After Fader Listen (AFL)
AFL may be After-Fader Listen or After-Fader Level, depending on whether the user is more concerned with the quality and/or content of the signal or with its level. It is similar in operation to Pre-Fader Listen (PFL) except that the signal is derived after the channel fader instead of before. As AFL is also derived after the Panpot in mono channels, AFL can be in stereo even where PFL is in mono.
AFL may sometimes be confused with the ‘Solo’ function used in recording studios, where the operator is usually concerned with the level and quality of the signal from a particular microphone after it has been processed by the channel dynamics and equaliser systems, before committing it to multi-track tape for eventual re-mixing, or from a previously recorded tape, perhaps from another studio.
The ‘Solo’ function singles out the required channel by simply muting all the other channels, leaving the selected channel to be monitored on its own. This is ‘Solo in place’, as the channel signal remains exactly as panned; some mixers allow ‘additive solo’ i.e. several channels may be selected at a time, and monitored as they are mixed. As this function is dangerous if mis-used (it is sometimes called ‘destructive solo’!) a ‘solo safe’ switch is sometimes fitted to disable the function during recordings.
Obviously Solo has no place in a broadcast mixer, but it is sometimes desirable to single out one channel from a mix without a change of level, which almost inevitably happens if PFL is used. AFL provides this facility.