Another Enclosure Question

[swissy]

I was considering building the 54 Liter Shiva Box and was curious if the DPL12 would be a good fit? A better question would be, which driver would be best for HT applications. The DPL12 would seem to need a larger enclosure, however, I was told if given the choice on the Rava, to take the DPL12 instead of the Shiva.

From my calculations, I see the net box size needing to be 70 L(2.48 FT^3) for the DPL12, however, this box size is only 54 L (1.91 FT^3). Will the insulation bring the system Q down from 0.775 to .707?

Or should I look at the 85L Vented DPL12 or Shiva design?

Finally, if I build the 54 L box will I have a subwoofer equal to the Rava?

[fire pinch]

Whoaaa! Lots of questions in that small text!

"I was considering building the 54 Liter Shiva Box and was curious if the DPL12 would be a good fit?"

If you talk about a sealed box, yes, the DPL12 will be even a BETTER fit compared to the Shiva, frequency curve wize. .

"A better question would be, which driver would be best for HT applications."

It depends of how you design the enclosures, and how much power you give to them. But I would favor more the Shiva for HT, for the punch factor. The Shiva is a more sensitive woofer and has a bit more of air displacement capability so it will be a bit more powerfull above 30 Hz compared to the DPL-12 in most situations. But I would choose more the DPL12 for music applications for its abitily to reach lower, flatter.

"The DPL12 would seem to need a larger enclosure"

For the same "Q" value, the DPL-12 will still be the winner in deep bass response. So Im not sure that the DPL12 needs a bigger enclosure. And for the same box volume, the DPL-12 and the Shiva have a similar Q value (you can even see this by looking at the Vas of both woofers).

"<...>however, I was told if given the choice on the Rava, to take the DPL12 instead of the Shiva."

Yes, if people told you to choose the DPL12 over the Shiva, its because they know that the DPL12 is more naturally suited for sealed box with its lower Fs. You can obtain easily flat response down to 20 Hz with that woofer in a sealed box in room.

"From my calculations, I see the net box size needing to be 70 L(2.48 FT^3) for the DPL12"

How do you base your calculations? I mean, how do you see that you need a 70L box, what are your criterias?

"However, this box size is only 54 L (1.91 FT^3). Will the insulation bring the system Q down from 0.775 to .707?"

Well, even if the Q value will be a bit different but CLOSE, the DPL-12 will extend lower its bass.

"Or should I look at the 85L Vented DPL12 or Shiva design?"

A 85L sealed DPL12... hmmm in my opinion, you should stay with the 54L enclosure if you have the choice between this one and the 85L. With a 85L, the DPL12 excursion goes more up drasticaly around 20 Hz then you will have to be more carefull on the amount of power given to the woofer so this would give you less dynamics.

"Finally, if I build the 54 L box will I have a subwoofer equal to the Rava?"

The FR curve of the DPL12 will be better in bass extension. Your F3 will normally be lower than Rava one in your room. However, the Rava will be certainly a bit more powerfull above 30 Hz if you wanted to know about the power. The difference in power depends too of how much power you wish to give to your DPL12...

Do you look for power or frequency response when you say what is the best between blabla?

*UPDATED*

[fabulousfrankie]

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On 11/10/2003 3:23:46 PM swissy wrote:

I was considering building the 54 Liter Shiva Box and was curious if the DPL12 would be a good fit? A better question would be, which driver would be best for HT applications. The DPL12 would seem to need a larger enclosure, however, I was told if given the choice on the Rava, to take the DPL12 instead of the Shiva.

From my calculations, I see the net box size needing to be 70 L(2.48 FT^3) for the DPL12, however, this box size is only 54 L (1.91 FT^3). Will the insulation bring the system Q down from 0.775 to .707?

Or should I look at the 85L Vented DPL12 or Shiva design?

Finally, if I build the 54 L box will I have a subwoofer equal to the Rava?

----------------

With heavy fill you can "fudge" the extra volume if you go by Nousaine's chart. The Rava is a 60L enclosure, I doubt you'd notice the difference between a Shiva in a 54L or 60L enclosure. With a DPL12 the Qtc would be a little higher(not terribly high though) but the response is much better. I say go for the DPL12 and add 16oz poly per cubic foot of internal volume. Another woofer you could consider is the Stryke SAE1204, you can do two of them in a 67L enclosure with a Qtc of .707. They are $109/ea or $199/pr, the parts to build it cost 2X what a Shiva costs.

[swissy]

Thank you to both of you for your responses.

I calculated my Qts with the sealed.xls spreadsheet from The Subwoofer DIY Page v1.1.

fire pinch-

I was asking about a Vented 85L enclosure. This question came up because I got a response from Adire and they said the vented 85L design w/ a 3 flared port would be better (Tuned to around 20Hz).

