XO parts order help!

[sangram]

Hi

Starting a new build soon, these are 2.5-way mains and 2-way center and surrounds.

Drivers are the W14 Silver Flute woofers, and the Hi-Vi K1 tweeters - bargain-basement priced drivers.

I need help with the crossover design for those mains, desperately.

I have three questions:

1. To design the L-pad for a 2.5 way speaker, do I need to take the combined SPL of the upper and .5 woofer together, or just one woofer? I thought it was only one, but I see Zaph's TMM uses no L-pad on the tweeter, so I'm a bit thrown off. I assumed the second woofer was only correcting the response in the baffle step area.

2. To create a basic set of crossover values, do I need to take the nominal driver impedance, or the actual impedance at the crossover point? I'm getting a very wierd set of values using spreadsheets, though they look a lot closer to real designs. I'm aiming for a 1.8 KHz crossover. This gives me 2.2. mH/3.5uF on the woofer for 2nd order LR, and 4.3 uF and 1.8 mH on the cap. That 1.8 mH looks wierd, but it could just be me. I thought the cap should be bigger, and the coil smaller at that frequency.

3. To derive the inductor for the .5 woofer, do I subtract the inductance of the first inductor? I am referring to the XO Zaph shows on his TMM project. I was aiming for a 1st order at the F2 frequency on a 7.5" wide baffle, giving me a 4.7 mH - so I was thinking what I need is a 2.5 mH after reducing the value of the first inductor.

Thanks in advance for your help.

Sangram

Edit:

Sorry three last Qs

1. When I'm calculating the tweeter XO, I had added the L-pad series resistance to the impedance at the XO point. Is that the right thing to do?

2. I'm guessing I'll need a notch filter - there is a nice one designed for this woofer on Zaph's page - could that be used, you think, without changing anything else?

3. With the zobel and the crossover cap, should I still put in a Zobel? This is becomign a very complex crossover if I need that as well.

[sangram]

Hi,

Need some help please.

Thanks

Sangram