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Most of the TC designs are actually LGLC - not that there aren't exceptions (there are many I'm sure) but their higher-end designs use a machined top plate that actually extends inside the basket and magnet, presenting a larger gap than appears at first glance when looking at the sub from the outside.

We went with the dual-gap motor architecture simply because it is the only way to accomplish a truly flat BL curve... you might note even the W7 uses it to some degree - notice how they cross-drilled the pole vent... right at the center of the gap? Hmm...

And we went with the XBL^2 approach not only because we've been licensees for years now, but because it's so much more practical and scalable than other approaches, such as JBL's very cool DDD design... it has it's own unique benefits, but is incredibly expensive to implement.

Even underhung motors simply can't compare, unless you are comparing subs on a "less than 10mm" basis...
...but in that case, almost ANY subwoofer can sound decent, when you are only operating it at low volume levels.
Who wants to do that all the time?

geolemon wrote:Well, we'll be selling them in volume, I'm sure. But if you get in quick, you can be the first, and since we only distribute via the web, you'll be unique like you were with your Brahmas.
Maybe I'll leak a picture of the prototype test mule here. It's essentially "the finished piece", save for some cosmetic touches. Let's see how well everyone does.

well I have 500.00 to take into consideration. What will they be called, and how about a sneak peek?

geolemon wrote:We went with the dual-gap motor architecture simply because it is the only way to accomplish a truly flat BL curve... you might note even the W7 uses it to some degree - notice how they cross-drilled the pole vent... right at the center of the gap? Hmm...

Question. This is coming b/c I've never designed a sub/speaker with an XBL^2 motor (ok, I've never really designed my own speaker, period ). All XBL^2 designs I've seen with a rather long excursion (think Extremis, Brahma, XXX midwoofer, XXX sub, etc.) always has that large ripple on either side in real life. For example, these Klippel tests:

http://www.diymobileaudio.com/forum/sho ... .php?t=664
http://www.diymobileaudio.com/forum/sho ... .php?t=665

For comparison, this klippel of the Excel W18NX midwoofer (overhung):
http://www.diymobileaudio.com/forum/sho ... php?t=1025

Both get you there, but the Excel IMHO is more impressive. I do realize these are specific examples and not particularly expressive of the full potential of XBL^2 (covering my ass ). With these you're talking about nearly a 10% fluctuation in the extremis comparing the center gap with the peak of the ripple at around 5mm, and close to a 20% variance for the XXX midwoofer (which has the longer stroke). True, it's not a drop in BL, but there is such a thing as too much. With some of the subs I've seen an even larger variance.

Compare these to the CSS FR125S:
http://www.diymobileaudio.com/forum/sho ... .php?t=832

Which looks almost exactly like the Excel does and not the other midwoofers. Longer "flat" region of BL, with a bit more gradual rolloff similar to overhung.

Product of a shorter distance between both gaps and more coil overhang? Curiosity creeping in. Every "flat" XBL^2 motor I've seen has shown this type of curve, performing more like the overhungs previously shown, while all the super long stroke midwoofers and subwoofers I've seen tested always have that unique ripple on either side. I'm sure you can strike middle ground, but I'm thinking the results are pointing to exactly how much distance there is between both machined gaps, relative to the VC of course.

my questions are simple, geo.. heh
how does this prototype compare to a XXX 12"?
Will the prototypes work well in aperiodic enclosures?
depending on the first two answers, how soon can I buy a pair? I'd like to use them in my Charger, and they'd get plenty of exposure once it's all together which may or may not be an added benefit for you.

Anyway, PM me if you prefer. I've kept my share of NDAs before, I can do it again.

thanks

Jonathan wrote:Question. This is coming b/c I've never designed a sub/speaker with an XBL^2 motor (ok, I've never really designed my own speaker, period ). All XBL^2 designs I've seen with a rather long excursion (think Extremis, Brahma, XXX midwoofer, XXX sub, etc.) always has that large ripple on either side in real life. For example, these Klippel tests:

http://www.diymobileaudio.com/forum/sho ... .php?t=664
http://www.diymobileaudio.com/forum/sho ... .php?t=665

Bear in mind I'm "bandwidth handicapped" right now... I gave up after about 10 minutes of waiting for those pictures to download.

