Using iPod with large cans

[Russell_L]

I've got a brand new 5G 30GB iPod and have discovered, to my amazement, that it's able to drive my old pair of Sony MDR-CD850 headphones to way more than adequate volume levels. Sounds pretty darn good, too. The 850's are pretty large and heavy closed cans (I used them years ago in my home stereo system--now I've got Stax SRS-3030's), but was delighted to discover that my little iPod could drive them pretty effortlessly. My question is whether I'd be taxing the iPod in any way when using these large cans. Their impedance is 32 ohms and sensitivity is 102 db, which seems to fall right in the range of more portable phones. Is this all that matters?

Thanks,
Russell

[technobarbie]

The maximum impedance for portables is around 64 ohms so your fine.

[Macromedia]

Apple says the ipod can drive up to 100 ohm. The ipod could drive more but the volume would be too low.

[thedodgyguy]

It depends on the specific response of the cans. The quoted impedance of the cans is an average across the entire frequency range. So taking as an extreme example, you could have a can which has a 150 ohm impedance at 50hz and an 16 ohm impedance at 5khz. The efficiency of a can is also measured at 1khz, so at certain frequencies it may be more or less efficient. Borderline cans with limited efficiency or odd impedance curves may not behave so well on the iPod.


I use a 70-ohm, 100db/mw (Qualia 010) and the 70-ohm, 105db-ish can (HD25) in the main and both are driven (rather well, as neither phone has overt quirks such as that referred to above) to ear-bleeding volumes on the iPod.