  We discuss pure $q\bar{q}$ axial-vector mesons in the Tamm-Dancoff
approximation of the Coulomb-gauge QCD model from NCSU. While recent studies
have put emphasis in configuration mixing with open meson-meson channels, we
here concentrate on the simpler closed-channel problem and follow the $1^+$
mixing through a wide range of quark masses. We also examine their radial
excitations and discuss with them the concept of insensitivity to chiral
symmetry breaking.
