Building new fronts and subs. Need advice

[Heliac]

Im ugrading from 250ti to DIY fronts. I have 2450sl+H9800, 2206, Sub 1500 and w15gti. 2pcs of each. I will run them in a four way active configuration. I want to keep the size of the fronts down, so i think a sealed enclosure for the bottom driver will be good.

But..

Sub 1500 or w15gti in the fronts or in the subs?

2206 ported or closed? I dont know crossover point...80-300 somewhere.

What do you think?

[pos]

I'd first try 2206 ported with the sub1500 crossover quite low.
But for that to work properly you have to take the rolloff of the ported 2206 into account, and possibly aim for a higher than normal port tuning.
If you cannot do that (with the right measurement and crossover tools and methods) then going sealed will be easier.

What crossover unit do you have?

[Heliac]

I'd first try 2206 ported with the sub1500 crossover quite low.
But for that to work properly you have to take the rolloff of the ported 2206 into account, and possibly aim for a higher than normal port tuning.
If you cannot do that (with the right measurement and crossover tools and methods) then going sealed will be easier.

What crossover unit do you have?

DBX Driverack PA2

[pos]

I will try some simulations tonight, but it looks like a ported design in a ~30L box would give you something very nice for a ~70Hz target acoustical crossover.

[Heliac]

Thanks for answer. I have the sub 1500 today in a sealed 70 liters box, and they play very good with some eq. So the plan for now looks like a sealed box with the same volume in the front cabs...and a bigger ported box for the w15gti:s.

[pos]

i would let the W15GTI out of the equation, unless you want to run them as dedicated LFE in a HC setup...

I run the numbers, and here is a solution you can try:

2206H in a 30L box tuned to 80Hz (~5cm long 4" diameter port) + 2nd order high pass electrical filter at 82Hz, Q=0.62

This should give you a fairly good approximation of an acoustical 6rd order (36dB/oct) Butterworth high pass filter at 85Hz, and also keep excursion within control.

The sub1500 shall then receive a 6th order Butt low pass electrical filter at 85Hz (assuming it does not have any major natural rolloff in that range...)
The resulting 6th order Butt acoustical crossover will give you a nice summed power response, which is perfect for that frequency range and give you more freedom with sub placement (no need to keep it close to the main as would be the case with an acoustical LR).
You will have to check polarity with measurement: the sub1500 probably uses a +=red convention whereas the 2206 uses a +=black, and the 36dB/oct crossover will invert polarity.


Then to get a good phase tracking, depending on whether you choose a sealed or vented alignment (or sealed with resonant high pass) for the sub1500 you will have to add either a 1st order or 2nd order allpass filter to the 2206H, centered at the sub1500 final resulting acoustical high pass frequency.

[Heliac]

Yes, the w15 will be lfe only. Thanks for the advices.