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DIY Subwoofer question...help me understand the Tumult vs. DPL-12


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#1 of 26 OFFLINE   Rob Bird

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Posted December 12 2004 - 07:34 PM

Ok, here are four configurations I've been working with in WinISD. The two drivers being compared are the Adire DPL-12 and the Tumult. I've double checked the parameters, and I can't really believe what I am seeing.

Blue: Vented DPL-12, 220.5L, tuned to 13.35 HZ
Green: Vented Tumult, 120L, tuned to 19 HZ
Yellow: Sealed DPL-12, 80L
Pink: Sealed Tumult, 75L

EDIT: Ok, my hosting server is down at the moment.

What I am seeing:
All of them taper fairly similarly down to about 50hz, where they are 1db down. At 30hz, the Blue and Green are 1.2db down, Yellow is 3db down, and Pink is 5db down. At 20hz, the Blue is 2db down, Green 4db down, Yellow 7db down and Pink 10db down.

Bellow 20 it gets crazy, and the Blue plot rolls down to -3db at 13.5hz. The Green Tumult plot is -10db at 15hz

I tried tuning the Blue and Green according to the EBS advice on the DIY Subwoofer page, so there is just a smooth rolloff on the shelf and no peaks)
----

Now, aside from the fact that the Tumult is walking all over the DPL in max output at 500W (116db vs. 111db), the DPL is (at least to my eye), simply an amazing woofer for sub 20HZ extension. It's absolutely dominating the Tumult.

Have I done something wrong here, or is the DPL-12 clearly better than the Tumult below 20HZ? Will these designs sound boomy? I read some mention of needing to be -9db at 20hz and -1 db at 30hz to account for room gain. Is that right, or should I be aiming for maximal flatness in the gain curves?
Much thanks,
Rob

#2 of 26 OFFLINE   michael.e

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Posted December 12 2004 - 11:48 PM

Hi Rob
Well,something to consider is the fact that the DPL is only 12" and the tumult 15",so most likely the tumult will require a larger box for a start.

Also I wouldnt be tuning a DPL12 to 13hz,less info there,and youl be excursion limiting yourself,even further.Probably best near 16hz-20hz.

Note that winisd pro is 2pi,so if you put your subwoofer against a wall part of the spectrum will raise by +3db,also room gain will happen at some low frequency corner depending on room volume.

Although its nice to make a curve that fits your room gain curve,you dont know your room unless youve measured it.

Note that the responses only vary below 20hz,above this they seem relatively similar.

The DPL12 efficiency is really low-but thats just because its a low Fs woofer which is ideal for HT

Then,after all this effort,you must consider vent air speeds and perhaps PRs due to extreme port lengths.



Cheers!
Mike.e

#3 of 26 OFFLINE   DanWiggins

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Posted December 13 2004 - 03:14 AM

Rob,

What you see is correct; the DPL12 is a monster in terms of low bass extension in mid-sized cabinets. That's what it was designed for (along with dipole use).

HOWEVER, in terms of clean output, you'll need about 4 DPL12s to equal a Tumult...

Dan Wiggins
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#4 of 26 OFFLINE   Jason Dalton

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Posted December 13 2004 - 03:32 AM

OK, my question is, why are you comparing the DPL12 and the Tumult?

#5 of 26 OFFLINE   Rob Bird

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Posted December 13 2004 - 03:44 AM

Thanks for all the feedback guys! What I've been considering is a tube with an isobaric pair of DPL-12's in one end, and a pair of 28.81" long 3.22" ports. WinISD says this puts the Vent mach at .08.

Hosting server looks to be back up...here are the four graphs I am talking about above:

Gain Curves:
http://members7.club....13-3e04&trans=

Group Delay:
http://members7.club....14-2a12&trans=

Phase Curves:
http://members7.club....15-66e9&trans=

SPL Curves (500W):
http://members7.club....17-235f&trans=

#6 of 26 OFFLINE   Rob Bird

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Posted December 13 2004 - 03:52 AM

I wanted to add that in an isobaric pair, the specs for the blue line box become:

110L, Tuned to 13.35Hz, two ports, .068m in diameter, 1.041m long...vent mach would be .06. I am thinking I should be able to fit those in the cylinder in a gentle-slope double helix configuration. Drivers would be mounted face to face in the end cap.

#7 of 26 OFFLINE   Rob Bird

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Posted December 13 2004 - 04:02 AM

Jason,
I actually stumbled onto the DPL-12, and checking its parameters, it looks like it was a good thing to investigate. My interest is fostered by the fact that it appears to go deeper than the Tumult, and that for the price, I can use a pair of them isobarically in a manageable tube size to get some pretty freaky sub-20hz extension.

