Its the information i'm finding hardest to obtain, but i know it should have a 4th order Linkwitz crossover.
I obtained the drivers from a friend who bought about 100 speakers cabs and drivers from an auction as the company castle went into liquidation.
They are the drivers from the compact range
castle.uk.com/compact_column.htm
Oh dear! I did not know Castle had gone into liquidation. Even though the crossover is fourth order, it still does not help, as some of the orders will be acoustic. There is always a order to the driver roll off, and they usually change, and your electrical crossover has to as well. The combined electrical and acoustic roll offs have to be perfectly symmetrical and combine to a flat response. It is not easy, and impossible without intimate knowledge of the drivers. The roll off of the two way will be first order almost certainly, with a zobel.
Unless you can get a copy of the crossover circuit, or a set of Castle crossovers, you have a failed project. Also those slopes are high, so you stand a good chance of burning out the tweeters with a generic crossover.
I'm sorry, but pending further information and a lot of information at that, I don't have a good solution for redeeming this project.
You might try and locate the owner, and see if he will help you.
Are you sure, Castle are liquidated? They seem to be owned by IAG now. In the UK service for International Audio group, is concentrated at Peter Walker's old Quad works at Huntingdon Cambs.
The service manager is one of Peter's long time employees from the glory days in Huntingdon.
He is a very helpful fellow, Bob Flain. This is his Email. "rob@iaguk.co.uk" <rob@iaguk.co.uk>
If he can't help you, and he likely can and will, then you are well and truly sunk on this one.