Mix bus effects chain question

  1. #1 by John Kingsley on 2 Weeks Ago
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    Mix bus effects chain question

    Our singer has is IEMs through mix bus 1. The bus was set to “post EQ” and he said he was getting a “megaphone” type sound and everything seemed very compressed. We changed the setting to “pre fader” and this seemed to fix it. Does anyone know why this might happen, or what the difference is?

    Sorry if it’s a basic question...just a guitar player trying to learn the gear haha
  2. #2 by Craig Fowler on 2 Weeks Ago
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    Posts: 1,997
    Block diagram.

    Typically post-eq is after the channel's eq, but before the channel's compressor. Pre-fader is post the channel's compressor, so changing it should have either included or excluded the channel's compressor's processing from affecting the sound in the IEM. However the eq and compressor processing blocks can be swapped, and in effect that would make post-eq and pre-fader the same thing. It's odd that there was a megaphone effect with only the eq, and none with the channel's compressor... I would have thought it'd be the other way around.

    Perhaps it was because without channel compression the channels' signals feeding the monitor bus are hot enough to trigger the bus's\beltpack's own compressor\limiter, and that's where the megaphone effect comes from. However, when you change the tap point to pre-fader (and include the channel's compressor,) the channels' compressors clamp down enough to keep the input level below the bus\beltpack's own compressor\limiter's threshold, so the bus's\beltpack's compressor\limiter doesn't kick in, hence no megaphone sound.

    If you can upload your scene file we might be able to get more of a clue.
  3. #3 by John Kingsley on 2 Weeks Ago
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    That’s super helpful, thank you so much! I’ll upload those scenes as soon as I can; I’m getting an IO error when I’m trying to save to my USB drive.