Here is my plan

Make both and see which I like better. Making the boxes is not that hard and since I can move the amp and driver from one to the other, this should be easy. The only drawback is not being able to directly AB. However, what is the worse that could happen (I start a never-ending comparison of drivers and enclosures and end up like Ear!!!)

I think the winner is the DPL12. I am worried about the lower end because my current crappy 50W distorts and bottoms out on scenes that have footsteps. Like when the Ents (sp?) are walking with the Hobbits on his shoulders in LOTR2T. I have no doubt the Shiva would work, but it would be nice to see what the lower range is all about.

I am ordering today so any comments are still welcome.

BTW, I figured on a PE 250W or the Adire 250W. Suggestions here?

[fabulousfrankie]

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On 11/11/2003 9:05:22 AM swissy wrote:

Thank you to both of you for your responses.

I calculated my Qts with the sealed.xls spreadsheet from The Subwoofer DIY Page v1.1.

fire pinch-

I was asking about a Vented 85L enclosure. This question came up because I got a response from Adire and they said the vented 85L design w/ a 3 flared port would be better (Tuned to around 20Hz).

Here is my plan

Make both and see which I like better. Making the boxes is not that hard and since I can move the amp and driver from one to the other, this should be easy. The only drawback is not being able to directly AB. However, what is the worse that could happen (I start a never-ending comparison of drivers and enclosures and end up like Ear!!!)

I think the winner is the DPL12. I am worried about the lower end because my current crappy 50W distorts and bottoms out on scenes that have footsteps. Like when the Ents (sp?) are walking with the Hobbits on his shoulders in LOTR2T. I have no doubt the Shiva would work, but it would be nice to see what the lower range is all about.

I am ordering today so any comments are still welcome.

BTW, I figured on a PE 250W or the Adire 250W. Suggestions here?

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Since you seem to be concerned with a strong low end, why not go vented instead? The difference between the PE and Adire amps are minimal. The Adire amp has a small 1dB boost at 20hz if that makes any difference to you.

Where they talking about venting the DPL12 or Shiva? If it's the Shiva in that vented enclosure it could use a slight boost in the bottom end so the Adire amp might be better, if its' the DPL12 you don't need any boost so the PE amp would be better. With both of your sealed choices, a boost would be helpful, but I don't know whether a 1dB boost would be audible or not. It might be better to just save money and go with the PE amp but like I said I don't know whether a 1dB boost makes an audible difference.

[swissy]

Adire did not say to go with Shiva or DPL12 for the vented, they just stated the same as fire pinch that the DPL12 will go a bit lower. They recommended the Tempest, but I did not want to go that big.

As I said, I will probably go with the DPL12 and PE 250W. In addition, I will make both vented and sealed boxes and check them both with Avia and some sound tracks. I would think after listening to them both, the choice should become clear. I hope...

[fire pinch]

Oh Swissy, Im sorry. I really thought that you talked about only sealed enclosures. What would be the tuning point with your DPL12 vented enclosure?

Anyway, I dont like too much a DPL12 in a vented enclosure. But of course this is my opinion and my taste. I would favor more the Shiva for vented enclosures.

Lets see how you can model up a DPL12 vented enclosure. First, if you choose a tuning point higher than 16 Hz, you will begin to see a bump in the anechoic frequency response even if you change your enclosure volume. So you will most likely have to choose a tuning of 16 Hz and below, not very usefull for a vented box as the goal of a vented enclosure is to increase efficiency around its tuning point. Second, even if you choose a tuning of 15-16 Hz, the FR curve will looks like very flat down to 20 Hz anechoic, but what about in room? You will most likely have a curve which goes up a little as the frequencies go lower. Really, I dont know why the DPL12 would be "very good" for vented application. It can be ok, but compared to other kind of woofers, I dont think that choosing a vented enclosure for the DPL12 is really the best idea or your goal is really to have less distortion and more efficiency between 14 and 18 Hz. But at this frequency range, where do you hear that powerfull bass?

Very agree with Frankie for what amp you should choose, I have nothing to add anymore.

[swissy]

fire pinch-

Adire said the vented will give a tuning of 20Hz. I ran calculations on this and it seems to work out pretty well. There is a small bump of about 1.4dB @ 35Hz. The optimum size is 145L tuned to 16.4Hz. That's a big box! A Sonotube may work better for this driver if ported.

I guess I'll see if this makes a difference.

I ordered the DPL12, 3" flared port and 300794 PE 250W amp. All I have left is to put the parts together for the 54 L box. Like I said, by building two boxes I should get a good feel for which is better (for my tastes of course).

Thak you again for all your help.

[fire pinch]

Effectively, a 145 L box isnt a small box But you know, you have always tradeoffs when you design subwoofers. A moderate sized ported box and low tuning is needed with the DPL12 if you want flatter frequency response. Anyway and I agree with you on this, the most important, is to see what it does in the real life, the true results in your room. Good idea you have, building those two enclosures so you will know the difference

I wish you very good luck and success for you project! Why not showing us some pictures when it will be finished