The "designing the perfect subwoofer driver" thread... (1 Viewer)

[Anthony_Gomez]

What's a Tumult?

A tumult is sort of like ...well...guys having multiple O's....no one "seems" to have one, but we guys wish we did!

 

[Jack Gilvey]

You mean over the course of a week, or what?

 

[Anthony_Gomez]

Jack....analagous to the opposite sex.
...but then again....for some...once per week..or even month is a rare treat

 

[Seth_L]

Leave it to Anthony and Jack to start talking about sex in a thread about subwoofers. I'd swear for a second there I thought I was reading a thread on AVS about buttkickers, star wars, and someone's wife.
Seth

 

[Geno]

...

 

[Chris Carswell]

----
"guys having multiple O's....no one "seems" to have one, but we guys wish we did"
----
Anthony,
I am so so so so so so sorry for YOU. I guess we all can't be THAT fortunate.

 

[DanWiggins]

Hi all,
We're still here! And I'm just back from being gone for 2.5 weeks; David had his hands full with other things until this time, so responses/replies have a been a bit slower than expected.
As far as the driver goes, we're just getting the final spider into production - realize that there are quite a few custom parts in this driver, and while you saw some of the design process earlier in this thread, you now get to see the manufacturing/building side (and its associated lead times) as well... Welcome to the world of building stuff!
As far as the design/XBL things go, I think Dr. Hyre said all that needed to be said. Hard empirical data (from a trusted 3rd source), lots of great FEA data, etc. Driver design is MUCH more complicated than many figure - magnetics, and field design, are tricky things! I'm not at all surprised that many are still confused by the technology, even when they disassembled a Brahma. There's a lot of things in magnetics that are counter-intuitive (use of copper increasing distortion in many cases being one).
As far as the "DUMAX" report on the Brahma 10, Mr. Overpeck failed to mention that the DLC individual who ran that test specifically stated it is NOT representative of Brahmas, and was for internal comparison of simple BL shape only. I think that pretty much states how much credibility one can give that particular DUMAX sheet...
Now off to 1200 e-mails and a 16" stack of papers...
Dan Wiggins
Adire Audio

 

[Seth_L]

He's alive!

Dan,

Any idea when the pre-order will start and when we'll have the drivers in our grubby little hands?

Seth

 

[Kyle Richardson]

I just spoke to Dan and a final prototype is done. Expect preorder information around the end of next week.

 

[Jack Gilvey]

Any chance we'll see some DUMAX or Klippel results before/during pre-order?

 

[Kyle Richardson]

Jack, Adire has their own measurement tool that they will use that has been verified as accurate by Dumax. I believe they are going to get them measured by an independant source though.

 

[Kyle Richardson]

It has been a long wait but hopefully the wait will be worth it. The Tumult begins preorder on October 23rd and runs through November 8th with a preorder price of $350. Production will be in mid November with delivery scheduled for the last week of Novemver.
A few items have changed from the initial specs so please note:
It is a dual 2 ohm voice coil driver which can be wired in series for a 4 ohm load for the home theater guys or parallel for a 1 ohm load for you car guys with the robust amplifiers. VC diameter is 3" in diameter.
Stiff epoxy treated paper/Kevlar pulp cone (like on Brahma), large roll foam surround. 8" diameter Nomex spider, solid poly dustcap (straight black - no logo!). Venezuelan 4 spoke basket, 48mm thick top plate, 13mm thick back plate. Dual stack of 1" thick magnets.
Shipping weight of this driver is 55 pounds (48 pounds for driver alone). Because of this our Canadian friends will need to order from the Canadian dealer since UPS is too expensive for international shipments and USPS damage rates are too high for this size of package.
Final T/S parameters:
Fs: 19 Hz
Qms: 5.5
Qes: 0.40
Vas: 113 liters
Xmax: 34mm one way
Sd: 749 cm^2
Vd: 5.1 liters of LINEAR displacement!
SPL: 84.8 dB @ 1W, 1m
Re: 2.6 Ohms
Le: 1.05 mH
Well, there it is! Now I cant wait until the end of November! You know where to go for order information.

