  We present model independent determination of the CMB from any kind of fluid
that has an equation of state taking four different values. The first region
has $w=1/3$, the second $w=1$, the third $w=-1$ while the last one has
$-1<w=cte<-2/3$. This kind of dynamical $w$ contains as a limit the
cosmological constant and tracker models. We derive the model independent
evolution of $\wp$, for scalar fields, and we see that it remains most of the
time in either of its three extremal values given by $\wp=1,-1,w_{tr}$. This
"varying" $w$ is the generic behavior of scalar fields, quintessence, and we
determine the size of the different regions by solving the dynamical equations
in a model independent way. The dynamical $w$ models have a better fit to CMB
data then the cosmological constant and the tracker models. We determine the
effect of having the first two regions $w=1/3,1$ and depending on the size of
these periods they can be observed in the CMB. In general, the CMB spectrum
sets a lower limit to $\D N_T$ and to the phase transition scale $\Lm_c$. For
smaller $\D N_T$ the CMB peaks are moved to the right of the spectrum and the
hight increases considerably. For $\Ompi=0.1$ the CMB sets a lower limit to the
phase transition scale $\Lm_c\geq 0.2 eV$.
