Buying a PA system can be a difficult choice to the newcomer with the amount of different products there are available on the market. When you don’t understand the technical terms and specifications manufactures provide it can make the decision even more difficult. In this article we’re going to look at the top 5 essential components of any PA system, giving you a concise insight into what they do and what you should consider before making a purchase.
Speakers are the most visible part of a sound reinforcement system. Speakers come in two flavours, active (powered) or passive (unpowered). Passive speakers require an external amplifier, as explained below, to work. Active speakers on the other hand have a built in amplifier making them easier to set up, however they are heavier and require mains power. There are two main specifications you should be looking out for when buying speakers, power rating and driver size. The power rating, measured in watts (W), tells you how much volume the speaker is capable of producing, 50W may be fine for doing karaoke at a house party but 300W upwards is necessary when playing a gig with a full band. They driver is the large circle part of the speakers which physically moves, moving the air and creating sound. The driver size, measured in inches, dictates how much low frequency sound the speakers can produce. 8” or 10” drivers are fine for voice or acoustic guitar but for playing back pre-recorded music or providing sound for a full band 12” or 15” drivers are necessary. For providing even more bass subwoofers (Also known as bass bins or bass speakers), separate speakers which amplify only low frequency sound, are used.
In a PA system the mixer takes the various audio sources, such as instruments and CD players, and “mixes” them into one channel of audio, ready to go to an amplifier or active speaker. A mixer has a number of channels, 4, 8 or very often more, each of which accept a microphone, guitar or other sound source. It is important to purchase a mixer with enough channels to allow you to accept all the required sound sources. Then the user can apply EQ (Change the level of the bass or treble), send the sound source to an effects processor and finally change the level of that sound source, allowing the user to create a balanced “mix”. Modern mixers often have built in digital effects, great for live band performances or karaoke, a built in amplifier and a USB socket for recording and playing back audio from a laptop.
As discussed above amplifiers take the low power audio signal from a mixer and amplify it to a high power audio signal suitable for driving speakers. When using passive speakers it is important to match the power the amplifier can provide to the amount of power the speaker can take, though it is not necessary to match them exactly.
In any PA system that needs to amplify an acoustic sound source such as a voice or acoustic instrument requires a microphone to create an electrical signal suitable for amplification. When purchasing a PA system you will come across two main types of microphones, wired and wireless. Wired microphones require a lead to be physically plugged into the mixer whilst wireless microphones instead use a wireless transmitter and receiver. Wireless microphones can be useful in many situations however they are more expensive and subject to radio interference. Handheld microphones are very common and can be held by the user or placed in a microphone stand. Headset microphones are worn on the performer’s head and clip-on (Also known as lavaliere or lapel microphones) are attached to the front of the performer’s clothes, again these can be a useful alternative in many situations.
As well as microphones a PA system can be required to reinforce pre-recorded music and other audio files. This can be achieved by a number of devices, MP3 players and iPods being a very common solution. Some PA systems may incorporate docking stations however this isn’t usually necessary, the audio can be taken from these devices via a lead going from the headphone socket of the MP3 player and then plugged into the mixer. The same is true for a laptop, just take a lead from the audio output on the laptop and plug it into the mixer. Many modern mixers and PA systems incorporate a built in MP3 player which plays audio back from memory cards or USB sticks. CD and DVD players again can be plugged into a mixer via a lead however in the computer age their use is getting less and less common.
Pro Audio Centre has a dedicated team of PA systems experts, able to help guide you through the process of choosing the right PA system for your needs. Contact us today via our site, counterpoint.co.uk or by calling us on 0333 050 4871.