At the time, it also fit the 24" stainless sphere I was considering using as an enclosure better than the Tumult, but that's not as much of a factor now since the "industrial hot air balloon" was nixed by my significant other Posted Image



Dan,
You mention needing about four DPL-12's to equal one Tumult in terms of clean output. Is there a better way to tune the Tumult for low extension? I couldn't seem to force it lower without significant rolloff (more significant than the DPL-12) using a vented configuration.

Thanks again!
Rob

#8 of 26 OFFLINE   Rob Bird

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Posted December 13 2004 - 04:32 AM

Ok, I just did some replots, tuning the Tumult lower and in a larger enclosure.

Blue is the same DPL12 IB config above
Green is the Tumult, tuned to 13.5 Hz, 200L box, 3 vents, .068m in diameter, .870m long

Gain Curves:
http://members7.club....46-408e&trans=

SPL Curves:
http://members7.club....47-9573&trans=

Obviously, in the SPL curve the Tumult crushes the IB dpl-12. But what about the rolloff in the gain curve? Is it "ok" (on either count!) The phase and group delay curves look almost identical now (probably since the Tumult is in an EBS configuration)...

#9 of 26 OFFLINE   Scott Simonian

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Posted December 13 2004 - 05:48 AM

I think if you want to get the extention that you are looking for you will need to implement some sort of EQ work. Prolly the best bet would be to add a Linkwitz Transform circuit to the Tumult. If you have the right amount of power you should be able to trounce a pair or two of DPL12s with one Tumult in SPL and extention.
Another supporter of 1080p and uncompressed multi-channel sound!

My Twin 18's. 50cuft of box, tuned to 11hz and with 2k watts on tap.

#10 of 26 OFFLINE   DanWiggins

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Posted December 13 2004 - 08:40 AM

Rob,

For a monster extension in-room vented Tumult design, look at 6 cubic feet tuned to 14 Hz with a 6" diameter port that is 60 inches long (or an equivalent slot port). It should provide, in a standard IEC room, flat extension to about 12 Hz.

Most people end up using Tumults in smaller sealed boxes (higher WAF) and EQ to get as much depth as desired.

Dan Wiggins
Adire Audio

#11 of 26 OFFLINE   stephanX

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Posted December 13 2004 - 10:56 AM

I can't IMAGINE what dans living room looks like... I would definately get a tumult over a couple DPL 12s, simply becuase a tumult has WAY more displacement, and if you got the money for a tumult, you should be able to get the money for a niiiicceee big amp, and a BFD.

I am surprised you havnt looked at the maelstrom, or even the tempest! im sure a pair of maelstroms would get REALLLLYYY low, and theyre nice and efficient too!

And Mr. Wiggins, i believe a current system description is on order!
Can your 450$(cad) sub hit 120db at 40hz?

#12 of 26 OFFLINE   Scott Simonian

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Posted December 13 2004 - 11:36 AM

Seriously, Stephan. I think I have come across a few pictures of the Adire shop. I don't believe I have ever seen/heard of what Dan keeps in his living room.
Another supporter of 1080p and uncompressed multi-channel sound!

My Twin 18's. 50cuft of box, tuned to 11hz and with 2k watts on tap.

#13 of 26 OFFLINE   Aaron Gilbert

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Posted December 13 2004 - 11:39 AM

Actually, of these three drivers, the Maelstrom will have the worst low end extension, due to the highest Fs and lowest Qts. A Tempest does make a nice choice, but the DPL12 provides better low end extension (about 4 Hz all else equal) in a box about half the size. Of course, it's the same price, so in the output per dollar race, the Tempest is the clear winner.

Whether any of them sound boomy will be primarily a function of the overall frequency response when placed in the room. I've found that when corner loaded, any sub which has anechoically flat response down to 20 Hz or lower can sound boomy in an average living room. Some solutions are to either move the subwoofer out of the corner, or design it with a built in rolloff starting somewhere around 40 Hz, no doubt there are others.


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#14 of 26 OFFLINE   Rob Bird

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Posted December 13 2004 - 11:41 AM

Thanks for the advice, dan! Looks like virtually the same curve as above with a much smaller enclosure.

I'm a bit confused about using EQ to get extension out of a sealed enclosure...is there a specific type of EQ that works best for this kind of application? Up until this point, I understood that you should really only use an eq to reduce the peaks in the response...are you saying I should use one to boost the lower end anechoically? Or is that applied in room? What size enclosure would you recommend Dan for sealed use on the Tumult? I love the group delay figures on that (and my Hales are sealed too).

On another note, how much volume does the Tumult occupy in the enclosure? Also, how much depth does the Tumult need in the enclosure?

