Zapco AG Reference-series User Manual
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1000.4 Special Features
There are a couple of features unique to the 1000.4, 500.1 and
1100.1 amps in the Reference line.
First, the 1000.4 has a Bass Boost port for the 45Hz bass equalizer
circuit. An optional DBC (Dynamic Bass Control) can be plugged into the
Bass Boost Port to give the listener up to a 12dB Bass Boost adjustment.
Secondly, the Sub-Sonic filter of these units is variable to allow
proper tuning of the car and the enclosure. Ported enclosures can easily
double the acoustic output of a sub woofer at the port tune frequency.
However these enclosures greatly decrease the ability for a woofer to
handle power below the port operating range. The variable Sub-Sonic filter
allows the installer to get maximum volume at the best port frequency for the
individual installation, and filter out the frequencies below that, to protect the
woofer from being over-driven.