I have came to tell the truth!!!!!!!!!

Yeah thats about right

RMS is usually classed as continuous power rating, this your speakers can take that amount of power ALL the time for continuous periods, assume its a loud signal like a sine wave - a speaker with a 200W rating could take 200W sine wave all day long.

Music - particularly live music has a high dynamic range (around 10dB), even recorded music has a range of between 3-6dB on average

3dB is double your power, so you can drive your 200W cabs with a 400W amp providing the music has 3dB of dynamic range with no worries.

With live music you can actually in theory have an even more powerful amp if you dont use compressors, however the drivers still have a 400W peak rating meaning you dont want to push it for damage reasons.

However drivers are relatively inefficient and the wonderful thing called power compression comes into play, above 500W (even if a driver is rated at 700W-1000W) no matter what people will say power compression comes into play, from a heat perspective, and the more power you put into the speaker will cause diminishing gains, with a higher risk for damage

so for example with a driver rating of 200W

100W amp - Output Low - Risk of Damage (Low but high if clipped)
200W amp - Output Medium - Risk of Damage Low (but very high if clipped)
400W amp - Output Optimum - Risk of Damage Low-Medium
600W amp - Output High - Risk of Damage Medium
800W amp - Output Overdriven - Risk of Damage High

This all assumes that your music has an "average" dynamic range.

I used to think an amp that matches the wattage of the speakers was the right approach and if you run a hire system you probably want to be running an amp thats even less!

But providing you arent running the amp with the clip light on all the time you will be fine - but remember the power compression with high powered drivers.

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Yeah just to think about clipping a bit more, if anyone uses a DAW get a track by some folk artist, then get a track by slipknot or some other loud thrash metal act

Look at the comparison of the waveforms one will look like this from a distance

/\/\/\/\/\/\/\

the other will look more this

IIIIIIIIIIIIIII

The reason being the peaks of the waveforms have been compressed.

The first thing to understand is there is a difference between Clipping and Compression or Limiting.

By compressing or limiting a signal you are essentially squashing the dynamics of the signal in order to achieve balance between difference parts and sounds and also to make your record sound "louder" by limiting the dynamic range of the material. In the studio you can go through hundreds of different compressors/limiters until you find one that gives you a tone that you like since they all tend to use different algorithms, and believe me they are very different! They also work with a latency delay meaning the processing has a look ahead value so that you dont overdrive the thing.

Clipping is literally over driving the circuitry of the system without any limiting or other processing going on, which is why its essential to have a good clip limiter on an amp or speaker processor, because the quality of the limiter determines the quality of the sound when the device clips, which is why there is so much emphasis on NOT clipping a cheap amp, because the likelihood is that the limiter will make a less than pleasant noise if it has to work. Find a cheap limiting plugin for your DAW which does hard limiting or direct chopping of the peaks i.e. with no smoothing algorithm to see what this can sound like.

In practice its ok for the clip light to come on occasionally to protect from the odd stray peak - thats what its there for after all, but running an amp regularly into clip or even as a lot of people do, HEAVILY into clip could prove fatal for both your speakers and amp.

The clip limiter is often named Clip/Protect - the latter is what it does but trying to make a single police officer guard an entire prison block is what you are asking an amp to do if you are regularly running it into clip.

Anyway the point in all this is that when a clipped signal is fed into a speaker the dynamic range has been limited, meaning there is actually more power in the signal than their was before so its a lot easier to overdrive the speaker with this clipped signal! Music with 3dB dynamic range has double the average power of music with a 6dB dynamic range.

Stu

Edited by Disco Stu - 18 March 2007 at 7:01pm