extremis and brahma replacements

Not really tought. It's gonna be a custom Brahma though. Instead of the baskets Adire used, I will be using Claw baskets. I have 15" paper cones i'll be using with the addition of an inverted aluminum dustcap. I'll have to get new coils (dual 4's) so that I can give a total power of 3k to both. The sooner I get my second brahma (at my friend's sister's house) the sooner I can get it reconed.

Unfortuantely I don't have enough room for a ported enclosure so I'll have to go with a about 5.5 cubes sealed. I may even get my recone through Fi. Just gotta make sure tinsel leads being used are not the same as the ones Adire used (they're known for tinsel lead snap). It was supposed to be an issue that was fixed when the MKII came out, but it still happened with it. Hopefully now I can break 140dB on the TL with music. Once I get 'em reconed, I'll definitely post pics.

Just so you know, the Robot Underground subs are far from the original Brahma performance.  They use a much longer coil which completely eliminates the XBL^2 motor topology, creating more of an evenhung motor.  This means that BL will be very peaky (Madonna's proven peaky isn't good ), distortion will be higher, and linear excursion will be much lower. 

Re-coning from a 12 to a 15 isn't a problem if you have a new larger basket and the proper soft parts.  However you have to be careful what parts you use as any changes will change the characteristics of the sub as can be seen by what I mention above.  For instance, a new basket might limit your excursion capabilities if it doesn't have the right clearances.  Also using an aluminum dustcap will change the Mms of the driver and have effects on the theile/small parameters.  Even changing from a dual 2 ohm to a dual 4 ohm coil will change things.  Speaker engineering isn't a big lego set where you just put parts together and hope for the best.  It is an extensive balancing act requiring careful compromises to achieve optimum performance. 

Having ran the warranty department at Adire Audio, I can guarantee you that lead slap was extremely rare with the Brahmas.  This was especially true later on with the braided leads we used on the MkII.  I don't know where you got the idea it was a problem because if it was, I would have been the one to hear about it.  I personally really liked it as it was very durable.

I have never considered replacing the basket as part of a "recone."  :shrug:

Steven if anyone on this forum knows anything about Adire it is you.  Thank you for your input on this.

It depends on the design.  The Brahmas used some mild glue along with screws to hold the top plate to the basket.  However the original Shiva/Tempest were attached in such a way that it would be impossible to change the basket.  This is probably one of the rare occations where it is possible for the manufacturer who has the correct soft parts.

I'd recommend whoever can get the correct soft parts to do it.  See if for a little bit more money they could order a custom wound coil that has the correct winding height so it would be a true Brahma.

Or for much less money you could order one of the Shiva X or Tempest X subs.  They use the Brahma motor, but have the classic Shiva/Tempest parameters. 

You are correct that the original MkI Brahma did have a few cases of lead slap.  The Brahma was the first sub at 27mm one way linear excursion and some design issues arose that needed to be considered, like how not to get the leads to slap the cone and spider.  The solution to this was a rubber coated tinsel lead and pads on the cone which almost always worked.  I had mine inverse mounted in an enclosure 4 feet from my head and I never heard lead slap.  However due to a few complaints Dan decided to come up with another solution which was released in the MkII.

Now in some situations people would push their subs past the designed excursion capabilities and eventually snap a tinsel lead.  Resoldering would change the length of the leads, and stiffen them up at improper points causing slap issues and eventual failure again.  Anytime this happens it is best to have the sub re-leaded which isn't hard to do if you have the right parts.

It is a combination of the motor and coil working together.  The coil height is designed to work with the flux heights within the two gaps to where it transverses from one field into another.  So in other words as it's leaving the flux of one gap, it is entering the flux of the other gap.  Using both gaps gives it a very long excursion for a given coil length and very flat BL as the already reduced stray flux is now part of the system. 

The original XXX was very similar to the Tumult.  And yes, it did use XBL^2.

I'm not 100% sure.  I know we got our coils back east somewhere.  Any coil company I'd imagine should be able to custom wind a coil for you for a price.  The hard part would be to find the correct coil length and wire awg needed.  And yes you are correct that the MkIV Brahma's used a 2.5" voicecoil diameter.