Perhaps the answers should be geared to the OP's level of understanding.

Ohm's Law: E=IR
Watts Law: P=IE
from these, all can be calculated.
without these, the impedance of the speakers, and the configuration of the amplifiers, all is guess work.

 

Mr R!f, if I had a 300W amplifier for low frequency what would be the output of amplifier for mid and hi frequency? Thanks...

 

Mr Audioguru you have said. Good sound systems use an active crossover using opamps to make the filters. Then the woofer has its own filter and power amplifier, the mid-range speaker has its own bandpass filter and power amplifier and the tweeter has its own filter and power amplifier. I dont understand (then the woofer has its own filter and amplifier and also for mid and hi). what kind of filters are these? Thanks

 

Mr Audioguru you have said. Good sound systems use an active crossover using opamps to make the filters. Then the woofer has its own filter and power amplifier, the mid-range speaker has its own bandpass filter and power amplifier and the tweeter has its own filter and power amplifier. I dont understand (then the woofer has its own filter and amplifier and also for mid and hi). what kind of filters are these? Thanks

did guru said that ?

Any ways
OP, if you want to use active crossovers then you have to tell me what type of amplifiers you have.
Or just tell me briefly what do you have as an amplifier.
Give me the specification or show me some pictures.

 

I dont understand (then the woofer has its own filter and amplifier and also for mid and hi). what kind of filters are these?

The active crossover circuit uses a lowpass filter to feed the woofer amplifier, a highpass filter to feed the tweeter amplifier and a combined lowpass and highpass making a bandpass filter to feed the mid-range amplifier.

I worked with sound systems for many years and for a PRO-Sound manufacturer. The PRO-Sound systems used horn high frequency speakers that are much more sensitive than home high frequency speakers. Then the high frequency amplifier power is only 1/5th the power of the low frequency amplifier.
In high quality home speakers the tweeter and woofer both have about the same sensitivity so the amplifiers have the same power. A sub-woofer amplifier has more power than the woofer, mid-range and tweeter amplifiers so you can feel the very low frequencies as a vibration.

Here is the active crossover circuit from the website that was linked to earlier in this thread:

 

Pish Posh...

Even as I type I am listening to music steered by that same crossover.

 

R!f, my amplifier uses 4 - K1058 transistor; positive & negative 45V; 8A power supply...

 

Is this a home brewed amplifier?

The point is, for a active crossover network you need a separate amplifier for each speaker, and the separation of signals is in front of the amplifier network. If your setup is a standard stereo amplifier you have no real choice but to go with a passive crossover network.

Somewhere I get the feeling we are not communicating. You seemed to have this down on post #43, then seemed to loose understanding at the end of the thread.

Filters in general can be broken down into Low Pass (Woofer), Bandpass (mid range), and High Pass (tweeter). Band pass filters can be very narrow, or they can be very wide. An audio system uses the latter.

 

R!f, my amplifier uses 4 - K1058 transistor; positive & negative 45V; 8A power supply...

Either u get some more low power amps or try for Passive crossovers