[Kevin Haskins]

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

Sure.... picking the right coil size is an exercise in tradeoffs.    The larger coil would have better power handling.   Most pro-audio drivers use the larger coil diameters for this reason.    It also allows you to get more BL out of a design, everything else being equal.   

The downside to bigger coil diameters is more moving mass, higher inductance, less usable spider suspension travel, and cost.

If we made the Maelstrom-X with a 4" VC rather than a 3" we would have better power handling, but give up some of that valuable spider landing for a nice linear suspension.     The suspension linearity takes priority over an extra 20% of pure power handling.   Mainly because we don't see the sustained power levels like you do in pro-audio.     

[blizzard]

I was wondering because I've recently seen other high-excursion drivers also opting to go 3" over 4".  Plus, I figured you'd get more BL out of the 4".  The higher inductance, I thought would have been somewhat controlled by the XBL2.  But, I didn't think about the spider travel -- makes sense now.

             Thanks Kevin,
                 Steve

[Larry McConville]

Kevin,

Do you suppose you could share a pic with us poor country folk per your review of the final 'engineering' sample?

I know what it's going to look like; however, I am from the 'Show Me' state for heavin's sake

Have a good one!

Larry

[Kevin Haskins]

Kevin,

Do you suppose you could share a pic with us poor country folk per your review of the final 'engineering' sample?

I know what it's going to look like; however, I am from the 'Show Me' state for heavin's sake

Have a good one!

Larry

Once I get a good one that is representative of the final build I'll post it.   The engineering samples don't necessarily have great cosmetics so rather than post something that looks bad, I'd rather just wait until I have production units. 

We should have the production run in April.   I'll have complete design guidelines by then and hopefully later this year, I'll have some mega 18" PRs to go with the Maelstrom-X.    The Sicko-18" PRs should be good for both designs.   You need some serious PRs for both of these drivers, especially the Sicko.   

[Kevin Haskins]

Update on Parameters:

VC in parallel

Re: 3.1
Le: 2.76 mH
Fs: 19.3 Hz
Qms: 3.89
Qes: 0.40
Qts: 0.36
Mms: 469g
Cms: .144 mm m/N
Vas: 286L
Sd: 1182 cm^2
BL: 20.7

Oh... that Sd is accurate.    Total swept volume 7.8L   

The production suspension will probably loosen up a little.   I'd guess the Cms will come in around 0.16-0.17 which will drop the Fs a little after break-in.   You don't see much if any practical change in the modeled response though.     I may add another 25-50g of mass just to level out the top-end.   In real life with a variable LP filter it doesn't make any difference but the modeled response looks a little more "normal".   

[Larry McConville]

Kevin,

I'm interested to see how it'll play through in application; however, there seems to be a significant increase in Fs, +~3Hz.
This does have him model considerably differently.

Larry

Update on Parameters:

VC in parallel

Re: 3.1
Le: 2.76 mH
Fs: 19.3 Hz
Qms: 3.89
Qes: 0.40
Qts: 0.36
Mms: 469g
Cms: .144 mm m/N
Vas: 286L
Sd: 1182 cm^2
BL: 20.7

Oh... that Sd is accurate.    Total swept volume 7.8L   

The production suspension will probably loosen up a little.   I'd guess the Cms will come in around 0.16-0.17 which will drop the Fs a little after break-in.   You don't see much if any practical change in the modeled response though.     I may add another 25-50g of mass just to level out the top-end.   In real life with a variable LP filter it doesn't make any difference but the modeled response looks a little more "normal".   

[Kevin Haskins]

Kevin,

I'm interested to see how it'll play through in application; however, there seems to be a significant increase in Fs, +~3Hz.
This does have him model considerably differently.

Larry

Update on Parameters:

VC in parallel

Re: 3.1
Le: 2.76 mH
Fs: 19.3 Hz
Qms: 3.89
Qes: 0.40
Qts: 0.36
Mms: 469g
Cms: .144 mm m/N
Vas: 286L
Sd: 1182 cm^2
BL: 20.7

Oh... that Sd is accurate.    Total swept volume 7.8L   

The production suspension will probably loosen up a little.   I'd guess the Cms will come in around 0.16-0.17 which will drop the Fs a little after break-in.   You don't see much if any practical change in the modeled response though.     I may add another 25-50g of mass just to level out the top-end.   In real life with a variable LP filter it doesn't make any difference but the modeled response looks a little more "normal".   

It shouldn't... the suspension just stiffened a little.   That is the reason Fs went up but the modeled response stays almost the same.   

I'm adding mass though so the Fs will drop back down and the high-end efficiency will drop to match the bottom.   Just dialing it in... nothing earth shattering in terms of changes here so it shouldn't model much differently.   

I have adjusted the Sd up because I've been schooled on a more accurate way of determining it based upon acoustical rather than physical properties.   

   

[Kevin Haskins]

Ok.... this is the final engineering sample parameters.   

