Get iPod to play through mixer

Discussion in 'Tracking / Mixing / Editing' started by Guitarfreak, Apr 16, 2009.

  1. Guitarfreak

    Guitarfreak Well-Known Member

    I'm in charge of AV for a final presentation at my college and I need to be able to play my iPod through a mixer. I have an aux cable but when I plug it into the mixer the songs come out in mono. I believe it is a mackie onyx of some sort. Not sure of a particular model as it seems to be an older one.
     
  2. Codemonkey

    Codemonkey Well-Known Member

    Maybe the playback is in mono...

    Knowing the output setup would help although this is probably beyond you (not in a bad way, but most places won't inform their students on the audio system, except where to plug it in and turn it on).
     
  3. Guitarfreak

    Guitarfreak Well-Known Member

    I experimented for almost a half hour before I got it to work. I had to run two channels, using an rca splitter then going back to 1/4". And even then I didn't even get any signal at all. It finally worked if you don't put the connectors all the way in for some reason, but even then the connection was intermittent. Could it be just a bad mixer? I was hoping there was an easier way to do this.
     
  4. djmukilteo

    djmukilteo Well-Known Member

    GF:
    Get a 1/4" mini stereo headphone jack to L/R RCA male...(Radio Shack)...use the headphone output jack from your iPod...hookup the RCA's to the Aux In L/R channel (red/white) on top of or back of the Mackie....should be stereo at the mains out...use the headphone jack on the Mackie to monitor and check your levels...
     
  5. dvdhawk

    dvdhawk Well-Known Member

    Which cables are 3 conductor TRS type?

    The 1/8" mini plugged into the iPod should be TRS. The two 1/4" males you're plugging into the mixer should not be - they should be just 2 conductor TS.
     
  6. djmukilteo

    djmukilteo Well-Known Member

    Sorry about that.....I meant 1/8" mini jack at the ipod my bad
    also the mackies use TRS on there 1/4" channel inputs balanced but if you plug in 1/4" TS they become unbalanced...I would use the RCA Aux input though...they always have those on their mixers for things like tape decks etc..already a line level going in....should work just fine
     
  7. Guitarfreak

    Guitarfreak Well-Known Member

    Yeah man, The first thing I tried was a mini-mini cable (TRS) and a 1/4" adaptor (Also TRS) and plugging it into the AUX input, it's not RCA but... DHawk, do I need to have a 1/8" TRS split going into to two TS 1/4"? because at this point I do not. Are there ways around it?
     
  8. dvdhawk

    dvdhawk Well-Known Member

    You could use a Y-cable that goes from stereo mini 1/8" TRS to two RCA males if your mixer has the RCA inputs. If the mixer doesn't have RCA inputs you could use that same cable and add two adaptors that go from female RCA to 1/4" TS male. There are obviously better ways to do this, but I'm trying to think of how you could solve this with a quick and relatively cheap trip to the Shack.

    http://www.radioshack.com/product/index.jsp?productId=2103865

    http://www.radioshack.com/product/index.jsp?productId=2062455

    Your iPod is sending the right channel audio on the Tip

    It is sending the left channel audio on the Ring

    And they also share a common ground on the Sleeve [X-shield].



    Here's the explanation if you want to understand why TRS to TRS didn't work.

    The input of the mixer automatically senses whether you're using a TS or TRS 1/4" plugs. And when you use a TRS it assumes you are sending it a balanced signal (the 1/4" version of an XLR).

    In an XLR the pin out is right in the name:
    Pin 1 is the ground or shield [X-shield]
    Pin 2 is the Line, or normal phase of the audio [+] [Line]
    Pin 3 is the identical audio signal with the phase Reversed [-] [Reverse]

    With a TRS balanced 1/4":
    The Tip provides a normal line audio signal [+].
    The Ring provides the identical audio signal with the phase Reversed [-].
    The Sleeve is the common ground or shield they share (X).


    A standard TS 1/4"
    The Tip provides a normal line audio signal [+].
    The Sleeve is the ground or shield (X).

