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Old 26th February 2002, 05:07 PM   #1
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Question Downfiring driver options?

I have looked at various subs for a downfiring, small sealed actively EQ'd, stereo sub application for HT. I have considered Audiomobile Mass 12, Earthquake Magma 12 and other high excursion/low vas/power handling subs.

For the price ($119), the Audiobahn Alum12X (www.audiobahninc.com) seems to have an impressive offering, optimized for small volume: cast basket, rubber surround, aluminum cone, 16mm one-way, 3" DVC, 120oz magnet, 1000W RMS, and excellent T/S params for small sealed HT modeling.

Fs 20
Qts .4
Vas 90

Please help me.
What do these other USA subs have that China's Audiobahn doesn't? Do they justify spending 200% more. I'll be using 1 to 1.4 cubes for each sub with high power. My objective is SPL/SQ compromise. 60% theater, 40% music.

Does anyone know if 16mm is linear or excursion limit?

Michael
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Old 26th February 2002, 05:16 PM   #2
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Well, for one thing I don't think any of the others mentioned have the excursion that the Earthquake does.
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Old 26th February 2002, 05:23 PM   #3
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Default Any experience with it?

You may be right, though the Mass is about the same, actually has more linear xmax I think. (And the wallet prompted the question)
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Old 26th February 2002, 05:32 PM   #4
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If you feel comfortable shelling out the cash, go for the Earthquakes. They are very impressive. I have used them for car audio in the past and am in the process of making an enclosure for a magma 15 out of a Piece of steel pipe with the correct inside diameter... its very heavy...
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Old 26th February 2002, 06:56 PM   #5
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Default Re: Downfiring driver options?

Quote:
Originally posted by masterp2
I have looked at various subs for a downfiring, small sealed actively EQ'd, stereo sub application for HT. I have considered Audiomobile Mass 12, Earthquake Magma 12 and other high excursion/low vas/power handling subs.
Michael,

All these that you mention are auto-sound drivers. Ususally lots of flash, exaggerated claims, and not great value for the money.

You should have a look at the large number of medium 12" designed for the home sub market. I have Adire Shiva and find it very good. I'd like to sell these and replace them with Stryke SAE1204s (John uses %$^^ frames so if you want to get to his home page you have to delete everything after .com/ in the URL). If you can afford the extra tariff the Lambda woofers he has (and won't have more of at anywhere near the current price) cannot be beat -- these are hand-built by Nick McKinney and use all the motor tricks of the skanning/ScanSpeak/DynaAudio drivers. Their specs might not seem as stellar as other woofers but the quality...

dave
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Old 26th February 2002, 07:24 PM   #6
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Default But the application is...

Thanks Dave for your suggestions. I see it this way. And correct me if I'm innaccurate.

Those subs won't reach serious spl's for HT at the 20HZ range in a small sealed enclosure. I'll blow'em. This application requires large (linear) swept volumes and higher power capability to EQ that response, yes?

This is why I seem to feel that some high end car subs may be the best candidate for a 1 c.f. HT subwoofer. The car sub has been optimized for this very application, i.e. high linear excursion, high power handling, tiny Vas. True, most of them have an early rolloff for optimum car gain use, so I am just picking from the ones with lowest Fs and reasonable Qts, and positive reviews for home use. Perhaps one with an F10 of 20 HZ, which the audiomobile, Magma and Audiobahn have. Equalization then takes over to flatten the curve, given enough excursion and power handling.

So please poke some holes in my plans. I don't want to make a big mistake. But I need to know why these subs would not do the best job, and not why someone else's favorite drivers (in another application) is recommended. I realize that small, sealed is not the usual route in the HT, but please bear with me, it is a concession I am trying to optimize.

Michael
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Old 26th February 2002, 07:50 PM   #7
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Default Re: But the application is...

Quote:
Originally posted by masterp2
Those subs won't reach serious spl's for HT at the 20HZ range in a small sealed enclosure. I'll blow'em. This application requires large (linear) swept volumes and higher power capability to EQ that response, yes?
Forget the specs. The Shiva or the Stryke (or the Lambda) will outperform the car woofers -- particularily in a home application. The Shiva is VERY popular for cars.

I have a big *** car woof down in the lab -- real pretty but you pay for pretty by sacrificing performance.

The common small box app is to put them in a cu ft and add a Linkwitz Transform EQ to them -- you did say you were going to EQ them.

And remember if you want your woofer flat to 20 Hz it has to start its modeled roll-off a lot sooner. Otherwise with room gain you will have way to much bass.

I currently have a single Shiva in a 1.7 cu ft box with 40 W (NAD watts) on each coil and it produces bass that can be feltand not heard -- i am working on a bigger box with two woofers in push-push so that i don't have to work them as hard.

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Old 26th February 2002, 08:11 PM   #8
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Default Really?

"I currently have a single Shiva in a 1.7 cu ft box with 40 W (NAD watts) on each coil and it produces bass that can be felt and not heard "


A sealed 1.7 box with, I presume 12 HZ, SPL at 40 W?? Please clear up my confusion. What is the SPL at 20HZ? EQ'd?
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Old 26th February 2002, 08:27 PM   #9
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I agree with planet10 - most of the autosound subwoofers are all glitz and no performance, with huge retail markups to boot.

The exception of the ones you mentioned is the Audiomobile MASS2012 - it still has a high price tag, but it has excellent performance as well, and is far superior to a Shiva. The Audiomobile MASS series is made by TC sounds - the same people who make the fearsome HE-15 sold by Stryke.

It should also be noted that the performance of the Audiobahn and the Earthquake have not been independently measured by a 3rd party such as DUMAX - for their "xmax' measurements, they are free to quote anything from one-way linear magnetic throw, to 2-way damage-limited suspension throw. Be wary of their numbers.

The Shiva and MASS2012 have both been DUMAX verified - they are both very honestly spec'd, and will do you quite well.

I personally wouldn't go anywhere near the Magma 12 for the price, I'd MUCH rather have the MASS 2012.

It should be noted that another incredibly well-performing contender has been left off the list - the one that I personally would buy if I had to do what you're doing.

The missing driver is Blueprint's BPD1203. At $219, it represents an incredible value, and is practically designed for your application.

It has gobs of linear xmag (over 25mm, DUMAX verified), and more xsus (suspension excursion) than *any* of the above mentioned contenders. The shiva weighs in at about 20mm, ditto with the audiomobile, but the Blueprint 1203 is in a class of its own at well over 30mm one-way!

Its near-identical cousin, the 1503 (which uses an identical motor) was DUMAX tested at 25.86mm xmag, and 36.18mm xsus. The 1203 will have an identical xmag due to the same motor design, but likely a little less xsus due to the limitations of the 12" basket as far as spider diameter and depth goes. I'd estimate it to have at least 30mm one-way though. The 1503 will happily handle 1000W or more (Blueprint has hammered their '03 motor with 2000W+ doing sine sweeps and other tests, and had them come out unscathed)

Basically, if you want ultimate EQ/transformed output out of a tiny box, but with massive power requirements, pick the 1203. If you want less output, less cost, and less power requirements, go for a Shiva or any of its cousins (Stryke SAE1204, Parts express 12" DVC, etc.)

- ThingyNess
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Old 26th February 2002, 08:28 PM   #10
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Almost forgot - the Blueprint website is:

Blueprint Drivers
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