What exactly is clipping and roll-off?

Discussion in 'Archived Threads 2001-2004' started by Vlad D, Jun 3, 2002.

  1. Vlad D

    Vlad D Screenwriter

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    I have read quite a number of post from members talking about their subs clipping and also about roll-off frequencies. But, I don't really understand what it means.
    Is it something that you can hear?
     
  2. Saurav

    Saurav Cinematographer

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    Clipping: When you drive your amp too hard, and it starts distorting. Yes, you'll hear it. If it continues for too long, it could cause permanent damage to your speakers. This is way it's usually better to have an amp that's more powerful than needed (i.e. puts out more watts than the speaker is rated to handle), than the other way round.

    Roll-off: Every speaker has a limited range of frequencies it can reproduce, a band of frequencies so to speak. Feed it a frequency outside of this band, and the output will be less than what it would be for a frequency within the band. For instance, take a small bookshelf speaker and feed it a 20 Hz tone, and you probably won't hear anything at all. Similarly, take a 15" subwoofer and feed it a 20 KHz tone, and again you'll probably hear nothing. If you plot a graph of output volume vs. frequency, you'll see a curve - it's flat in the middle (the 'band'), and starts to slope down as you go higher or lower than this band. Roll-off refers to this slope. The roll-off point (or cut-off point) is traditionally described as the frequency at which the output is 3dB less (-3dB, half the power, etc. are different ways to describe the same thing) than the maximum. So, to use a bookshelf speaker as an example again, if it says it has a cutoff frequency (or -3dB point) of 50 Hz, that means that the output at 50 Hz is 1/2 of what it is at say 5 KHz. Also, the slope of the rolloff measures how sharply the output falls off as you go down (or up) in frequency.

    I hope that makes sense. If any of that raises more questions, feel free to ask.
     
  3. Vlad D

    Vlad D Screenwriter

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    Thanks Saurav. It makes sense. Never thought taking Calculus and Physics in college would come in handy in everday life. [​IMG] [​IMG]
     
  4. Saurav

    Saurav Cinematographer

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