Description

An electronic unit powered from a 9V battery or
battery eliminator.
In use it allows only low frequencies to pass
through with a variable cut-off frequency so that
the effect of removing higher frequencies can be
studied in relation to degradation of quality in
audio communications.
It utilizes a second-order active electronic filter
which gives unity gain at low frequencies and
then 6db at the cut-off frequency and 12db per
octave thereafter.