Most recently formed under the Diamond Heart Club moniker, the renamed 1950 D.A. is, at its base, a rock 'n' roll outfit oscillating between aggressiveness and passivity. Each member has been associated with many past musical endeavors (most notably, singer Mark Hennessy used to front Paw) and brings a unique flavor to the Lawrence group, from pure rock to noise rock to blues. 1950 D.A. joins GD Gallows and Mosquito Bandito at 10 p.m. today at The Bottleneck, 737 N.H.