question about passive filters

[lokeycmos]

i have a question about RC highpass filter and LR lowpass filter. I attached a diagram. the top one is high pass RC. the bottom one is low pass LR. this is in reference to basic speaker crossover. My question is, can the 8 ohms of resistance of the speaker itself take the place of R1? or does the speaker go in parallel with the resistance of R1? thanks

 

[MrAl]

Hi,

You dont normally use a resistor in parallel with the speaker because it eats up power.

 

[MikeMl]

The speaker itself is anything but a pure 8Ω resistor. Its really a complex impedance that varies all over the place...

 

[audioguru]

A series capacitor feeding a tweeter to ground is a very simple highpass filter with a gradual slope. Low frequencies are not attenuated much.
A Tweeter is fragile and can be destroyed by low frequencies from a simple filter.

A series inductor feeding a woofer to ground is a very simple lowpass filter with a gradual slope. High frequencies are not attenuated much.
A woofer sounds awful when producing high frequencies.

These simple filters are "first-order". An LC second-order filter has twice the attenuation of unwanted frequencies and a third-order filter is 3 times better.
Here is a good article about a passive crossover network: **broken link removed**