Topic: What's The Deal With Double Drop Down Tuning?

I am attempting to learn a song -- Black Water by Doobie Brothers. The song calls for Double Drop Down Tuning. I have an electronic tuner. When I tune the high and low E strings to D it sounds wrong. When I go back to normal tuning it sounds almost like the Doobie's version. What am I doing wrong? Thanks.

Re: What's The Deal With Double Drop Down Tuning?

The drop is for the slide guitar.