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Does a keyboard need a direct box?

Discussion in 'Live Sound [BG]' started by drdunwoody, Jan 4, 2011.

  1. drdunwoody

    drdunwoody

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    At our gig the other night we asked for more keys in the monitors and couldn't get it because the keyboard was pegged on the PA. All other instruments had plenty of volume and room to move around. If this were a bass I would say, "Dah, you need a DI before running into the PA!" However, it aint a bass, its a keyboard. I told my none-technical keyboard friend I would look into it. He plays a Kawai (http://www.kawaius.com/main_links/digital/PRO/mp5-specs.html ) and runs the 1/4" out into the board. That night it went through a passive DI to go from 1/4" to XLR for the snake. Should he have an active direct box to control the signal level? If so, any recommendations? Thanks!
  2. MyMusic

    MyMusic

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  3. drdunwoody

    drdunwoody

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    Looks like that answer is "yes, he should have a Radial JDI." That was easy. Thanks!
  4. drdunwoody

    drdunwoody

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    Since his signal was too low, should he have an active DI? I see the Radial JDI is passive. Does that matter? I use a Sansamp active DI but I only bring it in case my amp dies in the middle of a show. I don't typically run my signal through it and instead I run the XLR line out of the back of my bass amp (currently a Genz GBE 750). So what is the benefit of the active versus passive DI?
  5. agedhorse

    agedhorse Development Engineer-Mesa, Product Support-Genz Supporting Member

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    Yes, use a passive DI, and be sure you weren't using the headphone output since the left/right signal can cause major problems with a TRS balanced input.
  6. walker rosewood

    walker rosewood

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    a DI is used to plug in a line level high impedance signal into a mic level low-impedance input. Line level for pro audio gear in the US is generally +4db and mic level is much less. So a passive DI will only decrease your signal level. An active DI has a pre-amp and can provide gain. Google DI box and you'll get lots of good info like this page http://www.jdbsound.com/art/art504.htm

    I've never seen/heard of a keyboard that needs added gain though. Something was not connected right. As mentioned maybe they were mistakenly using the headphone output, or the monitor amp volume may have been turned down, or the aux send to the monitor was post-fader instead of pre, etc.
  7. agedhorse

    agedhorse Development Engineer-Mesa, Product Support-Genz Supporting Member

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    IF (that's a big if) the problem is a lack of signal level, there's more available gain at the mic input, and even with a typical 6:1 passive DI, there will still be an additional 20dB of gain compared with a (typical) 1/4" line level input.
  8. drdunwoody

    drdunwoody

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    I know he was using the TRS mono output and not the headphone output. I didn't look at the passive DI they had so I don't know what it was. In our practice space and in other gigs I have done with this keyboardist he has typically gone from the mono TRS out direct to the PA and NOT through a keyboard amp. I know for a bass or guitar you would need a DI to do this but I'm obviously ignorant about the keys. Thanks for all the info! I guess my question is this: If he is typically running straight from the keyboard to the PA (without going through a keyboard amp) should he (as standard practice) be going through a DI?
    After reading the links suggested, it seems that the DI is only "necessary" if you are going long distances as most boards also have line level inputs. Still sounds as though best practice would be to have the DI though unless I'm missing something. Thanks again TBers! Where would I be without you!
  9. agedhorse

    agedhorse Development Engineer-Mesa, Product Support-Genz Supporting Member

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    I always recommend a passive DI for keys.

    A DI also allows for isolation of ground loops, and eliminates the questionable following of standards regarding 1/4" jacks... some TRS are not balanced, some are impedance compensated, some are balanced. In general, use a 2 conductor (tip-sleeve) type cable into a passive DI and you will "always" output a mic level balanced signal to the PA using an XLR cable and have the ability to lift the pin 1 audio ground in the event of ground loop hum.
  10. T-Bird

    T-Bird

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    Hi.

    If any keyboard player would demand me to plug into the desk without using a DI, I'd require a very, very good explanation as why?

    DI is IME/IMHO the only way to ensure best possible signal transfer when connecting sources of unknown qualities. Keyboards fall into that category better than any other MI.

    Regards
    Sam
  11. WayneP

    WayneP

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    I suppose you mean the “mono” jack on the keyboard, but it’s not TRS. TRS is a balanced connection. I’ve never seen a keyboard with a balanced output (but of course, I haven’t seen all of them inexistence either).

    That said, I’ve always wondered why keyboard manufactures don’t include a balanced XLR output. Seems like a no-brainer.

    Regards,
    Wayne A. Pflughaupt



    Administrator, Tobias Club
    Pedulla Club #45
    Big Cabs Club #23
    My Rig: Stage and FOH Friendly


  12. drdunwoody

    drdunwoody

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    Ok, not TRS. The mono side 1/4" jack. Thanks everyone. I'll tell him he needs a DI!
  13. thombo

    thombo

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    is it possible that the soundman was bluffing, and didn't turn the keys up for another reason? This often happens to percussionists- they'll be all miced up, but no one can hear them.
  14. MNAirHead

    MNAirHead

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    IF out shopping.. a rolls DB25 has a trim knob... makes it super simple to ensure not overdriving a board.. they're surface mountable and about $25
  15. drdunwoody

    drdunwoody

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    No, not bluffing. I know the guy and play with him in another line up.
  16. agedhorse

    agedhorse Development Engineer-Mesa, Product Support-Genz Supporting Member

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    Another reason to always use a DI is to isolate from phantom power. Even if the output is TRS balanced, you do not want to use a TRS to XLR adapter because many keyboards are not protected from phantom power placed on their outputs.

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