What does LPF mean on an amplifier?

What does LPF mean on an amplifier?

on November 17, 2023

The LPF or Low Pass Filter of an amplifier is the mechanism that allows all the frequencies coming out of a sound source to be distributed below the configured level. In other words, it is what facilitates the passage of low frequencies, eliminating high frequencies in a Car Audio system. At Genius Audio we would like to show you how it's done. 

In addition to the previously mentioned function, the LPF also has the function of providing greater smoothness in the output signal, eliminating fluctuations and extending trend levels. In this way it is useful to reduce hiss, attenuating extreme signals into a high-pitched sound that manifests itself in high frequencies. 

In simple words, an LPF allows you to transform unnecessary high frequencies into frequencies that are lower. This change not only improves the sound quality, it also protects the components of your car audio equipment from potential damage caused by the power of the frequencies. 

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How does it work?

 It works in three different ways, which are: 

  • Regulates the power and frequency field; by dragging the frequency, which allows a cut to be set. 
  • It manages the field and the order regulator, because it determines the order in which the filters will work. The interesting thing is that the greater the number of orders that can be established, the greater power will be felt in the sound effects that are produced. 
  • Regulates and manages the soft power field, adjusting the levels that soften in milliseconds the electrical signal in which the audio is transmitted from the sound source. 

When it is possible to combine an LPF of an amplifier with a high pass, two filters can be created which will create a pass band. The pass band is the one that eliminates all frequencies that are in the highest or lowest ranges, eliminating as much distortion as possible.

How to adjust LPF on an amplifier? 

How does LPF work?


It is possible to activate and deactivate the LPF in order to manage  the passage of the bass signal to the outputs of the speakers, tweeters and subwoofers, enhancing the bass. Enabling to adjust the functions of an LPF. 

Additionally, in each of the inputs to which each audio jack is assigned, independently, the function must be activated by connecting a bass boosted speaker, without a crossover function. For it: 

  • Select set up – audio settings on the main menu. 
  • Then, select where it says subwoofer Low Pass Filter. 
  • Then select the desired configuration: 
    • ON: is the one that is activated when the LPF is activated when you have a cut-off frequency of about 120 Hz. 
    • OFF: LPF is not activated. 

You must know that this function will not be activated when the device is being used in direct analog mode, or when the Bluetooth mode is set to Transmit mode. 


How do you adjust the gain of an amplifier? 


How do you adjust the gain of an amplifier?


When it comes to the initial process of adjusting amplifier gain in LFP, these are the steps to follow: 

  • Disconnect the amplifier speakers from the Car Audio System. 
  • Proceed to adjust its gain, this way the motor will be activated.
  •  Then proceed to check that the audio device is configured in its original way, that is, bass/treble at 0; balance/fader in the middle; equalized in FLAT and at about three quarters of the maximum volume it has.
  • Insert a CD into the sound source with the focal tools: if it is a single-channel amplifier, you have to adjust the frequency to about 150Hz, using a range of 14, which is approximately 50Hz. On the other hand, if it is an amplifier with between 2 or 4 channels, it must be placed in the Full function and use range 27, which is equivalent to 1kHz. 
  • Connect a voltmeter to the terminals of the output you want to adjust. 
  • Lastly, you must increase the gain progressively, until you obtain a reference value.

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The new amplification designs for car audio have multiple filters built into the input panel, which are useful if they are well adjusted or calibrated. They become filters whose purpose is to improve the way the speakers, tweeters, and subwoofers connected to the amplifier perform. 

When the adjustment has managed to calibrate these outputs, it will be possible to substantially improve the sound quality, protecting the components of your Car Audio System. This will prevent their membranes from having to move excessively and be destroyed. 

Therefore, by correctly using the well-calibrated and adjusted LPF, it not only improves the sound quality, but also prevents the Car Audio System from suffering damage, and this is achieved with quality items such as those offered by Genius Audio, which is why you should contact us, don't hesitate anymore. 

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