Studio wiring/ shielding

Discussion in 'Recording/Live Sound' started by louderock, Jan 28, 2008.

  1. louderock

    louderock Member

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    I have a wall panel in the studio with speaker and instrument ties from the control room to the live room. 1 instrument tie, 3 speaker ties. When running a head in the control room through the speaker ties while also running an instrument level tie through the instrument jack, there is a huge amount of crosstalk from the speaker line into the instrument line. The speaker lines are all 2 conductor 14 gauge. The instrument tie is shielded Mogami. Any ideas on how to solve this problem?
     
  2. drfrankencopter

    drfrankencopter Member

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    Probably this is caused by the fact that your guitar input line is high impedance...so it's acting like a bit of an antenna for noise. I bet the level of noise varies a bit depending on the guitar being used. Though from reading your post I don't really understand your layout....is the guitar being played in the live room, or in the control room? Typically if the head is in the ctrl room, then the guitar is there too....but in your case why is there an instrument line coming back from the live room?

    The easiest way to try to fix this is to run a buffered pedal before the instrument line goes into the wall....something with good drive capability, but that can keep clean would be the place to start. Or,if you have 2 passive DI's you can use them to balance your instrument signal, and then unbalance. This will help prevent the crosstalk issue (provided you have wired up for a balanced instrument input).

    Again though I might be misunderstanding the problem...

    Cheers

    Kris
     
  3. louderock

    louderock Member

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    Thanks. I'll try to clarify. The guitar is in the control room. It is plugged into a Radial JD-7 guitar splitter. One output feeds an amp head in the control room. The speaker output of this head runs through the tie line panel between the control room and the live room, where the speaker cab is located. Another output of the guitar splitter is 1/4" instrument level that also gets patched to another jack on the tie line panel. This feeds a combo that is located in the live room. So, you have both instrument level and speaker level being fed through different jacks/ lines on the same tie line panel. I guess I'm getting the bleed from the speaker signal into the instrument level signal because the level is so high in comparison.

    The instrument tie line is 1/4 TRS with 3 conductor Mogami wire. I have an RC Booster and a Zvex SHO which are clean boost pedals. Would this help? Also, the Jd-7 splitter has an XLR DI output on the back. Should I use this and then use another DI in reverse on the other end before the combo? Could this signal travel through the same panel or should I use a mic line instead? Thanks.
     
  4. drfrankencopter

    drfrankencopter Member

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    Which outputs on the JD-7 are you using...not all are isolated, and some are just direct pass through. I think the rear panel outputs are direct, while the front panel ones are isolated. Try using an isolated output first (like 2-6).

    Then, try putting a buffer pedal (even just any boss pedal for now, but the RC booster would be good) in the line going out to the combo (but put it in the control room side).

    If this doesn't work, then go to the balanced approach...

    Cheers

    Kris
     
  5. louderock

    louderock Member

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    I think I have it. The JD-7 has an XLR balanced output on the back. I've taken that, converted to 1/4" TRS and sent it through the wall panel. On the other side, 1/4" TRS into a passive DI to convert back to 1/4". Seems to solve the problem. No noticeable signal from the speaker line getting into the 1/4" instrument.

    I'll try the RC Booster later. I have been using output 2 which is transformer isolated.

    Thanks for the help!
     

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