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

crazyeddy01-06-2017 9:18pm

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bdp24 Details Discussions Posts This discussion Message User 9,408 posts 01-08-2017 at 05:31am Copy Comment URL Report Comment Edit Delete While a 16 ohm speaker may seem to "present an enormously easy load for virtually any power amplifier", such is not necessarily the case, as that 16 ohm rating is merely nominal. For instance, the original Quad ESL's nominal impedance was 16 ohms, but it’s impedance rose to 60 ohms at low frequencies, and fell to 1.8 ohms at high frequencies---anything but an easy load! That impedance characteristic is one reason the sound of the Quad ESL is so affected by the amp driving it, and why almost no solid state amp is a good match---it makes for overblown bass and missing highs. Ralph Karsten of Atma-Sphere has already explained this a few times. Related to my post above, using the lowest impedance tap on a tube power amp not only usually results in the lowest distortion and best sound the amp is capable of, but the amp’s damping factor is also highest, leading to the flattest frequency response it is capable of, irrespective of speaker impedance characteristics.
audioman58 Details Discussions Posts This discussion Message User 3,832 posts 01-08-2017 at 10:33am Copy Comment URL Report Comment Edit Delete Also remember the complexity of the Crossover is directly proportional To ohms,resistance to the drivers and demand affecting the Amplifiers Constant changing ohms ,and Amplifier Load depending on demand. A speaker can go from a 8ohm load to 2 ohms which Is very demanding For a conventional driver Loudspeaker. Panel or stats ,can dip down to 1ohm . This is where a Amplifier be rock solid .verify that the amplifier you are using Can handle the extreme for a given Loudspeaker before purchasing it.
charles1dad Details Discussions Posts This discussion Message User 10,227 posts 01-08-2017 at 12:39pm Copy Comment URL Report Comment Edit Delete Hi Bdp24, For sake of this discussion I’m referring to speaker load impedance characteristics that remain "relatively flat. So my hypothetical comparison would be a 4 ohm vs a 16 ohm. A speaker such as the Quad that you cite with its extreme fluctuations renders nominal rating meaningless lf both the 4 and 16 ohm speakers are stable, the higher ohm speaker demands less current and work from the driving amplifier as predicted by Oohm’s law. In reality there are speakers with both reasonably flat impedance characteristics and gentle phase angles. There are also those with widely fluctuating impedance and steep phase angles. It seems that the former would be preferable as it is far less demanding on a power amplifier assuming that either provides comparable sound quality. Charles
dlcockrum Details Discussions Posts This discussion Message User 2,190 posts 01-08-2017 at 03:57pm Copy Comment URL Report Comment Edit Delete Hi Charles, Usually it comes down to approach: picking the speaker you love and then finding the right amp or vice versa, or in a fortuitous alignment of skill and circumstance, finding both without significant compromise. Best to you Charles, Dave
almarg Details Discussions Posts This discussion Message User 9,670 posts 01-08-2017 at 04:24pm Copy Comment URL Report Comment Edit Delete bdp24 1-8-2017 For instance, the original Quad ESL's nominal impedance was 16 ohms, but it’s impedance rose to 60 ohms at low frequencies, and fell to 1.8 ohms at high frequencies---anything but an easy load! That impedance characteristic is one reason the sound of the Quad ESL is so affected by the amp driving it, and why almost no solid state amp is a good match---it makes for overblown bass and missing highs. BDP, a minor correction to your characteristically excellent inputs. The last phrase should be "it makes for missing bass and overblown highs." As you no doubt realize, and aside from some rare exceptions, in comparison with a tube amp a solid state amp will deliver more power into low impedances and less power into high impedances, for a given input signal level. Best regards, -- Al