Help building 12v remote cable denon / krell

I need to make a 12volt remote turn on cable that will run from a denon 3803 to a krell kav250a3. I think it is 1/8 mono plug but I am unsure of the polarity on either unit. My manuals don't have the information. Anyone know?
can't you just buy the 1/8 mono miniplug cable from radioshack? i'm pretty sure they sell them there.
Is the tip 12+ or the ring? Maybe it doesn't matter?