alphakenny1

03-07-2006, 03:19 PM

I’ve noticed there have been a lot of questions regarding the differences between active and passive crossovers. I am going to attempt to explain the differences between the two and also the advantages and disadvantages of both. I’m not going into a very detailed technical explanation, I just want a basic explanation for the people out there who don’t know the difference between the two.

Just some terms to know before reading:

Low pass filter

A low-pass filter is a filter that passes low frequencies well, but attenuates (or reduces) frequencies higher than the cutoff frequency.

High Pass filter

Exactly the same as a low pass filter but passes high frequencies.

Bandpass Filter

Is a combination of a low pass filter and high pass filter.

Octave

An octave is doubling the frequency. For example going from 50 Hz to 100 Hz is one octave. Going from 50 Hz to 200 Hz is two octaves, ect…

Crossover slope or roll off (reference www.bcae1.com)

Crossover rolloff (or slope) describes the rate which the audio level increases/decreases per octave as the frequency increases/decreases. Usually a crossover slope is given as 6db/octave, 12db/octave, 18db/octave, 24db/octave, etc. If you want to see a visual of this here is a great picture:

Cyan = 6dB/octave

Red = 12dB/octave

Green = 18dB/octave

Violet = 24dB/octave

http://i15.photobucket.com/albums/a356/misterassman52/xover.gif

As you can see the different types of slopes and also notice that the crossover point is 1k.

Crossover Point

This is where frequency where the roll off or slopes starts to begin. As with the picture from above the crossover point is 1 kHz roll off begins at that frequency.

2 way crossovers

These crossover have two difference types of crossovers: Low pass filter and high pass filter.

3 way crossovers

These crossovers have three different sets of crossovers: Low pass filter, bandpass filter and high pass filter.

Just some terms to know before reading:

Low pass filter

A low-pass filter is a filter that passes low frequencies well, but attenuates (or reduces) frequencies higher than the cutoff frequency.

High Pass filter

Exactly the same as a low pass filter but passes high frequencies.

Bandpass Filter

Is a combination of a low pass filter and high pass filter.

Octave

An octave is doubling the frequency. For example going from 50 Hz to 100 Hz is one octave. Going from 50 Hz to 200 Hz is two octaves, ect…

Crossover slope or roll off (reference www.bcae1.com)

Crossover rolloff (or slope) describes the rate which the audio level increases/decreases per octave as the frequency increases/decreases. Usually a crossover slope is given as 6db/octave, 12db/octave, 18db/octave, 24db/octave, etc. If you want to see a visual of this here is a great picture:

Cyan = 6dB/octave

Red = 12dB/octave

Green = 18dB/octave

Violet = 24dB/octave

http://i15.photobucket.com/albums/a356/misterassman52/xover.gif

As you can see the different types of slopes and also notice that the crossover point is 1k.

Crossover Point

This is where frequency where the roll off or slopes starts to begin. As with the picture from above the crossover point is 1 kHz roll off begins at that frequency.

2 way crossovers

These crossover have two difference types of crossovers: Low pass filter and high pass filter.

3 way crossovers

These crossovers have three different sets of crossovers: Low pass filter, bandpass filter and high pass filter.