A couple of power questions

Discussion in 'Archived Threads 2001-2004' started by GabrielC, Apr 1, 2002.

  1. GabrielC

    GabrielC Stunt Coordinator

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    1) If you have speakers that take a max of 250W, does that mean that if you have a preout going to a 500W amp you could turn the amp to halfway and keep it there all the time? Or if you had a 250W amp you could turn it all the way up (assuming the signal doesn't start clipping I think)? For the sake of argument, let's just say the impedances are matching [​IMG]
    2) The Paradigm site gives two numbers for the Studio 60's (among others):
    Suitable Power Amplifier Range: 15-200W
    Maximum Input Power: 150W
    What does this mean for the kind of amp you can power it with? Does the amp have to be a maximum of 200W or 150W?
     
  2. ColinM

    ColinM Cinematographer

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    That's just a guide to keep you from frying the speakers.

    If the Para's are 90db efficient, at one meter you need 1 watt to get 90 db's (LOUD).

    Then it goes like this - -

    watts / DB

    1 - 90

    2 - 93

    4 - 96

    8 - 99

    16 - 102 (Minimum rec.)

    32 - 105

    64 - 108

    128 - 111

    256 - 114 (Max rec)

    So you see, the power needed increases dramatically, but in real world situations you may never need more than 15 - 30 watts.

    Anything less than that and the amp will clip and fry the speaker, eventually or immediately.
     
  3. GabrielC

    GabrielC Stunt Coordinator

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    Thanks Colin, a bit more...how many dB are lost each meter further from that 1 meter?

    Anybody have an answer for the first question?
     
  4. ColinM

    ColinM Cinematographer

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    -6db every time you double the distance.
     
  5. TimothyW

    TimothyW Extra

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  6. ColinM

    ColinM Cinematographer

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    .....head...hurts....too...much....math....
     
  7. Phil Iturralde

    Phil Iturralde Screenwriter

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    FYI: For a more precise & easy maximum SPL (loudness) @ your listening position (distance) vs. AMP power vs. speakers (number) vs. speaker sensitivity, use C. M. Collins 'excellent' SPL Calculator @ his website = How Loud Will it Go?
    Phil
     
  8. GabrielC

    GabrielC Stunt Coordinator

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    Cool calculator....thanks for the info guys! Knowing how things work is always interesting to me [​IMG]
    Umm....anybody have an idea on the first question though?
     
  9. GabrielC

    GabrielC Stunt Coordinator

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    Anybody want to try the first question?

    1) If you have speakers that take a max of 250W, does that mean that if you have a preout going to a 500W amp you could turn the amp to halfway and keep it there all the time? Or if you had a 250W amp you could turn it all the way up (assuming the signal doesn't start clipping I think)? For the sake of argument, let's just say the impedances are matching
     
  10. Harold_C

    Harold_C Stunt Coordinator

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  11. GabrielC

    GabrielC Stunt Coordinator

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    Harold:

    I think I sort of understand, thanks for the explanation... so if I follow that at all, does that mean that I *could* set the amp to a full 500W if the preamp signal was very low?

    You also said:

     
  12. Harold_C

    Harold_C Stunt Coordinator

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  13. GabrielC

    GabrielC Stunt Coordinator

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    After that first sentence, I realised my mistake. All this time I've been thinking that the gain control increased the amount of watts being put in linearly. Now that I look at it, it has -dB ratings on it.

    Right now I'm using a Samson S1000 with my Acoustic Research S50 mains which can handle 250W. With all of these questions, I've been wondering how to set my amp gain control knobs without blowing my speakers up. Since the amp puts out around 380W/channel into 8ohms, and the speakers are rated at 250W, I've always thought that if I turn the knobs all the way up, they would kill my speakers.

    How should I setup this system?
     
  14. Harold_C

    Harold_C Stunt Coordinator

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