Any DIY designs using the Adire 6.8 extremis?

[digital desire]

It *seems* like a very good (and expensive) driver. I have seen an open baffle design and a couple kits, but was wondering if it was ever up for consideration amoung the gurus around here?

[Jed]

http://www.htguide.com/forum/showthread.php4?t=12992

[JonMarsh]

There's an Extremis MT design in the Missions Accomplished section- check that out.

I bought eight of them in the initial pre-order. Interesting underhung motor, reasonably low non-linear distortion, though not killer low (matched by some other drivers like RS180) but the cone is problematic if you use it in a two way, as Rick Craig and others found. Nice driver if you want to do a compact three way that goes low, preferrably in multiples. But for more general designs, considering the price, I ended up selling mine at a small loss; fortunately the pre-order price was attractive.

Dan Higgins did a dipole design with it that I bet would be pretty fun with an adequately powerful amp.

OTOH, think about it this way- for what two Extremis cost, you can buy a 10" Aurasound NS10-513, which is a really killer long throw woofer.



Which would you rather start with for a three way design? (the Aurasound 10" actually goes higher remaining in pistonic operation than the 6.5" Adire). Two Extremis will have a swept Sd of 280 cm2, the NS10 is 347 cm2; Xmax is about the same for each. The Extremis does NOT in my opinion have a surround properly designed for the rated Xmax (a tradeoff for maintaining adequate Sd); otherwise the half roll would be similar to the Aurasound. In my own testing, the efficiency was about 3 dB lower than specified.

Now this doesn't mean that you can't make a fairly decent sounding speaker with it, and if your goal is to see how much bass you can get out of a 28 liter box, then it's your midwoofer/woofer. But the value proposition would be better at a lower price- even since it's now typicallly $80, instead of the $99 after the pre-order was over.

So, think about your goals. If you really must have as small a box as possible with pretty good bass extension, and you're willing to do a three way (say, dome midrange) to stay out of the problem areas in the upper midrange, then it might be the right driver for you- even in a 44 liter box two will put out some impressive bass, tuned to an Fb of about 32. Remember that that bass extension comes at the price of efficiency (Hoffman's Iron law), so figure you'll need about twice the amplifier power (no, I'm not joking- that's what 3 dB difference in sensitivity means).

For me, I'd rather have a little bit bigger floor stander with that NS10 Aurasound and a downward firing port, say about 65-70 liters, flat in room to the low 20's. But that might be too imposing for some people; needs do difffer, and for those with spouses, WAF always looms.

Different strokes, etc, YMMV. And no, I don't work for Aurasound, or get spiffed by them.

Whatever you do, have fun doing it!

~jon

[digital desire]

Jon, thanks taking the time on the reply! (You too Jed- don't know why I did not find that thread.)

I just read the thread in Missions Acomplished.

One of your sentances resonates with me. "So, think about your goals."
I think I am looking at some towers, like the long wwmt thread. *BUT*, I also like the idea of maybe the nat p's and some bass bins, biamped. WAF is a definite factor here, and the fewer the seperate parts the quicker the approval process! Not sure I have real estate for crossovers/extra amps. I am still in the ask a lot of questions and study mode before I choose.

There is no way to make the nat p's and bass bins work effectively with a passive/ single amp solution is there? Make three ways out of existing two ways? I think I already know the answer, but one can dream.

[Jed]

Jon, thanks taking the time on the reply! (You too Jed- don't know why I did not find that thread.)

I just read the thread in Missions Acomplished.

One of your sentances resonates with me. "So, think about your goals."
I think I am looking at some towers, like the long wwmt thread. *BUT*, I also like the idea of maybe the nat p's and some bass bins, biamped. WAF is a definite factor here, and the fewer the seperate parts the quicker the approval process! Not sure I have real estate for crossovers/extra amps. I am still in the ask a lot of questions and study mode before I choose.

There is no way to make the nat p's and bass bins work effectively with a passive/ single amp solution is there? Make three ways out of existing two ways? I think I already know the answer, but one can dream.

Yeah, whenever Jon does that it makes me want to start a NEW project after my next NEW project. :B

[Dennis H]

There is no way to make the nat p's and bass bins work effectively with a passive/ single amp solution is there? Make three ways out of existing two ways? I think I already know the answer, but one can dream.

You've just described Brian and Chris's 3-way in the Missions Accomplished section. RS28 + (2) RS180 + (2) RS270. To really do it justice, it needs an amp a bit more beefy than a typical receiver.

http://www.htguide.com/forum/showthread.php4?t=11873

[ThomasW]

If you want something like the Extremis but at a fraction the price look at the Tang Band W6-1139SG (hint there's a reason it has more than a casual similarity to the Extremis)

http://www.partsexpress.com/pdf/264-832.pdf

[JonMarsh]

A closer match would be the Ascendent 6.5" poly woofer- the 6.5 Tangband Thomas refers to doesn't have much copper in the gap, and so the inductance curve climbs pretty steeply.

