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Discussion Starter #1
I have a customer with a CNC machine, that wants to pop out some cut parts for a Tempest-X2 slot port design. I've drawn this up to make it as simple as possible for someone to put together a killer sub, on a fairly tight budget.

Design constraints were that it needed to fit on a single sheet of 4'x8' MDF, and it had to use an off-the-shelf amplifier that had a subsonic filter that didn't need modification. In other words, you don't need to solder on the circuit board to achieve the proper filter. Easy....

I'm also working up a drawing, with a few easy modifications that will allow someone to cut their own if they have a table saw, and a router. A sheet of MDF cost about $20, the 500W version of the amplifier about $250, and the driver about $219 so the complete cost of this beast, should stay around $500 unless you want to get crazy on the finish.

I'm very confident, that there is nothing that will come remotely close to challenging it that can be bought off-the-shelf, so it represents a great bargain for anyone willing to perform a little sweat equity.



Here is the simulation, using 80% polyfill, just over 5 cubic feet and the slot port is 1.5" x 19" giving plenty of port area. Tuning frequency is around 21Hz which works great with the provided subsonic filter in the standard amp. In-room response will be into the teens and you get very good output from the ever so important 20-60hz range.



Click on this link and you can download the PDF drawing of the part. If you click on the drawing of the subwoofer in the PDF, you should be able to rotate it around and check out the design from any angle. I've made the braces blue, and the side translucent in order to easily see the inside features and port profile.

http://www.diycable.com/main/pdf/Slot-Tempest.pdf


Kevin Haskins
Exodus Audio
 

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Discussion Starter #3
Nice design! What 500 watt amp is this designed for?
It is the PE 500W or 1000W units. I'll have them in stock soon and I'll sell them for the same price or cheaper than Parts Express does. I'll make it so that you can add the amplifier to your shopping cart during checkout so that it will be one stop, easy shopping. ;-)

Kevin Haskins
Exodus Audio
 

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Discussion Starter #4
Performance comparisons.....


SVS PB13 Ultra..... munch munch... The Tempest-X2 has more cone area, more swept volume and if you use the 1000W PE amp, more power in a slightly larger box. Port area is about the same. No comparison on this one. The slot ported Tempest should eat it for lunch. $1600 plus shipping Internet Direct

http://www.svsound.com/products-sub-box-pb13ultra.cfm


AV123 MFW-15" munch munch.... Mark does a good job at offering good value but no comparison here. The Tempest-X2 is just a much more capable driver, with more power on tap in a larger enclosure. Strike one, two and three. $699 + shipping

http://www.av123.com//index.php?pag...facturer_id=0&option=com_virtuemart&Itemid=37


JL Fathom F113. This isn't even a fair comparison. The JL is sealed, with lots of power and a great driver but the laws of physics are on our side. I'll take Newton in my corner, thank you very much. It is smaller, a good compact sub with good output. The signal processing stuff is nice, but you can just get a Velodyne SMS-1 and copy all of that functionality. Price.... don't even ask, $3400 each!. You could build an entire array of Tempest-X2 slot ports and one of them alone should handily outperform a single F113.

http://home.jlaudio.com/products_subs.php?prod_id=371


Kevin Haskins
Exodus Audio
 

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Hi Kevin,

Thanks for all of the guidance. Aside from the quality products it is your customer service that makes me want to buy your products. In fact, I am in the process of helping my bro-in-law put together a system and their is only one option for the sub; DIY.

We plan on buying two Tempest-X2's, one for each of us. I currently have a HSU STF-2...that will get blown out of the water.

I will also post the build thread in your forum for good press but also for a little offer you mentioned...something to do with the Anarchy wid-woofer :)

Thanks

Brian
 

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Discussion Starter #7
Kevin,

Any idea how this compares to a servo sub like the Rythmik?

John
John,

I'm not sure I can give you a meaningful answer. It is sort of like asking how your car compares to another car with a different feature.

Servo is just a feature, that performs a function to lower non-linear distortion. It isn't something I do because the only time non-linear distortion becomes a problem, is at the limits of the device. We have the ability to listen to fairly high levels of non-linear distortion at these frequencies. I'd rather put my money into improving the transducer so that non-linear distortion is not audible, until you hit the limits of the device. At that point, it matters not if you have servo or not. The mechanical ability of the driver is the physical limit and there is nothing electronically you can do about that (except maybe a limiting filter).

I'm also a big believer in the KISS principle. A simple solution is always preferable to a complicated one, unless the complication buys you something meaningful.

Kevin Haskins
Exodus Audio
 

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Kevin,

Thanks for your response, I found it very helpful. I did not realize the servo concept was only helpful at the limits. It sounds like a non-issue for me.

John
 

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Discussion Starter #9
Kevin,

I did not realize the servo concept was only helpful at the limits.

