B&W 801 crossovers

I am debating buying tube crossovers. I have a pair of B#W 801 speakers and was wondering what type of crossover or just have the speaker crossovers rebuilt. If rebuilt who?

I have B&W 801 series 3 and considered the north creek crossover upgrade. Never got around to it.
I loved the North Creek upgrade until I sold the Matrix series for my current N802's. Highly recommended if you can find them.
Which model and series 801? Matrix? See my crossover upgrade thread.

Get the NC's. Much more managable now fhat teo bixes are used unstead of four.

Get the NC's. Much more managable now that four boxes are used unstead of four.
I am slightly detouring this thread for selfish intent, as I doubt any answers to my query will benefit the OP. But, here goes anyway: Is there still merit in the old units such as the Heathkit XO-1 tubed crossovers? Assuming their operational condition is as should be, possibly with upgrades? When used with a basic tubed system, how may they fare compared to modern examples, such as a Marchand? My question is more than academic. Thanks in advance to any respondents, also those just giving it some thought :)
The speakers are B&W 801 matrix series 2.
Replacing the caps do wonders and a relatively cheap fix. Bypassing the APOC in the tweeter is another option. Series 3 did away with that. Are they on stands? The soundanchor dedicated stands really open up and cleanup the sound and bass. Also using good bi wire improves things. These are a few options. My Matrix 802 series 3 are amazing. The caps used are sonicaps for the mid/treble drivers and Dayton caps for the bass. They replaced .89 cent bennic caps that were there. Hope this info works for you.
Can anybody advise how to remove casters on 801 series 2. They don't want to just pull out. They were repaired some time ago under warranty and I was given the choice of series 3 tweeters for the cost of one tweeter. How can I check if the APOC has been bypassed? Does anyone know what the part #'s are for upgraded caps and can a rookie make the change?
Thanks. Can't give them up.
Vivant - I have S3's - the orignal castors have threads so need to be unscrewed.

Thanks. I'll give it a go.
To Poloman:

Hello. Which of the caps did you replace with Sonicap and Dayton? Did you replace all of the caps or just a selected? Here is a scheme on the 15th and 16th pages http://www.bwgroup-support.com/downloads/techmanuals/bw/Matrix%20801%20S2-TM.pdf

Thank a lot and all the best,
Artem, Berlin.

I have not been inside of any of the upper end B&W, so I've not posted on this until artsensiva posted the crossover schematics....
These crossovers are well thought out in general design,  but the mid tweeter has a protection circuit that has zeners and switch's both in it,  these are very audible,  same with the woofer. The crossover points are at 380 on bottom and 3k on top, The tweeter rolls @ 24db per octave, the mid runs up and down at 12db per octave and the woofer is crossed up at 24db per octave.  Unless the drivers are fragile,  I would not use such a circuit on any of my own speakers.  Next,  they are spec'd with 100 volt mylar parts.  These are quite inferior to even low end to decent Poly prop today.  The compensation circuitry is well thought out,  So............  I would recommend bypassing the protection circuitry and replacing the caps with some quality 400 + volt parts.... Good Luck,  Tim
Vivant,  as far as your question... I don't know about the casters.  On the crossover,  If the components are mounted on a board and hand soldered,  you need to just cut the lead after the protection circuit and reattach the input behind that circuit.  If a circuit board is used, you'll need to break the trace and solder into the circuit in a similar fashion behind the protection circuit... sounds harder than it really is. 
The fantastic folks at Audio by Van Alstine sent me detailed instructions for their suggested crossover modification and it's been three years since completion.
With high grade parts, a soldering  gun and a spool of Cardas silver solder,  the whole project cost $70.00 or so. It took me about 3 hours. Now I would be able to do it in less than an hour. Easy peasy even for a first timer.
(Series II with Series III  tweeters, I am original owner).
The APOC is bypassed, the bass is better integrated than with the alignment filter (discarded) , and just as low (not measured, just my opinion)
The speakers completely disappear. Silky smooth with tons of inner detail.
AND no need to bi wire. The combination of this change along with the addition of a Synergistic Research Powercell LE V2 has added so much refinement, accurate and rock solid 3D imaging that blows your walls out, you will not believe your ears that it is the same speaker. And keep them 6 to 8" off the floor.
This speaker bought on the used market with these modifications is so stupidly cheap in comparison to what is offered for ten to twenty grand. Makes me wonder if a whole industry would halve evolved around the reselling of these vintage gems with these modest modifications for a boutique price, if they were not so plentiful.
I'm using a 2010 ASR Emitter II Battery integrated and Tara Labs Omega Onyx and Zero gold with an upgraded BOW ZZ8.
After this mod, I forgot all about a new speaker upgrade.