In this article: We'll run through some common amplifier terms along with a quick and easy method of tuning your amplifier gains, low and high pass filters, frequencies and bass boost.
You have an aftermarket amplifier to power your speakers or subwoofer(s), but how do you tune it to reach both your speakers, subwoofer(s) and amplifier's full potential?
CarAudioNow has put together a quick guide to do a basic tune on your amplifier to make your stereo reach its potential. Use it to tune subwoofers or speakers alike. But before we get into tuning, let's review a few basic and common terminology, features and functions that will help you better understand the tuning process.
Also see our Choosing the Best Amplifier post to see how to choose the proper amplifier to best fit your speaker and subwoofer setup if you haven't already chosen one.
Max (Peak) Vs RMS Power
The difference between “Peak Power” and “RMS Power” is simple, so don't let it confuse you. RMS Power is a measure of the amplifier's continuous power. It's the realistic amount of power that the amplifier is rated for. It's more of an average of the wattage output over a set amount of time. Peak Power can best be described as the “peak” amount of power that the amplifier can generate or handle in a very short amount of time, a burst. It is not the amount of power the amplifier emits on a continuous basis, but more of a quick burst.
Even though the Peak Power ratings are marketed by speaker and amplifier manufacturers to catch the eyes of consumers, it is not the Peak Power, but the RMS Power that you want to use as a tool to match the right speaker with the right amplifier.
Gain is the input sensitivity adjustment necessary that is used to match an amplifier's input to the receiver's output. A properly adjusted gain reduces background noise, distortion and prevents speaker damage.
Frequency is the pitch at which your speakers emit sound at. You will need to know the range of your speakers or subwoofer in order to tune your amplifier properly.
Low-pass (LPF) and high-pass filters (HPF) are filters that pass signals with a frequency lower/higher than a certain maximum/minimum frequency. If you choose the high-pass filter on your amplifier, the corresponding frequency dial will set the minimum frequency that the amplifier will send to the connected speakers/subwoofers (HPF is typically used for smaller sized speakers). Vice versa, if you choose the low-pass filter, the frequency dial will set the maximum frequency that your amplifier will send to its connected speakers/subwoofers (LPF is typically used for larger sized speakers and subwoofers). The optimal setup will have speakers that cover the high range frequencies, while subwoofers will cover the low range frequencies, without any gap in between the frequency coverage.
In addition to low-pass and high-pass filters, there is also a “Full” selection, that does does not filter the frequencies and sends a full range of frequencies to the connected speakers/subwoofers. If you have a system that does not have subwoofers, and the amplifier is being used to power 6.5″, 5″ x 7″/6″ x 8″ or 6″ x 9″ speakers, you can use this option to get a full range of sound.
Bass boost is a feature designed to boost the low range frequencies. It's typically used for subwoofers, however, can be very touchy and dangerous to use. We recommend not using bass boost unless you have to.
Tuning Your Amplifier
Great, so now that you have an idea of some of the basic terms, lets get to setting up your amplifier:
Step 1: Setting Volume and Gain Control
Turn your stereo off and disconnect the RCA cables that run to your amps. Then turn your system back on, turn the volume on your radio/receiver all the way up to max without any music playing on them. If your speakers are running off of your radio, and you are tuning your amplifier for an additional subwoofer, make sure that you disconnect all speakers before you turn your radio to prevent damaging your speakers.
Now that you have found the maximum volume (many radios denote the maximum by a number), turn back the volume to around 80% of the maximum, and set your radio's Equalizer to ‘Flat'. Then turn your amplifier's gain and bass boost to zero and turn the crossover filters to off or full.
Now, plug back in the RCAs into the amplifier channel for which you would like to tune (e.g. if you are separating speakers by channels and have separate RCAs that for each, choose one to tune). With your favorite genre of music, or purchase a test disk for tuning, slowly turn the gain up until you begin to hear distortion in your speakers. Once your speakers start to distort, back of the gain until you no longer hear distortion. This is the base gain that you will use now to tune frequencies.
Step 2: Tuning Frequencies
Now it's time to switch to the built-in cross overs and filters that are built into your amplifier. For subwoofers, select the low-pass filter (LPF) and for speakers (for a system that has a separate subwoofer or speakers to cover the low range frequencies), select the high-pass filter (HPF). If you are using the amplifier to power mid sized speakers that are meant to cover a full range of frequencies, select the full or off position, and disregard this tuning.
Now, find the frequency range of your speakers/subwoofers. If you are tuning for speakers and select the HPF, you will align the frequency dial with the lowest frequency that your speakers are rated for (note that the numbers on the dial may be in 1000s). If you are tuning a subwoofer(s) and select the LPF, you will align the frequency dial with the highest frequency that your subwoofers are rated for.
Step 3: Bass Boost
If you're feeling risky, and don't mind putting loudness in front of longevity, bass boost is a great way to increase how loud your bass is but can be very tricky to use and hard to set properly. If you are going to turn your bass boost up, make sure you turn the gain down. Each subwoofer is different, so finding the right combination of bass boost and gain is up to your ear, but bottom line is to have the highest output without distorting.
Step 4: Back to Gains
Now that frequencies and bass boost have been set, turn back to your gains while your radio is at 80% to max with music playing, and tune the gain again until you hear distortion, tuning back once you hear it.
Step 5: Finish it Up
Last step! Reconnect all amplifiers (if you were tuning channels or amplifiers separately) and turn your radio down to zero. Slowly ramp up the volume until you reach the 80% or distortion, whichever comes first. If everything is set correctly, you will reach the 80% without any distortion in any of your speakers. If not, find the corresponding gains for the speakers/subwoofers that are distorting, and turn the gain down until they no longer distort.
And that's it! Do not exceed the 80% maximum on your radio. Keep in mind that different genres of music might need different tuning to maximize the output. Now you're all set and your amplifiers are tuned!