Cross It Over
You might be wondering why amplifiers have features such as low-pass, high-pass, and subsonic filters. A lot of people will install an amplifier without properly setting these controls which can result in poor audio quality. We are here to make sure this does not happpen to you! Crossovers are filters which means they use capacitors and inductors to block or pass different ranges of frequencies. There are two types of crossovers: active and passive. Passive are not adjustable and require no work on your part as it is already installed and preset depending on the capacitor or inductor that is already installed inside the device or crossover. Active are usually adjustable in that you can select the crossover points. There are a few important terms to consider when refering to crossovers:
Low-Pass Filter- This allows the low frequencies to pass or be allowed to play. This feature is used mainly for subwoofers. The low frequency spectrum will contain any frequency of about 100 Hz or lower.
High-Pass Filter- This allows the high frequencies to pass or be allowed to play. Mainly used for Mid-bass drivers and tweeters. The high pass will usually be for frequencies of 100 HZ and up.
Subsonic Filter- This filter prevents any frequencies that are not audible to be blocked. This filter is usually set around 20 Hz. It is essentially a safe guard to keep you from damaging your subwoofer.
Phase- This feature ensures that the sound from your subwoofer reaches you at the same time as your speakers. For example, if you are hearing an echo, your should set your phase to 0. This feature is adjustable from 0-180 degrees.
Bass EQ- Also known as a bass boost, this feature is designed to boost select frequencies, usually around 40 or 45 Hz.
Gain or Level- This function is used to match the voltage that is coming from your headunit in order to prevent clipping.
Rolloff or Slope- This concept is the most difficult to comprehend. This describes the rate in which the audio level will increase or decrease per octave as the frequency rises or falls. Most commonly, amplifiers will have a 12dB octave slope. Basically what this means is that once you have changed the frequency of the signal by a factor of 2 or 1 octave, the signal will change by 12 dB.