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The Request
Hello there!
I would like to propose a crossover circuit, 70 Hz, 500 Hz, 5,000 Hz. I am interested in your solution to a very low crossover frequency, say 100 Hz or lower.
Best regards,
Tomas P.
What is an Active Crossover?
A crossover divides the audio spectrum into sub-ranges for the various drivers in a loudspeaker. Usually, the crossover is contained in the speaker and works passively, i.e. it does not require and power source other than the input signal itself and it contains only passive components, such as inductors, resistors, and capacitors. An active crossover, on the other hand, does require its own power source and active circuit elements, such as IC's, transistors, FET's, or tubes. Previously, passive crossovers were much less expensive than active ones. Not today. Large valued polypropylene capacitors and copper foil, air core inductors are very expensive. Whereas even very good IC's are fairly cheap, as are small valued film capacitors and resistors. Because of the high voltages used in tube gear the price differential is not as great.
Beyond price, ease of use and design performance are important issues. Passive crossovers require an enormous investment of time and patience to design and test, as the average speaker is an incredibly complex device: its impedance is not flat, its phase response is not flat, nor is its frequency response flat. Textbook crossovers are designed with resistors as terminating loads. When presented with an actual speaker, the odds are that the crossover will not match the textbook expectations. Admittedly, Zorbel networks and notch filters ameliorate the
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