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Amp FX loop -10dB/+4dB

Discussion in 'Accessories / Connections' started by Guitarfreak, May 5, 2010.

  1. Guitarfreak

    Guitarfreak Well-Known Member

    I'm looking at an amp that has a push button switch for -10dB/+4dB and I can't think what this would be used for? -10dB for floor pedals or +4 for rack units?
  2. Boswell

    Boswell Moderator Distinguished Member

    Is this switch in the external effects loop?
  3. moonbaby

    moonbaby Mmmmmm Well-Known Member

    Close enough. Very few stomp boxes are designed to be fed a -10dB signal, more like a -20 to -30dB signal, but it beats a +4 signal which will pummel many stompboxes into breaking up really nasty. Ideally the -10/+4 switch will set both the Send level and the Return level to properly match the amp to the effects unit.
  4. Guitarfreak

    Guitarfreak Well-Known Member

    Yes, it only applies to the loop. I think I know what you were thinking, where if it was for the input for the amp you would use +4 for passive pickups or -10 for actives right? Or the other way around?

    What could I run that would require a +4 signal? studio equipment that was not intended for guitar or amp processing I am guessing? Even guitar rack fx are still indeed designed to run with a guitar/amp signal in mind so I am a bit confused as to its practical use. Does it just change the loop from unbalanced TS to balanced TRS?
  5. Boswell

    Boswell Moderator Distinguished Member

    I don't know the amp you are talking about, but my guess is that the effects loop is unbalanced and the switch simply makes a 12dB difference in the send level and a corresponding 12dB in the return gain. You use it to select domestic-level outboard gear or professional-level.

    As Moonbaby points out, that sort of switch has no meaning at the input of this type of amp.
  6. boxcar

    boxcar Active Member

    quite a few rack effect processors run at -10/ +4 for guitar and bass.
    i used a yamaha spx 990 for guitar for awhile and in this case it had -20/+4. it had great delays.
  7. moonbaby

    moonbaby Mmmmmm Well-Known Member

    Exactly. I still use an SPX in my Rivera's loop. It's got some great reverb and ensemble algorithms.

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