 

[Seth_L]

Final T/S parameters:

Fs: 19 Hz

Qms: 5.5

Qes: 0.40

Vas: 113 liters

Xmax: 34mm one way

Sd: 749 cm^2

Vd: 5.1 liters of LINEAR displacement!

SPL: 84.8 dB @ 1W, 1m

Re: 2.6 Ohms

Le: 1.05 mH

Well... these changed quite a bit. All bets are off with this one.

Seth

Edit: After rerunning the numbers I'm disappointed myself.

 

[Michael R Price]

Looks to be tilted a bit more towards the car audio market. What causes the drop in efficiency even with a higher Fs?
Glad to hear it's done. I look forward to hearing all you guys rave about it while I wish I had more cash.

 

[David Hull]

No Message

 

[Kyle Richardson]

Seth, you're unhappy with a 15" driver that can fit into a 3.5 cu ft vented enclosure, tuned to 19Hz, has an F3 of under 18Hz?

Or one that can fit in a relatively large 50L sealed enclosure, with an F3 of 39Hz but a F10 of under 20Hz with a Q under .6? Throw it in a TINY enclosure of 1.5 Cu ft for a Q of .707 with an F3 of 39Hz and an F10 of 23Hz with minimal fill?

What makes you disappointed?

 

[Seth_L]

Kyle, the new Tumult no longer works as well as it did in the design I cooked up. That's why I'm disappointed. Now I have to buy different PRs. Any change you'll have a special on the Stryke 18" Dual spyder models to go along with the Tumult?

Seth

 

[Jack Gilvey]

Is the listed Le with the VC's in series? The Re seems to indicate this.

 

[DanWiggins]

Seth,
The softer spider we originally tried to use (which yielded the larger Vas and lower Fs you probably wanted) just didn't hold up mechanically over time. We had to go to a stiffer spider (thicker material and wider weave), which lowered Vas and bumped up Fs a bit. Still VERY close to the original alignments, though (we doinked around with the gap to get the Qes where it makes the response curves very similar).
As far as PRs go, I don't know of any PRs that I'd trust to work long-term. Start with extremely high linear displacement (and with XBL2 this motor can maintain all its force out to those limits), meaning at least 2 high excursion 18" PRs (or 4 high excursion 15" PRs). Then add in smaller boxes (under 5 cubic feet; larger than that and the response starts to get ragged) with low tunes, and you're looking at PRs with at least 2 kg of moving mass EACH. There aren't any PRs that I know of that I would expect to survive long-term with that much moving mass (nearly 5 pounds).
Personally, I'd look at a wrapped slot-port (standard vented design; something in the 3 cubic foot range, tuned to 18 Hz with a slot port that is 33" in area (around 80" long overall). Bend the slot back and forth 4 times, and you should be able to make it work, and not have excessive air speeds up to 1500-1600W delivered (note that 4 cubic feet with the same vent yields a 16 Hz tune, and a bit lower group delay as well).
Or as Brian and others are planning a Linkwitz Transform in a sealed box. Something around 44 liters net (about a 16" external cube), LT'd down to an F3 of 20 Hz and a Qtc of 0.577 looks real nice to me... In fact, we're working on some custom boards specifically for the Hypex amps we carry that will have a full LT on them. So you can bolt on a stout 750-1500W to the box with your LT built in.
Jack,
The listed Le is in parallel; in series, it should be four times that value (around 4.2 mH). My mistake! Still pretty low for a driver with lots of excursion...
Dan Wiggins
Adire Audio

 

[Seth_L]

Dan,
So you're telling me that 4 of your own Adire PR15x's massed to 1450grams (within the spec) in a 181.4L box won't hold up with 1400W on the Tumult? According to Unibox in a enclosure with no leaks and minimum fill the PRs reach an excursion of less than 28mm at 18.5Hz with 1400W. That's within the specs of the PRs as you list them on your site. Are trying to tell me that your specs on the PRs are nor accurate? If so why should I trust your specs for the Tumult?
Since we can't embed images anymore:
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So, from your post your saying this design won't work?
Seth