Impedance is the complex resistance of an electric circuit from a resistor, capacitance, and inductance, which acts when high-frequency alternating current arrives at the input of this circuit. Depending on the capacitance and inductance, the circuit impedance changes. At low frequencies, the active element (resistor) has a greater effect. At high frequencies - reactive elements (capacitance and inductance).
Column resistance, which parameter to choose
The content of the article
- Column resistance, which parameter to choose
- Features of connecting speakers
Acoustic systems consist mainly of power amplifiers, frequency separation filters and loudspeakers.
The bandwidth is 20-20 000 Hz. Power amplifiers are broadband and divided by frequency range.
- Low-frequency (20-300 Hz).
- Mid-frequency (300-5000 Hz).
- High-frequency (5,000–20,000 Hz) belong to class 3 band.
2-band amplifiers have two frequency ranges LF-MF and HF. The input signal is distributed by the filters through the frequency channels and fed to the respective amplifiers.
Radio amateurs to calculate the separation filters need to know the input impedance at different frequency ranges. For low frequencies, the speaker impedance is 4 or 8 ohms. Impedance can be taken equal to about 10% of these values.
You can measure it by connecting an audio frequency generator tuned to the crossover frequency (at least 6 kHz) through a 1 kΩ resistor to the loudspeaker. The voltage ratio across the resistor and loudspeaker will show the desired value. The impedance of the high-frequency head is found in the same way.
Features of connecting speakers
Several speakers are connected to the signal source in a sequential, parallel and parallel-serial manner. Accordingly, the parameter of the speaker group is calculated according to Ohm's Law. On the labels and in the operating instructions of the speakers, headphones, their resistance is indicated (4.8.16 ohms). If your speakers are not new, the operating instructions have been lost or you don’t know the speaker impedance for any other reason, you can measure it with a multimeter. What it is? This is a special device for measuring this parameter.
Having released the speakers in the speakers from the equipment, measure their resistance. The multimeter will show slightly lower resistance values close to the standard ones.
