Hi-Jack (couldn't resist)
This is a four channel amp (two stereo amps "A" and "B" in one box), with all filters set to "off" assumes you are going to use full-range speakers on all outputs (front on "A", rear on "B")
The most common configuration for using a four channel amp is to set stereo amp "A" to LPF (low-pass filter) and the frequency somewhere around 120Hz (not sure if your freq control is a four position switch or variable). The output of amp "A" is then used to drive a subwoofer, using the L and R speaker connections in "Bridged" mode for max power (combines the power of the left and right channels) to the subwoofer. To accomplish the "Bridged Mode" connections, you will probably have to google up a user manual for that model because bridge mode setup varies between models of amps.
Then you would set stereo amp "B" to HPF (high-pass filter) at roughly the same frequency as the "A" amp. You would then connect your two or four stereo speakers to stereo amp "B" speaker terminals in the normal fashion.
What all this filtering does is separate the bass from the rest of the music, if you put a full-range signal to a subwoofer, it can't reproduce the mid and treble, so that's just wasted power. Thus use Low Pass filter (High "block" filter, if you will) and the subwoofer gets only bass.
The HPF High-Pass Filter (or Low "block" filter) does the same thing in reverse. It will block the bass from being sent to your bike's little 4" speakers, since they don't reproduce bass very well they would distort, especially with all that bass at high power can easily damage the little speakers. So we block the bass because we have a subwoofer to do that, and let the 4" speakers get only mid and treble, which they do best.
The frequency settings can be twiddled until they sound best, a lower number blocks or passes only deeper bass depending on if HPF or LPF, a higher frequency lets of the lower midrange go to subwoofer or blocks it to the main speakers. And the two filter (A and B) settings don't have to be the same, as stated you can twiddle them until they sound best.
The sensitivity controls do exactly what they say. If you turn up the volume on your radio just a crack, and the amp is already too loud, turn the sensitivity down. Or if you have the radio at full blast and the amp is only at moderate volume turn the sensitivity up. A good starting point for the sensitivity settings is "1", you can go from there. It also allows to set the balance between the subwoofers and main speakers if you set up that way by adjusting "A" and "B" separately.
If you are not using subwoofer configuration you can use the sensitivity controls to adjust the balance between front and rear. Also it is recommended to set filters to "HPF" on both A and B and the frequency to the lowest setting (50Hz), this will block the very lowest bass from your speakers, and the little 4" speakers can't reproduce bass below 50Hz anyway. Also helps prevent speaker damage.
For the input connections, use "Y" cable and feed the same signal left and right to both "A" and "B" inputs. There are separate "A" and "B" inputs in case you have an equalizer which does the filtering settings HPF, LPF or front-rear fader etc. but is not needed.
Also, if your stereo doesn't have line out connections, it is recommended to get a pair of "Isolators" which take the speaker-level outputs and downconvert them to RCA Line level signals. You can get them from any car stereo shop.
Happy Holidays, and I hope this helps! Do google up the user manual!
Mark
