  We have characterized a novel photon-echo pulse sequence for a
double-$\Lambda$ type energy level system where the input and rephasing
transitions are different to the applied $\pi$-pulses. We show that despite
having imperfect $\pi$-pulses (associated with large coherent emission due to
free induction decay), the noise added is only 0.019$\pm$0.001 relative to the
shot noise in the spectral mode of the echo. Using this echo pulse sequence in
the `rephased amplified spontaneous emission' (RASE) scheme
\cite{Ledingham2010} will allow for generation of entangled photon pairs that
are in different frequency, temporal, and potentially spatial modes to any
bright driving fields. The coherence and efficiency properties of this sequence
were characterized in a Pr:YSO crystal.