Wow, thanks for all the feedback guys Posted Image Money is not really my concern, I just want to go the DIY route so I can get the style and control over the build process that I like. Take for example the sonotube for these enclosures...my significant other has actually suggested that I make it short, and very large in diameter so I can use a piece of torch-relieved granite for the top as a coffee table. I heard something about black ultrasuede on the tube, but I was already digging into WinISD Posted Image

And yes, I too would like to know what someone that makes some of the world's best sub drivers uses in his living room!
Take care,
Rob

#15 of 26 OFFLINE   Craig Treusdell

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Posted December 13 2004 - 12:21 PM

Rob - do a search on Linkwitz Transform. The first Google response has a good explanation. This forum has some good details as well.

1. Drop a Tumult in a 2.5 cu ft sealed box, add the Adire ADA1200 plate amp, set the Linkwitz Transform circuit to your taste, use the 2 band parametric eq to tame any room peaks and enjoy.
2. Or drop it in a 5.5 cu ft box using two Stryke 18" PRs with 2500g mass, set the HP filter to ~16Hz, and be prepared.
3. Or do as Dan says (he knows a thing or two about the Tumult...) and go with the ported box.

Any of the above and the results are incredible. Oh yeah, two is better than one.

For the dimensions and other specs, visit AdireAudio.

And I would be very disappointed if Dan didn't have a Parthenon in his living room....

#16 of 26 OFFLINE   Andrew Pratt

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Posted December 13 2004 - 12:39 PM

Rob I've built plenty of subs using shiva's, tempests, DVC15's and now the tumult and to me the Tumult walks all over the others hands down where it counts the most. Here's the in room response plot for my Tumult in a sealed 2.5 cubic foot box with the BFD and a QSC 830 watt power amp. The blue line is the pre EQ response with the pink line being the house curve I've got with the BFD in line. As you can see it has no problem hitting below 20 and really there's not many movies with info that low anyway. I've actually tweaked that plot a little since I generated that plot to reduce the peak at 20 Hz but you get the idea. Still there's no way I can bottom out this sub no matter how hard I push it with the amp I have now which will be a concern if you try to port a DPL12. There's nothing worse then watching a movie that you know has a deep loud boom and cringing that its going to bottom out your sub.

Posted Image


Posted Image

#17 of 26 OFFLINE   michael.e

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Posted December 13 2004 - 01:14 PM

Linkwitz transform for HT ? Doesnt sound like a good idea to me.

Power and excursion requirements are already high for sub 20hz levels.

Since you can do the large boxes,do them!Id do the suggested design by Dan.

Ofcourse subs modeled flat in 2pi boom in 0.5pi! youl have +6db output!

#18 of 26 OFFLINE   Rob Bird

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Posted December 13 2004 - 01:43 PM

michael.e: When you speak of modeling in 2pi vs. .5pi, what does that mean exactly? I'm a mathematician, so I'll understand if you want to get obtuse Posted Image

Andrew: What is the BFD? Sorry if this is obvious..googling for BFD brings up some interesting hits that don't appear to be relevant.

Wow, what a monster...I had no idea it was simply so massive. How cool Posted Image It should still fit in my target enclosure, which will likely be something like:
32" Sonotube, 13" high, downward firing with 3" legs and a 1" thick base plate. Granite top cap. Downward firing vents. That puts me right at about 18" high (perfect for a coffee table).

For an amplifier, I had been looking at the Parts Express 1000W plate amp. Any thoughts on how that compares to the Adire pieces?

Looks like the only real challenges now will be routing the vents and sourcing the granite Posted Image I think I'm fast becoming an Adire addict!

#19 of 26 OFFLINE   Brian Bunge

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Posted December 13 2004 - 02:14 PM

Michael,

I had a Tumult powered by a single channel of a K2 (800W) and an LT circuit for HT. No problems at all.

Rob,

BFD=Behringer Feedback Destroyer
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#20 of 26 OFFLINE   Andrew Pratt

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Posted December 13 2004 - 02:23 PM

Quote:
I had a Tumult powered by a single channel of a K2 (800W) and an LT circuit for HT. No problems at all.


Single being the opperative word right Brian :b

Sorry Rob BFD = Behringer FeedBack Destroyer. If you goto my website under the DIY area there's a link in the description of my sub to Sonnie Parkers BFD page that will explain everything (and more!) about the BFD. Its pretty much essential IMO to get perfect sub sound in most rooms.

The 1K plate amps are both good. The Adire one has the added EQ and LT features that would be handy with a sealed Tumult. I'm not sure about the Adire one but I know the Parts Express one I used for a friends sealed sub leaked a little no matter how hard I tried to seal it. That wouldn't really be a big deal on a ported sub but the perfectionist in me wanted betterPosted Image