Subwoofers

Add a subwoofer when the system must play music with full bass at level, such as in ballrooms, clubs, events and auditoriums. Full-range speakers alone usually roll off well above the deepest notes, while subwoofers here reach down to 30 to 45 Hz.

For speech-only rooms, a subwoofer is rarely needed. For example, the d&b 18S-SUB covers 37 to 140 Hz and the JBL PRX918XLF reaches 30 Hz at -10 dB, the range that gives music its weight.

A powered subwoofer has its amplifier and DSP built in and needs only mains power and a line signal. A passive subwoofer needs an external amplifier and processing.

The JBL SRX828SP (2,000 W Crown DriveCore) and Electro-Voice ELX200-18SP (1,200 W Class D) are powered models for events. The d&b 18S-SUB and 21S-SUB are passive installation models driven by d&b amplifiers such as the 10D, 40D or D40, which carry presets for them.

A cardioid subwoofer reduces the bass that radiates behind it, so more energy goes to the audience and less to the stage or the wall behind. This keeps stages quieter and the sound more controlled in reflective rooms.

The d&b KSL-SUB in this collection is a cardioid subwoofer with 3 × 15-inch drivers and 139 dB maximum SPL. It can be flown with KSL8 and KSL12 arrays, or ground-stacked as the KSL-GSUB.

At the -5 dB point, d&b rates the 21S-SUB from 35 Hz (33 Hz in INFRA mode), the 18S-SUB and E15X-SUB from 37 Hz and the 12S-SUB from 45 Hz.

At the -10 dB point, JBL rates the PRX918XLF from 30 Hz and Electro-Voice the ELX200-18SP from 40 Hz, and Bose rates the ShowMatch SMS118 from 29 Hz. Compare models at the same reference point, since a -10 dB figure always looks lower than a -5 dB figure.

Choose a model with an outdoor rating. The Bose MB210-WR is rated IP55 for direct-exposure outdoor installations and has 2 × 10-inch drivers, reaching 37 Hz at -10 dB.

This collection also lists weather-resistant versions of the d&b 12S, 18S, 21S and 27S-SUB and the E12X and E15X subwoofers. For terraces, pools and beach venues, also protect cable entries and allow for heat on cabinets in direct sun.

The crossover is usually set between 80 and 150 Hz, depending on the main speakers and the subwoofer. The Electro-Voice ELX200-18SP offers 80, 100, 120 and 150 Hz low-pass settings.

d&b subwoofers have standard and 100 Hz modes: the 18S-SUB covers 37 to 140 Hz in standard mode and 37 to 100 Hz in 100 Hz mode. After choosing the crossover, set the delay so the subwoofer and the main speakers arrive together.

Weight ranges widely. The d&b 12S-SUB weighs 16 kg, the B8-SUB 18 kg, the E15X-SUB 24 kg, the 18S-SUB 32 kg, the B6-SUB 41 kg and the 21S-SUB 54 kg. The flyable d&b KSL-SUB weighs 82 kg.

Among powered models, the JBL SRX828SP dual 18-inch weighs 65.9 kg and accepts the JBL WK-4S caster kit. Plan handling, floor loading and rigging around these weights.

Match the amplifier to the cabinet's impedance and power rating. The d&b 21S-SUB is 4 Ω and rated 650 W RMS and 2,600 W peak; the 18S-SUB is 8 Ω at 400 W RMS; the E15X-SUB is 8 Ω at 300 W RMS; the B6-SUB is 8 Ω at 500 W RMS.

d&b lists the amplifiers with presets for each cabinet: for example, the D40 for mobile use, and the 40D, 10D or 5D for installations, depending on the model.

Yes. The Bose DesignMax DM8C-Sub is an in-ceiling subwoofer covering 38 to 115 Hz with 70 V taps up to 150 W, and the DesignMax DM10S-Sub is a surface-mount subwoofer covering 35 to 125 Hz with the same tap range.

Both run on the same 70 V or 100 V lines as the ceiling speakers. Bose recommends a 40 Hz high-pass filter for each, so the amplifier or DSP should provide one.

Some can. The Electro-Voice ELX200-18SP and ELX200-12SP use the QuickSmart Mobile app over Bluetooth LE to control up to 6 speakers from the audience area, with Music, Live and Club presets.

The JBL PRX918XLF is set up through its color LCD or the JBL Pro Connect app, with 6-band parametric EQ, a low-pass filter and 20 ms of delay. The JBL SRX828SP also offers network control.