Audio only from two speakers

Discussion in 'Mac Accessories' started by Jazzimac, May 6, 2008.

  1. Jazzimac macrumors newbie

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    Jan 6, 2008
    Location:
    Queensland, Australia
    #1
    I have had my external speakers installed on my mac for the last 4.5 amonths and all has been working fine. I have external speakers connected via the headphone jack on the back of the screen. The speakers are logitech 5.1 surround sound. I have had sound through all speakers for my DVDs, CDs and itunes, without fail. Until this week. Now for some reason I am only getting sound through two speakers. I have checked my System Preferences>Sound, and the only option for audio output is Headphones, which has never been any different. ( I gather I don't have the 'external speakers' option, because they are connected using the headphone jack).

    All my updates are up to date.
    I hope you can help as this has a huge impact on the sound quality, and is extra frustrating as it has been working fine.

    Thank you.


    Model Name. iMac
    Model Identifier: iMac7,1
    Processor Name: Intel Core 2 Duo
    Processor Speed: 2.4 GHz
    Number Of Processors: 1
    Total Number Of Cores: 2
    L2 Cache: 4 MB
    Memory: 1 GB
    Bus Speed: 800 MHz
    Space left on HD 250GB
    Mac OS 10.5.2
     
  2. Icaras macrumors 603

    Icaras

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    Mar 18, 2008
    Location:
    California, United States
    #2
    This has nothing to do with the OS preferences. My guess is you must have accidentally switched the modes on your sound system to 6 channel direct or stereo. Double check the sound processing effect that is currently active on your 5.1 system receiver. Because unless your simply using a straight minjack to minijack connection from imac to external sound, the only way surround sound is achieved is via a matrixed algorithm effect such as Dolby Pro Logic II which processes two channel input into 5 channel output.

    5.1 is a crazy thing on macs i tell you!
     
  3. Jazzimac thread starter macrumors newbie

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    #3
    Thank you so much Icarus. I consider myself quite computer savvy, but not speaker/stereo savvy. Your advice was spot on and we just had to work out how to change it to the Pro Logic. Thanks for your prompt response, and for making my day.
     
  4. Jazzimac thread starter macrumors newbie

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    #5
    Unfortunately I have the same problem again. The other night when we fixed it, we didn't realize what sequence of buttons we'd used to fix it - so we can't replicate the solution. We can't seem to set Pro Logic II on it again. I don't know why the setting was 'undone'. The only thing I can think of is that there was another update during the week,and that it's done something....... Very frustrating, as it's Mothers Day and I have set up a great playlist for myself, and it sounds like it's coming out of two tinny speakers, instead of all of them. Any suggestions would be gratefully accepted and tried out.
     
  5. Pili macrumors regular

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    Nov 1, 2005
    Location:
    Orlando/Miami, FL
    #6
    If they are the z5500s then just hit the "effect" button on the receiver until you see pro logic II movie/music.

    I'm assuming that your just using a standard 3.5mm audio cable for audio which means the speakers are using pro logic II to replicate or "guess" what sound goes to which speaker. If you want true surround sound, I would take advantage of the digital audio out from the imac with a mini-toslink to toslink adapter and a optical audio cable to the logitechs. Then you will have better quality audio with true surround sound as long as its prerecorded (aka dvd's, not games).
     
  6. apfhex macrumors 68030

    apfhex

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    Aug 8, 2006
    Location:
    Northern California
    #7
    You beat me to it — the "headphone" jack on the iMac doubles as a digital optical port which is definitely what you want to use with the Z5500's. It's a waste of those speakers to not use real digital surround (and IIRC you can still use the PLII effect mode when listening to stereo music and such).
     
  7. Pili macrumors regular

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    #8
    Yes, you can still use PLII with the digital input. I have stereo out from my tv to the z5500s with digital out and use PLII for the standard cable. Whats nice is that it automatically recognizes dolby digital and switches to surround with hd programming so you dont have to switch the effect every time.
     
  8. Jazzimac thread starter macrumors newbie

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    #9
    Thank you guys for responding. I have further questions for you.

