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PA Speakers: Active v Passive

This can seem a tough choice to make when purchasing a new sound system, there are no set rules when choosing either, but here are a few notes and ideas to aid you decision.

Active Speakers

Active speakers have the amplifier built into the cabinet, these cabinets can be wooden or plastic and sometimes include a small mixer stage, so microphones and other audio sources can be connected. Technology has moved on in the last few years with many active speakers now using class D amplifiers, these are very efficient and lightweight.

Active or powered speakers can be connected directly to a music source or microphone. Low level signals such as these need to be connected using shielded cables. The internal amplifier in this style of speaker will also need to be mains powered so a suitable power socket will need to be found close by. As the amplifier is already inside the speaker cabinet, no thought needs to be given to matching the speaker driver to amplifier as this has already been considered by the manufacturer.

If you always need a simple and easy to use system with modest power then using active cabinets could be your best choice, if your requirements are more varied, then consider some other options before deciding.

Passive Speakers

Passive speakers use an external amplifier to power them, so some care needs to be taken when choosing the correct amplifier. It is always a good idea to buy an amplifier that is more powerful than the speaker its self, especially if it’s a Sub-bass cabinet. It is always best to look at RMS power ratings for amplifiers and AES or RMS ratings for speakers, so you can understand the most suitable combinations.

Most full range passive speakers have a crossover inside to split the audio signal to the drivers, so high frequencies to tweeters and horns and low frequencies to the bass. If you have chosen to include a sub-bass cabinet in your system, this will generally work fine with most full range cabinets, you can use a crossover to set the frequency balance.

Here are a few diagrams showing some system designs and options:

Things to think about when purchasing a new PA system

Set your budget
Think about the size of the venue the speakers will be used in
Ask yourself these questions: What size cabinets do I want, Is weight an issue for me, Do I need sub-woofers?
Get some advice from us by emailing sales@terralec.com or calling 01702 547571
Listen to the speakers before you purchase (you can visit our demo area for this http://www.terralec.co.uk/Store_and_demo/2592_i.html)

As you can see from the points above your first choice does not need to be passive or active, that decision should come later. Ask yourself the important questions first. Our general advice would be to use passive speakers for fixed installations, then no mains cabling is required to the installed speaker cabinets, only speaker cable. This will lower the cost involved for the installation and no qualified electricians are required. We would generally try and use active speakers for mobile applications, as long as we can get the power needed for the size of the venue, this cuts down on the amount of equipment that is required making set up quicker. Active speakers would be the choice for the less experienced as there is far less technical knowledge needed when using active speaker option.