5.1 dolby digital surround sound from imac

Discussion in 'iMac' started by hochun0809, Aug 13, 2012.

  1. hochun0809 macrumors newbie

    Aug 13, 2012
    How do I get 5.1 dolby digital surround sound from imac?

    Hi everyone, I am very very new to this forum so if I do something inappropriate, I apologize for that. =)

    Here are my questions.
    I have got a mid 2007 iMac and a Creative inspire p7800 7.1 speaker.
    What I want to do is to hear 5.1 dolby digital surround sound from the creative speaker (which does not support DD and DTS like Logitech z5500 and Logitech Z906 do).
    I have done tons of research and spend a lots of time in the internet to look for answers. I did find some solution on this issue but I am not 100% sure. And some more questions pop up. So I am hoping that some expert here can clear my mind. Thank you so much ^^

    So, here is some solution that I got from the internet. (please correct me if I am wrong)

    1. Buy a Griffin Firewave and connect it to my mac and thats all I need to do. As Griffin Firewave has dolby digital processor, so I think I will be getting 5.1 DD surround sound from the speaker. (Am I right?)
    But the problem is, there is only one firewave listed on amazon and one listed on ebay. The amazon one is really really expensive that I think it is really unreasonable to buy it. So as I may not able to get a Griffin Firewave, this lead to my second solution.

    2. Buy a external sound card like this:
    and connect it to the mac. But my question is, As I do not have any Dolby decoding device connected, will I getting 5.1 DD surround sound in my speaker? Or the program in my mac (i.e: VLC) already done the decoding and output as 5.1 multichannel analog so I don't need a extra decoding device?

    3. As I am not sure about those method on the above will get 5.1 DD surround sound in my speaker, I keep digging and find out there is actually one more option.
    Since the iMac supports s/pdif output, what I need is to buy a Digital to Analog converter(DAC) and use the mini Toslink to connect my mac with the DAC. Then connect my speaker to the DAC. Some DAC I found:
    and most of DAC support DD/DTS decoding, I should be able to get 5.1 DD surround sound at the end. Is it correct?

    My question is, is this the right solution to get 5.1 Dolby?
    If Griffin Firewave is available, will the result of method 1 same as the result of method 3?
    Or is it better to use a receiver instead of DAC?

    I know I have so many questions, I hope I did not make it too troublesome. But I really want to know the answer from you guys. I really appreciate for those who read through this. I know my english sucks and cannot express myself very well. I do apologize for that. Anyway, please leave any thought on this, even a sentence or yes/no XD
    Thank you sooooooo much
  2. Sharangad, Aug 13, 2012
    Last edited: Aug 13, 2012

    Sharangad macrumors member

    Oct 19, 2008
    The firewave for Mac solution will work though it's pricey.

    A couple of things:

    1) you won't be able to get surround sound from games as:
    a) Games don't come with their own DD/DTS encoders
    b) There are no Mac audio drivers (at least for the built in audio) which can convert 5.1 channel PCM in real time into DD/DTS like on the PC.

    2) What you need is a receiver (something which can decode DD/DTS) which can also produce outputs which can work with your Creative speakers (as I suspect they won't work with proper hi-fi outputs).

    3) Creative had a DD/DTS decoder called the DDTS-100 http://www.amazon.co.uk/Creative-Labs-DDTS-100-Decoder/dp/B0001A982K which was discontinued years ago. This was designed to connect a console with DD/DTS output to Creative speakers (it had appropriate connectors for a Creative Speaker set (i.e. 3 line-level stereo phono outputs like from PC soundcard) and optical and coaxial SPDIF inputs which would work with that. Actually this item, which you listed http://www.amazon.com/Digital-Analog-Audio-Decoder-Converter/dp/B0057UNPVO/ should work perfectly though you'll need 3 pairs (3 cables) of stereo mini-plug to phono X2 convertors.

    Even if you had 3) you would only get surround (DD/DTS) for pre-encoded content like DVDs and not for games.

    If you ask me you'd be better off getting:
    0) Somehow finding an unsold/second-hand DDTS-100 (no surround for games with an iMac)
    1) A receiver and a proper speaker system (still no surround for games with an iMac ) OR
    2) PC gaming system which can directly connect to the speakers without the need for unnecessary ( and lossy ) DD/DTS encoding/decoding to get sound to your speakers.
  3. Wardenski, Aug 13, 2012
    Last edited: Aug 13, 2012

    Wardenski macrumors 6502

    Jan 22, 2012
    I think option 1 and 3 would work - at the end of the day you need six discrete analogue outputs for each speaker as you identified. In theory, this setup should work for both movies and games since you do not need to encode to DD.

    Its a shame that there are few, if any, surround sound cards that offically support OSX but I remember reading somewhere that a few external PC USB soundcards work at a basic level.

    I would hold horses for more opinions/facts.

    For what its worth, I output DD 5.1 to a Denon Reciever which then outputs to ordinary speakers - works very well but I have a Mac Pro with X-Fi Titanium with onboard DD/DTS encoder via optical. Works only in Windows.
  4. Sharangad macrumors member

    Oct 19, 2008
  5. Wardenski macrumors 6502

    Jan 22, 2012
    I have been meditating and I am not sure if 3 would work for games.

    In 3, you output via optical which must be encoded for surround sound. For DVDs, 3 should work because it decodes an encoded signal and then outputs six descrete outputs for your speakers.

    For games though, they are not encoded so I suspect that DAC would just output stereo but I do not know, you may get lucky and it may pass through as 5.1.

