Powered speakers, also known as active speakers, have amplifiers built in. You can connect them directly to a sound source or mixing console, without using an amplifier. These speakers can be purchased with either active or passive crossovers built in. Powered type speakers eliminate the need for amplifiers to perform speaker limiting and matching. These type of speakers also reduce the length of the cable that runs between the speaker driver and the amplifier output. A powered speaker also eases set-up problems for your audio system, to a degree. Since some of the low-level cables are run from a signal source to the speakers, pickup of noise can present a problem. You can reduce or solve this issue by using balanced line inputs from the speakers. When the music is driven from the source by balanced cables and signals, noise will be reduced. Some manufacturers of powered type speakers, including Phonic and DM Technologies, incorporate wireless UHF receivers so that you only need a power lead for the speaker.
An unpowered or passive speaker does not have a power source of its own, and it pulls power from another place. Active speakers use a shorter cable between the speaker and the amplifier, and this can reduce power and signal loss. You can also match your amplifier to a speaker more exactly. Passive speakers tend to be cheaper and lighter, but they will require more cable that will be run to the separate amplifier. This is a good set-up if your amplifiers run to multiple speakers.
Powered speakers simply include amplifiers, speakers and the other electronic components in one cabinet. They eliminate the need to use heavy amplifiers, bulky speaker wire and external crossovers. You can also use these speaker set-ups to help provide an easier may to get optimized sound. If your speaker includes a tweeter and a woofer, then a crossover will split the frequency of the signal and will route low and highs to separate amplifiers. This is how the term “bi-amplification” came about.
The signals from the speaker-out jacks carry audio as well as power to drive the speakers. This is power that active speakers don't need, and cannot handle. You will damage your active speakers if you connect these leads to your powered speaker system. You could also damage your crossover and amplifiers.
The most commonly found connection between a powered speaker and a mixer is an unbalanced or balanced line. A balanced line offers excellent noise rejection and allows you to run lengths of cables between speakers and the mixing station without noise or interference. Most active speakers have balanced TRS or XLR jacks, or both. Most mixers today have output jacks that are balanced, with connectors for TRS, XLR or both.
If your mixer has unbalanced outputs, you will pick up more interference and noise. Don't try to run your cable farther than twenty to thirty feet if you use this set-up. Some powered speakers have digital inputs now, and they include a D/A converter to convert digital signals into analog signals, to allow for more balanced sound.