Anyway, two comments with regard to Klippel measurements:
I have a great deal of respect for the great Dr. Wolfgang (even met him myself at CES two years ago - and was honored that he remembered me and came up to me later in the day. ).

But he himself admits to an anomoly that isn't so much a function of the measurement system, as something that requires a knowledgable operator - that can produce some odd looking results with ANY driver that has significantly more Xmag than Xsus, or vice versa...
The system takes statistical measurements, and as I understand it, doesn't end up with enough measurement points at either end of the curve, based on what it learns automatically about the other curve, and as a result, the results aren't statistically accurate.

No measurement system is perfect, but Dan Wiggins himself brought this to my attention in discussing the measurement systems that he's used... and that's one big reason he favors DUMAX typically.

With regard to a "ripple", it's a balancing act. The exact coil length is absolutely critical with respect to the top plate dimensions, such that at any given point, exactly the correct number of windings are suspended in the "total effective gap". It's that simple, really.

Sometimes, observed in measurements like DUMAX, you might see what appears to be a slight ripple - but you have to take this in the proper context - you aren't really talking about a ripple...
...any more than you would describe glass to have a "rough surface" because things appear that way under a microscope - you're looking at a "ripple" of something like 0.1%, where Xmax itself is measured where BL falls to 71% of 'at rest' value.
So... ripple? I don't think I'd refer to it that way.

For comparison, this klippel of the Excel W18NX midwoofer (overhung):
http://www.diymobileaudio.com/forum/sho ... php?t=1025

Both get you there, but the Excel IMHO is more impressive. I do realize these are specific examples and not particularly expressive of the full potential of XBL^2 (covering my ass ). With these you're talking about nearly a 10% fluctuation in the extremis comparing the center gap with the peak of the ripple at around 5mm, and close to a 20% variance for the XXX midwoofer (which has the longer stroke). True, it's not a drop in BL, but there is such a thing as too much. With some of the subs I've seen an even larger variance.

I'll have to see what you are talking about when I've got a solid connection... a 10% variance sounds like a defect, pure and simple - I haven't seen a driver with such a variance where you describe... of course, as I pointed out, Xmax is measured where BL falls to 71%... but typically, save for minor fluctuations in between (let's say about 1% to be safe, rather than .1%), typically you are talking pretty picnic-table flat, and then rolling off pretty steeply down to that 71% Xmax limit point on either side.

Compare these to the CSS FR125S:
http://www.diymobileaudio.com/forum/sho ... .php?t=832

Which looks almost exactly like the Excel does and not the other midwoofers. Longer "flat" region of BL, with a bit more gradual rolloff similar to overhung.

Product of a shorter distance between both gaps and more coil overhang? Curiosity creeping in. Every "flat" XBL^2 motor I've seen has shown this type of curve, performing more like the overhungs previously shown, while all the super long stroke midwoofers and subwoofers I've seen tested always have that unique ripple on either side. I'm sure you can strike middle ground, but I'm thinking the results are pointing to exactly how much distance there is between both machined gaps, relative to the VC of course.

From what I've seen here too - all these measurements are Klippel, by npdang - performing unpaid research on grant-loaned equipment.

...and we're looking at (what I've seen) midrange drivers?

Just to clarify, I'm personally talking about a 12" subwoofer here (we're doing 10" and 15" in smaller quantities too).
...although a midrange driver with 30mm Xmax and 45mm rear clearance - wouldn't that be something?

GlassWolf wrote:my questions are simple, geo.. heh
how does this prototype compare to a XXX 12"?
Will the prototypes work well in aperiodic enclosures?
depending on the first two answers, how soon can I buy a pair? I'd like to use them in my Charger, and they'd get plenty of exposure once it's all together which may or may not be an added benefit for you.
Anyway, PM me if you prefer. I've kept my share of NDAs before, I can do it again.
thanks

Old XXX or new? Assuming old (since I don't believe anyone HAS new, and I couldn't make a comparison), it compares somewhat superior... similar in excursion, but with more of a SQ-oriented focus, and yet having much more mechanical excursion capability - I was never a fan of having a sub with a "Linear Xmax=32mm" and an "Physical Xmech=34mm". Our Xmech is more in the 45mm territory.

But I'd say visual appeal that compares to the "new" XXX, if that helps... since that's all I know about that sub anyway at this point.

Aperiodic?
Hmm...

