when setting your gains on amps why cant you turn them all the way up.

and if you have them less then half way are you still getting the rated power of the amp. say if the amp is 1000w RMS are you getting that no matter what the gains are set too.....

jamie

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when setting your gains on amps why cant you turn them all the way up.

and if you have them less then half way are you still getting the rated power of the amp. say if the amp is 1000w RMS are you getting that no matter what the gains are set too.....

The gain is a tool meant to match the output level of the processor or headunit directly before the amp to the input level needed by the output stage of the amp for maximum unclipped power. Most amps have a range of around .2-5V within which the gain section can match the voltage to the output section. Most all HUs' outputs fall within that range. You want to set the gain so that at max volume (usually less than max on the volume scale on the HU) the gain setting corresponds to the voltage coming from the source. If the gain is set too high, the amp will clip, producing a ton of distortion and heat. If it is set too low, you will not get all the power it is capable of producing. You are better off setting it too low rather than too high. You could leave it set a max if you wanted, but the range of volume control that you had would be tiny. You would be able to adjust the volume from 0 to whatever volume corresponds with the minimum input voltage of the amp. Increasing the volume beyond that level would only increase distortion and heat, not sound level.

The way an amp works is that the output stage takes an input signal and multiplies it a fixed number of times. The ouput section is limited by the power supply rail voltage (the amp power supply, not the car's 12V supply) as to what the maximum output voltage can be, after multiplication. If the signal to the output section times the multiplier exceeds this maximum voltage, any amount in excess is cut off or "clipped". Since there is no standard for the output voltage for car audio source components, there is no way to make a single input voltage for an amp that will allow the volume to be adjusted and the amp to make its max power without clipping. Enter the adjustable sensitivity control, commonly called the gain. All this is is a low current stage of amplification with an adjustable multiplier to convert the wide range of signal voltages to the voltage needed for the input to the output stage of the particular amp. As long as the signal voltage is within the adjustable range of the preamp stage of the amp, you will be able to adjust it so that you get maximum unclipped power from the amp. With modern HUs that have high-voltage outputs, the proper gain setting is generally somewhere just above minimum assuming that the input range is .2-5V.

Bass boost or any other type of EQ boost has the effect of boosting the voltage at that frequency. If you have the gain set properly with the boost off and then turn it on, the volume at which the amp begins to clip will be lower as the boost sends the amp past its limit sooner. If you plan on using boost, you must account for it when setting the gains to keep the amp from clipping.