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Question about Line Splitter

Discussion in 'Pro Audio Equipment' started by alfugazi, Oct 29, 2009.

  1. alfugazi

    alfugazi Active Member

    Oct 10, 2009
    What I'd like to do is this:

    I'd like to mic my amp cab and go direct at the same time for coloration. I have a Presonus Firestudio Project. I'd like to see what my options are for either purchasing a line splitter or if there is something else on the market than can achieve the same goal.

    Does anyone have a diagram of the signal flow? Im trying to wrap my head around this.


  2. dvdhawk

    dvdhawk Moderator Resource Member

    Dec 18, 2008
    Western Pennsylvania, USA
    What do you want the "direct" signal to be?

    Just the guitar, after a pre-amp, after a pedalboard, or after the guitar head?

    The first 3 can be achieved with a standard direct box.

    1/4" cable from guitar > direct box > 1/4" cable through to amp
    signal split to also provide > XLR to Firestudio

    The last choice, (after the amp) requires a special direct box or other interface with a much heavier transformer in it, that can take the high-output of the amp and step it down to a useable signal. It has to be made specifically for this job so it doesn't burn up the transformer or screw up the amplifier's output stage. You only need a few milliwatts to record, your amp might put out 200 watts or more.

    Good luck
  3. Kev

    Kev Well-Known Member

    Nov 13, 2001
    those DI boxes that can handle AMP-out usually have a resistive divider to knock the high voltage down to much, much lower voltage and then through the same transformer
    making it look like a normal microphone source

    if it is Line level out ... at say +4dbU ... then the transformer with be a little bigger and of similar size to other line level units

    hope that makes sense
  4. Boswell

    Boswell Distinguished Moderator Resource Member

    Apr 19, 2006
    Home Page:
    No DI box needed for initial recording - the FireStudio Project has two instrument inputs. Just use a TS dual jack adaptor and daisy-chain the guitar lead from the amp into the FS Project. Keep the lead lengths as short as practicable.

    Re-amping is a different matter. If you need to do this, get a re-amp box that is designed to take the line out from the FS project and produce a signal suitable for the amp input.
  5. jg49

    jg49 Distinguished Member

    Oct 16, 2008
    Frozen Tundra of CT
    I used to do that all the time with an A/B box and a solid state amp w/o any problems, but when I was using the same set up and an all tube amp I was getting significant hum from the amp. Maybe it was just the use of the A/B switch instead of a Y adapter, don't know but solved it with a DI. The instrument level inputs on the Presonus work great though I noticed just a little more headroom when using the Radial J48.

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