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Operating Instructions
If you have a line level source (such as a preamp output, surround processor output, or tape monitor insert
points on a receiver), send a full frequency range signal via shielded cables to the RCA jack line level inputs.
The INFRASUB will send the Left, Center, and Right channel signals to the built-in hi-pass filters. The resis-
tor network installed at Bag End sets the -6 dB frequency to 95 Hertz. The line level outputs of the hi-pass
filters are available at the Left, Center, and Right channel RCA jacks. Send these signals back, via shielded
cables, to the inputs of their corresponding power amplifiers.
If you have a speaker level source (the output of a power amplifier), send a full frequency range signal to
the Left and Right channel spring terminal speaker level inputs. As the impedance of this input is high, it is
not necessary to use heavy gauge speaker wire for these connections. We recommend running separate ca-
bles in parallel with your normal speaker wires connected either directly from your amplifier outputs, or from
the terminals on your left and right speaker enclosures. Please take care to maintain the correct signal polari-
ty by connecting the red or + terminals from your amplifier or speaker to the red speaker level inputs on the
INFRASUB. Note that there are no hi-pass filtered speaker level output signals available. In this configuration
best results will be achieved when using satellite speakers with limited bass response.
The INFRASUB combines the signals from all of the inputs and sends them through the INFRA dual inte-
grator and to the built-in 400 watt power amplifier and the specially designed Bag End EL-18P 18” driver.
Use the LEVEL control to match the volume of the INFRASUB to your satellite speakers. Use the POLARITY
SWITCH, if necessary, to reverse the polarity of the INFRASUB. This can be helpful to achieve a seamless
blend between the sound of the INFRASUB and your satellite speakers.