Speaker power outputs

[SMOKEU]

I've got a cheap Samsung 5.1 home theatre amp rated at 1000W RMS. Just by looking at the amp, I can tell it's nowhere near 1kW RMS. With a 12" 350W RMS car sub connected to it and a pair of 6X9s cranked up to the point just before the amp cuts out, it draws around 100W from the wall. Should a real 1kW RMS amp draw around 1kW from the wall under full load, or is that not how the RMS system works?

I'm looking at buying a set of this, so will that be more powerful than what I have now? The whole system is rated at 200W RMS with the sub being 130W RMS.

[tnarg]

Your problem is your trying to run car speakers which are 4 ohm with a system designed to run 8 ohm speakers. It will juice the power supply when you try and crank it up. So try getting some proper speakers or buy the Logitech's. I have read that they are supposed to be pretty good.

[paturoa]

Like all good questions - depends. Theoretically the answer could be yes in a perfect world, but in practice no.

If you fed it with sine waves of the optimum frequency in on every channel, so that they are out of phase then it could come near the theoretical rating.

Using music, then not even close.

But here is where it gets interesting, almost all consumer electronics manufacturers tell porkies by using peak power figures so they can write a bigger number on the box which will encourage you to buy their product over another manufacturer who tells smaller porkies. Box 1 says it is 850, but look at this one, it is 1000!

So what they do for the power ratings are various things, like adding up all of the peak power ratings of all of the amps (for all of the chnnels). So check that there isn't another acronym like pmpo lurking in the spectfications.

I'd suspect that it may well be 1000w pmpo, and, "oops" somehow our chinese manufacturer printed rms on the box.

[Akzle]

1kw RMS is the output, that's speaker side of the AMP. RMS = root mean square, it's a fairly vague term IRL.

the impedance of speakers shouldn't matter TOO much, car speakers are 8R so they don't vibrate themselves to death and can handle the shitty DC supply in a car (cars are horrible platforms for sound)

output being output has little to do with input. 100W draw from a 240VAC socket is half an amp. if it's drawing 100W @ 240V and it's rated at 1000W on the other side, that means your speaker outputs are about 10V which seems high.

anyway. NO. is the answer to whatever question you had. and i second buying logitechs or TDKs.

[bogan]

I'm with Paturoa on this one, they like to do funny things with their ratings. The rating are like a piece of string, sometimes knotted, sometimes stretched, a decibel meter is surely a better test anyway? Also, what are you doing that needs 1000W from a home audio system

the impedance of speakers shouldn't matter TOO much, car speakers are 8R so they don't vibrate themselves to death and can handle the shitty DC supply in a car (cars are horrible platforms for sound)

output being output has little to do with input. 100W draw from a 240VAC socket is half an amp. if it's drawing 100W @ 240V and it's rated at 1000W on the other side, that means your speaker outputs are about 10V which seems high.

What the fuck are you babbling on about?

[ducatilover]

What the fuck are you babbling on about?

Nobody knows! That's why we keep him here


SMOKEU, get moar doof ya poof. Get rid of the car speakers and buy real ones, not shitty beige cheap junk

[GTRMAN]

I've got a cheap Samsung 5.1 home theatre amp rated at 1000W RMS. Just by looking at the amp, I can tell it's nowhere near 1kW RMS. With a 12" 350W RMS car sub connected to it and a pair of 6X9s cranked up to the point just before the amp cuts out, it draws around 100W from the wall. Should a real 1kW RMS amp draw around 1kW from the wall under full load, or is that not how the RMS system works?

I'm looking at buying a set of this, so will that be more powerful than what I have now? The whole system is rated at 200W RMS with the sub being 130W RMS.

Oh where to start, oh yeah, Akzle shut up, you're an idiot.

Let's start with what RMS really is, it is not a vague term, it is around .707 of the peak power of the sinusoidal waveform when measured from the 0v crossing. PMPO can mean almost anything but the most common lie is to measure the distance between the positive peak and negative peak and call that the power output (think the distance between the inner most point of a drivers movement and the outermost point)

Now if you have an impedance mismatch you will run into trouble. to work correctly audio amplifiers need to 'see' the same impedance at the speaker as it outputs from the power amp. an impedance mismatch will cause waveform reflection which will eventually kill the amp.

[paturoa]

Wikipedia actually has some useful stuff on this topic too -> http://en.wikipedia.org/wiki/Audio_power

[ellipsis]

...my son just built some big bass bins...4x1000 watt speakers, playing it through a mixing desk and a big amp he scored...last night outside on the grass he played me some of my old vinyl that I managed to digitalise...circa '71... he had my 15inch Wharfedales doing the mid and top end stuff...i dont know what made me feel older...the music or the fact that I couldn't do the big sound thing to my head anymore...

[pete376403]

You need one of the Mythbusters Mercedes diesel powered super subwoofers 161dB @ 16Hz

[Flip]

Great idea lets redefine physics the get the number you want.

When I drop the clutch on my Harley, as the crank shaft decelerates it must produce about 300 ftlb's of torque, therefore my shitty old 2 valve 88 CI is making 200 HP (for about 1/3000 th of a second).

[bogan]

Wikipedia actually has some useful stuff on this topic too -> http://en.wikipedia.org/wiki/Audio_power

Thats quite interesting, the bit about THD especially so. The Logitech speakers I'm interested in give their RMS power at 10%THD (I'm assuming SMOKEU's posted ones will be the same), which seems a bit high. Further browsing suggests such high THD levels will make things horrible to listen to, and potentially damage the speakers. So it would be a lot nicer to have the numbers for THD of only a few percent. Though it must be proportional, so I guess a 1000W @10% THD is going to be louder than a 500W @10%. But, sustaining home theater volume with over a few hundred watts of input power still seems like a silly thing to aim for.

[paturoa]

But, sustaining home theater volume with over a few hundred watts of input power still seems like a silly thing to aim for.

Especially if the speakers aren't up for it!

[paturoa]

Great idea lets redefine physics the get the number you want.

When I drop the clutch on my Harley, as the crank shaft decelerates it must produce about 300 ftlb's of torque, therefore my shitty old 2 valve 88 CI is making 200 HP (for about 1/3000 th of a second).

It probably makes that every power stroke for a few degrees and then coasts for another 700 degrees.

[Geeen]

Thats quite interesting, the bit about THD especially so. The Logitech speakers I'm interested in give their RMS power at 10%THD (I'm assuming SMOKEU's posted ones will be the same), which seems a bit high. Further browsing suggests such high THD levels will make things horrible to listen to, and potentially damage the speakers. So it would be a lot nicer to have the numbers for THD of only a few percent. Though it must be proportional, so I guess a 1000W @10% THD is going to be louder than a 500W @10%. But, sustaining home theater volume with over a few hundred watts of input power still seems like a silly thing to aim for.

A good amp has 0.001% THD. As far as more watts = more volume goes, its wrong. More watts gives greater control
of the driver so the sound reproduction is more accurate.

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