    Is the mini toslink to toslink adapter something which goes in between the audio optical cable. I have been looking at pictures on the 'net and can't work out where both of these cables actually go. I don't have a mac store closeby, so would really like to know exactly what I need so I can order it online. I just want to clarify that I need two things, and that only one of them plugs into the imac.

    Thanks again, and I look forward to your replies.
     
  9. Icaras macrumors 603

    Icaras

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    Location:
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    #10
    Hey jazz, sorry to hear you were having issues again. The adapter you're look for is this: http://www.amazon.com/TOSLINK-TO-OPTICAL-MINI-ADAPTER/dp/B0002MQGRM/ref=pd_bbs_sr_1?ie=UTF8&s=electronics&qid=1210615449&sr=8-1. You just need one of these puppies, and you stick it the end that goes into your mac's digital out.

    I actually just recieved mine in the mail over the weekend. These things are so small and well made! This is all you need :cool:
     
  10. Jazzimac thread starter macrumors newbie

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    #11
    Thanks Icarus, so that means I don't need anything for the logitech end?

    Now I am off to find one locally (Australia) - thanks again for your assistance.
     
  11. Icaras macrumors 603

    Icaras

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    #12
    You have the 5500s, right? If so, you have a standard toslink optical input, so all you would need is one adapter (for the mac end). Goodluck! :cool:
     
  12. Jazzimac thread starter macrumors newbie

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    #13
    They are the z5400 Digital - I think the equivalent US model is the z5500s from what I have read. I am heading off to a large electronics store on the weekend, and I will pick up the adapter then. I will let you know how I fare.

    Thank you.
     
  13. Icaras macrumors 603

    Icaras

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    #14
    Sounds good. But you know, Pili is actually right. You just need to hit the effect button a few times to ge to DPLII. And the thing with DPLII, it will process ANY stereo source that you feed into it into 5.1, so it makes no difference if you were to use the optical adapter, especially if your just listening to music. In other words, with the current setup you have now, if the desired effect is simply sound output in 5.1, all you would need is simply to set your reciever to DPLII. No optical cable or adapter needed.

    However, using an optical cable and adapter will yield you "proper" 5.1 surround sound in DVD playback (Dolby Digital, DTS), which is definitely recommended if that is one of the applications you intend to use your speakers for, because when your Logitech reciever recieves the digital signal (via the optical cable), it will automatically digitally decode the bitstream for you, in whatever audio format the disc, or source, that was originally encoded at (DD/DTS).

    And of course with the optical cable, you can still set your reciever to DPLII for your music. And since you can probably find an optical cable for around $30, its all up to you.

    One thing to note: once you have your mac connected digitally, you lose OSX's software control on the volume. Meaning you can only control the volume via your Logitech reciever. Kinda bummed me out at first but i'm over it. :cool:
     
  14. Pili macrumors regular

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    #15
    That remote is a godsend :D
     
  15. Jazzimac thread starter macrumors newbie

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    #16
    That just brings me back to my problem though - I toggle to PLII Music and I get nothing at all through my speakers.....

    Does this mean I am back to square 1?
     
  16. Icaras macrumors 603

    Icaras

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    #17
    You mean nothing at all from any speaker? Are you sure your input is set to "Direct"? So you mean your sound is fine when you are not using DPLII, but once you switch it, all sound goes off?
     
  17. apfhex macrumors 68030

    apfhex

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    #18
    Are you using the correct input? Did you get a digital optical (toslink) cable? Make sure it's on "Optical" instead of "Direct" (or if you're still using direct, make sure it's on the right one as the speakers have 3 separate direct inputs).
     
  18. Jazzimac thread starter macrumors newbie

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    #19
    Okay guys, I am getting confused.

    I don't have the toslink cable yet, will get it on the weekend.

    The speakers are currently set to Input>direct and 6 Channel direct and the music is only coming thought the subwoofer and the back speakers. If I set the effect to Prologic II Music it comes out of no speakers at all.

    I just want to clarify things - I am presuming that I still need the toslink cable, but Icarus, you suggest that I should be able to get it to work now - am I understanding you correctly?

