Tag: frequency

Passive vs Active Crossovers

You may have heard the term “crossover” before. No, i’m not referring to SUV/hatchback vehicles or Chris Paul doing work on the court. I am in fact referring to audio crossovers. Most speakers are not going to be able to reproduce the entire spectrum of musical frequencies without distorting. For this reason, crossovers are put in place to separate frequency bands in order to get the best performance. There are two type of crossovers: passive and active.

Passive Crossovers

DLS Scandinavia Filter box

2-Way Passive Crossover

One of the main differences between the two is that passive crossover networks are unpowered which means there is no external power source.  They use capacitors and inductor coils to passively send frequencies to their desired drivers.  For example, in component speakers,  the crossover will passively send the high frequencies to the tweeters and the mid and lower frequencies to the mid bass drivers.  They will be wired in-line between the speakers and amplifier.  The amplifier’s output will be connected to the crossover’s input and the mid-bass driver and tweeter will be connected to the crossover output.  The disadvantages with passive crossovers is they are not usually adjustable and will actually cause a loss of wattage.

Active Crossovers

Hifonics HFXR

2-way / 3-way Active Crossover

Active crossovers are a different story.  They are essentially electronic circuits that divide the frequencies. They use the input side of the amplifier rather than the output like a passive crossover does.   It is a common conception in the audio world that active are more accurate and flexible than passive crossovers.  Active crossovers are adjustable and have variable filters such as low-pass,  high-pass, and gain.  They also have deeper crossover slopes.  This allows for a more customized and desirable sound for the user.  Another advantage to active crossovers is their ability to allow bi-amping.  This means you can use two amplifiers channels to power multiple drivers.

Usually, a component set of speakers will come with a passive crossover. However, the general consensus is that active crossovers are more accurate and a lot more flexible.  However, if you are looking for a good fixed signal then there is nothing wrong with passive crossovers.  Ether way you’re going to need one or the other in your audio system so what are you waiting for?


Amplifier Crossovers

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:

Hifonics GLX18001D

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.



Crossover Rolloff