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Question

RMS Power output

Jul 18, 2016 4:26AM PDT

I have been looking at a new Surround Sound system and I don't quite understand how to figure out the power output. On the power output it sais "Maximum power output per channel - RMS into 8 ohms" and next to that (i assume in Watts) it sais "85 x 5" which I assume the x5 is for the 5 speakers. I have looked about and vaguely know that the lower the RMS is the better,but still don't quite understand it. My old surround sound said it was 1000W but I dont know if this one is more powerful or less powerful (I cant find the RMS for it anywhere). Can anyone help?

Discussion is locked

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Answer
Frankly, spec tampering.
Jul 18, 2016 7:57AM PDT

RMS or Root Mean Square is on a sinusoidal signal is easy. You take the peak Voltage and multiple it by .707. This is well done on the web and such so to say the lower RMS is good is garbage.

There must be a typo in this post.

1000 is greater than 85 x 5 even if we use .707 in either side of the calculation.

But that 1000 Watts was likely spread over the set of speakers and did you always have it running at full power?

Note: edited for typo.

Post was last edited on July 18, 2016 8:19 AM PDT

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Previous system
Jul 18, 2016 8:11AM PDT

Cheers for the response. The old system was labelled as 1000 Watts (Though I know that's most likely not what it put out). I never put the speakers more than 3/4 after a week of breaking them in as to not ruin the speakers but it did anyway. Does the RMS actually tell you anything about the power then? I just basically need some understanding on how to gauge how powerful a speaker system is with using the Ohms and such that is provided in the spec. Or is the output power just 85W per speaker?

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RMS in AC is well done.
Jul 18, 2016 8:21AM PDT

So that's done. 100 VAC is supplied as peak or RMS. This area is so well done it's duplicating prior content so I stop here.

As to how to gauge the power, you have choices to make. Accept the specs or not.

As to the last question, you wrote 85W x 5 so I accept that as 85W per speaker. If the seller and maker will not answer questions, why buy this?

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Example product
Jul 18, 2016 8:32AM PDT

Thanks for the help. It was because I would like to know how to figure it out so that I can find the specific product I am interested in before inquiring with the supplier. The details for the product above was just one of the ones i have been looking at as an example.

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85 watts RMS per channel should be plenty.
Jul 18, 2016 8:41AM PDT

If you turn that up to the max. if your speakers can handle it, you'd drive your next door neighbor insane.

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They never complain
Jul 18, 2016 8:44AM PDT

I turn my 1000W up most of the way and they don't complain Grin

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You really can't make comparision when...
Jul 18, 2016 8:31AM PDT

they don't specific what they are. The only thing here you can be sure of is the power rating in RMS. They use BIG number for marketing purpose is what I think.

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Marketing purposes
Jul 18, 2016 8:40AM PDT

I saw on another forum that they use these large numbers but they are misleading which is why I was trying to find out how to figure out the actual one. I still don't understand how to work it out to be honest, but I just think I don't have enough knowledge in this field to.

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If it's not in the specification, then...
Jul 18, 2016 8:57AM PDT

there's no way you can figure out. There's peak, peak to peak, music power, and of course RMS., there might be more I don't know about. Peak to peak would give you the biggest number.

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Marketing is correct
Jul 20, 2016 3:11AM PDT

You'd need to go back to the days when manufacturers of cheap amps would tout "peak" power so they could sell against those who offered higher end units. Peak power is just what is available during short bursts in some music passages and those bursts may be less than 1 second. RMS is better stated as "continuous" power. I believe the argument over peak versus RMS developed more during the transition from tube type amps to transistor amps. The Japanese adopted and developed the higher powered transistors for audio use but didn't seem to know much about power supplies. It's the power supply that's the key. Tube amps used large transformers in their power supplies and output stages. Cheap transistor amps could use less expensive transformers but use large electrolytic capacitors for the reserve power needed to boost the peak power specs. The use of RMS was more of a "truth in advertising" move...at least that's what I recall. A lot has happened in the area of power supplies since then. Otherwise, you'd need a two strong people to deliver a 1000 watt amplifier. In short, RMS is just fairly standard and no one bothers advertising peak power anymore.