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Amplifier power usage and output

Discussion in 'AV Receivers & Amplifiers' started by alphabet, Aug 4, 2005.

  1. alphabet

    alphabet
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    I am curious to know if there is a direct relationship between the maximum power usage of an amplifier and the output current to speakers.

    I have checked the specifications of the amplifiers(receivers) that I felt always seemed to have some power in reserve and in every instance these were equipment that have higher power usage than the norm.

    Examples of these are:

    Rotel RMB-1067(990W)
    HK AVR335(890W)
    Cambridge Audio 540R(850W)

    Anybody able to provide some input on this?
     
  2. Reiner

    Reiner
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    I doubt there is a direct relationship as most amps also require power for the other circuits like pre-amplifier, DPS and decoders, video up-conversion (where applicable), OSD etc. - not much though (50-100 Watt I guess) and it depends on the design of the internal circuits (i.e. the components used) how much current the amplification stage(s) draw.
    Anyhow, since power is the product of current and voltage the current can in theory be anything but the voltage will be lower if the current is greater (and vice versa).
    Naturally the output power can never exceed the input power, in fact there are some losses somewhere so that the output is typically a tad lower than the input power.

    I suspect however that the main issue is that cheaper, or lower-quality amps if you like cannot provide the power to all channels simultaeneously. But a good amp, i.e. one with a capable power supply, can do so - which of course results in a higher power consumption / rating.
     
  3. chedmaster

    chedmaster
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    the azur has a toroidial power supply (spelt right?), and although i dont know much about PSU's i hear this is higher quality and more capable (usually found in more expensive amps :thumbsup: )
     
  4. Mofar

    Mofar
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    In the range of amplifiers you mention, there is a relation. These are class AB amps and the efficiency of these amps is about 65%. So if such an amp takes for example 1000 W out of the poweroutlet, it can deliver about 650 W continious, mostly at a 8 Ohms load. The other 350 W is lost in heat. That's why an amp gets warm/hot. A class D amp won't be hot.
     

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