MacBook Air 11.6 Headphone Minijack Impedance ?

Discussion in 'MacBook Air' started by canofbeens, Oct 26, 2010.

  1. canofbeens macrumors newbie

    Joined:
    Oct 26, 2010
    #1
    I am considering making the switch from PC to Mac, the desktop switch is easy, I would simply replace my Dell with an iMac, but I also need a portable computer (running OS-X not iOS) to replace my netbook. I will be using it for Internet access, light audio editing and streaming with Audacity, QuickTime and VLC (Ogg, FLAC, etc), some light spreadsheet work (I will switch to Numbers), heavy writing (I will switch to Pages), Sykpe, iCal, Mail, and Google Earth.

    I need to check the output of the headphone/lineout port, to see if it can drive the monitors that I use for linguistics. (16 Ohm Beyerdynamic DT100 and 24 Ohm Sony MDR-XB700). Any help would be greatly appreciated, I have looked around but I cannot find any detailed specifications for the headphone/lineout on the MacBook Air 11.6, the Apple Technical Specifications simply list the port as "Headphone Minijack". If any of you have low impedance headphones with large drivers and could spare the time to plug them in and let me know what the volume is like, I would be very grateful.

    Thanks for your time.
     
  2. hachre macrumors 6502a

    hachre

    Joined:
    Sep 26, 2007
    #2
    I would love to try this for you, but my MBP 13" is only arriving in around 10 days from now :(
     
  3. Sound Evolution macrumors 6502

    Joined:
    Oct 30, 2007
    Location:
    Netherlands
    #3
    Dear,

    The headphones you mention have a very low impedance. I can not imagine the headphone driver in any laptop is made to provide this much current. For sure it draws your battery as well. For such a high quality low impedance monitors I advice you to use separate USB interface with a decent headphone amplifier.

    My experience is also with the current MBP/MBA's that the sound quality of the headphone outputs isn't that great and doesn't do justice to the high quality headphones you mention (digital noise). Unfortunately the old powerbook's had much better headphone drivers and sound quality.

    I hope this helps.

    With kind regards,
    Bas
     
  4. canofbeens thread starter macrumors newbie

    Joined:
    Oct 26, 2010
    #4
    Thanks for your reply, my understanding of electronics is very rusty, Ohms law is a distant memory, so when I purchased my headphones it was based on the following recommendations; where lower impedance headphones are recommended for portable applications, such as iPod's and laptops, and higher impedance headphones are recommended for studio and home theatre applications via a desk or headphone amplifier, here are some examples:


    Beyerdynamic DT 770 - 32 Ohm

    "Highly efficient 32 Ohm impedance allows from use from any audio source, even laptops, iPods & iPhones without necessitating a headphone amp."


    Beyerdynamic DT 770 - 600 Ohm

    "High 600-Ohm impedance rating is perfect for use with headphone amps and high-power audio sources."


    Reading their guide on headphone amplifiers echoes what you are advising with regards to current, but another guide on impedance seems to confirm the general recommendation, that low impedance headphones should be used with portable devices:

    "low impedance headphones will sound louder when plugged in devices with low output voltages such as portable CD players, etc. In reality, because of the limited power available from portable players, headsets for portable use should have a maximum impedance of 64 ohms.

    Worth keeping in mind here that the lower the impedance, the more efficient headphones are in converting the incoming electrical energy into sound. On the contrary, the higher the impedance, the more electrical energy is required to drive the headsets tiny speakers.
    "

    I am grateful for your advice, it has helped me think; what will I actually be using these headphones for when I am on the road?, do I really need a full headset?, can I use a pair of earphones? Portability is critical with this machine (MacBook Air 11.6) so I may have to purchase some good quality earphones. In any case, a headphone amp would not fit in my backpack.

    Any recommendations are welcome, I have been looking at the Etymotic MicroPro ER4's however, if you are advising that the sound quality of the current MBP/MBA's headphone outputs isn't that great, maybe I should get something a little cheaper like the Etymotic MC5's ?

    Thanks for your help.
     

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