Buying a PA system? Speakers? Amps? Read this!

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Where do I begin!

I have been a professional sound engineer for several years and also have qualifications in sound engineering, I also run a sound & lighting hire & sales company!

The first rule is always; do not underestimate your requirements, always over estimate where possible, a few extra quid in the beginning can save you a lot of time and hassle in the long run!

MICROPHONES: Don't just buy a product because of the name, if I asked you which was a better live mic out of the Beyerdynamic TG-X48, the Shure SM58 or the Sennheiser E845 could you give me a genuine honest opinion on which mic is best or would you just plump with the SM58 because you have heard of it or you have heard someone else mention it is a good mic?  It is indeed a good mic but there are a lot better mics out there that suit different types of vocals, particularly if you are female, for example the Sennheiser e845 is much smoother, more detailed and takes longer to feedback! It also costs less than an SM58, now that is unusual! My above opinion is based on using a whole host of Beyer, Shure and Sennheiser mics in a wide range of applications.  If you can afford it then go for the Sennheiser E865 its around £140.00 but nothing comes close at this price in terms or warmth, detail and clarity, I use this mic with pro singers and they all love it!  If you've got the budget then get a Shure Beta 87 - you won't regret it.

AMPLIFIERS: Amplifiers, particularly at the cheaper end of the market often have wild power output claims such as 'peak output' or 'max output' what you really want to look for is the RMS rating which gives a true indication of an amps ability to deliver power.  When possible do not run your amps at 2 ohms as this is not a reliable way to run an amp, efficiency decreases when you run it this low, the exception to this is digital amplifiers which do not suffer from the same problems as traditional amplifiers such as heat and power compression.  Look for an amp that has a 'low-pass' or 'sub-sonic' filter built in, what this does is cut-off frequencies below a certain point (usually 40Hz or below), this stops your amps wasting power on frequencies that some people can't hear and in most cases the speakers can't actually deliver.  It can also 'tighten' up your sound and help reduce feedback and hum.  There is an exception to this which is when using an amp for bass bins and you require serious low bass, that said, even if you are running bass bins, unless you want very low bass extension then a 'high-pass' or 'sub-sonic' filter is a good idea for the same reasons as above, it can also help to extend the life of your equipment.  The same can sometimes be true for high frequencies but this is a less common feature on power amps and because high frequencies require less energy to produce it is not usually an issue.  NOTE: You are more likely to blow your speakers with a low powered amp than a high powered amp, a low power amp will have to work a lot harder to produce the same volume as a high power amp and in doing so will be producing a 'harsher' signal which can sometimes verge on clipping (distortion) which will kill even the most powerful speaker in the world over time. For example; you can quite safely use a 200 watt amp for a 100 watt speaker as the 200 watt amp will not be working hard, the sound it produces will be a lot cleaner.  This is just an example and is the same if using a 1000 watt amp and a 500 watt speaker etc. etc.  Bigger amps will not get you more volume, the only way to increase volume is more speakers.

SPEAKERS: This is one area where you probably have the widest choice, key things to look for are the RMS power handling which gives a true representation of a speakers ability to handle the power you throw at it.  Compression drivers / horns, these are much better at delivering high frequencies than 'piezo drivers' found in cheaper speakers and monitors.  SPL or Sensitivity, this is very important if you are after volume as well as clarity, a rating of 96 dB @ 1 watt or above is good, some high end speakers are capable of well over 100 dB @ 1 watt. Thats loud!  The more sensitive a speaker is, then the less power (watts) will be required to generate the volume you are after.  As I have said a above, a 500 watt speaker can safely be driven by a 1000 watt power amp (within reason!).   All my hire power amps are rated at delivering twice the wattage for the speakers at any given impedance, i.e if I have a 1000 watt (RMS) bass bin rated at 4 ohms then I power it with an amp capable of delivering 2000 watts (RMS) at 4 ohms.  I have never run into to problems with this ratio and have never had to replace a blown driver, the sound always remains clean and the amps barely break a sweat!

CABLES: Cables! Where would we be without cables! Cables are the life blood of your system and should not be overlooked, they should be at least 10 - 15% of your budget consideration.  I have found vann damme cables to be faultless but they are not cheap, look for good quality metal connectors (neutrik) rather than plastic, where possible always use shielded / balanced cables as this will reduce interference, crackling, hum etc.  Most common problems with PA systems can be traced back to poor cables.  Speaker cables: Use as thick as possible, names are not so much of an issue here but make sure the connectors are good quality, Neutrik (brand name) if possible, also make sure they are as thick as possible, at least 1.5mm per core, ideally 2.5mm or above, you would be surprised at how much of your amplifier power can be lost in cables because of resistance.  For example when using a 10 metre 1.5mm cable at 4 ohms only 89% of you amp power is delivered to your speaker!  If you were to use a 4.00mm cable then 95% of your amp power is delivered to your speaker, quite a difference! Whats the point in spending the extra pounds on a more powerful amp and then loosing your extra power in cheap, thin cables?

We (dymondaudio) hope that this guide has been in some small way useful, it only really scratches the surface of these topics!  If you have found this guide useful or even if you havn't and feel you have some more questions or would like some free advice then please do not hesitate to contact us.  We are not aloud to print our contact details here but a quick search on the net will find us or use the 'email seller' buttons in one of our listings.

We would be grateful if rate this guide as to whether it was helpful or not, many thanks.

Best regards & happy shopping!


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