Power consumption

[croseiv]

I'm sure this has probably been asked but I couldn't seem to find a concrete answer.

On the back of a typical receiver there is rating that is often stated like this:

630 VA 480 watts

What exactly does this refer to? Is this a maximum current draw or an average? Does this equal it's maximum output?

Just curious. Thanks.

 

[Tod]

I think the numbers on the back are just a rating - for the actual consumption, the specs in the manual usually have standby and max power usage.

 

[mtrycrafts]

I'm sure this has probably been asked but I couldn't seem to find a concrete answer.

On the back of a typical receiver there is rating that is often stated like this:

630 VA 480 watts

What exactly does this refer to? Is this a maximum current draw or an average? Does this equal it's maximum output?

Just curious. Thanks.

This has been covered in a post or two but I don't have it bookmarked.
In essence it is the L/R channel at full power plus the rest at 1/8 power, if memory serves me correctly; I think it is a UL standard perhaps.

 

[Haoleb]

The power consumption rating doesnt have anything to do with power output, directly. I have noticed most of the folks who have no idea about audio equipment think automatically it indicates power output which of course is not the case, Just read some Ebay ads for amplifiers To clarity what Mtry said, Its the amount of power consumed by the unit when driving those channels to that amount of power, I am not sure on if that statement is true or not however.

Nearly all appliances have a power consumption rating on them. This is amount of power that the unit consumes for one hour of sustained operation.

 

[TLS Guy]

I'm sure this has probably been asked but I couldn't seem to find a concrete answer.

On the back of a typical receiver there is rating that is often stated like this:

630 VA 480 watts

What exactly does this refer to? Is this a maximum current draw or an average? Does this equal it's maximum output?

Just curious. Thanks.

A receiver is a reactive load. An electric fire is a resistive one. For the fire the VA and Watts would be the same. It would be said to have a power factor of 1. However in reactive loads, voltage and current are out of phase. The VA rating is the apparent power. The current is real and has to be allowed for in the circuit rating. However the power in watts is what is consumed, and what you pay for.

These ratings are given to make sure a unit is properly powered. A circuit supplying that unit must be able to provide sufficient current and power. So a circuit supplying that unit must be able to supply 5.25 amps if it is a 120 Volt circuit. If you just used the watt rating you would think that the circuit only had to provide 4 amps, but you would be wrong.

Now both criteria for an AC circuit have to be satisfied. The circuit powering that unit must be able to provide 5.25 amps at 120 Volts and provide 480 watts.

This confuses people a lot, as they use DC math for AC circuits, and it's not so. These leads to errors in calculating circuit loads, and why circuit breakers trip, when people think the circuit is adequate.

Does this all sound familiar? Same thing with amps and speakers, which is why a continue to highlight why an amps ability to deliver current to speakers is so important.

 

[Seth=L]

630 VA 480 watts

Looks like an old Pioneer receiver or amplifier specification (it could be just about anything, it just reminds me). I am assuming that specification would be old mostly due to how inefficient that is. The Yamaha RX-V663 has a 500VA power supply

 

[TLS Guy]

Looks like an old Pioneer receiver or amplifier specification (it could be just about anything, it just reminds me). I am assuming that specification would be old mostly due to how inefficient that is. The Yamaha RX-V663 has a 500VA power supply

That just means that the maximum current draw from the wall outlet will be 4.2 amps at 120 volts. However the actual power draw will likely be less than that due to the power factor of the device. Specifying the VA rating and the power consumption in watts, and unless the device is PURELY resistive then the two numbers will be different, is IMPORTANT. So what is the issue? For anybody wanting to power from a UPS, they need either the VA spec and the power rating in watts, or either one with the power factor of the device specified. The reason is that the UPS must provide enough current to meet the VA spec and provide enough continuous power to meet the power rating in watts. This is what this is all about, and the reason that full and accurate published specifications are important.

When I sized the UPS units in my studio, getting correct and accurate specs from some of the manufacturers took a lot of work. That's wrong, that sort of information should be readily available. Also it ought to be explained in the instruction manuals, but have you ever seen that?

 

[croseiv]

I guess what I'm wondering mostly is if it is a receiver's rating, can it substantially produce/draw more current than that spec at times?

 

[TLS Guy]

I guess what I'm wondering mostly is if it is a receiver's rating, can it substantially produce/draw more current than that spec at times?

5.2 amps would be its maximum operating current draw. However at turn on the current could well be significantly higher. I ran into that problem and had to install slow break breakers in the panel. The turn on current at peak may well be as high as 15 amps for that unit. I have never seen the number specified on any unit, but it is a potential problem. The max current draw for any amp occurs at turn on, and settles to the the quiescent current draw after a second or two.

Just as an aside for my own benefit, have I explained the difference between the VA and watt specification in a way that you can understand it? This one is always tricky to explain.

 

[croseiv]

Just as an aside for my own benefit, have I explained the difference between the VA and watt specification in a way that you can understand it? This one is always tricky to explain.

Yeah. You've ceratinly helped! Thanks.