[Kevin Haskins]

I worked on this today.   The graphs and information will probably change once I have final T/S parameters but most of it should be close.   

Let me know if you see any errors.   It helps to have a couple sets of eyes looking at it.   

http://www.diycable.com/main/pdf/tempest.pdf

[JohnR]

pg 2. simple to build and make an idea ideal first time DIY project
pg 3. This would represent be right at the edge of realistic maximum output
The header says "Exodus Audio Tempest-X Application Guide" but the footer says "Exodus Audio Owner’s Guide".

I love the way you call an 8.5 cubic foot enclosure "small" 

You might want to plug the Woofer Widget a bit more   I can't find it on your site though?

[Kevin Haskins]

Ha!   Its not available yet.   In fact, it won't be available in volume for a couple months.   I should have a small production run in December though.

Thanks for the keen eyes.   

And John, 8.5 cubic feet IS small.   My room is 2500 cubic feet so a 8.5 cubic foot sub is only 0.35% the size of my room!   Tiny... .you could hardly find it.

[JohnR]

And John, 8.5 cubic feet IS small.   My room is 2500 cubic feet so a 8.5 cubic foot sub is only 0.35% the size of my room!   Tiny... .you could hardly find it.

Hah, I'm worried now that people might lose their subs if they don't make 'em big enough !

But seriously, you got me thinking... when you put it like that, why not just build it into the room. Even if you can't do IB, there are other possibilities. For example, I'm in the early throes of renovation planning right now and my architect keeps trying to put in little benches everywhere for "storage." Well, thinks I, why not just "store" a couple of bigass sub motors and a load of polyfill in there? Here's one idea:



The reason for the opposing subs and the braces is because my house rattles... I'm not using my subs at the moment because of that.

[Kevin Haskins]

And John, 8.5 cubic feet IS small.   My room is 2500 cubic feet so a 8.5 cubic foot sub is only 0.35% the size of my room!   Tiny... .you could hardly find it.

Hah, I'm worried now that people might lose their subs if they don't make 'em big enough !

But seriously, you got me thinking... when you put it like that, why not just build it into the room. Even if you can't do IB, there are other possibilities. For example, I'm in the early throes of renovation planning right now and my architect keeps trying to put in little benches everywhere for "storage." Well, thinks I, why not just "store" a couple of bigass sub motors and a load of polyfill in there? Here's one idea:



The reason for the opposing subs and the braces is because my house rattles... I'm not using my subs at the moment because of that.

I hate to discourage you but if your structure vibrates, and that bothers you (some of the HT guys love that),  the last thing you want to do is to fix mount subs.   

A better approach would be to build a small sealed sub and use an isolation platform.   I think Auralex makes one for subwoofers.   You can copy the design easy enough and DIY one.      Its just a MDF platform with a couple layers of acoustic material on the underside.   You may want  to buy some of their material simply because the density of that was probably a somewhat trial/error effort.   

Or... you could make one of your benches the sub, just don't attach it to the rest of the structure.   Make it heavy enough that it won't move and build a stealth base under it with the acoutic foam (its hard, not squishy).

[Carl V]

Consider buying "subdudes"....these work quite well acutally.
This will decouple your sub enclosure from the floor....it will
not do anything about the room resonamces & knick -knack
rattles...doors...windows et. al.,

[JohnR]

I hate to discourage you but if your structure vibrates, and that bothers you (some of the HT guys love that),  the last thing you want to do is to fix mount subs.   

Hm... well, the idea of having the subs effectively bolted together and firing in opposite directions is to minimize vibrations. But maybe even that wouldn't be enough. OK, back to the drawing board

[jonwb]

The reason for the opposing subs and the braces is because my house rattles... I'm not using my subs at the moment because of that.

Wait a minute... does your house rattle from the box rattling on the floor... or is the problem w/ the sound waves (being so low) making things in your house (walls, windows, nick-knacks) vibrate?  I suspect its more the later.  If that's the case, then how you mount the box won't matter.  The only thing you can do is stay away from the frequencies that excite those items (usually just set the cross-over higher).  I would think the more rigidly the box is configured the better platform the driver will have to vibrate the air (overall making a more efficient the package).  In the end, if your windows have a resonant frequency at say 25Hz, content from your sub at that frequency will get the windows dancing (depending on the amplitude).

Jon

[Kevin Haskins]

I've updated the Tempest Application Notes to reflect the production parameters.   The Cms was a little lower which pushed the Qts higher and the result is that the sealed box applications got smaller.    The ported alignments are pretty much the same.

