Sound Power - watt

[b4u]

Can anyone explain to me how this power works?

I'm looking for a home theater, DVD + AV, and someone tells me about the output power, something like "you have 4 columns with 20w power, for a total of 100w" ... what is that? (the example I gave was invented by me, so it must be a real messed up one )

Thanks ... I don't know where to start, I'm googling it right now, but some of you could give me a brief explanation

 

[Shockwave]

Brief? OK, most receivers / amps are rated at (power) x (number of channels)
Example.
Superduper Amp. 50x6

Its 50 watts per channel, 6 channel. Generally 8 ohm for home, 4 ohm for mobile unless otherwise listed. Most high power mobile amps rate at lowest operating impedance which ends up being 2 or 1 ohm.

 

[Heisenberg]

Watt is a rating of power. Typically amplifiers are rated by how many watts each channel produces. You can then add up all the channels to have a total wattage. Modern amps do at least 5 channels (front left and right, center, surround left and right). If each channel is 75 watts, then the total power is 75 x 5 = 375 watts.

 

[Muadib]

Since you sound like you're a newbie to the home theater world, you might find it helpful to list your budget, and what it is you need.

 

[Mday]

Originally posted by: b4u
Can anyone explain to me how this power works?

I'm looking for a home theater, DVD + AV, and someone tells me about the output power, something like "you have 4 columns with 20w power, for a total of 100w" ... what is that? (the example I gave was invented by me, so it must be a real messed up one )

Thanks ... I don't know where to start, I'm googling it right now, but some of you could give me a brief explanation

i suggest reading some home theatre magazine, or doing a google search for home theatre websites. or even getting a book or going to the library.

the wattage in this case is how much power the amp can send to each "speaker." this is important in matching the speakers to the amp. if the speakers have a higher wattage rating, then the speakers wont really reach their full potential. if the amp;s wattage is higher than the speakers', then if you crank up the volume all the way, the power sent to the speakers will blow them out. other things to consider is the impedance (ohms). this is resistance in the AC world, the importance here is to maximize the power utilization to provide the best response.

and by speaker, i refer to a piece with one or more drivers. drivers provide the sound.

 

[glen]

Without knowing the efficiency of the speakers, watts is a meaningless term in regards to the loudness.
Some speakers, liek the Legacy Focus are rated at 96db/watt/meter
Many home theater speakers, like the Paradigm c70 series are rated at 84db/watt/meter
So, if you have legacy Focus speakers, 1 watt per channel will drive them nicely.

 

[KMurphy]

Don't forget about peak vs. rms power. Cheap speaker and amplifier manufacturers will list peak power; you want to compare rms power.

 

[b4u]

Originally posted by: KMurphy
Don't forget about peak vs. rms power. Cheap speaker and amplifier manufacturers will list peak power; you want to compare rms power.

What is RMS power?

What is impedance?

 

[Shockwave]

Originally posted by: b4u

Originally posted by: KMurphy
Don't forget about peak vs. rms power. Cheap speaker and amplifier manufacturers will list peak power; you want to compare rms power.

What is RMS power?

What is impedance?

Root Mean Square.
Peak

RMS = time averaged power. You can count on this number. Derived from peak power
Peak = Quick burst of power. Not a good rating for power. RMS is what you want to look for.

Impedance is just that. The impedance of the speaker. Usually 8 ohms for home audio. Power rating should be figured at 8 ohms using RMS power. The lower the impedance the higher the power (Generally, not always true). So rating a home amp at 1 ohm peak power is horribly inaccurate. Rating at 8 ohm RMS is very accurate. They may use 4 ohm for home amps as well, home theater is *not* my area of specialty by any means.