
Originally Posted by
CAFO - FAQ
How do I set my gains?
Amplifier gain control is not a volume knob that determines the maximum volume. As long as the head units signal (which runs down the RCA cords) has sufficient power the amplifier is able to produce its maximum power output level.
It's a matter of getting the full volume range of the head unit to match the full output range of the amplifier(s).
"GAIN" controls do exactly that, also used to match other amplifiers in the system (in the case of a multi-amp system). Different Head Units have different maximum preamp output voltage. Some are capable of producing 9 volts on their preouts while others are only of 1.5 volts.
Most head units will reach their maximum just before the volume control reaches the upper end of its range (usually at a point of 85-90% of its maximum range).
Assuming your amplifier is the right power for the speakers (around the same as their rating), the proceedure of setting the gains is not overly difficult. First you set everything onto zero. All amplifier gains turned right down and all head unit boosters (like the loudness button) should be off.
1)Turn your deck up full volume, then back it off to about 85-90% (eg if your Alpine deck goes to 35, bring it up and then back off to 33-34)
2) on the amplifier, slowly bring the gain up until the distorting becomes audible. Once it's audible, turn it back ever so slightly and that is your gain set for that amp.
REMEMBER if your amplifier output is much higher than your speakers rating (e.g. running 50 watt speakers with a 500 watt amplifier) the amp will destory the speakers before it begins to distort
It can be difficult to set the gains when there is more power available than the speakers can handle.
You have now insured the entire volume range of the head unit (e.g. 0-35 on Alpine head units) matches the entire volume range of the amplifier. In multiple gain / mulitple amplifier situations, usually recommend setting the midrange amplifier first as is it easiest to hear distortion through midranges (human ears are most sensitive to 1000-2000hz).