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What is the impedance of audio output in cell phone. I mean 3.5 jack for headphones. Is that somehow standardized? Do we know ranges among cellphones? Or mp3 players. I haven't found any information about impedance, when searching manuals for cellphones or mp3 players.

Does anyone have experiences, how non-matching impedance of audio output and headphones impact the quality of sound?

I'm trying to find perfect headphones for Sony Experia L.

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closed as off-topic by Andy aka, Leon Heller, Matt Young, Chetan Bhargava, Nick Alexeev Nov 17 '14 at 5:16

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "Questions on the use of electronic devices are off-topic as this site is intended specifically for questions on electronics design." – Andy aka, Leon Heller, Matt Young, Chetan Bhargava, Nick Alexeev
If this question can be reworded to fit the rules in the help center, please edit the question.

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    \$\begingroup\$ Perfect headphones don't exist. \$\endgroup\$ – Andy aka Nov 16 '14 at 11:52
  • \$\begingroup\$ Byt the way, there is now a beta sound.stackexchange.com where such questions may be more welcome. \$\endgroup\$ – Fizz Jan 11 '15 at 1:03
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In audio applications it is the goal to control the voltage over the speaker or the headphone as exactly as possible. Because the impedance (alternating current resistance) of speakers and headphones is frequency dependant, it's not advisable to achieve impedance (and power) matching.

While the output impedance of phones, MP3 players etc. is usually in the range of several ohms, the impedance of headphones goes usualy from 20 to several 100 ohms.

The headphone manufacturer has (among others) one problem, high efficient speakers are expensive to manufacture. A headphone with low impedance could be produced cheaper, but the frequency response will also be worse. A headphone with a high impedance will eventually not produce enough volume.

Generally speaking headphones with a higher impedance could have a better frequency response, but as usual ther are other points ...

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  • \$\begingroup\$ Thanks, your answer is great. I might not know what number of impedance I'm looking for, but knowing those new information made me courios and I'm gonna run some measurements and subjective tests of audio quality to understand better. \$\endgroup\$ – user50222 Nov 16 '14 at 13:26
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This article might answer your questions.

As a rule of thumb, the load impedance (headphone) should be at least eight times higher than the amplifier output impedance.

If you can't find your phone's output impedance just check what its peers(Samsung, LG etc.) use, it's usually close.

In practice you shouldn't get any problems with a headphone with impedance between 20 to 60-70 ohms on most portable devices. There is no "ideal" impedance that you want to match for the best performance. Sound quality depends on lots of things.

What Kitana said is also true, you don't want to get a headphone with an impedance that your device can't drive. Just make sure you don't get 200+ ohms headphones(Check for beyerdynamic DT series for an example) to use without an amplifier. Then they might feel "underpowered". Low volume, weak bass etc.

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