The Ascendant Audio poly midwoofer uses a Neodymium magnet structure, has a flat impedance curve similar to the Extremis, about 12 mm Xmax, cast metal frame, and goes for $35. Plus it has a cute little phase plug.

[joecarrow]

Gosh, I still don't know how any of these 6.5" woofers perform at the end of their excursion range! What, am I going to have to buy one of each and test them myself?!? 8O

I have a 300 watt BASH amp on the way, and a hunch that I can add a sub behind the TV without my girlfriend ever finding out :twisted:

[dawaro]

Gosh, I still don't know how any of these 6.5" woofers perform at the end of their excursion range! What, am I going to have to buy one of each and test them myself?!? 8O

I have a 300 watt BASH amp on the way, and a hunch that I can add a sub behind the TV without my girlfriend ever finding out :twisted:

Curt C has started testing a set he bought. His initial impressions are posted on the PE board.
Ascendant Impressions

[Rolex]

But the value proposition would be better at a lower price- even since it's now typicallly $80, instead of the $99 after the pre-order was over.


~jon

Where is this driver available for 80 dollars? I've only seen it for 99? Could someone provide a link?

Thanks!

[Eric H]

Jon,

I'd like to see (or try to design ) a smallish and affordable dipole speaker like the Wiggins DDR that you speak of. I'd like it to extend to 60-80 hz if possible. Would the AA 6.5" work for dipole? What driver/tweeter recommendations would you suggest? My speaker building knowledge is limited to kit building, but a reasonably sized and priced dipole design might be enough to make me delve in a little deeper.

Thomas, if this needs to be in it's own thread, please move it.

Thanks, Eric.

[JonMarsh]

The AA 6.5 is similar in performance to the Extremis 6.4; the Extremis 6.8 is nominally 8 ohms, not 4 ohms. The majority of published desigs may use the 6.8. Two 4 ohm drivers in series will behave somewhat similarly, at least it's a starting point. With this impedance driver I'd suggest using 4 together in a series/parallel array for a dipole. Maybe you would use a tweeter between the top two drivers, but with that many drivers, you're looking at line array behavior in the mids unless you go with a 2.5 way approach to the crossover design- two woofers in series as bass augmentation, two handling midrange duties running up to the tweeter. That would give you some radiating area.

[digital desire]

You've just described Brian and Chris's 3-way in the Missions Accomplished section. RS28 + (2) RS180 + (2) RS270. To really do it justice, it needs an amp a bit more beefy than a typical receiver.

http://www.htguide.com/forum/showthread.php4?t=11873

I was reading that whole thread, and was digging it until this pic put them into perspective:

http://www.radhometheater.com/photos/3way_cabinet_brian.jpg

I think I read somewhere on that thread they were approaching 200lbs!



Nice, but BIG!

Power is not a problem, I have nice healthy adcom 555mkII that (IIRC) is somewhere around 345 watts/4 ohm.

The Nats P's sitting on a smaller 10" sub cube would be nice.

Everything is a series of compromises, still trying to figure out where I want to go!
Short list includes the wwmt and a kit with an 8 in it.

[Brian Bunge]

I was reading that whole thread, and was digging it until this pic put them into perspective:

http://www.radhometheater.com/photos/3way_cabinet_brian.jpg

I think I read somewhere on that thread they were approaching 200lbs!



Nice, but BIG!

Power is not a problem, I have nice healthy adcom 555mkII that (IIRC) is somewhere around 345 watts/4 ohm.

The Nats P's sitting on a smaller 10" sub cube would be nice.

Everything is a series of compromises, still trying to figure out where I want to go!
Short list includes the wwmt and a kit with an 8 in it.

BIG, AIN'T THEY!! I love mine and can't imagine not having them in these large open floor plan houses.

Another thought would be something like the Exodus 2641's. The cabinets are relatively small and you could use virtually the same exact cabinet with one of the Seas tweeters, the RS150 as a mid, dual RS180's as woofers. I've built the cabinets several times and they're not overly large.

[digital desire]

Thanks for adding one more speaker to the list!
Had not seen these yet...

[Dennis H]

The Nats P's sitting on a smaller 10" sub cube would be nice.

Yeah but it would be terribly inefficient if you built it with a passive XO. Hoffman's Iron Law says a small box for the sub part leads to low efficiency. It would work with an active XO between the sub and the Modula, with the sub receiving much more power, but that's not what you proposed for a totally passive design. Chris and Brian's passive design only works because the 'sub' part is big and has two woofers.

So, you get to choose -- passive XO or small bass bin. Your choice. Damn physics just always gets in the way of what we'd really like.

[digital desire]

Just finished reading fryguys thread on his decision to build the 2641's.
The more I read, the more I am convinced I am going to build a set of wwmt's.
They are to replace a 20 year old set of bose 10.2's, and I am quite sure the difference will be vast. Before you boo hiss the bose, (I know they are cheapies, I bought them used for $300 10 years ago) they did make me happy. I love the direct/reflecting stereo everywhere sound in my rather narrow set up.
But I think I am heading for the wwmt's!