driver placement

[speedie]

What are your thoughts on the placement of bass driver?
I am building floor standing towers, have developed concept from bass box pro, I designed the towers in a two box configuration internally divided, the top section will house the two 6.5 inch nomex mids and a ring radiator tweeter in mtm format it has a rear firing port tuned to 47hz, the lower box houses a 8 inch nomex driver with a forward firing port tuned to 30hz
My question is where should the driver be placed in the lower section on the baffle, my thought was to place it low in the box to get bass response from the floor and to position the port mid way up the remaining baffle, also it will ballast the tower with having a lower centre of gravity.
The crossover point is to be 240hz which has a wave length of 1436 mm which is longer than the tower is high(1200mm)
If I place the driver on the baffle closer to the top of the lower box and put the port at the bottom do you think that there would be any audible difference?
With The mtm section I have placed the drivers in a vertical array off centre which is to aid in diffractions losses etc and placed the crossover point at 2380 Hz which has a wave length of 145 mm.
The center spacing of the three drivers is as close to 145 mm as I can get hopefully this will do the job
Any suggestions will be greatly appreciated.
Would it be better practice to design a three way crossover for the entire system or to use a two ways third order Butterworth for the top section and a separate second order Butterworth for the bass?

Regards speedie

[Dr.EM]

Originally posted by speedie
If I place the driver on the baffle closer to the top of the lower box and put the port at the bottom do you think that there would be any audible difference?

This is the typical way to do it. Gaining you boundary reinforcement of the low frequency port output whilst keeping the woofer nearest to the other drive units. The port can also exhibit undesirable noises, like chuffing or midrange leaking out, and placing it away from the other drivers is usually preferred

[speedie]

when you say typical way i would assume it to be the correct way
most of the reading that i have done informs us to try to match wave lengths with driver positioning
i understand that lower frequencies require more room space
thanks for your input.

[901Fixer]

Tri-amping with active or PLLXO would be the best way to go if possible. Any 3-way passive crossover is difficult to get right.

The ~240hz crossover between woofer and mids will need to have both close together to avoid combing, probably look better too.

[speedie]

it is an interesting point re active xo as i am sure that it would work out cheaper on components but then you have to amp each drive another cost
has any one been down this avenue before
i was checking out some kit active xos i suppose the good thing of going that way is the ease of tweaking things