A speaker will 'blow' from either the mechanical failure of its components or from electrical thermal damage, both of which can be avoided through correct use. The most important factor above all is firstly to buy a system that's capable of performing in the way you wish it to. So if you're a working DJ for example, or you like to play loud music at gatherings, you simply cannot buy the cheapest speakers and expect them to work (not for long anyway) as they just aren't capable of those output requirements.
THERMAL FAILURE
The most common cause of 'blown' speakers comes from a mixture of low level or poor quality signal (music from a mobile phone or laptop for example) which is “too quiet” then wrongly boosted at the amplifier or a mixer through either dedicated gain control or the units E.Q, which will either be a standard set of Bass / Middle / Treble knobs or a slider based graphic equaliser. The biggest mistake people make is to use these controls full up to further increase volume on top of the systems actual volume control.
Budget systems suffer this mistake the worst, as the signal gain from an E.Q can be as much as +10dB (ten times the original signal) with all the controls fully up, which is a horrific amount of gain and the amplifier's input and output stages become overwhelmed. The amplifier simply cannot deal with such a huge signal properly and immediately starts to cut that signal down best it can, by cutting off the peaks. This is referred to as ‘clipping’ as the amplifier sends what it can to the speakers and leaves what it can't, which results in you hearing a heavy distortion to the music, with muffled mids and often cracking and popping noises. This same effect can also happen when the amplifier itself is underpowered, even with a quality input signal, as it will quickly reach and exceed its capabilities if you're trying to get sound levels from it that are higher than it was meant to produce.
The results are the same though, as electrically, these clipped signals have much larger voltage output than a normal clean signal, and cause the voice coils in the speaker drivers to quickly overheat, which destroys them.
COMPONENT FAILURE
Not as common, certainly not in budget systems or active speakers, is a blown speaker due to mechanical failure. This is where the actual driver has torn or ripped under stress, or the voice coil has fallen apart. There are usually two main causes for this to happen, the first being cheap or inferior components and occasionally this does happen from time to time with mass-produced equipment and is unavoidable. All new ElectroMarket products are warrantied against production defects so this would of course be replaced.
The other way this can happen is common in separate amplifier / passive speaker setups, where the amplifiers output rating far exceeds the speakers' capabilities. Whilst it's always good practice to have a higher power amplifier than the speakers require, this of course is reliant upon the user exercising caution and recognising the limits of their speaker units. If for example you have a 4000 watt RMS power amplifier and you're running it into a pair of 100w budget speakers and the amp's volume is up even halfway, you can expect a fairly dramatic demise of those poor little speakers. It doesn't require technical knowledge any more than it just needs some common sense applied.
INPUT SIGNAL & GAIN
Make sure your music feed is of suitable quality, recorded at a decent level, isn't distorted (YouTube for instance is heavily compressed and is a terrible audio source)
If using a mobile phone, portable mp3 player or laptop as a direct source, ensure the volume for the output jack/headphone socket is up at a good level, around 60% is a good place to start.
If feeding your source to the amplifier via a mixer, or using a media controller then you have much more control over the signal level, and the VU meters will give you a visual guide to get your output signal as close to its 0dB unity gain as possible, which is what the amp wants to see.
Gain for Dummies
In the most basic of basic explanations, think of the audio signal going into your amplifier as water coming down a hose, and you're aiming at a bucket….(stay with me!)
The tap is the volume knob, turning it up and down decreases or increases the flow of water or ‘power’, but it's controlled, and even full up it's still a smooth stream and will all go in the bucket. Now think of your thumb as the gain control, and start to put it over the end of the hose. In doing so you increase the resistance and raise the pressure, making the flow seem even more powerful than it was before, and to a point this is true, but what else happens? Too much thumb pressure and the flow triples in width and becomes erratic, and now a portion of that flow will be missing the bucket completely and is lost, and the water that does make it into the bucket is hitting it really hard and even splashing back out.
And that's the essence of too much gain. Your amp and speakers end up feeling like that poor battered bucket. Gain is a useful tool in signal control, but it can get you in trouble fast if you're not very careful, so think of your sound system as a chain, if you feed it distorted rubbish then that's exactly what you will get out of the other end only louder.
EQUIPMENT SUITABILITY
A 5000w RMS PA amp with £20 of pc speakers isn't going to do your party, and nor will a pair of £3000 passive cabs being fed from a 25w powered mixer amp. Your amplifier and speakers act as one unit and must be thought of as such. They should all be of similar quality and ratings and should be designed to cope with the specific tasks you have in mind for them. We all like to save money, and there are excellent budget systems available which are great when used correctly, though that doesn't mean they are automatically suitable for your needs.
There is often a misunderstanding at the term ‘correct use’ when it comes to audio equipment, with people confusing incorrect usage with misuse or abuse. It goes without saying that you shouldn't drop speakers, get them wet etc. When a seller or manufacturer states ‘correct use’ they are referring to the equipment being operated within its specifications and limitations.
Again, common sense prevails, and it should be fairly obvious that providing adequately loud music for a party, wedding or outdoor event will require a professional PA system not a set of home party speakers.
CONCLUSION
Firstly, to repeat the important opening statement;
The most important factor above all is firstly to buy a system that's capable of performing in the way you wish it to.
As with all consumer electronics, whatever the cost of the unit or its stated capabilities, it is completely in the hands of the end-user to ensure it is set up and operated correctly in order that it does not exceed those capabilities. So for instance, if you're planning a party for 500 people in a hall or large marquee, you aren't going to be able to do what you need to with a set of £89 10 inch party speakers, no matter how good you think the price is. If you decide to go ahead anyway, and not only ruin your party but also the speakers you shouldn't have bought, that is incorrect use resulting in damage. You may have taken perfect care of them, but they simply weren't up to the task presented to them and this is not a fault of the unit or the seller.
Here at ElectroMarket, we offer free advice on all of our available products and their suitability to your requirements. We are happy to specify the equipment which will suit you best and will endeavour to stick to any budget constraints you have in place, or advise you that your proposed budget is either too big or too small for the performance levels you want from the system.