Well, as I mentioned, it's got pretty "mid-Q" specs, so it would work - technically...
...but all my mind keeps coming back to, with respect to an aperiodic setup, is "man, these subs have the displacement capability to just BLOW an Aperiodic membrane to pieces". And I think that's really the bottom line...
These subs may have purely too much displacement capability, I can't even imagine an Aperiodic membrane that could withstand that sort of air permiation... and even if it could, would it even be effective?

You COULD artificially limit excursion and displacement via controlling power tightly - however, excursion is also a function of frequency, something not affected much by an Aperiodic install... with "little enough" power, it would probably work - in all other respects, for a pure SQ install, it's got benefits.

OK, maybe the question I should have asked from the start...
...WHY Aperiodic anyway?

yes I meant the old XXX. I thought I'd mentioned XBL^2 which isn't a core of the new models. Sorry about the lack of clarity there.
with two 12" subs, I'll be using (am using) a bridged orion 2250SX on each sub, so power output is up to 1-1.5Kw per sub, although I have no intention of ever pushing them that hard. I just love the amplifiers and they had the power for my old style XXX12s.

front loaded aperiodic because I have a trunk, in a rather huge fastback design vehicle, and it's purely being done for SQ. I have no care about SPL events, but I want the 2nd and 3rd order harmonic elimination of an AP membrane with the improved driver control it offers. Mainly two reasons. Better detail from the drivers, and because I can. I like AP enclosures with the right subs, partly because I listen to more complex music where detail is more important than volume, and I like a smooth blend from my 8" midbass to the 12" subs, instead of just something that's going to pound the car and listener to pieces.
I have a big block to accomplish that feat :)

Visual I wasn't too worried about, since the subs most likely won't be visible anyway, at least to most.

So any chance I can get on the waiting list for a pair of these?

geolemon wrote:Bear in mind I'm "bandwidth handicapped" right now... I gave up after about 10 minutes of waiting for those pictures to download.

Anyway, two comments with regard to Klippel measurements:
I have a great deal of respect for the great Dr. Wolfgang (even met him myself at CES two years ago - and was honored that he remembered me and came up to me later in the day. ).

But he himself admits to an anomoly that isn't so much a function of the measurement system, as something that requires a knowledgable operator - that can produce some odd looking results with ANY driver that has significantly more Xmag than Xsus, or vice versa...
The system takes statistical measurements, and as I understand it, doesn't end up with enough measurement points at either end of the curve, based on what it learns automatically about the other curve, and as a result, the results aren't statistically accurate.

No measurement system is perfect, but Dan Wiggins himself brought this to my attention in discussing the measurement systems that he's used... and that's one big reason he favors DUMAX typically.

With regard to a "ripple", it's a balancing act. The exact coil length is absolutely critical with respect to the top plate dimensions, such that at any given point, exactly the correct number of windings are suspended in the "total effective gap". It's that simple, really.

Sometimes, observed in measurements like DUMAX, you might see what appears to be a slight ripple - but you have to take this in the proper context - you aren't really talking about a ripple...
...any more than you would describe glass to have a "rough surface" because things appear that way under a microscope - you're looking at a "ripple" of something like 0.1%, where Xmax itself is measured where BL falls to 71% of 'at rest' value.
So... ripple? I don't think I'd refer to it that way.

Ripple is more a description of what it looks like

For reference, since you are limited in bandwidth:

Extremis: Centered around -1.25mm, around 9.4 TM at that point. Rises to around 10.2 TM at +4mm, and rises to a bit over 10TM at -6mm excursion. Falls sharply to 70% at +8.5mm, and -11mm, but suspension limits it to +8 and -7.5.

XXX: Centered right around 0, around 3.8 TM at that point. Rises to ~4.4TM at +7mm, and ~4.1 TM around -7mm. Falls to 70% at +/- 12mm. Suspension limited to +12, -10.

Excel: Center at 0, 7.7 TM at that point. Stays flat to +/-5mm, then a gradual rolloff with 70% occuring at +10, -11mm. Suspension limited to +9, -8.

CSS FR125: Center at 0, BL of 4.05. Flat to 2.5mm, rolloff to 70% at +/-6mm.

