  We derive an M_bh-sigma relation between supermassive black hole mass and
stellar velocity dispersion in galaxy bulges, that results from self-regulated,
energy-conserving feedback. The relation is of the form M_bh v_w \propto
sigma^5, where v_w is the velocity of the wind driven by the black hole. We
take a sample of quiescent early-type galaxies and bulges with measured black
hole masses and velocity dispersions and use our model to infer the wind speeds
they would have had during an active phase. This approach, in effect,
translates the scatter in the observed M_bh-sigma relation into a distribution
of v_w. There are some remarkable similarities between the distribution of
black hole wind speeds that we obtain and the distributions of outflow speeds
observed in local AGN, including a comparable median of v_w = 0.035 c.