John
That isn't correct.... it is helpful at lowering non-linear distortion BEFORE you hit the limits of the device. My argument is pretty simple, if the non-linear distortion isn't audible anyway, then what is the point?

Kevin Haskins
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Kevin, do you have any dimensions for the above box? Can't wait to get the subs next week!!

We want to get to work on the boxes soon.

Thanks
 

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Kevin, do you have any dimensions for the above box? Can't wait to get the subs next week!!

We want to get to work on the boxes soon.

Thanks
Hi Kevin,

Any update for me? Getting pretty excited but need a little help with the dimensions.

Thanks a bunch.

Brian
 

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Discussion Starter #13
Hi Kevin,

Any update for me? Getting pretty excited but need a little help with the dimensions.

Thanks a bunch.

Brian
Sorry, out of the loop for the weekend and Mondays are catch-up day.

Ahh... there is nothing that requires you to stick to the above dimensions. If you want to build the model above, it is 20.5" W x 24" D x 25" H (without legs). It is just over 5 cubic feet internal, tuned to 21Hz via the slot port which is 1.5" x 19" x the depth of the enclosure.

Kevin Haskins
Exodus Audio
 

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Long time lurker here. Just wanted to say thank you to Kevin for the support(and awesome deals!) you provide to this community. I think this Tempest slot load build looks great and sealed the deal on which path I wanted to go with my build.

Since it's tuned for 21hz with the dimensions and slot you provided, would it be okay to pair up an O-Audio 500w plate amp with it? The O-Audio amps are set for a filter at 18hz, correct? Right now they are still offering free shipping so for $219 out the door it looks like a nice matchup.
 

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Discussion Starter #15
Actually, I don't recommend the O-Audio amps for these ported designs, not because they are bad amps, but because of the Q of the variable subsonic filter. When you set the subsonic filter to 20Hz, it has a high Q which provides the amplifier with approx. 5dB of boost @ 20Hz. The FR wouldn't be so much an issue because it is likely to be swamped by in-room response issues anyway. The bigger issue is that with only a 500W amp, you significantly lower your overall headroom by using 5dB of gain @ 20Hz. Remember, that for every 3dB of gain, you have to double amplifier power so you have a three-four fold decrease in available amplifier headroom @ 20Hz compared to not running boost (actually, the headroom is the same, 500W is 500W, it is just that you will hit it easier due to the gain structure).

The short non-technical explanation, is that the O-Audio amp will clip significantly before a 500W amp without that kind of boost curve with most program material. If it were a 1000-1200W amp I'd feel much more comfortable about recommending it.

Right now, I'm bringing in several of the PE 500W & 1000W amps because they have the correct subsonic filter and should function without modification for the designs I'm publishing. The 500W version will be $250 including shipping, so while it is a few bucks more, you will likely be much happier with the final results.

Kevin Haskins
Exodus Audio
 

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Hey Kevin.. Is there a more powerful amp out there for less than the Dayton? If I do this i dont want to give it minimal power so I would like to go with something with 1000 + rms.. I know theres a few options out there with some " lower quality europower" amps that need hi passes, but if i wanted to get the loudest deepest bass I could out of this sub what enclosure and amp would you recommend.. I still would like to keep it all under $700
 

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Discussion Starter #17
Hey Kevin.. Is there a more powerful amp out there for less than the Dayton? If I do this i dont want to give it minimal power so I would like to go with something with 1000 + rms.. I know theres a few options out there with some " lower quality europower" amps that need hi passes, but if i wanted to get the loudest deepest bass I could out of this sub what enclosure and amp would you recommend.. I still would like to keep it all under $700
Dayton has a 1000W version of the same amp and they have a rack-mount 1000W subwoofer amp. That is what I'd recommend as it has the subsonic filter needed and everything else is the same.

The 1000W amp is $450, the driver $219 so you are pretty close to staying within your budget.


Kevin Haskins
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What about a tempest-x2 in a sealed enclosure? Can it compete with the JL fathom? What would be the dimensions for a sealed tempest-x2?
 

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What about a tempest-x2 in a sealed enclosure? Can it compete with the JL fathom? What would be the dimensions for a sealed tempest-x2?
Should be close but the JL would require more power, handle more power and be better optimized around a smaller enclosure.

You are basically comparing a smaller diameter driver with more stroke, to a larger diameter driver with less stroke. The JL uses a larger coil, would be better suited to heavily equalized small sealed boxes which is what they sell.

Price wise it isn't really a good apples to apples comparison. The JL driver is around $1K and you could buy five Tempest-X2 for that price.

Kevin Haskins
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I'm sorry Kevin I meant the eD A7S 450. How would the tempest-x2 compare with this sealed sub in a similar enclosure? These are the 2 subs I have narrowed my search down to. I think the eD is in a ~4ft^3 enclosure. How will the tempest compare with this. I plan on ordering tomorrow.
 
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