6 Ohms & 8 Ohms Speakers, which one better choice ?

[JoCaBa]

So if I have an amp that can output to 4ohm or 8ohm, which should I use if I have 6ohm speakers?

 

[shyamv]

Can't we look it at this way, Same Amp can push more power to 4 Ohm speakers, So they are in fact easier to drive?

All things being equal and for the same voltage, a speaker with 4 Ohm nominal impedance will draw twice as more current than a speaker with 8 Ohm nominal impedance and theoretically will be only 3dB 'louder' at the same volume level. However, more power from the amp is not necessary a good thing as it might put the amp in overload conditions. Considering that a real-world speaker has an impedence curve rather than one impedence value, a 4 Ohm speaker further draws more current from the amp during music transients, thereby making it harder on the amp. So more than impedence, efficiency in terms of dB SPL, which in some ways is another side of the same coin, is a more reliable measure of loudness.

 

[raghupb]

Can't we look it at this way, Same Amp can push more power to 4 Ohm speakers, So they are in fact easier to drive?

No. In this case it is electrical resistance.
Unlike mechanical resistance, when electrical resistance dips (from nominal), the amp should produce more current.
Which means the amp has to work harder.
Cheers,
Raghu

 

[alpinecat1]

Thanks for your explanation, Raghu. Quick comment, when you’re calculating the current pushed by the amp based on wattage and impedance, you seem to be using ohms law incorrectly. Am I incorrect in stating that Power=I^2R, not IR, (that equals voltage). So at 70W at 8 ohms you get 2.96 Amps and at 100W at 4ohms you get 5 Amps (not 25 A), no? Intuitively 25 Amps through a typical speaker wire sounds problematic. Am I off base?

 

[Shammi Dang]

At moderate volume level, in terms of getting better sound quality which impedance speaker should we buy ?

6 Ohms
8 Ohms

Which one ?

I have one set of bookshelf speakers that has impedance of 6 ohms but the manual says compatible with 8 ohms or 4 ohms amplifier. I have another set that is 8 ohms. When I compared these speakers I found no difference when a 8 ohms amplifier drives any of these. However as per the reviews ppl say 8 ohms is easier load. Moreover I feel the sensitivity also plays a role, when a speaker has sensitivity of say 89-90 db & higher they are easier to drive. My 6ohms speakers are 85 db sensitive so when played they need a wee bit more vol then the speakers that are 8ohms (87db sensitivity). However this is just my observation as I am not a very technical person.

 

[Prateek-Epitome]

An 8 ohm speaker will be relatively easier to drive. That’s it