  We discuss the stochastic gravitational-wave spectrum from dark confinement
and chiral phase transitions in the early Universe. Specifically, we look at
pure Yang-Mills theory for an arbitrary number of colours as well as SU(3) with
quarks in different representations. We utilise thermodynamic lattice data and
map it to effective models, such as the Polyakov-loop and the PNJL model. This
allows us to compute gravitational-wave parameters and the corresponding
gravitational-wave signal. We compare the signal to future gravitational-wave
observatories such as the Big Bang Observer and DECIGO.
