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419 Views 7 Replies Latest reply: Jun 26, 2012 5:46 PM by audiotaxi RSS
audiotaxi Just Startin'
audiotaxi
4 posts since
Jul 17, 43467
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Apr 6, 2012 10:37 AM

M9 making my FX loop squeal

Hi all

 

I have an M9, which I've been running into a Boogie Mk5 with no issues.

I've now switched to a Marshall JVM, and in both the serial AND parallel loops, when the loop is engaged, there's a horrendous squealing until it's disengaged.

 

In troubleshooting, I've tried the following:

 

Line level (+4dB)  and instrument level -10dB  settings both tried.   Same result.

 

Mix control in parallel loop at various settings- same result.

 

patch cable only in FX loop to see if loop driver tube bad- no whistling.

 

So I'm thinking there's something about the M9's signal the JVM isn't liking. I've seen people using an M5 at least with the JVM, and having no issues.

Am I being dumb, and missing an output level setting on the M9 that may make the signal less hot? It's the only thing I can think of that could be causing this..

  • audiotaxi Just Startin'
    audiotaxi
    4 posts since
    Jul 17, 43467
    Currently Being Moderated
    Apr 10, 2012 8:16 AM (in response to audiotaxi)
    Re: M9 making my FX loop squeal

    anyone?   I'm sure this has to do with the M9 output signal.   When I turn down the "mix" on the digital delay, all the noise goes away.  (along with the effect obviously)

    • Kneehow UberGuru
      Kneehow
      6,750 posts since
      Dec 26, 2007
      Currently Being Moderated
      May 23, 2012 5:48 PM (in response to audiotaxi)
      Re: M9 making my FX loop squeal

      Does this squeal exist with other effect models? For example... a Modulation type? You'll most likely want to be driving the signal of the effect loop of the Marshall at "Pedal" level, as most tube amps Line level signal is too hot and may clip/overload the M9's input circuit components.

      • sturge Just Startin'
        sturge
        50 posts since
        Jan 28, 2007
        Currently Being Moderated
        May 23, 2012 6:57 PM (in response to Kneehow)
        Re: M9 making my FX loop squeal

        I noticed the same thing with my M13 in the effects loop tonight.  I put it in front of the amp and it went away but the 4cm made it squeal like crazy, even without effects engaged.  What gives?  Can it be a cable problem or is it a unit problem?

        • Kneehow UberGuru
          Kneehow
          6,750 posts since
          Dec 26, 2007
          Currently Being Moderated
          May 25, 2012 2:50 PM (in response to sturge)
          Re: M9 making my FX loop squeal

          Probably that the amp's effects send signal level is just too hot. When you run the M series pedals before an amp's input, those effects are processing an instrument level signal (your guitar or bass).

           

          Inserting a hotter (usually line-level) signal from an amp's effect loop will introduce a higher signal that could cause clipping, the noise floor of the signal is increased (more hiss/noise) and sometimes undesirable hum/buzzes can be introduced.

           

          The "Stompbox" Modellers (as they labelled) are really modelling effects that were traditionally placed *before* the amp's input... like you would with most pedal effects.

      • audiotaxi Just Startin'
        audiotaxi
        4 posts since
        Jul 17, 43467
        Currently Being Moderated
        Jun 26, 2012 5:46 PM (in response to Kneehow)
        Re: M9 making my FX loop squeal

        Sorry guys, I missed the updates on this thread. So, to answer peranomoly's question it happens on all types of effect. When in bypass, no whistling- as soon as an effect is activated- bang, not even an ISP decimator will shut it up.

        It seems like the overloading the input answer is probably valid, as there is no problem with the JVM' clean/crunch channel, or even Overdrive "green" mode. But this problem only rears it's head on orange and red modes, where the monster gain lives. So the output must simply be too hot for the M9. Like I siad in the OP, there is a -10db instrument level pad, but it doesn't make a jot of difference to the whistling.

         

        Curiously, it didn't happen when I had a Boogie Mk5, so clearly the signal wasn't as hot (or better designed).

        Its a real shame, as I love the M9's features, and really wanted to run it for delay and chorus in the loop.

         

        Interestingly, I tried a TC Flashback delay in the loop, and no such issue. Could it be that simply has more input headroom?

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