25-04-2022, 06:49 AM
If you connect your speaker up to an amp and sig gen then measure the voltage across the speaker terminals at various frequencies starting from 20hz say you'll find the voltage varies with frequency. This means as Jeffrey says impedance is changing with frequency though the DC resistance might always be 12 ohm.
At some point you'll find a peak, where the coil/loadspeaker is resonant, or to put it another way at some frequency the stars align, the moons in the right quarter and the speaker is having a good hair day. Because Z (impedance) changes with frequency, the nominal frequency will be under the peak frequency, it's a fudge, from 20hz to 1khz say the Z will be about 15 ohms, ish. This gives you an idea what the driver was designed for, IE guitar or Hifi.
Z changes too when you put the speaker into a box, the resonant frequency will change too depending on the box design.
Mark knows this stuff better than I do, he's the speaker guru,hopefully he'll have the time to chip in.
Andy.
At some point you'll find a peak, where the coil/loadspeaker is resonant, or to put it another way at some frequency the stars align, the moons in the right quarter and the speaker is having a good hair day. Because Z (impedance) changes with frequency, the nominal frequency will be under the peak frequency, it's a fudge, from 20hz to 1khz say the Z will be about 15 ohms, ish. This gives you an idea what the driver was designed for, IE guitar or Hifi.
Z changes too when you put the speaker into a box, the resonant frequency will change too depending on the box design.
Mark knows this stuff better than I do, he's the speaker guru,hopefully he'll have the time to chip in.
Andy.
