Hi-Fi Speaker Crossover Network Design

To ensure overall fidelity and clarity of sound reproduction, Hi-Fi speakers are required more and more.

 

When it comes to high-fidelity audio systems, one cannot ignore the crossover network.

 

Due to the prevalent design approach of multi-driver configurations in today's speakers, there is a necessity for a device that can divide the full-range audio signal from the amplifier into separate outputs for high-frequency, mid-frequency, and low-frequency ranges, corresponding to the respective speaker units. This device is known as the crossover network. If the full-range signal is directly fed without division into the high, mid, and low-frequency units, the "extraneous signals" beyond the units' frequency response range could adversely affect the reproduction of signals within the normal frequency band, potentially even damaging the high-frequency and mid-frequency units.

 

From an electrical circuit perspective, a crossover network fundamentally consists of capacitors and inductors forming an LC filter network. The high-frequency channel is a high-pass filter, allowing only high-frequency signals to pass while blocking low-frequency signals. Conversely, the low-frequency channel is a low-pass filter, permitting only low-frequency signals to pass while blocking high-frequency signals. The mid-frequency channel functions as a band-pass filter, allowing frequencies between its lower and upper cutoff points to pass through, while attenuating both high and low-frequency components. In practical crossover designs, to balance sensitivity differences between high and low-frequency units, attenuating resistors are sometimes added. Additionally, some crossovers include impedance compensation networks composed of resistors and capacitors to flatten the loudspeaker's impedance curve psychologically, facilitating amplifier driving.

Classification of Crossovers

 

Passive Crossover

Passive crossovers are integrated within speakers, comprising filter networks of capacitors and inductors positioned between the power amplifier and the speaker. These crossovers divide the full-range audio power signal from the amplifier into low-frequency and high-frequency outputs, or into low-frequency, mid-frequency, and high-frequency outputs, directing each frequency band to its corresponding speaker unit. In systems utilizing passive crossovers for full-range, high-mid-low or high-mid-bass audio distribution, the passive crossover circuitry handles the crossover task.

Advantages

Simple structure, low cost, integrated with the speaker without needing adjustments, and easy to use in system connections.

Disadvantages

Must handle significant power and current on speaker components, requiring large-sized inductors. Accuracy can be compromised due to variations in speaker impedance and the nonlinearities introduced by capacitors and inductors.

 

Active Crossover

Active crossovers process the full-range audio signal at a weak signal level using active electronic circuitry placed ahead of the power amplifier. After splitting the signal into low-frequency, high-frequency, or low-frequency, mid-frequency, and high-frequency bands, these signals are then sent to respective power amplifiers which drive the corresponding speaker units. This approach, termed active crossover, uses low-power active filters to achieve the crossover function.

Advantages

Minimal signal loss and distortion due to handling weak signal electronic processing, resulting in high-quality

audio reproduction. Allows for higher crossover attenuation rates (e.g., up to 24dB/octave) and reduces

interference between high and low-frequency units in the crossover region.

Disadvantages

Higher cost due to needing additional power amplifiers and active electronic crossover equipment, which complicates system setup and adjustment.

In conclusion, crossovers are indispensable in high-fidelity audio systems employing multi-driver configurations. They play a critical role in ensuring that each speaker unit receives the appropriate frequency range, thereby optimizing sound reproduction and protecting speaker components from damage.

 

Requirements for Crossover Circuits and Components

 

The DC resistance and inductance value errors in the circuit should be minimized. To achieve a flat frequency response curve, it is preferable to use air core inductors.

Capacitive losses in the circuit should be minimized. It is best to use audio-specific metallized polypropylene capacitors.

Ensure that each speaker unit receives a flat signal power distribution and provides protection for high-frequency speakers.

 

UF Capacitors Audio Capacitors for Cross Over Design

 

UF Capacitors is an ISO9001-certified manufacturer in China, founded in 1995. We hold military qualifications for tantalum capacitors, MLCC, and other products. Additionally, we have a UL-recognized test laboratory located at our factory site.

We UF Capacitors offers premium metallized polypropylene film audio capacitor. With cross reference as below:

 

Audio capacitors
Photo	Description	UF Capacitors Series Code	ERSE	Mundorf	Clarity Cap	Jantzen Audio
	MPX Series: Premium Metallized Polypropylene Film Capacitors Axial Lead,	MPX Series	PEx Series Metallized Polyester	MCAP Series MKP Series	CSA Series	CROSS CAP Series
	Pulse Audio Capacitors Metallized Polypropylene Film Capacitors - Axial Lead	PAC Series	PulseX Series C - Cap Series Metallized Polypro	***	PUR Series CMR Series

 

 

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