How to buy a PA system

17th Mar 2011 | 16:12

How to buy a PA system

Food for thought for function bands and gigging musicians

Okay, so you are a band and you are gigging regularly but the venues you play in don't all have an in-house PA system installed. What do you do?

There's always the option of hiring in a PA but the costs can add up and eat into your profit. And then there's the logistics of organising it all – far better perhaps to own your own PA so you've always got it at hand and at a fixed cost too; once it's paid for all you need worry about is the odd bit of maintenance.

What type of PA to get pretty much depends on two major factors – the kind of music that you play and the size of the venues in which you play it. If you didn't already know, PA stands for Public Address. The main reason for a PA is to let voices be heard - drums can be loud, guitarists have amps, but the poor old singer needs to be heard over it all.

"There's always the option of hiring in a PA but the costs can add up and eat into your profit."

A PA is thus essential unless you are an acoustic band doing really intimate gigs in the back room of a pub or perhaps a totally instrumental band. However, even a band without a lead singer will probably want to make announcements. Also, putting some or all of the instruments through a PA can enhance the sound considerably, creating a better balance than relying on how the drums sound acoustically and turning up the bass and guitar amps to match.

Obviously, the bigger the venue that you are playing, the bigger the PA system you will need. As PAs get bigger the number of constituent parts increases. More and bigger speakers and amps are needed, so let's look at how a PA is made up...

What do we need?

The most basic type of PA is the easily portable all-in-one type based around a combined mixer and amp and a pair of full range speakers like the Fender Passport system. Whereas a larger PA system will have a separate mixer and power amps, a mixer amp like those in Peavey's XR range combines the two functions.

These amps with multiple input channels are easily situated onstage and will allow you to connect a microphone into each channel and set the level and EQ for each, and perhaps add reverb or any effects if they are built-in.

The output of the amp feeds a pair of full-range PA cabs that may or may not be mounted on stands, one each side of the stage and placed a little in front of the band (a vocal mic set forward of the axis is a recipe for feedback).

Now, if the venue is small and onstage instrument levels not too loud the singers may well be able to hear their voices from the PA cabinets, but really the best solution is to add monitors to the system.

Monitors are fed the audio signal via a mixer channel's aux sends and are generally wedge shaped to be unobtrusive and to project the sound up to the performer. They can be self-powered with an integral amp or run from a separate power amp.

A PA of this type with, say, four to eight channels and a couple of auxiliary sends for monitors is certainly fine for solo acts or duos, or smaller gigs where you just need to amplify the vocals. As far as power goes, something like 200 watts RMS could just do it.

Headroom

One golden rule when buying a PA is to try to buy one with more power than you think you'll need. It's much easier on the listener to hear a PA system running at way under capacity than a rig that's straining to be heard and distorting as a result.

You'll never hear a band complaining that they should have bought a smaller PA, unless they are moaning about humping it about which brings us to a salient point – transportability. PAs can be heavy and bulky and the mic stands and leads all take up space too, so you'll need to have decent transport (preferably a van) to cart it all around and room to store it too.

Moving on from the smaller pub gigs to larger venues you will need something bigger and it's time to start looking at systems with a separate mixing desk, amps and speakers. This approach may be the most logical in the long term as you can add components to create a larger and more versatile system over time.

If you are primarily a function band that plays weddings and parties, it may be worth investing in some CD decks and a small lighting rig. That way you can offer a DJ service in addition to live music and charge a premium for supplying the soundtrack to the whole evening.

It's also worth considering getting all of your newly-acquired gear PAT tested by a qualified electrician. More and more venues outside of the traditional gigging circuit insist on this for health and safety reasons.

It's all in the mix

What size mixer you choose will depend on just what you intend to put through the PA. Vocals would obviously go through it, as would keyboards and acoustic guitars via DI boxes. Bass guitar is another contender for a DI feed.

Smaller guitar amps could benefit from miking rather than having to use up all of their headroom, and although there may be no need to mic up the whole drum kit for all gigs, the kick drum will usually need a little help to cut through the mix.

"The kick drum will usually need a little help to cut through."

Add that lot up and a 16-channel mixer looks like a smart choice. If you intend to have several monitors onstage, it would be wise to find a desk with plenty of aux sends so you can work up individual mixes for each one.

Aux sends are also needed if you want to add an external effects processor such as a reverb or delay unit. You need pre-fade sends for the monitors and post-fade for the effects but some desks will let you switch between pre and post.

For amps and speakers there's the choice of separate units or powered speakers with the amps built into the cabinet. A pair of full-range speakers, designed to cover a wide frequency range may suffice but in a larger system you might wish to have separate speaker cabinets for the different frequency ranges in the front of house sound so will also need a crossover in the system to split the frequencies between them.

A two-way crossover will split the high and low, a three-way crossover will also separate the mid range. There are speaker management systems available that provide the crossover functions as well as EQ for sorting out any potential feedback problems in the room.

Extras

When figuring out costs don't forget microphones, stands and leads. For vocals there are plenty of choices including the ubiquitous Shure SM58 but if you are planning to mic up other instruments there are dedicated mics for certain jobs (a kick drum mic needs to be able to handle low frequencies and high SPLs) and you'll need DI boxes for any instruments that you wish to plug directly into a PA's mic inputs.

It's not uncommon for bands to put together their own PA system like this and operate it themselves with the mixer nestled at the side of the stage but, with lots of instruments and vocals to take care of, it may be time to employ a sound engineer and situate the mixing desk in front of the stage, connected to the rest of the system with multicore.

That all may be a step too far for many bands, however… perhaps the way to go would be to buy a small PA that you can operate yourselves for the smaller gigs and hire in a commercial PA complete with engineer for the larger ones.

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