Zapco AG Reference-series - Manual (Page 20)

19
Bass EQ Control
In vehicle sound systems they have a tendency to peak at about
100Hz to 120Hz and to roll off after that. This leaves a hole in the bass
response in the 40Hz to 50Hz range.
To compensate for this effect, ZAPCO has provided all Reference
Series amplifiers with a variable Bass equalization circuit. Each amplifier
has a “Bass Boost” control, which allows adjustment of the bass from 0dB to
as much as 18dB. This adjustment is made at a frequency of 44Hz.
Use the Bass EQ with caution. Too much equalization can easily
cause amplifier clipping and may even damage your speakers.
Bass Equalization Curves