Adjust a Car Amplifier

How to Tune and Adjust a Car Amplifier

So, you just bought and installed a wicked new amplifier in your car’s stereo system, but when you fired it up, it doesn’t seem to do anything. Don’t rage just yet, and there’s nothing wrong with your brand-new amplifier, it’s just not properly tuned yet.

You need to tune and adjust a car amplifier to make the most use of the car’s speakers; you need to do a bit of tweaking until you get the right audio quality for your listening pleasure.

Don’t worry, tuning a car amplifier or a subwoofer isn’t as hard as it sounds.

The Terminology of a Car Amplifier

You will be encountering quite some technical terms in this article, so you should familiarize yourself with them so you won’t get lost.

Gain – This is the setting that adjusts the sensitivity the amplifier, meaning it sets the power coming out of the amplifier to a certain level that can be easily handled by the speakers. Simply speaking, you adjust this setting to reduce the amount of distortion coming from the speakers.

Frequency – This is the pitch of the sound that the speakers emit. Finding out the frequency of your speakers is quite easy as they are usually clearly labeled on the speakers outer casing. If not, you can find the frequency numbers at the back of each individual speaker. You will need to get these numbers because you will need them to tune an amplifier correctly.

Low-pass/High-pass Filters – These are built-in frequency filters that, when turned on, will only let a maximum/minimum range of frequencies pass through the output jacks. For instance, if you will be using small speakers, like tweeters, to handle the high-frequencies, you will need to turn on the HPF on the corresponding output channels. Also, if you will be using all medium-sized speakers (no tweeter and subwoofers), you can set the filters to “full”, meaning the output channels will let out a full range of frequencies (lows, mids, and highs).

How to Tune an Amplifier.

Step 1 – Volume and Gain Control Adjustments

Turn everything off, unplug the RCA cables connected to your amplifier, and turn your stereo system back on. With no music playing, turn up the volume on your head unit all the way up, and take note of the number displayed on the head unit.

Now that you know the maximum volume of your system dial it back down to around 80%, and then set the stereo’s Equalizer settings to “Flat”. Go back to your amplifier and set the Gain and Bass Boost to zero, and set the crossover filters to off/full. Plug back all of the RCA cables into the speaker channels that you want to tune (most aftermarket amplifiers have separate RCA jacks for low, mids, and highs). Now, play your favorite music on the radio, and then slowly increase the gain setting until you hear a bit of distortion coming from the speakers. Slowly reduce the gain until you don’t hear any more distortion, this will be the base gain setting that you will use to tune the different frequencies.

Step 2 – Tuning Individual Frequencies

Now that you have your base gain settings, it’s time to switch the crossovers and filters back on. If you’re tuning your sub-woofers, choose the low-pass filter (LPF), and use the high-pass filter (HPF) for the other speakers. If you are using mid-sized speakers to cover all frequencies (meaning you don’t have a sub-woofer box installed), you can disregard this step and just leave the crossover and filters on the off or full position.

If you are tuning your sub-woofers, check the maximum rating of your sub-woofer and then set the frequency dial to the same number. On the other hand, if you’re tuning the rest of the speaker system, find out their lowest frequency rating and set the frequency setting to that number.

Step 3 – Bringing the Bass

If you’re the type of person who likes chest-thumping, window-rattling bass coming from your car’s sound system, then you need to increase the bass boost setting of your amplifier. Do take note that this can be quite tricky, and will also place a lot of stress on your sub-woofer.

To turn up the bass boost, you need to set the gain down. You need to adjust these two settings at the same time, your goal here is to get the highest bass output without getting any distortion. This might take a while since you will be adjusting two settings at the same time, but don’t worry, it will all be worth it in the end.

Step 4 – Back to Gains

Now that all of the speaker frequencies and bass boost are set up, you can go back to set the gain. Turn on your radio and set the volume back to 80% of the maximum, turn the gain up slowly until you hear any distortion coming from any of the speakers, and then gradually dial down the settings until the distortion disappears.

Step 5 – Fine Tuning

Reconnect all the amplifiers (that is, if you were tuning them separately) and then turn the stereo’s volume all the way down to zero. Now, gradually turn up the volume until you reach the 80% mark or until you hear any distortion. If you have turned everything correctly, you will hit the 80% volume without hearing any distortion whatsoever.

On the other hand, you hear any distortion, find out which speakers are the culprits and then turn down their gain settings until they no longer distort.

Final Notes

You should never exceed the 80% volume setting on your stereo, prolonged use at maximum setting will increase the wear and tear experienced by the speakers, and of course, you also risk tearing up your eardrums.

Also, different genres of music will need different amplifier tuning settings. For instance, you want a lot of basses if you like listening to hip-hop and rap, but not so much if you like country or folk music. If you like listening to two or more different music genres, then you need to tune and adjust a car amplifier to find the happy medium between all of them.


high-pass filter (HPF) - wikipedia
low-pass filter (LPF) - learningaboutelectronics

Last Updated on: 06/04/2020

About the Author Simon Adams

Simon graduated with a Mechanical and Electrical Engineering Degree. He has over 20 years of servicing experience in both Japanese and German car dealerships. He now acts as a freelance mechanic's instructor for local schools.

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