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SI 4" coil DS4-18 info and discussion


Electrodynamic

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Soon we will be offering the DS4-18" subwoofer to our lineup. This design was in motion long before I decided to stop selling direct so Sundown Audio will be handling the orders for this driver (just like the HT subwoofer was). The driver should be available for shipment around April 2016 with a pre-order opened much earlier.

Some quick highlights and specs:

4" diameter dual 2 Ohm copper voice coils
27 mm Xmax
220 mm OD advanced FEA optimized triple stacked ferrite motor
234 mm OD nomex spider with bolt-down ring
Flat sewn-on leads
Large 4 AWG speaker terminals
One piece inverted dust cap
High-roll rubber surround
Cast basket
Magnet ID shorting ring

Cutout: 16.7"
Mounting depth: 9.5"
Weight: 50.0 lbs


T/S parameters:

Re: 3.9 Ohms
Fs: 18.7 Hz
Qes: 0.65
Qms: 2.19
Qts: 0.50
Le: 1.52 mH
Sd: 121736.4 mm^2 (18869 in^2)
Vas: 270 L
BL: 19.9 
Mms: 561.42 g
Cms: 128.2 uM/N
SPL; 86.1 dB 1W/1M
SPL: 89.1 dB 2.83V/1M
Xmax: 27 mm
Xmech: 50 mm
RMS Power: 1200 w

Enclosure recommendations:

Sealed: 4 ft^3
Vented: 6 to 20 ft^3


Price will be under $270 shipped per driver inside the lower 48 continental United States. We will offer a pre-order with a $10 discount. Pricing on this driver is aggressive so there is no room for higher discounts.

DS4_1_web.jpg

Here is a picture of the rear of the driver. The driver is sitting on its face/surround in the picture.

DS4-Production-Rear.jpg
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I've gone ahead and modified the order of events at the g2g this weekend. First we will Klippel the ds4, the the hs24, then the hst-18 then si18, then the 2242, then the td12x, then ls-6 towers, then the jbl 308i's, then the tv speakers. I don't want a single driver in my GD house that hasn't been klippel verified...

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I've gone ahead and modified the order of events at the g2g this weekend. First we will Klippel the ds4, the the hs24, then the hst-18 then si18, then the 2242, then the td12x, then ls-6 towers, then the jbl 308i's, then the tv speakers. I don't want a single driver in my GD house that hasn't been klippel verified...

 

Don't forget your cell phone speakers. Last thing you want to do is find out your phone is klippel verified at 1/2 mm when Samsung promised you 3/4th mm.

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About that whole "K" verified thing. When a manufacturer displays the "K" logo on their advertising and say that the product is "verified" it doesn't mean that the specs reported are what were measured on that German transducer interrogation thingy. That is what most would assume but what it means is that the engineers or technicians at said manufacturer are in possession of a system and are trained and certified on all 4 major test modules. Of course if you spend the big dollars to have one and get the training it likely means that you are using it during development and design to help make improvements. Who buys a super cool tech toy and doesn't have fun with it?

 

Point is it does not mean that the xmax spec is what was measured on the machine.

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What? Lies on the Internet? Embellished "specs" in promotional materials?

 

That's nonsense. All manufacturers post all of their Klippel data, good bad, or otherwise, because the Internet demands it...

 

Next, you'll tell me that my iNuke 3000 doesn't really deliver 3000 watts. Everyone knows they do.

 

So much posting over so much nonsense. That extra 1.3 mm of "verified" x-max makes all the difference in the world with those high-power simulations (that rely on the linear extrapolation of non-linear small-signal parameters...). 

 

Sure, I'm concerned about throw and linearity, but they're not my main focus, provided they're adequate for the goals of the design at hand. If not, I chose the wrong driver. I'm far, far more worried about the moving parts hitting the stationary ones, and I can find that limit myself, no Klippel needed.

 

"Not enough... Not enough... Too much!!!!"

 

Back to your regularly-scheduled programming.

 

That's a solid looking driver. All these driver options are making it hard not to punch the easy button and run a bunch of sealed subs...

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Hell, I dunno what I am doing wrong.

 

I'm copying the link to a shared image on my Google drive, it previews fine, but I get nothing but:

 

"You are not allowed to use that image extension on this community."

 

as an error message when I try to post it. I've tried .jpg, .jpeg, .png, and .gif.

 

No soup for me. Internet is hard.

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If you modeled it against the Ultimax 18" and saw an almost exact low end performance but with better top end performance (much lower Le) for the DS4 you modeled it correctly. The DS4 has more linear motor travel and higher thermal power handling than the UM and also costs less. Honestly we did not intend for the models to blend so close to each other but that's how it worked out. We had a price point to reach with this driver and the DS4 was/is the best we can do while meeting the price point with a 4" voice coil. Larger coil, higher Xmax, much lower inductance, almost exact deep bass extension as the UM-18 but for a lower price. Mission accomplished.  B)

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If you modeled it against the Ultimax 18" and saw an almost exact low end performance but with better top end performance (much lower Le) for the DS4 you modeled it correctly. The DS4 has more linear motor travel and higher thermal power handling than the UM and also costs less. Honestly we did not intend for the models to blend so close to each other but that's how it worked out. We had a price point to reach with this driver and the DS4 was/is the best we can do while meeting the price point with a 4" voice coil. Larger coil, higher Xmax, much lower inductance, almost exact deep bass extension as the UM-18 but for a lower price. Mission accomplished.  B)

Nick I just hope you make enough on this new woofer for you to keep it around for a long while.:)

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