[Kevin Haskins]

We have some updated pre-production parameters.    We have had two pre-production units built and there is one more coming which will hopefully finalize the design.   We are at the point now where we are just playing with suspension compliance & Mms to dial it in.

This is a dual 8 ohm VC design like the Shiva-X & Tempest-X.    Parameters with VC in parallel.

Re: 3.1 Ohm
Le: 2.65 mH
Fs: 16.3 Hz
Qms: 5.39
Qes: .39
Qts: .36
Mms: 475g
Cms: .200 mm/N
Vas: 327L
Sd:  1080 cm^2
X-Max: 33mm
X-Mech: 41mm
BL: 19.66
Spl: 87.5 1W/1M
Vd: 7.1L 

Wow.... this is serious output.   The Tempest-X is no slouch at 4.3L of swept volume.   The old Tumult had 5.0L so this is a driver reaching the limits of what can be done with traditional suspension components.   We can design more motor travel but it becomes less and less usable due to the limitations of how much power can realistically be used in a driver (you need 1800W to reach full excursion in some designs @ 15A breakers are becoming a limit) and suspension components that operate well under >60mm of P-P displacement.    I don't care how many spiders & what you do with the surround, they become non-linear the more you push them and the self-noise increases with throw so there are limits to what can be done with traditional suspension components and we are pushing up against them.   

The motor BL is linear to within 10% out to about 27mm with the 30% down being our X-max.    The inductance is managed with our AlCu motor technology that balances the Le curve for symmetry using variable width & thickness shorting rings made of either copper or aluminum depending upon the need.    The VC is a 3" all copper design with black anodized aluminum former for maximum heat dissipation.    Overall we pulled out all the stops on this one.   Notice in the sectional drawing below both the notches cut for the XBL^2 motor and the two shorting rings of differing size/materials.    This is all carefully designed to minimize inductance & BL based non-linearities.   Not your run of the mill motor design.



This is working in slighly smaller boxes than the Tempest-X.   Looks good in anywhere from 7-10 cubic feet for vented/PR alignments and it likes to be tuned down around 16-17Hz.  Its going to take a PR or a big slot port because your not going to fit a big enough port with this kind of displacement in the smaller size boxes.    You should be able to port the upper 10-12 cubic foot designs.   

I have a 15" PR in the works but it will take four of them to keep this beast happy.    No immediate plans for an 18" PR as two 15"s are cheaper and work well with the Tempest-X & Shiva-X also.   

Price is holding steady @ $349 and they will probably start shipping sometime in April/May.

[klh]

aa

[Larry McConville]

Looking good Kevin; can you share any pics?

[Kevin Haskins]

The pictures are pretty bad.     

The cone looks just like all our other drivers.   Its black, with a black dustcap & a big foam surround.    The basket is a 6-spoke cast unit and the motor is black.    I'm afraid marketing cosmetics are not our strong point.        We don't have any plans for fancy cones or glitzy logos.     I'm sticking with good ole black with a cast aluminum frame and a big black motor.   

[Larry McConville]

I completely understand and agree with this direction as it aids in keeping costs inline; I was merely inquiring as I’m susceptible to the influences of woofer porn. I'm certainly ready to try out a pair!

[Kevin Haskins]

Its a big sucker.   It makes the Tempest-X look small.   

I might build a couple for VSAC, tuned low so I can shake the entire hotel with a 15Hz sine wave.    Think of tube microphonics on a very large scale. 

[Larry McConville]

Hmm, 16ft^3 @ 13Hz looks really good!

[Kevin Haskins]

That is too big of a box for me.   I don't like those EBS type designs because I don't find much use for output down to 10Hz. 

I'd keep the upper end around 10-12 cubic feet.   I actually like it in about 8.5 - 10 cubic feet tuned to around 15-16Hz.   You can even go smaller, this thing models pretty good all the way down to 6 cubic feet but you would be limited to a PR based system in that small of a box.   Either that or design a big slot port.     

I'm modeling a 26" cube with four PR-15s, and a Maelstrom-X.   Its about 8 cubic feet internal with 100% fill.   The four PRs are tuned to 17Hz and I'm using a subsonic filter @ 18Hz with a Q = 1.0 to boost the bottom a little.    Even if you model VC heating, Cms non-linearities, BL non-linearities, Le compensation, and Cms non-linearities of the driver & PRs it hits over 125db @ 20Hz 1M in room with 1800W.     In-room you still get over 120db @ 15Hz.   That simulation shows the driver using less than 30mm of one-way X-max so you are not overdriving it at this level at any frequency.     A pair of these gives you stupid output.    Well over 130db in room from 17Hz on up.   Nobody needs that much headroom.     

[Larry McConville]

Interesting; I'll digest this over the evening, perhaps I'm being influenced by some of the builds on AVS.
Let me play around with the 10-12ft^3 sim...

[Larry McConville]

Kevin,

Do you feel 12ft^3 @ 16Hz (X2) would work well for a dedicated HT application?

I must admit that I've gotten caught up in all the EBS/LLT threads on AVS; I really want to feel/hear the effects folks are reporting on some of the tracks such as Pulse and WOTW.