    If you install Windows in bootcamp, then in theory you could use a PC USB soundcard and make life a little easier.
  6. hochun0809 thread starter macrumors newbie

    Aug 13, 2012
    First of all, I thank you all of you to help me through this.

    So what I am getting is, the firewave option and the third option should be able to do.

    Well, I am not a gamer, I mainly just watch movies, a lots of movies and sometimes listen to songs. So I think I am ok whether or not I will get DD5.1 from games.

    Can you suggest some inexpensive receiver which can decode DD/DTS for me?

    I found a DDTS-100 on amazon but it cost me about 330USD which is too expensive for me. Besides, it is used and not even brand new. And I could not find any on craigslist.

    Do you think this one works?
    Or you think the one I listed before is better?

    How much for your Denon Reciever? And where can I get one?

    I once had a bootcamp, but I rarely boot into it and I delete it at the end.
    I think I will just stick with the Mac OSX. I admit that there are few advantages of using bootcamp though.
  7. Sharangad, Aug 14, 2012
    Last edited: Aug 14, 2012

    Sharangad macrumors member

    Oct 19, 2008
    The device you listed: http://www.amazon.com/Digital-Analog-Audio-Decoder-Converter/dp/B0057UNPVO/

    is in effect a mini-receiver without an amplifier. The difference between it and a proper receiver is that it comes with mini-plug connectors for PC (surround) speakers like your Creative's which have their own amplifier built in.

    An actual receiver would require you to have some proper hi-fi connectors (terminals) instead of mini-plugs and would provide an already amplified output. The speakers wouldn't have their own amplifier. You wouldn't be able to connect hi-fi speakers (real speakers) to the mini-receiver above). However Creative's amplifier integrated speakers will work with the 'mini-receiver'.

    THis is what a real receiver will use to connect to speakers:


    The mini-receiver comes with three of these (what your Creatives need):

    So it would work.

    The device has connectors like these:


    So it accepts a pre-encoded surround signal via optical/coax and outputs 3 analog mini-plug outputs.

    It wouldn't work for games. However I'm not sure the Griffin Firewave will work for DVDs unless Apple DVD/VLC can decode to 5.1 channel outputs as I suspect the Griffin will present 3 stereo (5.1 channel) PCM outputs. I'm not sure it'll have a DD/DTS decoder and have a pseudo-SPDIF (optial/coax) port to which the Apple DVD player can bitstream the raw DD. Apple DVD player and VLC do have DD (and DTS in VLCs case) decoders and on Windows VLC can output 5.1 channel PCM (3 x stereo). But I don't know whether the OS X versions can decode to anything higher than stereo (Front L-R). They should both be able to bitstream (send the raw optical/coax DD/DTS) data to a suitable optical output. If the Griffin has a bogus SPDIF port which it presents to OS X for Apple DVD to bitstream to and a suitable decoder built in you should be okay. Whether it does this is not know to me.

    The Firewave review here states that an app that comes with it supports Dolby processing, but I'm not sure that the refers to decoding DVDs or simply upmixing 2 channel signals (i.e. music/stereo videos) into 5.1 using Dolby Prologic II upmixing.

    The review over here does state that DVD playback works in surround. If that is the case Firewave would be your best bet as it supports amplified speakers and can support games (and possibly) DVDs.

    Perhaps someone who has one can comment.
  8. hochun0809 thread starter macrumors newbie

    Aug 13, 2012
    what I am gonna do now

    Well Thank you for this detail explanation.
    I think what I will do is go look for Griffin Firewave and try it.
    I found one on ebay but I am not sure if I can take it down.
    It already goes up to 60usd

    If it goes too far from my bugget, I think I will go get a DAC(mini-receiver) from amazon. Although some comment on those DAC from amazon said that it cannot process DD/DTS signal and they just output stereo.
    Is there anyway to make sure that what I get can really decode surround sound? Do you have any suggestion?
    What about this one?
  9. Wardenski, Aug 15, 2012
    Last edited: Aug 15, 2012

    Wardenski macrumors 6502

    Jan 22, 2012
    It was about £350 but its a proper AV reciever, its big, its an old model (AVR 1910) now but the new versions can be bought from most Hi-fi retailers.

    Given those reviews on Amazon I would avoid those types of products (option 3). They seem to be the same device but with a different logo on it.
  10. Sharangad macrumors member

    Oct 19, 2008
    I don't know how well any of these mini-decoder/DAC boxes would work. Since they're relatively cheap their decoding capabilities probably won't match that of a proper receiver. A receiver could have room correction and dynamic range controls (Late night/normal/full range). However that would cost more and you would need proper speakers to go with them. I think even the DDTS-100 had some issues with decoding midstream (you had to turn it off and on again or you got static sometimes).

    I suspect the Griffin being a bonafide Mac product will suit your needs perfectly. However, I have never used one and can't really comment on either of them.

    I have used AVRs (receivers) and they work really well unless you're dealing with HDMI switching (but you wouldn't be), in which case sometimes (though not always) things can get a bit iffy.

    Can you link to the comment where surround decoding didn't work and the user got stereo? I don't think the decoding would be that bad (i.e. stereo downmix). There's probably a switch somewhere on the DAC to indicate how many speakers you've got (2.0/4.0/5.1, the usual speaker configs for PC speakers, though these days they're just 2.0 or 5.1). Alternatively its possible he/she was playing back a stereo source or had their output device set to downmix to stereo instead of encoding to DD/DTS. An xbox 360 has settings to configure it to output 5.1 instead of stereo and it will default to stereo. A PS3 has a myriad of output options ranging including both DD and DTS IIRC. It too will default to stereo unless configured otherwise.

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