Portable stereo speaker

Last year i built a portable bluetooth 2 way mono speaker which runs off a Makita 18v battery. Had a lot of fun doing it so now looking to build another one, but a different style, slightly bigger and bassier!

I am looking to use 2x full range speakers, stereo left/right. I am thinking of using:

Faital Pro 4FE32 Neo - 4" 30W 8 Ohm 91dB

And for the bass either:

1x Beyma 10BR60V2 - 10" 100W 8 Ohm 92dB

or

1x Beyma 12BR70 - 12" 125W 8 Ohm 93dB

My questions:

1. Would the 2x 4" be able to keep up with the 10" or 12" sub?

2. If yes, where would you reccomend crossing them over at?

3. Is there a formula to work out what size, mid/top to bass ratio at all?

I understand to look at the driver sensitivity dB itself. But the physical size of the driver has an impact too on sheer volume, which is where im unsure how to match it. As its going to be portable, i dont want to overkill the bass and have to turn the gain down loads when i could of just used a smaller driver. Whereas on the flip side i dont want to under do it as it will be used for bassy music.

My previous portable speaker was just a mono 2way so i knew what i was using would cope fine together and the crossover points were roughly dictacted by the tweeter anyway. But struggling a bit to find the answers and dont want to waste money on them to find out they arent suitable.

Amplifier ill be using the amp out my previous build which is a Sure Wondom 4 channel Jab5 DSP amplifier. 1 channel for left, 1 channel for right. Then the remaining 2 channels bridged for the Bass. 

Cheers 👍🏼

When i get home ill post the winisd results on here too

On my previous speaker the bass is ~6db higher but could be more really. So ill use that as the benchmark i guess.

For the 12" driver i modeled it in a 40L box, tuned to 44hz and it looked pretty good to me, but im still learning. Anyway ill post results when home. Interested in your opinion. 

I ended up building this and have finished making it now, real happy with how its turnt out. Here is some build pictures.

The back looks like a Canadian off South Park

With the build side of it finished I started taking measurments using a umik1 and rew, outside, on concrete floor, taken within roughly 1m, mic tip on the ground, then aimed the box so the centre of the drivers are aimed directly at the mic. Im still learning with this side of things but this is what i done and the outcome. Id be very interested in your opinions and if i done it correctly.

- first i took a measurement of the 2x 4"midtops, smoothed the curve. then measured again after e.q.  Repositioned the box to suit the sub driver, then took measurment, smoothed the response with e.q then measured again. 

- next i looked at the responses and set the crossover.

- with all drivers response smoothed and xover set, i repositioned the whole box so the centre point of all the drivers together aimed at the mic, and took a measurment of it altogether.

- e.qd that to what i have read or been told is a good nice sound. Which did sound loads better after.

Here is the rew response curve as it stands now. 

I havent had a chance to take it to the field just yet, to play it full volume and to make some more adjustments. It will only ever be used with a mobile phone bluetooth on spotify to play music i expect. So want to see if it distorts at full volume and to make some adjustments if so. 

Hopefully it sounds bassy enough too, sounds good in the garden or home but cant blast it loud obviously here. Also I have always been led to believe its best to only ever 'take away' when e.qing and not to boost, (not boost more than the original response anyway). But anyway if anyone has any advice to get the most out of it, or things to change let me know.

Cheers 👍🏼

Went through my old posts from other topics to find someone posted a link about equal loudness contour graph and tried it like that and what a difference it has made! Its also been really interesting reading about equal loudness and how its percieved throughout the frequency range. Anyway  real happy with how it sounds now! Heres the response: