How do inductors help impedence matching?

Presumably there is a capacitor that couples the tweeter to the amplifier for higher frequencies. This lowers impedance at these frequencies. The inductor that couples the woofer to the amplifier increases the impedance of the woofer circuit for higher frequencies. If you remove the inductor the woofer will be paralleled with the tweeter at higher frequencies, so that there will be a lower overall impedance at these frequencies.

The frequency response of the woofer is probably going downhill at the crossover frequency, so you may not hear much of a change when you remove the inductor.

However, manufacturers generally don't use components that are not needed. I would leave it alone, or, if you must tweek, replace it with an air core inductor of the same electrical value.

Eldatford - if I understand properly, a cap can be seen to decrease impedence as freq increases, while a coil can be seen to increase impedence as freqs go lower. The resulting overall impedence curve vs. freq is flatter than it would be without the crossover components. Am I correct?

A related question: other than experimentation, how might I predict effects of changing output taps on my SET amp from 4, 8, and 16 ohms? I do plan to experiment, but it isn't trivial because I have to reconfigure the output taps of the transformer each time. And ohms law doesn't apply, since we are discussing AC, correct?

Thank you for your response - I really appreciate the opportunity to learn.

scott

Skushino...About the impedance...correct.

Think of the transformer as being like an automobile transmission. The taps are like different gears. Suppose you want to get 2 volts out of the amp, and you set the volume so as to get this from the 8 ohm tap. The 4 ohm tap will have 1 volt, and the 16 ohm tap will have 4 volts. So you would need to boost the volume if you connect to the 4 ohm tap, and you could reduce it if you used the 16 ohm tap. Use of the 4 ohm tap might mean that the amp circuit couldn't put out enough voltage, and use of the 16 ohm tap might mean that the amplifier circuit couldn't put out enough current. Sort of like trying to go up a steep hill in high gear. The speaker impedance, modified by the transformer, is the load seen by the amp circuitry. Use of the correct tap will optimize power delivery from the amp circuit.

It depends if the inductor is in parallel or in series with the woofer. If it's in series, then its function is to increase the inductive reactance (why though, it's easier done with a resistor) and if it's in parallel, its there to reduce the reactance - possibly to match with the impedance of the other drivers (because the woofer coil is an inductor).

If you remove the inductor and it changes the sound, that is not unexpected. Whether it's better or worse - who knows- but I would agree that extra components are there for a reason and should not be removed. Crossovers filter because of the inherent impedance mismatching the components provide so changing the relationship will affect the performance of the speaker in one way or another.