    Thanks again for your help with this.
     
  19. Icaras macrumors 603

    Icaras

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    #20
    Yea, you never needed the toslink cable to get surround. You had surround working before, right? Rear speakers and subwoofer is odd though. Never heard of that one before lol.

    Well me and Aphex are suggesting the same thing, and thats to just make sure your receiver is set to the correct input. Now just go down the checklist of troubleshooting at this point.

    First, double check to make sure your mac is going into the Logitech's FRONT SPEAKERS input. It is the first of the three inputs needed of 6 channel direct. Then if you have a LEVEL button, toggle through the levels of each and every channel on your receiver, double checking that all speaker volumes are dead center.

    And I know this sounds silly, but double check to make sure your mini jack cable is inserted ALL the way in. Since you're using a stereo jack, it has two rings on its connector, one for mono, and one for stereo. If you only have it inserted to the first ring, you'll only get mono sound. So make sure thats secure.

    Other than that, I can only suggest you double check the wiring on your speakers though I doubt tinkered with them.

    Hope this helps....
     
  20. Jazzimac thread starter macrumors newbie

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    #21

    Checked that plug goes into front speakers on receiver, and now the front speakers work and not the rear ones (plus subwoofer) I have also checked all the volume levels and they are all in the centre.

    Jack is pushed in all the way into rear of imac

    I haven't done any changes to the speakers' wiring. Testing through the receiver shows that all speakers are working, so it's something in the communication from imac to logitechs.

    What do I do now? So the toslink cable isn't needed?

    It still baffles me, as to how come it worked for a few days and then stopped again.
     
  21. Icaras macrumors 603

    Icaras

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    #22
    Yea I'm baffled too. What was the last thing you remember doing before everything went wonky? Ok well at least your front speakers work, but not the subwoofer? Not at all? Still strange. And one last check: Your input is DIRECT and you've tried setting DPLII mode, and still no luck? For some reason I feel like that the problem is probably something really simple and small and it might be just one of those things that we've simply overlooked.

    You have an ipod or cd player? Try using the mac end of the cable and connecting it to the headphone output on a portable device of some sort, and see if you still can't achieve surround sound with DPLII selected. Not sure why I am suggesting this, but I'm running out of ideas too lol.

    And yes, the toslink cable is not needed for surround sound in music. You only need it if you want proper surround sound in movies, in which case, toslink is absolutely recommended. You don't want to get a Dolby Digital or DTS movie and process it in DPLII. Its going to sound completely unnatural and not the way it was intended to be listened to.
     
  22. Jazzimac thread starter macrumors newbie

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    #23
    Hi Icarus and apfex.......

    It's with great disbelief that I report, the problem is fixed! Like you Icarus, I knew it had to be something simple, although I am still baffled and don't comprehend exactly what happened.

    I got the receiver and changed the plugs around, and ended up with the black plug in the green hole (don't you love my technical explanation :D) Now all the effects are options and can be chosen, where before only one effect worked!! I still don't understand how settings and plugs could have changed, as I am the only one who uses this computer and I know I haven't touched it.My husband confirms that we had the black plug in the black input thingy.........so as I was limited with what I could actually change, I just started pulling plugs out and moving them around.......

    I had a response from Logitech this morning, and she told me to ensure that the green plug was plugged in, but that didn't work, so I started playing around in earnest - I couldn't stuff it up anymore.

    Thanks so much for persisting with me, it's helped knowing someone else was interested......:)
     
  23. apfhex macrumors 68030

    apfhex

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    #24
    I forgot that there is a physical switch on the back that switches between "Direct" and "6-channel Direct". The former allows you use any of the 3 direct inputs for stereo speakers and you can toggle between Direct 1, 2, 3. The latter, 6-channel direct, is for analogue surround sound speakers that use the 3 inputs together (front, rear, and subwoofer).

    Using Direct (analogue) input you can only get simulated surround sound using the ProLogic effect mode. While it's not bad, the difference between that and true surround sound is very noticeable (much more discrete).
     

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