extremis and brahma replacements

haemphyst wrote:

---

Well... Creative Sound won't ship to the US... other suggestions? Seems Adire (we know) AND mpyre sites are completely gone...

---

I'm pretty sure he will.  Bob recently shipped stuff to me, and he has US prices on all his stuff. 

Kyle at acoustic-visions.com is great, as is Kevin at DIYcable.com as Dyohn linked to.  Bob has a new extremis replacement driver coming out soon called the SDX7.  Kevin at DIYcable has another one already available IIRC, but isn't selling it outside his kits.

haemphyst wrote:

---

Say, Dyohn... How about a Shiva iso-loaded, stuffed TL? Driven by 1kW, real power... OH, wait! Add a SECOND PDX1.1000 for the OTHER woofer!

---

Should be damn good.  I am building a dual Shiva-X dipole driven by 1Kw for HT use right now.  Initial tests show outstanding promise.

I'm just waiting for Dave to start referring to his car as "the shiznit."

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.

DYohn] wrote:

---

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

---

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.

donpisto wrote:

---

Steven, I agree with you 100%. I recognize using different parts will entirely change the t/s parameters. Per the information in regards to the Brahmas RU makes, I did not know that. Would you suggest having Fi doing the recone instead?

---

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. 

donpisto wrote:

---

As for the tinsel lead issue, from my understanding it was infamous with the early models of the Brahma. It's known across many forums and I've talked to several Brahma owners and they were aware of the issue, though to those who I spoke, they never had the problem.

I personally had this issue with the MKII I was using, however, I bought the driver used and the person who had it before me did a horrible resoldering job, so in that respect, I cannot say it was due to driver, rather than a poor soldering job. I really look forward on trying out the MKI once I pick it up from my friend's sister since the only thing wrong with it is a slight crack in the dustcap.

---

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.

donpisto wrote:

---

Steven, seeing as you worked for Adire I had a couple questions. Is it the motor or the coil that uses the XBL^2 topology. I have heard people say it is the motor and others the coil. If you could inform me that would be much appreciated. 

---

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. 

donpisto wrote:

---

Second question, is the RE XXX (older version) similar to the Brahma? As in, does it use XBL^2 as well?

---

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

donpisto wrote:

---

Third, where can I get the proper coils for the Brahma. If I was told correctly the MKIV's used a 2.5" voice coil, or at least that is what Robot Underground uses. Seeing as though I have the MKI and MKII motors, which voice coils would I need and where would I be able to get them from?

---

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.