Would a subwoofer with a sealed enclosure work well for HT? (1 Viewer)

[Tubby]

I am thinking about using a SI Mag D2 or Fi Q 12" or 15" for a home theatre subwoofer in a sealed enclosure. Will sealed work good for HT? I have had good experiences in car audio with these subs sealed so was wondering about HT. Thank you.

 

[Robert_J]

A sealed sub works great in a home theater IF you know their limitations. The resonant frequency is higher therefore the frequency rolloff starts higher. But that rolloff is shallow. With some EQ you can boost the low end a little. For example, I use a pair of 15" TC-3000's in sealed enclosures for my home theater sub. I power them with a Behringer EP-2500 @ 2 ohms stereo. I use a Behringer Feedback Destroyer for the EQ.

Stereo Integrity and Fi Car Audio both make excellent subs but you can do better for the money. A Q 15" is $279. For $91 dollars cheaper, you can get a Tempest X with XBL^2 (like the new Mag has). For $270, you can get a pair of Shiva-Xs. Check out DIY Cable dot com.

As will all DIY sub projects, did you just pick these drivers out of thin air or did you actually look at the T/S parameters? What are your goals? Extension, SPL or both? What is the largest enclosure size that you can use? What amp? Music or movies? Percentage of each? How large is the room? Open to other rooms or sealed off?

-Robert

 

[Tubby]

First off thanks for the response! I was going with the SI Mag because it works well in a 1ft3 sealed enclosure. It works great in my car but no i didn't think T/S parameters were that important for a sealed enclosure as long as you use an enclosure close to what is recommended. Im not too worried about SPL just want good low end for movies. Won't be playing much music at home. The room is about 22'x15' but it has a hallway without a door. As for enclosure i want to keep it as small as possible but can go big if its necessary.

 

[Robert_J]

That 1 cf enclosure is the car recommendation. From SI's forum:
Well, the new Mag and the new BM will have Qtc's higher than .707 in their sealed enclosure recommendations. They will be lower than 1.0, but higher than .707.

Minimum, you want a Qtc of .707 for home theater. I really like my Qtc around .500. You need the full T/S parameters to determine that using WinISD or Unibox (my favorite). Since SI hasn't published them yet, I wouldn't recommend them. The Exodus Audio Shiva-X is $100 cheaper and should provide the same or better performance.

-Robert

 

[Tubby]

What size enclosure would you recommend for the Shiva-X subwoofer? Also what exactly is Qtc?

 

[Robert_J]

Qtc is a numerical representation of the response of a sealed sub. Here is a graphical representation of Qtc - link.

As the poster there mentioned, a Qtc of .5 is the most accurate. That's what I went for with my sub and just boosted the low end about 6db so that I have a flat response down to 17hz.

I've never modeled the Shiva X. Download Unibox and give it a try. Or better yet, use the designs that Kevin (owner of DIY Cable) came up with - link.

-Robert

 

[Tubby]

Thanks robert!