PA Speakers Powered or Passive
"Powered or passive speakers?" It's a question you'll encounter early on in your search for a PA system, and one of the most important questions you'll need to answer. There are pros and cons to either choice, and depending on your application, the decision could be fairly straightforward. Understanding the differences between the two is key in putting together a system that does exactly what you need it to do.
The defining characteristic of a powered speaker is that it has an internal amplifier, meaning you won't need to carry around (or buy) a separate amplifier to get it up and running. DSP and crossovers are typically built in as well; the latter is technically what qualifies a speaker to be considered "active," though the terms powered and active tend to be used interchangeably.
- Crossover – An electronics device that takes a single input signal and splits the audio signal into separate frequency bands that can be separately routed to loudspeakers optimized for those bands (ex. a 1" tweeter to handle high frequencies and a 12" woofer to handle mid and low frequencies)
- DSP – Digital Signal Processing, which utilizes specialized processors to manipulate audio; commonly used to apply EQ, compression, reverb, delay, etc. allowing you to fine-tune your sound exactly how you like it
Powered speakers are great because they're a breeze to set up: you plug them in, send audio to them, and you're ready to rock! You can also daisy chain as many powered speakers together as you need without having to worry about the limitations of an external amplifier, although you will need to have a sufficient number of outlets to plug the speakers into. Unless you have a specific reason to go passive, it's typically best to stick with powered speakers simply for their convenience.
Passive speakers, in contrast, need power from an external amplifier to function. This requires additional setup and know-how but provides far greater flexibility when putting together large, complex systems and installations. Having your system separated into multiple components rather than an all-in-one speaker cabinet greatly reduces the risk of speakers overheating during long, intense periods of use and makes maintenance both quicker and easier to troubleshoot. Adjusting your amp settings will be as simple as checking your rack, rather than having to break out the ladder to climb up to your speakers mounted on the walls.
Passive speakers are also preferable for installations because you won't have to worry about having power outlets in close proximity to your speakers, a luxury you generally don't have when mounting your speakers near the ceiling. Instead, you would simply need to run speaker cable from your amp to your speakers. To achieve the best possible sound, you may want to run the audio signal into a crossover before running to your speakers. This will allow you to direct specific ranges of frequencies to the speakers best suited to produce them, such as sending your bass frequencies under a given threshold (AKA the crossover point) to a subwoofer.
Matching Passive Speakers with Appropriate Amps
Not all amps are created equal. Power ratings, Ohm loads, and channel counts vary greatly, and it is important to take these specifications into consideration when selecting an amp that will work for you. Ideally, you should be choosing an amp that works with the speakers you want to use and not the other way around. Either way, it's crucial that the specifications line up properly to ensure you get good sound, and more importantly, don't damage your speakers. Here are some basic guidelines to keep in mind:
- At minimum, you should provide your speakers with the program power rating (double the continuous power rating or half the Peak Power rating) listed to allow for ample headroom, which is the amount of room you have to turn up your signal before clipping/creating distortion. If you plan on cranking up your system, make sure you give your speaker plenty of wattage so it can function at its full potential.
- You are better off providing your speakers with some excess wattage rather than not enough, as under-powering speakers is far more damaging to them than overpowering. Wattage is like food to your speaker. If you give it an excessive amount, it will generally only take what it needs. If you don't give it enough, it will starve.
Don't starve your speakers!
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- Never go outside of the recommend Ohm (O) load ratings for your amplifier. Doing so could at best provide little to no sound and at worst could light your amp on fire (literally). Your average full range speaker has an 8 Ohm rating and your average subwoofer has a 4 Ohm rating, though you must always double check your speakers as not all passive speakers follow this generalization. The equation to calculate an Ohm load on larger systems is rather complicated but for basic PA systems, all you need to remember is that the Ohm load is cut in half for every speaker you add.
- Example: Two 8 Ohm speakers hooked up to a single channel on an amplifier create a 4 Ohm load. Adding another 8 Ohm speaker to this chain of speakers would drop it down to about a 2 Ohm load (2.33 O, if you want to get technical). Hooking up two 4 Ohm subwoofers to the second channel on the amplifier would bring the second channel to a 2 Ohm load as well.
- On most power amplifiers, you have two channels, left and right, which make up a Stereo signal that can be combined into a single, more powerful channel. Running your amplifier into a single mono channel, referred to as Bridge-Mono mode, allows you to create a channel that puts out more power than you could get from each of your individual channels in Stereo mode. This means you may be able to properly power speakers your amp couldn't handle otherwise, however the overall number of speakers you can connect is still limited by the Ohm load.
ElectroVoice ZLX-15 Passive Speaker
Power Handling (Continuous/Peak):
250W Continuous/1000W Peak
Impedance: 8 Ohms
The ElectroVoice ZLX-15 Passive Speaker has a Peak Power rating of 1000W and an 8 Ohm rating. If you wanted to power a pair of these with the Crown XLS1502 XLS DriveCore 2 PA Power Amplifier, you could not do so in Stereo mode, as you would only get 300W per channel at 8 Ohms. However, if you put the amplifier into Bridge-Mono mode, you would get a total of 1550W of power, since connecting these two 8 Ohm speakers into one channel would drop you down to a 4 Ohm load. This would be a sufficient amount of power to run your speakers and still have enough headroom.
Still not sure which way to go in regards to your speaker system? Here's a quick list of questions to ask yourself:
- Is this for portable use or a permanent installation?
- If this is for portable use, is quick setup required and/or desired?
- Do I already have an amp(s)? If so, will it be able to power the speakers I'm looking to use?
- Will someone with sufficient knowledge of power amplifiers and pro audio be operating the system or does it need to be dummy proof?
Deciding between passive and powered speakers is a big step but once you've done that, you'll still need to determine the specific brand and model you want to invest in. Give one of our trained Gear Advisors a call at 800-945-9300 and we'll make sure you get speakers that are just right for you!