11 Replies Latest reply: Jul 25, 2008 12:59 PM by Austin Hearst
Nawyecky Level 1 Level 1 (5 points)
hi all

i've hooked up my 20" intel imac to a surround amp with a mini-toslink cable, however i can't seem to get any audio out of the mac except the left and right channels.

i've got a quicktime file encoded in ac3. in its audio settings i have 6 channels which i can route to any output (left, right, center, lfe etc). but nothing arrives at the amp (which recognizes the digital in signal as "linear pcm l-r-sw", except that even the sub doesn't sound).

a trip to audio midi setup reveals that i can only select "built-in output" which is not configurable (gray letters say "output is not supported"). i'm using the imac's internal output. what's going on here?

thanks for any help.
  • 1. Re: imac and 5.1 surround
    Chipell Level 1 Level 1 (0 points)
    Nawyecky,

    Since you are hooking up your 5.1 speakers via optical out, the only way I know how, then OS X 10.5x will only support 5.1 output if the file is natively encoded for 5.1. For instance, you can't get 5.1 sound out of an .mp3 that you download from the net or the Apple store.

    There was a usb sound card out there made by Griffin, called the Firewave, but it is not compatible with Leopard, and they have no plans to make it compatible for they are discontinuing it. Some people have reported success, but I have one and it will not function on Leopard.
  • 2. Re: imac and 5.1 surround
    Nawyecky Level 1 Level 1 (5 points)
    thank you chipell. apparently it's an app-independent setting. i managed to get the 5.1 quicktime file into my amp with vlc, choosing "encoded audio" instead of just "audio" in the audio track menu. this works fine (gloriously even) but for the time being it's the only app i could coerce into doing this.
  • 3. Re: imac and 5.1 surround
    Dah•veed Level 7 Level 7 (30,315 points)
    Have you configured your Mac for 5.1 surround in Audio MIDI Setup. The instructions are located in the Help file titled Setting up external speakers available in the AMS Help menu.
  • 4. Re: imac and 5.1 surround
    Dah•veed Level 7 Level 7 (30,315 points)
    The only folks who need an external sound device, such as Firewave, are those whose kit does not support directly connecting to the Mac with a digital toslink cable. The folks whose external speaker system only has multiple RCA cables.
  • 5. Re: imac and 5.1 surround
    Nawyecky Level 1 Level 1 (5 points)
    the help file says : "Choose the audio output device from the Properties For pop-up menu, and then click Configure Speakers."

    like i wrote in the original post, my outputs are not configurable (button grayed out). i'm using the internal imac sound interface. is yours configurable? i'm asking this because it's also grayed out on my macbook (both machines running 10.5.2).

    thanks.
  • 6. Re: imac and 5.1 surround
    Dah•veed Level 7 Level 7 (30,315 points)
    I do not have a multi-channel capable set of external speakers, but everything for me in Audio MIDI Setup is fully configurable. When Properties are set for built-in output and I press the Configure Speakers button another sheet slides down with options for stereo or multi-channel.
  • 7. Re: imac and 5.1 surround
    Nawyecky Level 1 Level 1 (5 points)
    well, imho the audio midi setup interface should win an award for "most unintuitive dialog box design" since, after reading your reply, i finally found the "properties for" list box. i say that because the entire window is laid out, logically, with "inputs" on the left (including clock source) and outputs on the right (including the speakers). the reason for placing the "properties for" list on the left, and in the middle of everything else vertically, is beyond me.

    moving on, with my mini-toslink inserted, the only option in "source" is "digital out". in the "format" list box i have options for 2-channel output with several bit-depths as well as an "encoded digital audio" option. when i select that and go into "configure speakers", the only available option in "multichannel" is "stereo". all the other surround options are grayed-out.

    i'm only trying to figure this out in order to get 5.1 output in front row and quicktime. however, this is starting to get really unnecessarily complex (considering that, in vlc, i can just choose audio > audio device > encoded audio).

    still, out of curiosity, any ideas why the multichannel options are not available?

    thanks again.
  • 8. Re: imac and 5.1 surround
    hebron Level 1 Level 1 (0 points)
    I could be wrong, but I think some kind of driver is needed for your amp...but I don't know if one exists.

    When I tried to add a Yamaha keyboard (in Audio Midi Setup) to use in Garage Band, the device was invisible until I found the correct driver from Yamaha.

    I may be way off...
  • 9. Re: imac and 5.1 surround
    Computer Fraggle Level 1 Level 1 (0 points)
    I don't think it has anything to do with drivers... I have exactly the same problem. I can' t configure anything. I use a Logitech z-5500 connected via the optical cable.

    Strange thing is that when I play a dvd I get sound from all 4 speakers.

    I have been googling it but can't find a decent answer either. Hope some Mac garoo Can help us out!
  • 10. Re: imac and 5.1 surround
    Beaumon Level 1 Level 1 (0 points)
    I am having the same issue. I have a audio file that has 5.1 channels. I can not tell my MBP to output more than stereo in the MIDI setup.

    TOSLINK is one way optical. There is no 2 way communication coming from the speakers to the computer. So the MAC just needs to output and not care what it is plugged into, since it will never know.

    I am trying to go to a YAHAMA RX-V863. It will handle basically anything.
  • 11. Re: imac and 5.1 surround
    Austin Hearst Level 1 Level 1 (0 points)
    read this- think you can play DVDs in 5.1&soundtrack pro- not sure about digi
    design or what is the best Midi amp to get surround out for cross format mixing