Robot sound with the irig with iphone 3gs

edited February 2012 in Equipment
Hi everybody,
I have been waiting a lot before writing this message, trying to solve the problem by my self but it seems like I can't.
I'm using loopy with my iphone 3gs, and irig and a sm-58 mic of Shure with a impendance matcher audion technica 1201.
Whereever I go (I mean no matter the amplificater or the soundsytem, I have my loops that sound "metalic" or robot like. It seems to happen when there are many of them.
It's not the irig because I changed it to verify. And it's not doing it when I'm talking or beatboxing in the mic live. It's the recorded sounds that does it.
Does something like this happened to any of you?
Thank you some much in advance (it can be a funny effect but it's not what I want the people to hear...)


  • Hey @coadjuteur - Does this happen in any other apps, like the Voice Memos app?
  • Hi Michael,
    As always, thank you for coming back fast.
    No it doesn't do it with other apps. I tried the same rig with italk and Vocal Live and none of that robotic echo...
    It's strange because it's what's recorded that does that. The live input of my voice through the mic is not affected. It's really a problem right now.
    The other thing is that when I use the phone's mic, it never does it.This is when I thought the problem was related with my irig device (because when I use the phone's mic, I just use the regular output of the phone. But again, I bought a new device to verify that and that aspect remained.
    Can you help?
    Thank you so much for
  • This is very weird!
    I have to say I'm a bit baffled right now, but perhaps something will come to me. In the meantime, would you mind emailing me a sample? (support at atastypixel dot com) - something that contains some complex sound (speech, or something) and then as pure a tone as you can produce (perhaps a whistle?), and then some impulse noises (clicks - perhaps tap the desk with your fingernail a few times), so I can see what the waveform looks like.
  • I am having the same issue with Loopy and the Tascam iXZ/Ipad2. Very tinny almost robotic sound with line-in devices.
  • Thanks heaps for the audio samples, @coadjuteur! That was very helpful - my diagnosis: You're just getting echo from the speaker. It sounds robotic because it's phasing a bit (phasing is what happens when you combine a signal with a slightly delayed version of itself, which causes constructive and destructive interference in ways that affect various harmonics in the signal).

    Here's what your clicks look like:

    You can see the echoes, about 17ms apart. Once you turned down the volume of the iPhone, your claps looked like this:

    You can see the echoes are gone (and accordingly, the sound is fine again).

    So, this is a hardware/studio setup problem - you'll need to find some way to reject the output audio from the input signal. I'm not a professional audio engineer, but my understand is that the usual solution is to use a microphone with an envelope that rejects all audio except that right in front of it. Or, of course, to use headphones (unless the problem is due to cross-talk in your audio cables, where the output signal induces a copy of itself in the input path).

    There are software solutions to this as well - primarily, echo removal by autocorrelation and signal subtraction, but I've found that iOS devices aren't yet powerful enough to do this with good results for music, so it's not yet viable for Loopy, as far as I can tell.
  • edited March 2012
    Hi Michael (and whoever is following this and can help),
    Thanks for the diagnosis.
    It is weird though since I'm using a sm-58 cardioid mic (unidirectionnal) and that I'm pointing the speakers in another direction, and as you already know I don't have much power.
    Anyway, you are probably right I guess. But thenI have a new problem now: I have no power, no volume, no gain...
    The phone is maximum volume;
    The amp is max volume
    And the final result is very low: it just enough for people being around the speakers. I need to hear more. I will transfer this new problem to another discussion then. Thank you so much Michael.
    P.s. I did transfer the problem to another discussion and somebody suggested that it requieres a pre amp between the mic and the irig (and loopy).
  • Hey Michael, when I use loopy with irig on my headphones..the output goes back to every channel as input..with low volumes there isn't much phasing issues..but even the metronome gets looped..any solutions? I just got my irig from rediff on a huge discount..could this be a fake irig hence the issue or if there's anything better then I can still return the irig. Thanks!

  • I'm having this problem but I'm plugging my guitar directly into my iRig, no microphone in the chain. Michael, I don't think this is an echo from the speaker since I'm playing direct. Any idea what could be causing this and how I might solve it?

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