which behringer mixer? i take it you are using the mixer's pre-amp. how far from the vocalist is the mic positioned? is the mic positioned above, even with, or below the vocalist' mouth.
Ditch the NT-1 and get something like a AT 4050. The NT-1 is about the worst mic for "warm" vocals there is!!! Everything I have every heard recorded with one sounds very harsh and brash sounding. It just isn't a very good vocal mic unless the singer has a VERY dull voice.
you know what get you a cheap art tube mp preamp and roll off your highs on the mixer. Nothing warms up vocals like a tube pre or if you got a lil more go with a blue max fro presonous 149 average price lots of times negative equing works better then positive eqing with vocals. try to cut stuff back before u boost anything. Even slight boosts in eqing in the wrong spots can ruin a vocal track.