The Art & Science of Audio & Video

Determining X-over Freq. of Passive X-over

How do you determine the crossover frequency of a speaker with a passive crossover if you do not have the manufacturers specifications?

To perform this test we will need a Pink Noise generator and a RTA. This will also require a little bit of manual labor on your part but it’s rather simple. I’m going to assume that this cabinet does not allow you to bi-amp it meaning that we have no external access to the two sections of the crossover. First disconnect the speaker from any power amplifiers then let’s get into the cabinet shall we. Every speaker is different when it comes to construction of the cabinet so the method of entry will vary depending on the make and model of your particular speaker. The majority of speakers are assembled using some type of removable connectors on the back of the drivers or at the crossover network to allow for serviceability. Simply disconnect the tweeter either at the crossover board or at the driver it self. Now with your speaker reconnected to the power amplifier play the Pink Noise through it. Using your RTA monitor the output of the woofer. You should clearly be able to see where the crossover is dividing up the frequencies. There will be a distinct decrease in amplitude all the way down to “0”. The type of crossover will determine the rate or “steepness” of the slope. A first order crossover (or single pole) will decrease in amplitude 6dB per every octave. For every additional pole the slope increases by 6dB. For instance a fourth order (four pole) crossover will decrease in amplitude 24dB for every octave.


February 27, 2008 - Posted by | FAQ's | , , , , , , ,

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