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Question about Watt v.s Voltage

post #1 of 2
8/20/11 at 10:30pm
Thread Starter 

This is my second question in a row and I feel like a complete noob at this sometimes.
1. Sorry if this is the wrong section.
2. Sorry if you don't deal with what I'm about to ask - its more speaker than headphone related

I'm not sure if I'm allowed to post links such as this. But this is what I'm looking at.
http://www.dealextreme.com/p/160w-hi-fi-stereo-amplifier-mp3-player-w-sd-usb-for-car-motorcycle-red-silver-12v-91314

I have two loudspeakers - 8ohm, 80 watts, and right now they're being powered by a large receiver, not a small 12v DC one like in the link.

As I understand it. 12volts - 80 watts, the speakers would have to be less than 1ohm.
Given 8 ohms, this would power them less than 20 watts each. Is this correct

I know a lot of you are going to cringe that I'm even using them, but I need to make these play for a large hall, and the people in it are really not sticklers for the sound.

I just don't understand how a small little 12v DC gadget that usually powers things like phones, can possibly power those.
Maybe someone could also give me the basic. (BASIC) formulas for understanding these types of things.
And what numbers I need to look for on a speaker/receiver --- ohms, volts, watts, amps? etc


Edited by zumax - 8/21/11 at 10:17am
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post #2 of 2
8/21/11 at 10:03pm
Quote:
Originally Posted by zumax View Post

This is my second question in a row and I feel like a complete noob at this sometimes.
1. Sorry if this is the wrong section.
2. Sorry if you don't deal with what I'm about to ask - its more speaker than headphone related

I'm not sure if I'm allowed to post links such as this. But this is what I'm looking at.
http://www.dealextreme.com/p/160w-hi-fi-stereo-amplifier-mp3-player-w-sd-usb-for-car-motorcycle-red-silver-12v-91314

I have two loudspeakers - 8ohm, 80 watts, and right now they're being powered by a large receiver, not a small 12v DC one like in the link.

As I understand it. 12volts - 80 watts, the speakers would have to be less than 1ohm.
Given 8 ohms, this would power them less than 20 watts each. Is this correct

I know a lot of you are going to cringe that I'm even using them, but I need to make these play for a large hall, and the people in it are really not sticklers for the sound.

I just don't understand how a small little 12v DC gadget that usually powers things like phones, can possibly power those.
Maybe someone could also give me the basic. (BASIC) formulas for understanding these types of things.
And what numbers I need to look for on a speaker/receiver --- ohms, volts, watts, amps? etc

 


Decibels: The ratio of the intensity of the sound to a standard intensity at 1 Khz. eg/ Normal conversation: 60dB, Rock Concert (Front Row):        120dB 

 

Hertz: Frequency - Last note on a piano: 4 kHz, Middle C: 262 Hz (NOT volume)

 

Watt: Power and drive. More watt(power) = bigger sound. Power is the Current times Voltage.

 

Amps (I, Current): The flow

 

Voltage: "pressure"

 

Ohms: Resistance - More resistance less Voltage. The higher the impedance, the harder the headphone is to drive.

 

If you like formulas, it's 

P = VI = (I^2)R = V^2/R

 

note:

I haven't done Physics for a long time but this is what I remember. Hope I helped. biggrin.gif

 

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