amplifier/speaker combo theory

I have made a spreadsheet for calculating series & parallel circuits consisting of single speaker (1 load) and pairs of speaker (2 loads) and want to make sure I'm on the right path.

I am currently wanting to purchase a set of new speakers, that are going to be as follows:

20w RMS @ 4 Ohms (4 speakers) - 300-20000Hz -
^I was told this would be my midrange and tweeter all-in-one?
40w RMS @ 4 Ohms (4 speakers) - 150-3500Hz
and
90w RMS @ 8 Ohms (2 speakers) - 30-350Hz

Anyways, from those speakers chosen, I went the parallel route, and figured I should look for an amplifier(s) that would do the following:

50w RMS x 2 @ 2 ohms
100w RMS x 2 @ 2 ohms
200w RMS x 1 @ 4 ohms

After some searching, I realized that I was never going to find one amplifier like this, and would have to split it up which would induce a bigger headache that I did not want, so I changed things up:

75w RMS x 2 @ 4 ohms
100w RMS x 2 @ 2 ohms
200w RMS x 1 @ 4 ohms

My reasoning behind this goes:

I would connect the 20w speakers in series, thus making them 8 ohms, and they would receive 18.75watts each. (75w x 2)
I would then connect the 40w speakers in parallel, thus making it 2 ohms, and they would each receive 50 watts each. (100w x 2)
Lastly, connect the subwoofers in parallel, 4 ohms and placing them in the last channel so each speaker gets 100 watts.

Is my math correct? I know I am not accounting for any sort of loss, through wires/amplifiers/radio/where ever else it may happen.

My main question is: If my math is correct, is it okay to give those 20w speaker, 18.75w ?

And also... where can I do some more reading?!!?

What are you using as a crossover? When building a 3-way system the passive crossover makes all of that math not necessary, and if using active crossovers, you'll have separate amps for each speaker. So what's you plan?

Also, you ask "is it Ok to give a 20W speaker 18.75 watts." The power rating on a speaker represents the MAX safe continuous power, not the minimum required. So yes, it's not only OK it's required.

-------------
Support the12volt.com

I think I'll be using an active crossover?

I am in the final stages of figuring everything out before I make a purchase and my setup would include:

Audio Control DQ61

https://www.crutchfield.com/S-0Hx1e7g7U8E/p_161DQ61B/AudioControl-DQ-61-Black.html?XVINQ=DST&XVVER=CCC

I was told this would act as a crossover and as a line output converter due to the fact that my car's system has 8 speaker level inputs so this would go in between the amplifier and the headunit.

The amplifier I am contemplating choosing would be, if my calculations are correct, is this:

https://www.crutchfield.com/S-GtHnDbdRaEX/p_13698605/JL-Audio-XD600-6v2.html?XVINQ=DST&XVVER=CCC

I was also told/advised that the speakers I chose do not have crossovers in them:

The "midrange/tweeter" driver I chose goes from 200-20000Hz, the woofer I have chosen goes from 48-4000Hz, and the subwoofer is 30-350Hz. I guess all of this frequency will be addressed in the processor?

I think I'll be using an active crossover?

I am in the final stages of figuring everything out before I make a purchase and my setup would include:

Audio Control DQ61

https://www.crutchfield.com/S-0Hx1e7g7U8E/p_161DQ61B/AudioControl-DQ-61-Black.html?XVINQ=DST&XVVER=CCC

I was told this would act as a crossover and as a line output converter due to the fact that my car's system has 8 speaker level inputs so this would go in between the amplifier and the headunit.

The amplifier I am contemplating choosing would be, if my calculations are correct, is this:

https://www.crutchfield.com/S-GtHnDbdRaEX/p_13698605/JL-Audio-XD600-6v2.html?XVINQ=DST&XVVER=CCC

I was also told/advised that the speakers I chose do not have crossovers in them:

The "midrange/tweeter" driver I chose goes from 200-20000Hz, the woofer I have chosen goes from 48-4000Hz, and the subwoofer is 30-350Hz. I guess all of this frequency will be addressed in the processor?

I clicked it once, I swear.