I was a bit curious seeing those BL curves, but after checking things this also shows up in the Dumax tests of drivers like the Brahma (Brahma Mk I Dumax is on Adire's site). And the Extremis Klippel analysis looks almost exactly the same as that of the Brahma on the PDF file, though it is a bit more extreme in variance. In case you don't have it on tap, the Brahma Mk I Dumax has around a 5% variance within +/- 7.5mm excursion, then past that BL rises to around the same value of the motor at center at around 15mm each way (the "ripple", if you will ). Enough of a variance to be notable as something other than a picnic table . But seeing this was leading me to believe that these Klippel measurements could be right, or at least close. And most of the XBL^2 drivers I've seen tested (subs, midranges, whatever) seem to be pretty consistent with this in both Klippel and Dumax, even consistent in the fact that in this "ripple", BL tends to rise highest on forward stroke and is only slightly higher than center on rearward stroke. The exception is the CSS mid, which is what made me curious. I was wondering if the coil length relative to the gaps had changed, or if it was simply a matter of Dan getting better with FEA modeling of the drivers. But the CSS came out right around the time that the Extremis did, so that again made me wonder. I'd think that you could alter the gaps and coil so you could have a compromise, with that compromise being the flattest possible BL or the most excursion. After all, XBL^2 is essentially a hybrid that combines attributes of overhung and underhung designs. B/c of that, I'd think you could simulate certain attributes that are characteristic of one or the other by changing things around a bit. But again, I haven't fiddled with XBL^2 to know what kind of negative side effects you'd run into.

GlassWolf wrote:with two 12" subs, I'll be using (am using) a bridged orion 2250SX on each sub, so power output is up to 1-1.5Kw per sub, although I have no intention of ever pushing them that hard. I just love the amplifiers and they had the power for my old style XXX12s.

Well, the last time Aperiodic was a popular means of implementing a sub for SQ was back.. around 1990-ish? And if you remember the subs of the day, back then - a 10mm Xmax was huge.

I'm just worried, expecially with that much power (these are quite efficient too), about the possibility of blowing apart a membrane...
...but, assuming you'll be building them yourself, that's just somethig else fun to experiment with, no need really even being constrained to the usual materials to sandwich in there, I suppose!
A more restrictive membrane would seem to also help - well - lower efficiency, if that's a plus, given all that power!

front loaded aperiodic because I have a trunk, in a rather huge fastback design vehicle, and it's purely being done for SQ. I have no care about SPL events, but I want the 2nd and 3rd order harmonic elimination of an AP membrane with the improved driver control it offers. Mainly two reasons. Better detail from the drivers, and because I can. I like AP enclosures with the right subs, partly because I listen to more complex music where detail is more important than volume, and I like a smooth blend from my 8" midbass to the 12" subs, instead of just something that's going to pound the car and listener to pieces.

Well, this is a great sub for "elimination of distortion" and "clarity and detail".
It would be interesting to combine that with an aperiodic install.
And it also offers you the possibility of trying the sub out in more traditional setups - try it out sealed, too, and compare...

...for SQ, personally I've always been a simple stuffed/sealed sort of guy.
With subs like these (even playing with Brahmas and XXX's) though, when "the sub itself" has certain distortion-eliminating properties, when you put that sub in an enclosure type that itself has certain distortion (blurring, if you will) properties, it becomes VERY interesting to listen to - a sub like this, in a "sq compromised" enclosure - even bandpass - still sounds cleaner than most subs in sealed boxes. It's an interesting thing to discover.
I even played with one in a high-tuned SPL-style box - something a friend of mine had knocked together - and I'll be damned if it STILL didn't sound clean, to the degree that you almost didn't notice the tremendous SPL peak that the box inherently created - or I should say, you almost bought it that the SPL peak 'must be in the recording'. Pretty cool.

My point is - you might experiment with this sub stuffed/sealed, and you might find it to be cleaner than your past experiences with Aperiodic setups!

Hopefully you'll tell us all how it goes, because I've definitely got my hands too full (and definitely no vehicle appropriate for it) to try an Aperiodic setup anytime soon. I'm curious though.

So any chance I can get on the waiting list for a pair of these?

Absolutely - I've got you mentally noted right now (I haven't mentioned it anywhere else, so it's easy to track interest right now ) - I'm going to be building a "priority list" of people like yourselves, make sure you guys get the royal treatment - I'll create something more official as we get closer to April/May.

um..I have a box, and a woofer..and that is all I understand.