Using IMac and Apple TV for Hifi System

Discussion in 'Apple TV and Home Theater' started by applefun2, Sep 29, 2012.

  1. applefun2 macrumors newbie

    Joined:
    Sep 29, 2012
    Location:
    SengKang
    #1
    Hi,
    I understand that I could use the IMac as the control station for my Hifi system by connecting the Apple TV to the DAC of the Hifi system.

    May I know if there is any problem of humming from the speakers when the IMac and Hifi system are switched on? I have tried using the Acer laptop to connect the the DAC via an USB cable. But, the moment I power up the laptop using its AC supply cable, there is this annoying humming sound from the speakers. When I turn the laptop AC supply off, the humming stops, ie when the laptop runs on its battery source. Well, I hope that by going wireless with the Apple TV, I would not face this problem.

    May I request some feedback and advice from someone who has used this set-up for his Hifi system?

    Thanks and regards,
    applefun2
     
  2. Attonine macrumors 6502a

    Joined:
    Feb 15, 2006
    Location:
    Kent. UK
    #2
    I run an Apple TV connected optically (toslink) into a Cyrus 6XPd amplifier with onboard DAC. Apple TV is connected wirelessly to ITunes on my MBP. I have never experienced any humming or feedback. I have also connected my MBP directly to the same amp using a mini toslink to toslink cable, and similarly have never experienced any humming/feedback/electronic interference.

    It sounds to me like the humming you are experiencing is coming from electrical interference being generated inside your laptop when the AC power is connected. I don't think there is much you will be able to do about this other than replace the laptop. I think this kind of thing is quite common especially with such things as laptops where the space is very confined, manufacturers are trying to cut costs with cheap components, reduced insulation etc.

    I am certain you will be fine using the iMac.
     
  3. waw74 macrumors 68030

    Joined:
    May 27, 2008
    #3
    might be a ground loop,
    is it a low hum?
    does the power adapter for you laptop have the third pin for grounding?
    is your laptop plugged into a different wall outlet as your stereo?

    an optical connection will not have this problem. so if your HiFi has optical input, i would go that route.
     
  4. applefun2 thread starter macrumors newbie

    Joined:
    Sep 29, 2012
    Location:
    SengKang
    #4
    IMac with Hifi Set-up

    Hi Attonine,
    Thanks for your reply.

    Sorry, may I know what is MBP?

    By the way, is the lossless format offered by Apple as good as FLAC?

    Cheers!
    applefun2

    ----------

    Hi waw74,
    Thanks for your reply.

    Yes, it is a low hum. Many said that it was a ground loop problem.

    My laptop adaptor has the 3rd pin for grounding and humming persists when I plug my laptop into a different wall socket, away from those for my stereo.

    By the way, would the 'cheater' plug solve the problem? I heard from many that this plug must be avoided as it could lead to damage to my stereo even though it could remove the humming. Is this true?

    Cheers,
    applefun2
     
  5. waw74 macrumors 68030

    Joined:
    May 27, 2008
    #5
    MBP = MacBook Pro

    you'll want to plug into the same outlet to avoid the hum, it's the voltage difference between the 2 different grounds that causes the problem.

    all houses should have one common ground for all the outlets, but who knows what people do.

    pulling the ground pin might help, you can use a ground lift available at any hardware store for a couple bucks (pic in second post for US plugs) if you don't want to permanently alter your power cord.

    or if you use an optical connection, you won't have the problem either. (need a cable like this one)
    all macs for the past several years have optical out built into the headphone port.
    this fixes it as the extra voltage can't flow over the fiberoptic.

    also if you don't have a television at that location, you're better off going with an airport express ($69 refurb) the aTV doesn't play well with no TV attached.
     
  6. zhenya macrumors 603

    zhenya

    Joined:
    Jan 6, 2005
    #6
    As noted, if you'll be connecting via the toslink connection from your iMac, there will be no hum as the two will be electrically isolated.

    I too would suggest an Airport Express instead unless you already have the iMac stationed in close proximity to the hifi. It doesn't require a tv to manage like the AppleTV, and carries a lossless signal to the DAC. Use an iPhone/pad/Pod and the remote app to control your selections.

    The Apple lossless protocol is no different than flac or cd for that matter. It's lossless.

    The above is somewhat different if you'll be using a USB connection between the iMac and hifi. The hum issue may still be present, but USB gives you the option of sending bit perfect high-Rez audio.
     
  7. applefun2 thread starter macrumors newbie

    Joined:
    Sep 29, 2012
    Location:
    SengKang
    #7
    Hi waw74,
    I plug my laptop into a different outlet but same extension cord. Is this as good as using the aulet?

    Ground lifting for laptop is deemed as dangerous by some; what do you say? Will it damage any hifi components in the long run?

    I have a tv in the same location as the hifi system. However, the IMac is in the next room?

    By the way, have you tried connecting your MBP to your amplifier using USB cable? Any humming?

    Cheers!
    applefun2
     

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