Active PA Speaker Product

Overview

An active PA speaker packs an entire small sound system into one cabinet: a two-way loudspeaker, the power amplifiers that drive it, and the signal processing that ties them together. Where a passive speaker needs an external amplifier rack and careful matching, an active design is engineered as a closed system — the manufacturer knows exactly which driver each amplifier channel feeds, so crossover slopes, equalisation, and protection limiters can be tuned to the specific transducers at the factory. A typical 12-inch model produces around 131 dB peak SPL from an 18 kg cabinet, enough to cover an audience of several hundred people.

The acoustic work is split between the LF Woofer Assembly, which covers bass and midrange up to about 1.9 kHz, and the HF Horn Section, a compression driver on a constant-directivity horn that carries the signal to 20 kHz. Power comes from the Class-D Amplifier Module fed by a universal-input Switch-Mode Power Supply. The Input and Control Panel accepts microphone or line signals, the Ported Cabinet provides the tuned air volume and the structure, and the Rigging and Mounting hardware lets the same box sit on a pole, hang from a ceiling, or tilt back as a stage monitor.

How it works

Incoming audio arrives at a balanced Input Preamp, which rejects hum picked up on long cable runs and scales mic- or line-level signals to the converter's operating range. From there everything is digital. The DSP Board implements the crossover that splits the band near 1.9 kHz, typically with 24 dB/octave Linkwitz-Riley filters, then applies driver-specific equalisation, a small delay that time-aligns the horn to the woofer, and the protection layer: an RMS limiter that tracks voice-coil heating and a peak limiter that stops mechanical over-excursion. Preset curves selected on the LCD Panel re-voice the same hardware for full-range use, monitor wedge placement, or operation above a subwoofer with the low end rolled off.

Each band gets its own Class-D Output Stage. A class-D amplifier converts the audio into a pulse-width-modulated square wave switching near 400 kHz; because the output Power MOSFET devices are either fully on or fully off, very little power is dissipated as heat, and efficiency exceeds 90 percent. An Output LC Filter strips the switching carrier, leaving amplified audio at the voice coil. This efficiency is what makes the format practical — a kilowatt of amplification cools through a passive rear Amplifier Heatsink with no fan noise. The Switch-Mode Power Supply uses a PFC Stage so the unit draws clean current from 100 to 240 V mains, with bulk Rail Capacitors supplying the short bass transients that momentarily exceed the supply's average rating.

Acoustic design

The woofer is a conventional moving-coil driver scaled for professional duty: a treated paper Woofer Cone driven by a 63 mm LF Voice Coil in the gap of a Neodymium Magnet motor, suspended by a Spider and Cone Surround in a cast Driver Basket. Neodymium motors halve driver weight against ferrite equivalents, which matters in a box meant to be lifted onto a pole.

High frequencies need a different approach because a 12-inch cone becomes severely directional above roughly 2 kHz. The Compression Driver couples a lightweight titanium HF Diaphragm to a chamber much smaller than the diaphragm area; the resulting pressure gain pushes sensitivity above 107 dB for one watt. A Phase Plug equalises the sound paths from different zones of the dome so they arrive at the horn throat in phase, and the HF Horn flare then sets a constant 90 by 60 degree coverage pattern, keeping the tonal balance similar for listeners off-axis. On many cabinets the horn rotates 90 degrees so the box can be used on its side as a floor monitor.

The Ported Cabinet is a bass-reflex design: the air mass in each Reflex Port Tube resonates with the compliance of the internal air volume, typically tuned near 55 Hz, so the port radiates much of the deepest bass while reducing cone excursion around tuning. Birch plywood with internal bracing keeps panel resonances above the bass band, and the trapezoidal cross-section both fights internal standing waves and gives the correct angle for monitor use.

Deployment

For portable use the Pole Mount Cup seats the cabinet on a 35 mm pole or subwoofer-mounted distance rod; dual-angle cups add a 7.5 degree down-tilt so the horn aims at the audience rather than over it. Installed systems hang the box from M10 Rigging Insert points using forged Rigging Eyebolt hardware rated with a minimum 5:1 safety factor. The XLR thru on the rear panel daisy-chains signal to additional cabinets, so a complete distributed system needs only mains and one signal line per box.