Yet another receiver ouput thread ...

Discussion in 'Archived Threads 2001-2004' started by Daniel Lindgren, Jun 17, 2002.

  1. Daniel Lindgren

    Daniel Lindgren Stunt Coordinator

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    Hello.

    Yes, this is another thread about home theater receiver/amp output, but hopefully with a twist.

    Can someone that knows how things work please answer these questions, I'm aware that there are some slightly incorrect assumptions in my reasoning below, but bear with me.

    1. If the total power consumption of a receiver/amp is lower than the total given output effect, the given output invariably is false? Example: Receiver X has total power consumption of 290W. Manufacturer claims that it has 6x75 watts output. This means that the claimed total output of 450W (6x75=450) can NEVER be accurate with all channels driven, since it only consumes 290W. True?

    2. The figures given for output are (almost) always related to an 8 ohm load. If I would use 4 ohm speakers with receiver X, which automatically increases the load on the amplifier, would the 6x75W rating be closer to 6x150W (not really, but for the sake of argument), ie a total output of 900W, all channels driven? If so, how on earth could this be done with a total power consumption of 290W?

    3. If I were to purchase this receiver X and (by using pre-outs) let my old stereo receiver drive the front channels, would this mean that the total power would be "redistributed" to the remaining four channels on receiver X? That is, the previous 290W/6 = 48W/channel would become 290W/4 = 73W/channel?

    4. I live in europe. This debate doesn't even exist over here. Is that in any way related to the fact that the US has 110V standard and we (at least in Sweden) have 230V? Does that affect the receivers ability to perform?

    If someone could answer these questions I would really appreciate it.
     
  2. Mike Veroukis

    Mike Veroukis Second Unit

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    Some good questions and I too would like to see some answers. However, I'll take a guess at number 3:
    All the receivers I've owned or used have a setup menu with which you can configure which channels are large, small or not connected (NONE). I would hope that no power would be wasted on any speakers that are set to NONE. Of course this is easily tested by hooking up your receiver to all the speakers and then go to the setup menu and toggle between NONE and large/small. The results should be painfully obvious. [​IMG]
    Now, one thing to remember with these "under powered" receivers is that it's not the amp itself that's causing us problems but the power supply inside the receiver. The better the supply the more power available to each amp and the more the amp can safely amplify. So if there are less speakers to drive more power will be available to each of the amps and there for you will have a noticeable increase in watts per remaining channels. For example, some of the tests that S&V do include 6 channels, 5 channels and 2 channels driven and you will always see that the 2 channels have power ratings close if not more to the rated power. All-channel driven usually is about 3/4 to 1/2 of the rated power. From this we can conclude that the "extra" power in the 2 channels driven tests comes from the unused amp's allotted power. Make sense?
    - Mike
     
  3. Saurav

    Saurav Cinematographer

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  4. chella

    chella Stunt Coordinator

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    As a side point, when you turn off the speakers from the menu, I would think it only affects the bass management and other processing (for example setting no speaker for CC would redirect the CC signal to L and R). I think this will produce undesirable effect on the signal in the pre-out too. Just not connecting speakers to the output terminal will be way to go when connecting external amplifier.
     
  5. Mike Veroukis

    Mike Veroukis Second Unit

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  6. Daniel Lindgren

    Daniel Lindgren Stunt Coordinator

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    Saurav: Thanks for your reply, excellent information!

    I've seen that Rotels amps always have enormous power consumption, Rotel are known for their ability to deliver on their claimed output effect.

    The Yamaha RX-V 630 (HTR5560 in US?), which by the way is "receiver X" in my previous post, has 5x75W with a 290W power consumption.

    The new Rotel RSX1055 also has 5x75W output - but with a power consumption of 450W.

    Just do the math and everyone sees that Yamahas figures are a bit optimistic, with all channels driven. How important is that? I'll leave that up to everyone to decide for themselves.
     
  7. Earl Simpson

    Earl Simpson Supporting Actor

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    That was the first thing I checked before getting my 3802. I looked at all the backs of the rcvrs and compared power consumption and the weight of the rcvr. None of the low end stuff comes even close to half its power rating(except the 520). The high end stuff comes closer at a very high price. That's why I am becoming a separates convert. There has to be a tremendous profit in selling 800 watt rcvrs that only do 400 watts on a good day.
     
  8. Tony Lai

    Tony Lai Stunt Coordinator

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    What you don't say is that Rotel charges a lot more for their stuff than Yamaha.

    This is truly a case of getting what you deserve for your money.

    T.
     
  9. Saurav

    Saurav Cinematographer

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  10. Tony Lai

    Tony Lai Stunt Coordinator

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    My amp also fades out if you turn it off - also spookily, the power LED stays on for 10 secs after it is switched off from the wall!

    I thought it was possessed by the devil when I first got it!

    The amp is the Parasound 1206 which is typical for what is largely a two channel amp (for my uses) trapped in the shell of a six channel amp.

    T.
     

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