  During the last years it has become clear that global O(N) defects and U(1)
cosmic strings do not lead to the pronounced first acoustic peak in the power
spectrum of anisotropies of the cosmic microwave background which has recently
been observed to high accuracy. Inflationary models cannot easily accommodate
the low second peak indicated by the data. Here we construct causal scaling
seed models which reproduce the first and second peak. Future, more precise CMB
anisotropy and polarization experiments will however be able to distinguish
them from the ordinary adiabatic models.
