Choosing a suitable P.A System

Choosing a suitable P.A system, which consists either of an amplifier and loudspeakers, or a pair of active speakers (Speakers with built in amplifiers) is often as personal as buying a car. What may sound good to one DJ, may sound awful to another. For this reason we recommend listening to any system which you are interested in, BEFORE committing to buy, and since speakers rarely sound the same in a large town hall with 200 people, as they did in the Disco Equipment Retailers showroom, we would also advise that your hire / hear a similar system in the real world environment!.

The most important thing, is to budget as much as possible towards your sound system, and buy the best that you can afford, even if it means waiting a while to buy your dream lighting rig. Expensive lighting effects can often wait for a few months, but skimping on poor audio equipment and cutting corners may prove more costly to your business and reputation in the long run.

Speaker technology and Amplifier design has come a long way, and it is now possible to buy good quality speakers and amplifiers on a realistic budget, and without spending a fortune. Reasonable Quality, perfectly usable speakers rated at around 300 Watts RMS can now be found for around £150 - £300 a pair and will handle most venues and functions likely to be encountered by a Mobile Disco with ease.

Don't be Misled!

When comparing amplifier and speakers, ensure that you are not being misled with specifications. When looking at Wattage figures you should consider only the RMS continuous figures and not those which state the PMPO or Maximum ratings, since these have no place in professional audio!.

To SPL or not to SPL

Many DJ's make the mistake of buying purely on wattage figures alone, however buying a speaker with a huge wattage rating won't automatically make it a good speaker, and neither will it mean that it will sound good. Contrary to popular belief, a 600 Watt RMS speaker will not sound twice as loud as a 300 Watt RMS Speaker, of course it will handle more power, and work with a bigger capacity amplifier, but the increase in loudness may only be slight,  how  much louder it sounds depends on another factor, and that is called SPL.

SPL is the measure of how efficient a loudspeaker is at turning power (Watts) into actual sound (Decibels). The higher the SPL figure the more efficient a speaker is and the louder it will sound. For example it is possible to buy a 250W RMS Speaker with an SPL of 125db and it will sound better and louder than a 350W RMS Speaker with an SPL rating of 94db!, so wattage isn't everything to consider. To get a decent sound you need to be looking at speakers with an SPL of over 100db - the higher the figure the louder it will sound, even driven at modest power levels.

How Much Wattage do I need

As we have stated above, power isn't everything, but how much power do you need to drive your system?. This really depends on the type of functions and venues which you intend to cover, and it is also worthwhile remembering that it is a good idea to have more power than you actually need. As A rule of thumb, a small pub, village hall or Kids party will usually be manageable from a 600W system (2x 300W RMS). A function such as a Wedding with upto 150 guests, then 1000W (2x 500W RMS) is enough. However for large halls with 200+ guests then you need to be looking at a system capable of at least 1600W (2x 800W RMS) and 2x 1000W RMS for 300 people+. Of course if you can find a good quality speaker with high SPL levels then some of these figures could be reduced, whilst retaining clarity.

Matching Amplifiers and Speakers

Always choose a system which will work well together!, and don't be tempted to try and run your 100W speakers from a 1000W at high power levels. It is a good idea to have an amplifier which is slightly higher rated than your speakers to allow for headroom. So if you have speakers rated at 500W RMS @ 8 Ohms then buy an amplifier which can deliver 600W RMS @ 8 Ohms. Remember that an amplifier will increase distortion levels the harder it is driven, so the sound from an amplifier being driven at 40% of it's capacity will sound clearer and run cooler than an amplifier being driven at 95% of it's design capacity!. So even if you only need 600W of output power, it is wise to choose a 1000W system running at 60% capacity than a 650W System running at almost full capacity!.

The amount of power which an amplifier provides does depend on the combined impedance of the speaker load which is connected to it. So for example a Amplifier rated at 500W RMS @ 4 Ohms may only provide 2x 300W RMS @ 8 Ohms. More about speaker impedances can be found by clicking the link below.

http://www.djsite.info/idx/7/001/article/Understanding-Speaker-Impedances.html

Active or Passive

Again, this depends entirely on personal choice and preference. Active speakers contain amplifiers in each speaker which means that you don't have to connect a seperate amplifier. Simply provide each speaker with a mains input and a signal from your mixer output, and away you go!. Active speakers tend to be heavier than conventional speakers because of the amplifier, heatsink and transformer and on occasion this may add as much as 10kg when compared to a passive speaker of the same size and rating. Another drawback of active speakers is that if the internal amplifier should fail, it is impossible to physically connect the speaker section to another amplifier as an emergency measure, meaning that if failuire does occur during a gig, then you have lost the speaker output, and it will be very difficult to provide a workaround in the short term.

There are advantages of using Actives, mainly that you do not need to purchase a seperate amplifier, and your setting up / packing away time may be decreased too, because there is less to set up and interconnect.

Abs or  Wood cabinets?

Another rumour circulating is that ABS cabinets do not sound as good as conventional wood cabs. Having used both types, I personally don't agree with this. There are good speakers and bad speakers, and most of the time it has nothing to do with whether they are made of wood or ABS Plastic! but more about how well they are designed, the SPL figures and the quality of the components used!. ABS, by default tend to be a little lighter than wood cabs, and so this is an area which should be considered if weight is a factor.

Speakons or Jacks

Even the matter of how you connect your amplifier to your loudspeakers can make the difference of how reliable they are, and also the difference to whether they work at the gig, and keep working!. Cheaper speakers do tend to use Jack Plug type connectors, and these can be very unreliable especially at higher power levels. Try and buy a speaker which uses the professional 'Speakon' style connector. Older speakers which use XLR canon type connectors are also ok, and fairly reliable too, although XLR's are rarely used in loudpspeaker manufacture today.

What to Buy?

This depends entirely on your budget, and the application and intended use, Again it is important to only take into account the wattage and SPL figures on any loudspeaker which you are considering. Buy the speaker with the highest SPL rating that you can afford!. There are speakers which fall into the budget range that have got quite a good reputation.

The <£200 speakers include Class D Speakers and the Soundlab range of 300W RMS Cabs which can be found on Ebay at extremely competitive prices.

Other recommended speakers include NJD, OHM RWS Series, Peavey Hi-Sys and HK Lucas systems.

Active speakers which are highly recommended for DJ's include the Mackie SRM450 series, FBT MAXX Range and the Alto Range of powered speakers.

Recommended Amplifiers for driving passive speakers include Behringer Ep1500 and Behringer EP2500, QSC RMX Range, C-Mark MR Range (also badged Audiohead), and the Numark Dimension series.

These are just some of the suggestions, which cover all budgets from £200 a pair to £1800 a pair!. But I would once again refer you to my first piece of advice, and that is to hear any speaker first before parting with your money!,