What is the relationship between Speaker Volume and the Power it consumes?

[RadMan]

In general, as one turns the volume up, how does power consumption increase? I have Logitech Speakers rated at 400W RMS. At what point would I see a power consumption of 400W?

Thanks,

RadMan

 

[Ionizer86]

Watts are a unit of power, so losses aside, it really should be directly related.

 

[Howard]

Never. The amp doesn't push 400W.

 

[compudog]

Your Logitech speakers will never consume 400 W of power. But as you increase volume, the amp that drives the speakers does use more power.

 

[TuxDave]

From what I heard, there's an exponential relationship between power and what we hear. So to HEAR twice as much sound, the amp must push out 4x as much power.

 

[Viperoni]

Originally posted by: Howard
Never. The amp doesn't push 400W.

I'm pretty sure the relationship is logarithmic.
When you double the wattage a speaker receives, you receive a 3db increase in sound pressure level (or speaker volume). 3db is a small but definetely noticeable increase in output.

For example, if you were to send a typical Logitech Z560 satellite a 20watt signal, it might put out 95db, which is loud. To get to only 98db, noticeably louder but not much louder, you'd have to give it 40 watts.

Now if you're giving a 15" subwoofer 1000 watts, and it's putting out 140db, bumping that up to 2000 watts will gain you 3db. Mind you that's all theoretical: when you account for non-linearities such as speaker design and a whole bunch of other stuff, you'd be lucky to get 2db when jumping from 1000 to 2000 watts. Same idea for the Logitech satellite example: I doubt you'd even get as high as 97db when going from 20watts to 40watts.

Hope this helps somewhat

 

[RadMan]

Thanks guys,

I appreciate the input.

RadMan

 

[Viper GTS]

It is exponential.

Take for example my Tempest 15" sub. It's capable of 89.1 dB @ 1W/1m. I've clipped (maxed out) my 850W rack mount amp into it & it peaked at around 115-120 dba.

2^10 = 1024W (120.1 dba)
2^9 = 512W (117.1 dba)

The decibel scale is logarithmic, hence the power requirements to reach a given SPL are also logarithmic.

Viper GTS