  A reanalysis of $\pi\pi$ amplitudes for all important partial-waves below
about 2 GeV is presented. A set of once subtracted dispersion relations with
imposed crossing symmetry condition is used to modify unitary multi-channel
amplitudes in the $S$, $P$, $D$, and $F$ waves. So far, these specific
amplitudes constructed in our works and many other analyzes have been fitted
only to experimental data and therefore do not fulfill the crossing symmetry
condition. In the present analysis, the self consistent, i.e. unitary and
fulfilling the crossing symmetry, amplitudes for the $S$, $P$, $D$, and $F$
waves are formed. The proposed very effective and simple method of modification
of the $\pi\pi$ amplitudes does not change their previous-original mathematical
structure and the method can be easily applied in various other analyzes.
