Power ratings:
This is a minefield, and I hate this one, as what I am going to explain here in basic terms, makes no sense and has no bearing on sound quality or performance. A speaker needs to physically move air, and the more air it moves, the more power it needs, that is generally understood. BUT that does not mean that a higher power speaker is louder nor more efficient. Power is measured in Watts, and this is where the manufactures have decided to confuse us further.
There is an RMS power rating, which is generally only ever referred to by audiophiles using the more expensive stuff, but to be fair, this is the true figure that should be used, but it isn`t. However, RMS figures are often low in value, not understood very well, and as far as the manufacturers are concerned, they don`t appear sensational enough to sell speakers. So with a bit of a recalculation, the manufacturers then turned our RMS figure into a MAX POWER figure. Now the clue is in the word MAX. It is not a figure that the speakers can endure for any length of time, it is the level at which they will expire. In other words, if you put 200W into a 200W speaker, it will go pop. The MAX POWER figure is the one you will often see on the side of a speaker box in the shops. However, in order to appeal to the mainstream market and sell more speakers, the manufacturers of car audio decided to then double this figure and call it “Ultimate MAX POWER”, (or often referred to as “Max Bullshit Power” by the retailers), and if you see a figure of 1000Watts against a speaker the size of a fag packet, then you must realise that this is a poor quality product and will not perform as well as the packet artwork states.
A WARNING:
If you are actually attracted to and have reason to believe this 1000W figure is true, then please switch off your computer now and go and join your Chav mates in the local Mackie D`s car park – as this forum is obviously not for you.
It is important therefore, to make sure that you know which band of figures you are referring to, and to stick with them when deciding on power ratings. Most of you here will be using the MAX POWER ones. So what power figure should you be looking for? Well, as a general rule of thumb, the power output of a speaker should be at least double that of the head unit driving it, but not too much more. If you have a head unit, of say 50W per channel, then 100 ~ 150W speakers would be ideal. If your speakers are rated too low, then the stereo may exceed the power rating and burn them out, and if you go too high, then your stereo may not be able to power them at all.
If we consider a 50W head unit and 500W speakers, then running flat out, the head unit will only provide 10% of what the speakers can take. By now, you should be able to understand why your OEM 15W head unit is never going to power your 100W speakers, and why your aftermarket 50W head unit is going to instantly blow your 25W OEM speakers.
Part III to follow