If you are an experienced Sonic Electronix customer with vast product knowledge and technical skills, setting an amplifier can prove to be a rewarding task . You set your configuration to your liking and suddenly you have transformed your aftermarket system into a piece of art. But for those of you with less product knowledge, the entire process can be overwhelming and tedious, not to mention when improperly executed your sound will be distorted and your components can be damaged.

This blog highlights the most important configurations commonly used when an amplifier is set by the professionals. By following the guidelines laid out in this article, you will develop a basic understanding of all the features. In the long term you will save thousands because you will avoid frying your speakers and woofers, and believe me this happens all the time.


For starters, level and gain is an interchangeable term. Essentially this setting is used to pair the output voltage of the head unit and amplifier. Be sure these levels match or else your aftermarket project will turn into a disaster. Be cautious not to set the gain to high because you will be overworking the amplifier. What happens is that a distorted signal will be sent to your subs, drivers, and tweeters, causing these components to flat wave.

Here’s a fun fact; you can get full output from your amp with the gain set all the way down. However, if you set the gain all the way up you can destroy your subwoofers, drivers, and tweeters faster because of the source distortion. In other words if the gain is set all the way, the source will flat wave and amplify that 100x over.


3sixty rockford crossover

The crossover filters frequencies (lows/highs) to ensure each component of your car’s audio is fed the right frequency. Obviously highs are sent to your tweeters, lows to your subwoofers and mids to the driver. If you do not incorporate a crossover into your aftermarket project it is possible for the wrong frequency to be sent to the wrong component. This can damage your parts and can prove to be very costly. Imagine your tweeter trying to play the frequencies your subwoofer is responsible for, that would end in disaster. Your crossover prevents this from happening. Higher end amplifiers allow you to choose the type of crossover setting you want, based on your audio configuration.

Low Pass Filter / High Pass Filter

Low Pass Filter (LPF) ensures that your system only feeds your subwoofer low frequencies. Woofer crossover begins at 80hz and below, obviously requiring the LPF. This function puts a ceiling on the maximum frequency your subwoofer will play. If your subwoofer were fed frequencies ranging in the thousands, this would generally result in terrible sound.

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Whereas High Pass Filter (HPF) allows your tweeter and mid-driver to focus on the higher frequencies. Without such an arrangement, your tweeter and mids will blow because they do not have the capability of playing such low frequencies. These filters really help each component focus on what it was manufactured to do.


Generally, phase should always be set to zero. This exists only if you come across a phase issue in your system. When speakers and subs are operating out of alignment, your phase can be used to resolve the issue. However I have to re-emphasis this knob should only be adjusted if there is an alignment issue amongst speakers. For instance if you want to invert your subwoofers without having to rewire your setup you can utilize the phase knob to invert your woofers. The experts suggest always rewiring but if you do not have the time or resources, the phase knob will be your best solution.

Bass Boost

bass boost is bad

This is an artificial boost generally at 40 hz. If your bass boost is turned past halfway, consider this a subwoofer cooker, because your sub will not last very long. You are placing a tremendous amount of stress on your voice coil. Either invest in an additional woofer, or upgrade to a higher RMS power rating rather than using bass boost to compensate. And chances are if you invested in an aftermarket subwoofer there is no need for a bass boost. However if you insist on using bass boost, only turn it up slightly. If you hear distortion you have two options. Either reset your gain so the bass boost has less impact or turn the bass boost off; the experts at Sonic Electronix suggest the latter.

Subsonic Filter

A healthy human ear can hear between 20 and 20,000 hertz. So why would you want your subwoofer to play frequencies underneath 20 hz? A subsonic filter prevents your sub from performing at such a low level. This frees up your woofer to operate in the most efficient manner preventing overheating and encouraging longevity.

Remote Bass Control

After investing all this time and money into your aftermarket sound system, it is only logical to want full control over your bass. Please note however, if you choose to turn your bass knob all the way up, the amplifier will not play past where the gain/level is set. The gain/level is an input level knob monitoring output levels. This will prevent you from blowing your subs, but if you are really determined to play only the most aggressive bass, you will have to reset the gain in order for the bass control to be set lower.

Sonic’s Secret: How you Should set your Amplifier

Hifonics amplifier settings
This picture features common amplifier settings

I got some great insider information after speaking with our head technician on how to properly set your amplifier. Music taste, subwoofer size and enclosure build will greatly influence where your LPF is set. Source and source voltage directly affects the gain, which is all dependent on your head unit. Bass boost should always be set halfway or less. Phase is generally always at zero unless there is an alignment issue, in which you are recommended to rewire but if you are opposed you can use the phase to help resolve the issue. Lastly your subsonic filter should always be set to 20 hz. All of these tips are accurate about 75% of the time. Aftermarket car audio is highly customizable so there are always exceptions to the rules.