Driver selection for a midfield system

[NadMk]

Hello everyone,

I want to build a midfield system with 2 sealed monitors and a subwoofer actively crossed around 80Hz.
I would like the monitors/satelite to have just one wide-range driver each and would love it to be a closed box, since the enclosures are being made in granite and I want to avoid extra labor like tunning por holes or tunning issues.

The goal is to achieve around 95dB SPL with an analytic smooth and flat frequency response.

I have been watching the specs of Mark Audio Alpair drivers, and seems that 12P would be the wide-range driver to go, but it seems can´t go down to 80Hz in a closed box.
Can it be possible to go that low in a closed enclosure? Is there another driver that would fit better for such purpose?

Still haven´t looked for the sub driver. Any suggestion about this?

Thanks..!!

 

[perceval]

It will be a granite box, or only a granite baffle?

Hope you have strong stands. How thick will the walls be?

You will probably need a bigger cone to reach 80Hz with a single wide band driver. And be prepared to lose some top end. Can't have it both ways.

You didn't mention how big your room is, or if it is for near field listening. If it is small, you stand a chance of reaching low enough and with significant spl. If it is big, you will lose some output at 80Hz from your wide band driver.

 

[NadMk]

It will be a granite box, or only a granite baffle?

Hope you have strong stands. How thick will the walls be?

It will be the complet enclosure. I think granite thick will be around 3 cms (1.18"). Would it be enough? Size and weight is not a problem.

You will probably need a bigger cone to reach 80Hz with a single wide band driver. And be prepared to lose some top end. Can't have it both ways.

I want to avoid XO filters in the mid area, and I will use a sub, so I think the logic way would be adding a tweeter instead crossing the sub higher.
I don't mind adding a tweeter crossed at, let say 10khz, but want to keep the sub XO low.

You didn't mention how big your room is, or if it is for near field listening. If it is small, you stand a chance of reaching low enough and with significant spl. If it is big, you will lose some output at 80Hz from your wide band driver.

The distance between the "sweet spot" and the speakers will be around 2 or 3 meters. Room is around 35 square meters (376 square feets).

Thanks..!!

 

[perceval]

Most stone factories will cut at 2". Thinner than that, and you take the chance of cracking the stone, although granite is more resilient.

If thinner, you will need to back the stone and laminate it with either plywood or aluminium.

Adding a tweeter with a simple cap on top will do fine.

Your room is a bit on the big side of things.... Might consider doubling the woofers per side?
Depends on your expectations with the low end of the music, and the kind of music you plan to listen the most.

 

[NadMk]

I may be wrong, but I think the factory I have been to has those 1,18" thik granite. If more is needed, maybe 2 layers will do. How thick do you think it should be so it won't have resonances?

Do you mean 2 subwoofers per side? Or 2 wide-range per satelite.
I would like to reach the same SPL at lower frequencies.