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Why are low impedance speakers harder to drive than high impedance speakers

I don't understand the electrical reason for this. I look at it from a mechanical point of view. If I have a spring that is of less resistance, and push it with my hand, it takes little effort, and I am not working hard to push it. When I have a stiffer spring (higher resistance)  I have to work harder to push it. This is inversely proportional when we are looking at amplifier/speaker values.

So, when I look at a speaker with an 8 ohm rating, it is easier to drive than a speaker with a 4 ohm load. This does not make sense to me, although I know it to be true. I have yet been able to have it explained to me that makes it clear.  Can someone explain this to me in a manner that does not require an EE degree?

Thanks

128x128crazyeddy

Showing 4 responses by unsound

unsound
7,310 posts
 
Charles1dad, sometimes a speaker designer will add components to a cross-over to lower the impedance  in order to make the impedance flatter/smoother. Sometimes lowering the impedance allows for more current delivery in order to facilitate stronger bass response.
unsound
7,310 posts
 
 ^ Lest anyone get the idea that the increase/decrease of power output by ss amps into decreased/increased impedances would suggest that frequency linearity would be compromised, the opposite is actually the case, they actually provide better frequency linearity. Most typical speakers will decrease/increase their sensitivity in direct proportion to the increased/decreased impedance changes.
 Furthermore, there are many other considerations that speaker designers need to consider besides impedance. With the advent of amplification that can adjust power output to speaker impedance/sensitivity, speakers designers were now able to permit more attention on other speaker considerations such as wave form fidelity, dispersion characteristics, box resonances, etc..
unsound
7,310 posts
 
Atmashere, the OP said nothing of ESL's. I did make mention of :  "Most typical speakers....".
unsound
7,310 posts
 
I think choosing speakers first has it's advantages. More so than with other components speakers need to be paired more carefully with the room in which they will be placed. More so than with other components speakers are the most colored components, and vary in sound more so than other components. As such it behooves one to make sure those colorations are the least offensive. Working backwards from the listening position will less likely box oneself into technological obstacles. 
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