This actually worked out pretty well because now you can choose based upon desired box size all the way from 85L sealed, to 300L ported and you have a range of sizes & output to choose from.    Parts Express has a box that works perfectly too, the 85L sealed would match their 3 cubic foot 15" subwoofer box.   You can get the plate amp and the complete assembled enclosure from PE for about $355 so it is an affordable and easy bolt together solution.

The Shiva boxes vary from 56L-140L so there is good overlap between the available box sizes and output choices.

If you have downloaded this earlier you should delete it and get the most recent version.

[Oborous]

The Cms was a little lower which pushed the Qts higher and the result is that the sealed box applications got smaller.

If you have downloaded this earlier you should delete it and get the most recent version.

Hello Kevin,

I have problems getting the file from the link in this thread.

I'm wondering about your latest revision of the applications file, my modeling of the sub now shows that it's larger in sealed boxes.  I have the Tempest-X going from a production goal of Qts 0.42/Vas 402L, to a Qts 0.42/Vas 394 now with latest revision of Qts 0.51/Vas 324 which for a Qtc of 0.707 going for Vb of 219L to 214L to 351L...

Am I doing something wrong? I'm looking at the Tempest for my first sub project, but I want a Qtc of 0.707 and Wife limit is 300L box size...

Jason

[Kevin Haskins]

Sorry, fixed the file.

Ignore your simulation and follow my recommendations in the Application file.    The text-book Q = 0.707 is fine an dandy for text books but our drivers are not necessarily aimed to be used in a text-book way.   

Trust me.... we know what we are doing.    Build a big sealed box and you will have a great musical sub.   You can come in well under your WAF limit too as long as your building sealed.    Brace it so you don't have any more than 18" of unsupported open span on any wall of the enclosure.   Stuff it with 100% fill.

I love big sealed Tempest designs.   

[Oborous]

Trust me.... we know what we are doing.   

I love big sealed Tempest designs.   

Oh, I know you know what you're doing... you're the only person out there advertising linear CMS... http://www.google.ca/search?hl=en&q=linear-CMS+subwoofer&meta=

The reason being, I was reading the following: http://isp.imm.dtu.dk/nonlincomp/Klippel.pdf (Slide 32 on page 12)
Your subs allow me to deal with the top three concerns talked about by Kippel.

It wasn't so much the 85L design, it's just the Vas vs. Qts change (due to Cms change) wasn't compensating for actually making the box smaller.  I'm extremely lucky if I can get one project done a year due to time constrains and was worried that I've wasted time with my simulations. (Your recently posted semi-DIY box looks awefully tempting for me.

[Kevin Haskins]

You do your homework. 

Cms is a curve though, looser near the center and stiffer at the extremes.    It helps restore the cone to center (along with the inductance curve) so you deal with some non-linear suspension behavior to get the driver to operate properly.   About the best you can hope for from a suspension standpoint is that the cms curve is symmetric, in both forward and rearward ranges of stroke.     Most suspension non-linearity's are 2nd order though so if your going to have distortion, that's the best kind to have. 

The PE boxes are great.   You may want a little EQ on it but you have the single PEQ band which can be used to tailor the response.   

I like bigger subs though.   You can EQ your way there but its not the same.   They just never have exactly the same qualities as the larger sub without the EQ and the exact same low-level FR curve.   The air suspension dominates the suspension stiffness at lower box volumes and your pumping a lot more power, to emulate the same response in the larger box.   More power equals more compression, more non-linearities due to VC inductance etc...    So you don't get something for nothing. 

[AK]

Kevin, do you have tempest-x distortion measurements available? I know it is great at lower frequencies, but I consider to use it as woofer with 4in full range driver in open baffle. I am interested to see how cone breakup and higher frequencies distortion look. I assume distortion shouldn't rise with frequency as this is low Le driver.

[Kevin Haskins]

No... not at this point.   I've only had them for a few weeks and have just not gotten around to getting all the measurements I want.

I may do some ground plane measurements of a couple finished subs with some distortion measurements @ different power levels but the danger is that you really should use the same measurement set-up to compare vs. different drivers or even finished subs.    The "how it is measured" varies the results significantly, so I'm not sure how valuable the distortion measurements are without a context of their meaning and how it compares vs. other drivers.   

For your set-up, I'd probably say the Shiva is more than enough driver.   At any SPL the little 4" on an OB is going to dominate your distortion in the finished system.