When dealing with weaker singers, sometimes a more transparent mic is too revealing. You want to use something that adds weight to their voice like a tube condenser, such as; Neumann U47, Neumann U78, or Telefunken C12. It's wise in these situations to go into a more transparent pre-amp such as a Focusrite so in the mix phase the mixer isn't boxed in with too much warmth in the vocal tone.
