Increased Power Output per Channel when using an additional stereo amp? - AVS Forum
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post #1 of 7 Old 03-27-2013, 03:09 PM - Thread Starter
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Hi,

A general question about AV Receivers. When using a stereo amp connected to the preouts of an AVR and then connecting the main speakers this way, will this actually increase the power output of the remaining channels (surround, center).

Let's say an AVR can deliver 5x20W, would this method then lead to an output of 3x33W for surround and Center, since there's no power going through its internal amps for the mains?
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post #2 of 7 Old 03-27-2013, 03:26 PM
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Nope.
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post #3 of 7 Old 03-27-2013, 05:42 PM
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Usually in benchtesting, power output in 2CH is higher than 5CH or 7CH. Testing is not usually done for 3CH specifically but it's likely that 3CH output is higher than 5CH, but whether the small difference when translated to audible increased loudness is debatable/doubtful.

Audiosceptics accept audio trials using 25 people. A recent Oxford study with over 353,000 patient records from 639 separate clinical trials shows for every 1,000 people taking diclofenac or ibuprofen there would be 3 additional heart attacks, 4 more cases of heart failure and 1 death every year.

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post #4 of 7 Old 03-27-2013, 06:02 PM
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Power output depends on how much voltage the output transistors can swing and whether the lower supply can "service" the power demands. Taking load off theoretically increases available power in the remaining channels with typical receivers because their power supplies can't support full output on all channels at once. Unless you enjoy listinening to test tones all night you are not likely to ever drive all channels equally. For example if these surrounds are 3dB (one notch, to most folks) quieter they need only half the power of the front three. Bottom line is if you don't have audible xistortion with the receiver alone you won't perceive a difference.
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post #5 of 7 Old 03-28-2013, 02:34 PM - Thread Starter
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Well, I' a testtone fanatic and just love to listen to that sounds all day long..... wink.gif but well, I'm asking, because I currently have a Marantz NR1603 at home for testing, but still waiting for my new speakers to arrive (KEF R500, 200c, 100). With my old magnats this small receiver can deliver enogh for my listening levels, so far no distortions. In some test of the receiver they said that output in 5 CH is 19W per channle, while tech specs of the KEF says that power demand is 25W up. And since I liked the idea of spacewise being able with such a smaller receiver to add a stereo amp I was wondering If I might or might not run into any trouble. Since the center and surrounds would run in "small" mode making only the mains and sub being responsible for the more demanding low frequency output, I would them assume that the remaining power for the three other channels should still be enough.

Thanks for your insightful inputs!
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post #6 of 7 Old 03-28-2013, 09:21 PM
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That setup should be okay so long as you don't watch action movies at high volumes very often. It seems that the power supply is the limiting factor as they quote 50w/ch in stereo.

The centre you have on order is 90dB efficient which helps a bit (the mains are given as 88dB, which doesn't seem much different but in reality is).
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post #7 of 7 Old 04-22-2013, 04:08 PM - Thread Starter
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Actually, the R200c is quoted 87dB which is 1 dB less efficient than the R500s. Btw... they have arrived. As surrounds I'm still using my old magnat vector 11 which are 89dB, wasn't sure yet wheter to get the R100 or the dipoles... but it works still fine for the moment, I also had to turn the surrounds about 5-6 dB more quiet than the mains, so those should then consume less power as the others (like JAHz said). Also, I set the center and fronts to small with crossovers of 80 and 60 Hz to take a bit of load of the amps. In 2 channel I can still turn off the sub and enjoy the towers at full range if I want.

So far, I could not hear any distortion on the KEFs either. It's probably gonna be fine, since we mostly watch movies at night where we can't go too loud anyway due to neighbours and our sleeping boy smile.gif So probably for the current situation it's ok.

Nevertheless I'm still thinking of adding a poweramp as some sort of life insurance for the fronts smile.gif And maybe a notch up in quality...
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