crossover design for dipole rears

My hurdle now is verifying the crossover cap and coil values with the ones haemphyst came up with using his program.  For instance, the value for the tweeter crossover at 3500 Hz:  C1 and L1.  Instead of using a 12 ohm impedance for the series-wired 6 ohm tweeters, the program seemed to have used about 17.5 ohms for the tweeter impedance.  What is the program looking at that I wouldn't know if I used a calculator or a chart?

The other cap and coil values listed don't match with the chart or calculator, either, but not off by as much.  Can anyone verify?  haemphyst, do I go with what your program says?  Is it taking into account the differences in impedance with the individual speakers as talked about earlier ("These values are pretty exact, and provide/allow some fashion of impedance control.")?

Just want to be sure before I order the parts.  Thanks.

Cap and coil alues don't have to match exactly.  Within 10% is more than fine.  I also usually have a few small value caps handy that can be soldered in to make fine tuning adjustments when building a crossover as you can never be 100% certain using any calculator.  Remember that calculators use ideal values and every speaker, cap and coil is different; none are ideal!  Also, surround speakers are not nearly as critical as mains in terms of having a dip or peak at the crossover point.  I doubt very much you'd hear it if it was there.

The JBL program is very good and accurate.  I am not certain if they use dynamic compensation or straight DCR, but I say trust it and use it as a basis for the circuit then make fine tuning adjustments if necessary.

Done deal.  I'll use the values you listed and maybe pick up some spare parts when I order.  Thanks for the replies, gentlemen...and I'll let you know the results when it's all said and done.

Just a note:  I used  thiscalculator later on, and entered the info for a 2nd order crossover for 3500 Hz......I used 12 ohms for the tweeters and 4 ohms for the woofer.  Guess what?  The values were the same (precisely for the tweeter) as the values given by the JBL program.  Interesting differences in calculators given the same information.

More tidbits, just for fun.   While shopping components, looked at a pre-made crossover at PartsExpress, and clicked on details..... http://www.partsexpress.com/pdf/260-150s.pdf  Looks like the folks there are using the same JBL program, huh?

Actually, not a bad price on that at $40.  I have $70 in parts for my two crossovers.  Looking forward to building it and I hope it all fits on the smaller 4 X 7" board.

Parts list for (2) three-way dipole crossovers:

C1:  http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=027-414&scqty=2

L1:  http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=260-733&scqty=2

R1:  http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=004-4.3&scqty=2

PC boards:  http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=260-122&scqty=2

Other:  resistors, 20 watt:  http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=017-.27&scqty=2  and  http://www.partsexpress.com/pe/pshowdetl.cfm?&DID=7&Partnumber=017-1.75K&scqty=2