[kitaoji]

Hi,

I used to think that "higher impedance" meant "use more battery power to just to hear sounds from headphones/earphones", and I still think that that holds true, which prompted me to get a fair number of 16 ohms earbuds in high school.

Then in came "sensitivity". Is sensitivity more of a factor in deciding more of the volume that comes out of your 'phones? After all, I find that the Ultimate Ears are really the ultimate when it comes to setting the volume on any sources I use.

Then, my DT880s came. With their insanely high impedance (to me, anyway, since I've never really tried such brilliant pieces of Hi-Fi) and decent sensitivity, and despite the warnings of many other head-fiers on this forum - I can use them on my laptop, without any amp whatsoever. And that's with the volume knob on max and the software (onboard?) volume control at near minimum. And on my iAudio 5, I don't have to go beyond 25/40 (this was for a very, very soft recording.)

Of course, the sound isn't that refined, but I'm not audiophile, and I can't hear a great WOW difference between the DT880s and the eH350s. At least, the DT880s just sound more smooth, while the eH350 are more "in your face".

So, can someone clarify for me? There are a whole bunch of headphones that really need an amp to sound nice, or to even just hear the music, and these seem to be ones that need 50 ohms and above. So why can I hear the music on my laptop?

 

[Jam_Master_J]

Not only do the 880s need a good amp to shine, they also benefit from a better source. That's not to say that your laptop can't drive them loud enough, I'm not surprised it can. My Rio Karma drives my DT880s plenty loud but my Dynalo is more authoritive and dynamic sounding at similar volume settings.

 

[angler31337]

Impedance--which is measured in ohms--is the AC (alternating current) analogue of resistance. High impedance headphones are generally harder to drive. That is, it takes relatively more mW of power to drive a high impedance headphone to produce (say) 10 decibels of noise than it takes to drive low impedance headphone to produce the same 10 decibels of noise, all else held equal. High impedance headphones tend to be less susceptible to the noise floor of a given source. Also note that manually altering the impedance of a certain headphone will generally alter its sound signature.

Sensitivity--measured in decibels of SPL (sound pressure level)--is a measure of how loud a headphone is when driven by some arbitrary amount of power. The industry standard (if I remember this right) is to measure the SPL at earpiece when 1 mW of power is applied to the headphone. Sensitivity is strongly negatively correlated with impedance, but impedance is not an exact predictor of sensitivity.

Very few headphones require an amp to generate an audible level of noise on common conventional sources. Even high impedance headphones (like the HD600) can be driven to loud levels by (say) laptop onboard soundcards; they just won't tend to sound as good as they could. When audiophiles say that these types of headphones "require" an amp, what they mean is that the sound quality of the headphone (measured in terms of clarity, dynamics, size, etc...) will improve greatly if a dedicated headphone amplifier is used.

-Angler