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Blocking phantom power?

Discussion in 'Electronic Repair Modifications DIY' started by achase4u, Jun 15, 2016.

  1. achase4u

    achase4u Active Member

    Edited for clarity.

    So, I am setting up for some hybrid mixing for the first time and have db25 connected from the analog out of my converters to the input of my radial lunchbox. The lunch box has preamps for recording as well as an eq. I accidentally sent phantom to the analog out of my converters(from a preamp on the radial) for approx 1 minute. It seems to work, so I am thankful there.

    Anyway. Since I will only use the db25 input on the lunch box for receiving DAW line levels(from the converters analog out), is there some sort of device that can block 8 channels of phantom on the db25? I guess there isn't much need for this product since most people have more dedicated setups. Just curious...

    Perhaps I could mod the Radial to have a jumper that blocks dc from the db25?

    I suppose I could get an XLR box that is a transformer isolation for 8 channels, run dsub out to xlr to the iso, then xlr to dsub on the other end... this would definitely color the sound, though...
  2. Boswell

    Boswell Moderator Distinguished Member

    Your post isn't fully clear, but if you were worried that you enabled phantom power when the DB25 plug was connected, then there is nothing to worry about. Phantom power is supplied at the XLR connectors only - you need no blocking device for the DB25.
  3. achase4u

    achase4u Active Member

    I apologize for any confusion. Yes, through the db25. I measured with a meter and yes, phantom goes through the db25 of the radial, unfortunately.
  4. Boswell

    Boswell Moderator Distinguished Member

    What's the make and model of the pre-amp modules you have plugged into the lunchbox? The types I have used have all had their microphone XLR inputs on their front panels, specifically to avoid phantom power being routed to whatever connectors the lunchbox has on its the rear, while the rear XLRs have carried the line-level inputs on the modules.
  5. achase4u

    achase4u Active Member

    Phoenix DRS1r(pair) A Designs P1(pair) Vintech 573. Interesting. The radial runs phantom to all input connections on the chassis - XLR, 1/4" and dsub.
  6. Boswell

    Boswell Moderator Distinguished Member

    Nice modules. However, it's not the Radial lunchbox chassis that sends the phantom power round to the rear panel connectors, it's the modules. The 48V PP line arrives on pin 15 of the connectors and the module chooses what to do with it after that.

    Some makes of lunchbox chassis choose to take the PP to module connector pins 15 via breakable jumpers or cuttable tracks so that PP does not find its way to the rear panel in the manner that you are suffering from. It's worth a look to see if the Radial box has this facility.
  7. achase4u

    achase4u Active Member

    Interesting. I will check into the manual - as a jumper would be a great feature to keep it from the dsub... Thanks

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