Question about M-Audio Omni problem

Discussion in 'rec.audio.pro' started by TNKS, Sep 2, 2003.

  1. TNKS

    TNKS Guest

    Hello,

    I have a problem involving a balanced signal and my M-Audio Omni Studio.

    I've been using the Omni Studio for a few months now. For the most part,
    I've been happy with it. The basic layout of the Omni is two inputs, Lines
    1 and 2, with kind of non-so-impressive pre-amps. . . and two inputs without
    pre's, Lines 3 and 4.

    I have a stand-alone pre-amp has a convenient knob that lets me output
    either a mic-level signal or a line-level signal over the balanced XLR
    output. When I run a balanced mic-level signal to the XLR inputs of either
    Line 1 or 2's pre-amp, everything sounds sort of fine. However, when I run
    a balanced line-level signal through the TRS jacks of either Line 3 or 4, I
    get a considerable loss of bass signal among other tonal-differences (I'm
    recording a bass guitar). It really sounds to me like the Omni isn't
    handling the balanced signal correctly and there's inappropriate signal
    cancellations going on.

    Does anyone know what might be going on with Lines 3 and 4? I recorded the
    balanced output of my pre-amp as a stereo signal, and its output looks good,
    with the appropriate phase-shift between the two signals, so I'm assuming
    the problem is with the Omni. I really don't like the idea of going through
    the pre-amps of Lines 1 or 2. It's just adds noise and colors my signal
    unnecessarily. I bought the Omni with the idea that I would seriously put
    at least three of the lines to use.

    Is there any reason to believe that M-Audio paid more attention in designing
    the main lines of the Omni, and neglected inputs less likely to be used? If
    so, what other audio interfaces might someone recommend. I like the fact
    that units like the Omni have convenient montoring outputs, like phone outs.
    How do the Aardvark audio interfaces compare to M-Audio's? Aardvark seems
    to pride itself on it's noise-prevention, and that caught my attention. I'm
    looking for something that offers a similar configuration to the Omni, but
    without this balanced problem, maybe better ADCs, less noise, and more
    dynamic range couldn't hurt. I'm willing to spend a few more hundred
    dollars for such an upgrade, but I don't think it would be wise to buy a
    unit with many more than 4 input channels. I'm really open to any
    suggestions as far as recommendations are concerned.

    This is kind of a first pass questioning of this problem. I'll probably end
    up refining my questions as I have more discussions.

    Thanks for reading this post, and thanks in advance for those that respond.

    -TNKS



    --
    Note: To reply to me personally, you'll have to remove the "NOSPAM." domain
    extension from the address I've supplied.
  2. Mike Rivers

    Mike Rivers Guest

    In article <zZV4b.6149$Lk5.561@newsread3.news.pas.earthlink.net> youlost@NOSPAM.earthlink.net writes:

    > I have a stand-alone pre-amp has a convenient knob that lets me output
    > either a mic-level signal or a line-level signal over the balanced XLR
    > output. When I run a balanced mic-level signal to the XLR inputs of either
    > Line 1 or 2's pre-amp, everything sounds sort of fine. However, when I run
    > a balanced line-level signal through the TRS jacks of either Line 3 or 4, I
    > get a considerable loss of bass signal among other tonal-differences (I'm
    > recording a bass guitar). It really sounds to me like the Omni isn't
    > handling the balanced signal correctly and there's inappropriate signal
    > cancellations going on.


    It's not a cancellation thing, but it might be a wiring thing. Did you
    build the cable that you're using to go from the preamp to the line
    inputs on the Omni? Or do you know how it's wired? Is it XLR-TRS, or
    XLR-TS? There are several possibilities for wiring a cable like this,
    none of them clearly standard, and some of which may be incorect for
    your particular set of outputs and inputs.

    Open up the connectors and see how it's wired.

    > Is there any reason to believe that M-Audio paid more attention in designing
    > the main lines of the Omni, and neglected inputs less likely to be used?


    No, other than that they probably put an additional stage of
    amplification on those that can accommodate microphones. It's possible
    that the "line" inputs aren't actually balanced, and that can affect
    certain balanced output configurations (but not others).



    --
    I'm really Mike Rivers - (mrivers@d-and-d.com)
  3. TNKS

    TNKS Guest

    > > I have a stand-alone pre-amp has a convenient knob that lets me output
    > > either a mic-level signal or a line-level signal over the balanced XLR
    > > output. When I run a balanced mic-level signal to the XLR inputs of

    either
    > > Line 1 or 2's pre-amp, everything sounds sort of fine. However, when I

    run
    > > a balanced line-level signal through the TRS jacks of either Line 3 or

    4, I
    > > get a considerable loss of bass signal among other tonal-differences

    (I'm
    > > recording a bass guitar). It really sounds to me like the Omni isn't
    > > handling the balanced signal correctly and there's inappropriate signal
    > > cancellations going on.

    >
    > It's not a cancellation thing, but it might be a wiring thing. Did you
    > build the cable that you're using to go from the preamp to the line
    > inputs on the Omni? Or do you know how it's wired? Is it XLR-TRS, or
    > XLR-TS? There are several possibilities for wiring a cable like this,
    > none of them clearly standard, and some of which may be incorect for
    > your particular set of outputs and inputs.
    >
    > Open up the connectors and see how it's wired.


    Hmm, the cable I'm using is a Monster Cable StudioLink 500 XLR-TRS
    interconnect. I just unscrewed the connectors off on both ends to see the
    wiring. It's as follows:

    Pin 1 -> Sleeve (looks to be a ground line)
    Pin 2 -> Tip (it's a white wire)
    Pin 3 -> Ring (it's a black wire)

    It's true that the A/B test I described above, my XLR-XLR cable was a Studio
    Pro 1000 cable (higher end). It's possible that I'm just noting the
    difference between the two cables. If that's the case, then I'm really
    impressed with the SP1000. But I'm not convinced that that's the case.


    Also, I'm still really interested in how people think the Aardvark 24/96
    matches up against the M-Audio Omni Studio. I just heard someone say that
    the ADCs are better in the M-Audio line. Anybody here have any opinions?


    Thanks,
    TNKS
  4. "TNKS" <youlost@NOSPAM.earthlink.net> wrote in message
    news:hTa5b.6348$tw6.5870@newsread4.news.pas.earthlink.net...
    > > > I have a stand-alone pre-amp has a convenient knob that lets me output
    > > > either a mic-level signal or a line-level signal over the balanced XLR
    > > > output. When I run a balanced mic-level signal to the XLR inputs of

    > either


    I've started noticing some screwy stuff on my Omni which I don't think acted
    like this before. (More noise, etc.) One thing I've been trying getting
    someone to confirm for me (but having no luck) is the fact that the Stereo
    Aux In's swap channels when used as recording inputs! When using them as
    monitors only they work one way and when you depress the switch to record
    them right and left are swapped! WTF?

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