    Your TRS 1/8" to TRS 1/4" was processing the right channel normally, but simultaneously sending the left audio channel to the part of the mixer that inverts the signal. And when the channel combines the in-phase and out-of-phase signals anything they have in common (equal and opposite) is effectively cancelled out. The only sound that gets through are the things panned out of center.

    This also explains why when you unplug it halfway and just the Tip of the connector is making contact with the Ring contact inside the mixer, you will get sound. The signal is out-of-phase - and you're losing the left channel, but you will have sound.


    If you plug in a mono TS 1/4" plug it physically connects the Ring to the Sleeve, the mixer senses this as an unbalanced signal and deals with it.

    NOTE* TRS 1/4" headphones - are wired like the iPod phones shown above T= Right / R= Left / S=Shield)
    TRS Insert cables are a Y-cable that go from the TRS insert to two TS cables, allowing the insert jack to simultaneously be used as an effects send and return.


    So as I've been telling people for years, "Just because it fits in the hole - doesn't mean it's the right connector."


    Hopefully that all makes sense. If not, I'll have to bust out the illustrations.

    Good luck!​
     
  9. TheJackAttack

    TheJackAttack Distinguished Member

    GuitarFreak- go to Amazon and invest in the Yamaha Sound Reinforcement Handbook. All this good stuff is in there and it is IMO one of the best sources of this type of info out there.

    http://www.amazon.com/dp/0881889008/?tag=recording.org-20

    You'll be glad you did in the long run. You are really enthusiastic which is good but your basics are pretty sketchy. I really don't intend that to sound anything other than as a helpful nudge.

    Other helpful hints for someone with a burgeoning interest or career: when someone posts a need specific wiring post or jpg I think might be relavent to me even if in some unforseen time in the future, I copy it into a file and stick it in a folder on my HD. These little bits of wisdom can help answer questions or lead to new avenues of investigation. It's all good.

    In the end, it's all just wires.
     
  10. djmukilteo

    djmukilteo Well-Known Member

    have to agree with JackAttack....you should too
     
  11. ouzo77

    ouzo77 Active Member

    Guitarfreak, you should get this cable and adapters dvdhawk mentioned and plug them into two channels of the mixer. pan them left and right. that should work!
     
  12. Guitarfreak

    Guitarfreak Well-Known Member

    Thanks DHawk, that actually explained a lot. I'm still confused why when the phase is changed back it cancels out the center, but this does not happen with XLR even though the same process is present. But I will look up the book. Thank you everyone.

    P.S. I just remembered I have that exact connector in my basement for plugging my iPod into the stereo for working out..however rarely that occurs. It didn't even occur to me because I thought a stereo and mixer would be different animals, but when it comes down to it signal is signal isn't it? lol
     
  13. TheJackAttack

    TheJackAttack Distinguished Member

    Your iPod headphone feed is NOT a balanced signal. I think this is where you are confused. The connector looks like a balanced signal but that is erroneous. Your headphones are just combining two independent signal lines with a common ground so there is no true out-of-phase signal.

    If you plug those TRS/TS plugs half way in to the jacks you are getting two channels of right side-no left whatsoever. (in your original scenario-dvdhawk's explanation is quite clear and cogent)

    edit: oops, dvdhawk's explanation.
     
  14. Guitarfreak

    Guitarfreak Well-Known Member

    Wow, see now it's a thread like this that makes me question everything I've been told. That's one thing about listening to people cause they're all full of $*^t. Let me reach for an understanding here. Is the iPod sending L and R instead of phase + and phase -? And the mixer taking the L and sending it and getting lost somewhere, then copying the R over to the left output and that's why the center gets cancelled out?
     
  15. jg49

    jg49 Well-Known Member

    Two seperate ideas the first "Is the iPod sending L and R instead of phase + and phase -? " The answer is yes, left and right, common ground using TRS connectors.

    Plus, minus phase from the 1/8" jack on the Ipod? NO.

    As far as your next idea, not sure but this convoluted thought probably not, especially the idea that the mixer is copying anything. Mixers route like highways or train yards, not record so can't truly copy.
     
  16. TheJackAttack

    TheJackAttack Distinguished Member

    If you are splitting TRS-->2 TRS then the tip of both of the down stream pair are still right channel. The ring is still both left channel and the sleeve is common ground.

