Active PA Speakers
A powered or ‘Active’ loudspeaker features a built in amplifier unit to power itself. This offers most users a huge advantage over traditional passive systems, as it cuts down on equipment, cabling, and the expense of needing a standalone amplifier.
Amongst its many benefits, the biggest plus, certainly from a technical perspective, is that you are ensured an amplifier that can deliver to you the full capabilities of the speaker system, as its power rating, matched impedance to the speaker drivers, and crossover network will guarantee you are getting the best quality signal level, with minimum distortion and better dynamic range.
Instead of carrying an already amplified signal over metres of cable from an amp to speaker, which brings about signal loss due to resistance (resulting in treble / top end loss), the low level signal travels relatively unimpeded down the cable to an active speaker, and after being amplified has just a tiny amount of internal wiring to reach the driver. This reversal of the traditional signal chain gives a far cleaner output, with the amplifier being able to work far more efficiently, which allows for greater power output and clarity, and much better low end response.
Active speakers can be connected directly to a mixing console, or fed from a low-level audio source, and many also feature direct microphone inputs and mix controls so can be used completely independently. Some newer models feature bluetooth connectivity and digital eq presets which can be controlled remotely from iOS and android devices.
With just a few exceptions now, the majority of professional active speaker units are ‘polycabs’, or resin cast from PVC (polyvinyl chloride) plastic or from ABS (Acrylonitrile butadiene styrene) acrylic, which are both extremely durable materials, and their ability to be molded allows seamless enclosures which are airtight, lightweight, and fairly indestructible. Compared to traditional wooden enclosures, the weight saving is significant, even with the added heft of the onboard amplifier. It also allows carry handles to be built into the design rather than screwed on as extras.
A standard set up is obviously a pair running in stereo (left and right audio mix). Most modern active speaker units also have signal passthrough, which allows you to add on further units should you wish.
You can also add on an active subwoofer if required to handle all your low end, which can then mean you could use smaller sized main speakers as they won't be handling the heavier bass signal.The main units then become mid / top only, taking the stress off of the inbuilt amplifier from needing to supply the higher current required for bass reproduction.