Parameters with VC in parallel:

Re: 3.1
Le: 0.87mH   That is right!   Earlier numbers where the raw VC.   Measured performance with AlCu inductance rings gives us significantly lower Le!   
Fs: 17.7 Hz
Qms: 7.8
Qes: .38
Qts: .36
Mms: 494g
Cms: .170 mm m/N
Vas: 324L
Sd: 1182 cm^2
BL: 21.17
Xmax: 33mm
Xmech: 42mm

This is a "go" and I'd expect the production numbers to be very close to this.   This is a beast in 8 cubic feet tuned to 19Hz.   

[Larry McConville]

Well, I'm certainly ready for my pair

[Kevin Haskins]

Well, I'm certainly ready for my pair

You want some PR's to go with them?   

[Larry McConville]

Hey Kevin,

Well, I have been modeling vented alignments; I'll likely use something very similar to your 8ft^3 - 10ft^3 examples. I would really like to investigate a build utilizing one Acoupower 7" port per cabinet. My curiosity is the onset of chuffing/turbulence; the extreme flare really has me intrigued and the overall port length would be <= ~28”.

Since I talked myself into picking up a second F1200; I may actually go with four Maelstrom-X’s; nothing like being flat to STUPID!

My entry into the PR camp will likely come with the release of the SICKO-18; I will have ZERO use for this guy (see above), but I must succumb to my own immaturity.

Btw – you should have received a F1200 order over the weekend…

Larry

Well, I'm certainly ready for my pair

You want some PR's to go with them?   

[Kevin Haskins]

Your amp is on the way.   It went out Friday and I'll get you the tracking number later today.

Are you going to run two Maelstroms per amp?   

[Larry McConville]

Yes, two per...

Your amp is on the way.   It went out Friday and I'll get you the tracking number later today.

Are you going to run two Maelstroms per amp?   

[Kevin Haskins]

Yes, two per...

Your amp is on the way.   It went out Friday and I'll get you the tracking number later today.

Are you going to run two Maelstroms per amp?   

You should be fine then.... with only 1200W you won't get into port compression issues too bad.   

[Larry McConville]

Sounds good; we'll bump my initial commitment up to four Maelstroms then

I wont cut any material yet; however, I'll base my final cabinet design utilizing this latest set of parms.
Additionally, I'll probably submit an order for the ports this week too.

Getting excited here; this should really be a nice package once I decide on veneer species...

Larry

Yes, two per...

Your amp is on the way.   It went out Friday and I'll get you the tracking number later today.

Are you going to run two Maelstroms per amp?   

You should be fine then.... with only 1200W you won't get into port compression issues too bad.   

[Larry McConville]

Merely an enthusiastic bump.

[macnewma]

These latest spec's look great.  When you get a preorder ready, you can count me in for 2. 

My setup will be large.  I'm still planning to do the convertible setup.  Easily swapped between a single opposed dual driver sealed to two massive EBS setups.  I can then pick which I prefer.  450-500l per enclosure.  My sims show a Q of around .5 and a very doable LT setup.  In fact, my Crown K1 will most likely run out of steam before the drivers.  Well, actually, my ears will run out of steam before anything so it should be great.

[Kevin Haskins]

These latest spec's look great.  When you get a preorder ready, you can count me in for 2. 

My setup will be large.  I'm still planning to do the convertible setup.  Easily swapped between a single opposed dual driver sealed to two massive EBS setups.  I can then pick which I prefer.  450-500l per enclosure.  My sims show a Q of around .5 and a very doable LT setup.  In fact, my Crown K1 will most likely run out of steam before the drivers.  Well, actually, my ears will run out of steam before anything so it should be great.

I'm going to put up a pre-order item on the web site next week.   You will be able to go through the shopping cart on the web site.   With the interest shown to this point I'm afraid of them selling out before I get the first shipment.   With the pre-order I'll be better able to adjust the second order for current demand.

A Crown K1 should be a great amp to drive them.   

[norpus]

  
Excellent news Kevin!
Will these be good to replace my Avalanche 18's when they break?  (rhetorical)
How much power would you recommend in a 2x18 IB?

Love my Tempest-Xs by the way. Congrats on a fine job!

IB  IB  IB

[Kevin Haskins]

 
Excellent news Kevin!
Will these be good to replace my Avalanche 18's when they break?  (rhetorical)
How much power would you recommend in a 2x18 IB?

Love my Tempest-Xs by the way. Congrats on a fine job!

IB  IB  IB

Oh...I'd put 500-600W on each in free-air.   The DPL-15 is a more economical IB choice and you get deeper response from its higher Qts design.    It has less stroke but you just use more of them to accomplish the task.   It does good with a couple hundred watts per driver.

I know your joking about the Avalanche but just to answer your question(other people are thinking it so I'll go ahead and answer), I doubt it.  From what I remember, it had different enough parameters that you would want to model it before doing a substitution.   This is an entirely different driver, the only thing it would share would be the fact that they both where XBL^2 motors and 18" drivers.      People paint every driver that uses XBL^2 as the "same" design but that is a poor assumption.    Nobody makes that same assumption about overhung/underhung motors so I'm not sure why?

I'm glad the Tempest-X are doing the trick for you.   How about some pictures?