    A true TRS-->2 TS adapter has the original T->right side T (of the TS) and the orignal R->left side T (of the TS) and the sleeve of all three plugs connected.

    edit:
    There is no phase to flip unless you manually press a phase switch on the mixer.
     
  17. dvdhawk

    dvdhawk Well-Known Member

    I think you're heading in the right direction. Here are some generalizations that might help you get a handle on this.

    What you have to understand is that there are two amps in that first stage of the pre-amp of a mixer. That single TRS or XLR connector you're plugging into goes to both amps - one normal amp and one inverting amp. Before it gets down to the business of amplifying the signal, the mixer wants to clean it up first.

    If you're sending it any balanced signal;

    the Tip of a TRS or Pin2 of an XLR carry the normal signal in the correct phase [+] to the normal amp.
    the Ring of a TRS or Pin3 of an XLR carry the identical signal with the phase reversed [-] to the inverting amp.
    the Sleeve of the TRS or Pin1 of an XLR send the shield wire(s) to ground [X] draining off most of the interference.


    A concept called Common Mode Noise Reduction is the reason they go through all the trouble to reverse the phase. Two identical signals out of phase with one another cancel each other out and become inaudible and the circuit designers use that to their advantage to cancel out noise that would bleed through the shielding and otherwise show up in your audio. The shield can get rid of a lot of the potential interference, but not all of it.

    Typically you might have a 30ft. mic cable into a 100ft. snake with potential for noise every foot of the way. Any length of wire is a potential radio antenna. Interference from high-voltage electrical cables, radio signals, etc. would all get through the shield and pollute your audio - if it weren't for the genius who thought up the balanced concept. How many electrical cables does your mic cable cross, or lay parallel to before it gets to the snake? How many electrical cables does your snake pass on the way to your mixer?

    Simply by inverting the Pin3 signal at the source and flipping it back to normal at the mixer you can eliminate virtually 100% of that stray noise picked up by that 130ft. of cable. The two conductors are run side by side within the cable and would be exposed to the exact same noise issues. When the two signals reach the mixer, the normal Pin2 signal is left alone and the Pin3 signal is flipped back to normal and combined with the normal Pin2 signal. But any noise that got through the cable's shield now would cancel itself out, because it would have been present in both conductors in the same phase. And by flipping the Pin3 conductor with the inverting amp and summing it with an identical noise that is now in the opposite phase - presto the noise disappears. I wouldn't say it goes away, but it becomes inaudible. Another victory for science!


    The mixer assumes you are giving it a balanced signal when you use a TRS plug and the inverting amp does it's thing. So, what was happening with your first cable, the Right channel stayed normal, the Left channel got flipped and anything they had in common got cancelled when the channel summed them together.

    The resulting audio just sounds weird, because anything in the recording that is panned down the center (lead vocal, kick drum, bass guitar, etc.) gets cancelled and all you're left with are things that might sit wider in the mix (guitars, keys, background vocals, etc.). And since nearly all effects these days are stereo, you can still hear the reverb of the lead vocal - but the original dry vocal is gone. (Yes, that's how most vocal eliminators work.)

    Anyway, probably more than you needed to know at this point - but it might be helpful to the next person who stumbles across this thread.
     
  18. Guitarfreak

    Guitarfreak Well-Known Member

    Dude, that's sweet. Awesome thanks DH.
     
  19. djmukilteo

    djmukilteo Well-Known Member

    your making it more complicated than it is...
    iPod headphone to RCA adapter....use the RCA Aux in (Tape in) on the mixer which is already L and R and your there....get the adapter DVDHawk and ouzo77 linked at Radio Shack...
     
  20. dvdhawk

    dvdhawk Well-Known Member

    I know. It seemed like he was open to some skoolin'.

    I think it's in the Bible -
    Give a man a Radio Shack adaptor cable he makes music for one day.
    Teach a man why Radio Shack adaptor cables can still screw you up just as bad if you don't know whether you're going TRS or TS because the person working there sure as heck won't know - and he'll make music for a lifetime.
     

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