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Effects loop problem

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by mightypudge, Nov 13, 2003.

  1. mightypudge

    mightypudge Member

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    When running my three Boss FX pedals in the effects loop pf my Duncan amp, I get a "motorboating" sound. I have tried replacing my cables, using batteries instead of my pedal board power supply, and reducing/increasing the effects loop send level, but nothing seems to help. I've also tried running only one pedal at a time hoping to isolate the problem to one specific pedal, but no dice.

    Anyone know what might be causing this?
     
  2. Mark C

    Mark C Member

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    Just a guess, but I think the loop is intended for rack gear operation at a different level than your pedals. Those pedals are designed to go in front of the amp. Maybe someone who knows more about this will chime in.
     
  3. John Phillips

    John Phillips Member

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    A quick thing to try - run a cable directly from the send to the return, with no pedals. If it still does it, you have a problem with the amp.

    If not, I'd guess the same as Mark - some kind of level mismatch. I can't provide much specific help on this one since that guy who had the Convertible I worked on never used pedals except a wah in front of the amp.

    Which 3 Boss pedals BTW?
     
  4. mightypudge

    mightypudge Member

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    Thanks guys.

    The pedals are a Boss Digital Delay, Super Chorus, and Super Phaser.

    John: I'll try your suggestion tonight.

    Mark: In most cases you are correct. However, even the Duncan manual states that the effects loop can be used with pedals. I also know someone with the same amp that has been running pedals in his effects loop for years with no problem.
     
  5. John Phillips

    John Phillips Member

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    I'm beginning to have a bad feeling...

    The reason that I asked about which pedals it was is because some of their newer ones (the BF-3 Flanger for definite) are all-digital, including the dry part of the signal path, and have latency - this causes trouble in parallel effects loops. It's still analog when the pedal is off though.

    The PH-2 Super Phaser and CH-1 Super Chorus are all-analog, and the DD-3 and DD-5 delays are analog dry signal at all times (I'm not sure about the DD-6 though), so if those are the models it isn't a latency problem.

    ... the bad feeling is that you may have a problem with the amp, if someone else has been running the same type of set-up with no trouble.
     
  6. mightypudge

    mightypudge Member

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    I also suspect it's an amp problem. I ran the exact same setup in my Rivera Rake effects loop and never had an issue.

    With that in mind, what should I be looking at? Obviously the effects loop circuit. But what would cause the motorboating sound?
     
  7. mightypudge

    mightypudge Member

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    Well, I fixed it.

    I tried putting a cable from the send to the return, and the noise wasn't there. So I knew the problem wasn't amp-related. YEAH!

    Next, I tried using a different power source for my wah and octave pedal, even though they aren't in the loop. Guess what? Problem solved.

    There must be some weird sort of power issue with the Furman PL-8.
     

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