Attached are measurements of the frequency stabilisation taken from this morning.
Noise spectra and the transfer functions are plotted for common gains of 20 dB and 22 dB,
and fast gains of 22 dB and 8 dB respectively.

    At lower frequencies the noise is lower with the common gain at 20 dB.  However this
results in a slight decrease in the unity gain frequency.  With these settings the UGF
is ~450 kHz.  With the common gain at 22 dB, the UGF is ~650 kHz.  Anecdotally it seems
that the frequency servo is more glitchy with the common gain at 22 dB.

    Improving the cross-over by looking at the spectrum and flattening it and adjusting
the fast gain, improves the flatness of the spectrum but then increasing the common gain
does not push the noise floor as low as the two cases illustrated.