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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
mapman's avatar
mapman
21,838 posts
 
I think the trend towards speakers with lower impedance corresponds to the trend for speakers to be smaller yet more full range to fit into people’s lifestyle. Also as we know from experience the best sounding gear is not always the ones that measure lowest in distortion. Lower impedance tougher load speakers just means amps must work harder. Some are able do that much mbetter than others. Newer more efficient amp technologies like Class D perhaps do it best. Class D offers a much larger higher pressure "garden hose" for your speakers.   For example I have 500 w/ch class d amps that can deliver almost 40 amps of current  that are about the size of a shoebox.    My harder load speakers shine and easily surpass my smaller easier load ones with these.     


charles1dad's avatar
charles1dad
10,230 posts
 
Unsound,
That makes sense and with the advent of transistor power amplifiers I can see where the 4 ohm load speakers becomes more plausible to manufacture . One could make a case for either type of load characteristic. Higher impedance =easier load and less work for a given amplifier. Intuitively this seems to be ultimately more desirable.

There was a time when 8 to 16 ohm speakers were the norm and one could use modestly powered amps that were of high "quality ". 16 ohm speakers are quite rare these days. This would present an enormously easy load for virtually any power amplifier.
Charles
mapman's avatar
mapman
21,838 posts
 
It’s all about the bass, about the bass,. Not the...

well it’s also about size and cost actually.

The reality is low power tube amp lovers have limited speaker choices at least if bass extension matters. Still good ones out there though if a low power tube amp is what one chooses to build around.

Making music especially bass is a lot of work. Somehow combo of amp and speakers must be up to the task else results suffer in comparison. A nice high pressure shower makes for a much better clean. The actual amount of water used might still vary widely though.
twoleftears's avatar
twoleftears
5,313 posts
 

As watts got cheaper with ss, designers could not put as much effort into creating high imp. speakers and could also experiment with low imp. designs.

But my question is: %-wise, what contributes to impedance: the overall design (enclosure, drivers, venting, etc.) or the crossover?  I've always suspected that the crossover had a big role, and fancy crossover topologies often make for low imp. speakers (I suspect).

mapman's avatar
mapman
21,838 posts
 
Ports in ported designs are always a major factor it seems. 
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