the richer the sound and the more detail the speaker can convey. However, it is worth remembering that subwoofers as a class are designed for low and ultra-low frequencies in the range from 20 to 150 (sometimes 200) Hz. Therefore, in fact, a significant difference in sound is noticeable only with a large difference in the reproducible ranges (for example, 20-200 Hz and 50-150 Hz).

Also, do not forget that an extensive frequency range is not yet a guarantee of high-quality sound; and in some cases (for example, if the main speakers of the speaker also cope well with low frequencies), it may be completely redundant.

The number of individual speakers in the subwoofer design. The vast majority of modern subwoofers have a single speaker; therefore, it is customary to indicate this number only when it is greater than 1. The speakers themselves usually have the same dimensions and characteristics.

Such "multi-charge" in a subwoofer can serve different purposes. Most often, the manufacturer thus provides high sound power without a significant increase in the dimensions of the speaker — several small speakers are easier to fit into a compact case than one large one. And with 3 or 6 speakers, their diffusers can be located at an angle of 120 ° to each other, thus ensuring uniform sound radiation in all directions.

Note that the use of several speakers significantly affects the cost of the column, this feature is typical mainly for high-end models.

The diameter of the speaker(s) installed in the subwoofer.

It is believed that the larger the speaker ( 15 ", 18 " and more), the more power it can produce and the deeper the bass will be on such acoustics. However, in modern subwoofers, manufacturers use various tricks that allow achieving good sound depth even with relatively small speaker sizes ( 10 ", 8 "). Therefore, it is possible to compare different models only if they differ significantly in this indicator; and even then, in such cases, it is worth paying attention not so much to the speaker diameter as to the price category. The golden mean among sizes is 12-inch subwoofers.

The subwoofer has its own level control, in other words, a volume control. Adjusting the bass with such a control is often easier than digging into the settings of an amplifier or other external device.