Replacement tweeters for tannoy p10

You need a ton of info to get right,  if you can get it right...if there is any pad in the original crossover that can effect the bsc.... The only Audax spec that I have is on a TW025A0... not the 01 version. Do you have a schematic from the Tannoy?  It isn't likely that the Audax is a direct drop in, you'll probably need to change a piece or two in the tweeter circuit besides BSC.
I assume that you measured DC on the tweeter and the width of your cabinet to figure BSC? 
If I can get enough info, I'll be glad to help,  Tim

Well, the pdf I saw showed about a 4db drop at 7K.... Go here and confirm which tweeter that you have:
Go to the old Zalytron site.  www.zalytron.com
Left side, click on audax, scan to the bottom of the page, click on pictures & specs.... on the next page,  you see a French word for Archives...go into there. Find your tweeter and let me know.  Tim

after I get your correct schematic and the correct tweeter, you can pm me and I'll draw up new crossovers for you trying to keep your changes as minimum as possible,  but you will need some changes. 

Glad the new crossover worked out, enjoy