Headphone impedance question...

[97tbird]

I like to listen to music with headphones at times
But most of those times are not with my Music Hall main amp, which will have no problem driving any headphones with high impedance.

It's when I use laptop or my iphone that I am concerned about: I have only experience with 32 ohm headphones, but I am thinking of a set of headphones with a higher ohm rating to let quality not suffer at hands of lower impedance AND when I do listen with the main amp, i can get the full experience/make use of abilities of the 'phones.

would a typical laptop sound-card (Lenovo T520 factory sound card), or an iphone have trouble driving a set of phones with 250 ohm impedance? (without an external headphone amp, that is)

 

[d00df00d]

Isn't efficiency important here, too?

 

[97tbird]

Yes.
one set I am considering has 96 dB/mW, and the other 105.
oops the one with 105 db is actually a 80 ohm set.

 

[JHZR2]

According to Ken Rockwell, the iphone 5 output is pretty darn good...

Quote:
Used directly with headphones plugged into the 3.5mm jack (use the Grado adapter for real headphones with 1/4" plugs), it also sounds swell so long as its usual 1V RMS maximum output is enough. It even sounds swell with the Audeze LCD-3, with which it goes plenty loud. It's plenty for 32 Ohm; headphones, but for classical music with 600 Ohm; headphones, might not be. No problem, just add a great headphone amplifier like the Woo Audio WA7 if you need more headphone output.


Quote:
Audio Quality Measurements

I used a $50,000 Rohde & Schwarz UPL audio analyzer to perform these measurements.

The traces are color coded for the Left Channel and for the Right Channel. When they don't lie on top of each other, it's due to channel imbalance.

I loaded the CBS CD-1 standard test CD into iTunes as ALC files, synced my iPhone 5 via iTunes 10, and then played-out from the iPhone 5's standard Music app at maximum gain (volume) under battery power.

Output Voltage

Load 0 DBFS @ 1 kHz
200 Ohm; 1.0158 V
600 Ohm; 1.0075 V
37.5 Ohm; 916.3 mV

Output Source Impedance

4.5 Ohm.

Output Noise Levels

-106.8 dBV, A-weighted, playing zeroes (silence).

-116 dBV, A-weighted, idle.



http://www.kenrockwell.com/apple/iphone-5/audio-quality.htm

 

[97tbird]

Thanks!
(for some reason I thought Mr Rockewell only wrote about Nikon DSLRs)

 

[Tosh]

You have it backward: All else being equal, an amplifier is 'happier' driving a larger impedance load. A smaller impedance will try to pull more current for the same power (P=I^2 *R) and be a more difficult load (all else being equal)....