Turning a speaker set into a fully-fledged PA

If you’re a performing DJ or musician and you’re beginning to outgrow your set of speakers, then what can you do? Basically, you’ve got two choices: you can either invest in a new set of speakers or expand on your current set. Which option is right for you? This blog tells you everything you need to know.

Time to expand

If you’ve already invested in a set of active full-range speakers and you want to expand on them, what is the next logical step? Your first thought may be to buy more of the same speakers and spread them out around the room for more amplification. The problem is that some frequencies will be amplified in some areas but muted in others, a phenomenon known as comb filtering, which you don’t want.

Don’t look up, look down

In this case, it’s a good idea not to focus on your speakers, but rather invest in on one or two powerful subwoofers. When purchasing a single sub, make sure that it has stereo inputs and outputs! You can then add any active speaker you want, but a full-capacity model from the same brand or series is likely to offer the best results. A good rule of thumb is to always choose a sub that’s a size bigger than the speakers so the frequencies can blend together more seamlessly. That means a 10-inch speaker is best paired with a 12 or 15-inch sub, a 12-inch speaker works optimally with a 15 or 18-inch sub, and a 15-inch speaker performs best with an 18 or even a 21-inch sub. Connecting is easy and can be done in one of two ways. An active woofer is often equipped with an internal crossover that automatically separates the frequencies, which means you can connect the sub directly to the speaker. If there is no internal crossover (which is rarely the case) or if you want more control over your sound, then you can connect to an equalizer via an external crossover, but in that case you’d need to connect everything separately.

Connect the dots

Once you’ve found the sub of your dreams, it’s time to hook it up and get a signal running through the set. Your signal travels from the audio source (DJ/sound engineer: mixer; band: instrument → microphone → mixing console) to your woofer first, then to the speakers. This process will terminate some functionality on your speakers like Bluetooth, AUX or mic inputs because the audio is being filtered from low (via your sub) to high. The bass cabinet actually separates the sound and sends the high frequencies to the rest of your set, not the other way around.

Passive/active perils

Some active speakers and woofers are equipped with a passive output so you can connect a passive speaker. In a setup like that, however, the output capacity of the active speaker’s built-in amplifier is distributed between the two, which is far from ideal. If there’s a passive bass cabinet in the set as well, then the high-to-low filtering we mentioned before will result in a loss of energy and could even cause overheating. A more ideal setup is a powered sub combined with one or two passive speakers. In this configuration, the sub would have two or three amplifiers on board and the distribution would take place internally, which is very efficient!

Troubleshooting

If you’re starting out with two passive speakers and a separate amplifier, then adding one (or two) passive subwoofer(s), an amp and possibly a crossover makes for a great complete set. Instead of an amplifier, you could also opt for a powered mixer (a mixing console with an amplifier built in). You could then use an active sub to drive the speaker set via the main output at line level and even use the passive cabinets as monitors, should the need arise!

Are you running into other problems with your PA? Let us know!

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