Quote:
Originally Posted by dogbass  [...]what would really be helpful is either a reference to a schematic drawing showing some sort of capacitor or isolation xformer on the DI leg[...] |
The block diagram shows you have a ground lift switch on that amp. Phantom power (+) is carried on both pins 2 and 3, while phantom power (-) is carried on the shield: pin 1 and/or the connector shell. I would say your safest bet is to make up a short female-to-male patch cable that allows
only pins 2 and 3 to pass through. This is a simple ten-minute job with a stripper and a soldering iron. I would not trust only the MB's ground lift because, depending on the particular DI cable you're handed at a particular venue and how it's wired, your amp could still "see" mixer ground via the connector shell, and that would mean trouble. Now, IF the MB500 ground lift switch lifts both pin 1
and the connector shell [1], then you're safe, but only if you remember to engage the ground lift (!). However, all you need is one failure to remember and you'll kick yourself for not having made up that patch cable in the first place, which is why I recommend going that route.
[1] I can't answer that question since I don't have a 500, only a 200 and a Backline, and I'd prefer not to infer 500 behavior from either or both.
.... but what would really be helpful is either a reference to a schematic drawing showing some sort of capacitor or isolation xformer on the DI leg OR info from someone who has used it on a board with 48V phantom power running and not gotten fried. 
Closing the loop on this... 
