The A-weighting filter is one of the oldest ones used in audio analysis – providing a measure of loudness as perceived by the human ear from unweighted measurements. Yet the Audio Precision machines do not come with one built in as standard.
The plug-in architecture allows for adding an A-weighting card, such as the one offered here.
AP System One/Two A-weighting filter
This filter implements the A-weighting frequency transfer function.
A-weighting frequency transfer function
When measured using the inverse of the A-weighting standard used as measurement equalisation, the frequency transfer function is flat:
Flat frequency transfer function when digitally inverse A-weighting equalised
Three AWT filters installed in SYS-2322 (for triple A weighting…)
Autodetection (obviously you don’t need three A-weighting filters)
Filter transfer functions perfectly overlap between the three A-weighting filters; we like consistency
Universal filter PCB – other filter functions are available