Larry

[Kevin Haskins]

Actually.... if I where building something for myself I'd aim for 9-10 cubic feet tuned to about 16hz.     The problem will be the port.    You have a hard time getting a large enough port in these high output subs.     A large 10" port gets long and you get resonance issues.    It also presents problems in terms of fitting it in the enclosure.    A slot port is an option and I'll probably publish a couple reference designs showing how to build them.    Another option is the PRs which keeps the box small, and gets around the port limitations.   

The PR's are the other option.

[macnewma]

Do you have any suggestions for sealed applications?  Maybe large sealed?

[Kevin Haskins]

Do you have any suggestions for sealed applications?  Maybe large sealed?

Sure... it doesn't even need that large sealed.   All of our drivers T/S parameters are balanced between ported/sealed alignments, with the exception of the dipole/IB drivers.   

You can use 150-200L but depending upon your goals, you may want a little boost down low to extend the bandwidth.   

[macnewma]

I was planning to get a few Tempest-X's but I think I might try 2 Maelstrom-X's.  Here is my plan:

Buy enough 24" diameter sonotube to build 2 6' sonosubs 8" port tuned to 14-15hz.  I plan to make one convertible to sealed with an additional endplate to hold the other driver instead of the port.  This should make for a naturally critically damped opposing dual sub enclosure.  It will allow me to try both large sealed and large vented to see which I prefer.  Fortunately, soon I will have a 16' wide room with a 2.5' deep screenwall.  These beasts will lay flat.

So 1 sealed sonosub with 2 Maelstrom-X in ~17 cu ft vs. 2 ported sonosubs with 1 Maelstrom-X in ~17 cu ft per, tuned to ~14hz.

I really don't know which I will prefer.  I have a feeling that both will be exceptional and give me extraordinary headroom.  According to my models, I will be amp limited by my K1's 550w/channel.  Maybe I should get a K2. 

What do you think, Kevin?  Also, what is the mounting depth?  I need to make sure my port length will be OK.

[Kevin Haskins]

We don't have the final production parameters on the Maelstrom-X yet so I wouldn't get too far into the process.   

When we design a driver we get pre-production models that are hand-made one-by-one by the prototype department at the build-house.    We get pretty close with those pre-production models but its not unusual to see a little change when it goes to production.    The production line drivers end up being built much better but even though we use the same parts, motor, VC etc... I've noticed that we see a slight change in compliance and Mms.     Nothing earth shattering but I like to publish the production T/S parameters rather than the engineering samples.

Both of those enclosures are larger than I'd recommend for a Maelstrom-X.   For whatever reason bigger than traditional alignments seem to be all the rage right now. I tend to prefer more traditional alignments that don't have a sagging LF response on the bottom.   Most of the action is in the 17-60Hz range and I see little reason for output down to 10Hz.    For HT its kind of nice to have the in-room measurement with a little lift under 30Hz.    It may be a Fletcher-Munson thing or it may just be that like that LF lift.    Also... rooms vary a lot and have a tremendous influence on the <30Hz gain.    Smaller enclosed rooms get a fair amount of pressure vessel gain.   Larger rooms that are open to other parts of the house never get appreciable pressure vessel gain so the LF curve of the smaller enclosure may be a better fit in that situation.   

What is your room like?

[macnewma]

I'm aware that these are pre-production numbers, but I won't need them for 3-4 months anyway.  I will probably get either the 2 Maelstrom-X's or 2 Tempest-X's (or maybe 4 depending on alignment chosen) in a similar setup.  The additional headroom of the 18's is attractive.

Are you saying that the sealed box of ~17 cu ft is too large?  I was under the impression that you couldn't have a sealed enclosure that was too big.

Honestly, I'm not sure what I will think of the "LLT" style EBS alignments.  I understand what you saying in reference to them being tuned too low, but I figured I would give it a shot.  It would be easy to try a smaller box with a higher tune, but modifying one of the sonosubs.

My room is 16'x22'x8.5' so about 2900 cu ft.  It will be very well sealed and will have ample bass trapping.

[Kevin Haskins]

No... sealed you can run them as large as you like.   I'm talking about ported designs. 

You have a good room, nice size and having it sealed off will give you some additional gain on the bottom. 

There is nothing wrong with your approach.   It allows you to try them both ways and come to your own conclusion about what works best in your room.   You will have enough power to get good output but the amp is certainly going to limit you before the driver gets close to breaking a sweat.   You can always upgrade the amp later if you find you need the additional output.   My guess is your going to have plenty.   If not the Face Audio F1200-TS is $660 plus shipping.   It should drive a pair of them nicely. 

[mdrake]

Any news on when your NEW woofer will hit the market? How about update parameters or pricing? This looks like a really exciting and promising product!  aa 

[Kevin Haskins]

Any news on when your NEW woofer will hit the market? How about update parameters or pricing? This looks like a really exciting and promising product!  aa 

Its Chinese New Year right now so everything is at a stand-still.   After the holiday we expect to get the final engineering sample.   After I'm happy with the design we place the order and in about 60 days I have product ready to ship.   

So... my best guess right now is late April or early May.   

No sense updating the parameters with every engineering sample.   They have not changed significantly and our final production parameters will be pretty close to the design goal.

[blizzard]

Hi Kevin,
  Pretty nice specs on this guy.  A question on the design -- You used a 3" voice coil on these guys.  Any advantage to using the 3" instead of a 4" coil?

               Thanks,
                   Steve