Ported volume for 6.5" then adding a 4" volume??

Hi I am building some speakers each with a 6.5" SB Acoustics SB17NRXC35-8 for the lower frequencies. This needs between 17 and 25 litres for a ported enclosure. I have calculated it to 22.5 litres with a 19.5 cm x 43 wide port.

I would like to ad a midrange driver the Dayton DSA115-8 4" but this needs a ported volume of 3.68 litres.

How do I add this, does it change the volume I already have calculated for the SB Acoustics 6.5" ? Does it change the port size by adding the mid range Driver??
 
The mid should be in a separate chamber. The mid chamber is usually sealed.

3+ liters, vented, for a 4" is to extend the response below 120Hz. Surely you don't want to go that low on a "mid"? The 6-inch is fine to hundreds of Hz. The mid would then be in a small sealed chamber (like a margarine tub, or coffee can) to control excursion.

Isn't there a "multi-way" section where they may know something?
 
I did this today but made the sealed chamber 0.53 litre by mistake instead of the recommended 0.05 ft3 which is 1.416 litres not 0.53 litre like I have.

Sadly I don't have room anyway (see pic) I am crossing from my SB 6.5" woofer to the 4" mid around 600 Hz.

Would I be ok with the smaller size 0.53 litre for the 4" mid as I'm not using it for low frequencies at all?

I could modify it to 0.75 litre of that helps?

IMG_20210807_200053_854.jpg
 
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If you are going to play with speakers, you do have to become comfortable with basic design tools.

Closed Box Simulator

Looks like a good bump-up at 300Hz. In an active crossover you could shave this. With passive crossover, not so easy. A series cap gives a droop and peak shape. A 2-pole filter needs careful choice of Q.
 

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