15" Subwoofer recommendations (1 Viewer)

[SteveCallas]

So now 36" length with a 188hz first port resonance IS ok? I see how it works.

Bud, if you do go ported, which I would recommend you do, use all of the available space, no need or want to decrease it at all. I'd also go with two 8" diameter ports, but I'd tune a bit higher, ~13hz with the ports being 30" in length. Sonotube would probably be the best choice of matrial to use for these ports considering the size. You'd want to add a 3/4" or larger roundover to outer layer of (MDF?) to act as a semi flare.....what are you building this out of by the way, I think I missed that. You'll also want to make the baffles - the walls the drivers are attached to - a few inches thick.

Aside from the obvious advantages of greater output and less distortion by going ported, the resulting natural FR will mesh extremely well with typical room gain, and you will likely need minimal EQ, if any at all. I can show you some real world examples of this if you like.

 

[Bud Huey]

Thanks again for everyone's help! The stage is made out of 3/4" OSB and the interior is seriously braced with 2 x 4s. I can do jumping jacks on top of it without the slightest bit of give.

Any examples you can show me would be appreciated! I can also send pictures of the enclosure if that would help. I wish I could post them in the thread.

Thanks,
Bud

 

[Mike Frezon]

Bud: You've got 33+ posts at the HTF now, so you are eligible to post pictures and links (you need at least 15).

You just need to take the digital images (or if they are film photos, scan them and digitize them) and get the hosted on a free photo-hosting site like PhotoBucket. Once there, you will get a link to where the photos are hosted and be able to put them into a post in your thread so everyone can see what you are talking about.

When you enter the link in your post, it will look something like this:

[ img ]www.photobucket.com/BudsPhotoofsubwoofers123[ /img ]

except that there wouldn't be spaces on each side of the "img" tags. I just put them there so you could see the code...otherwise it would have disappeared.

Good luck!

P.S. If you use PhotoBucket, they actually provide you a link witht he "img" tags already in place. or, if you just have the URL where the photo is sitting, you click on paste the URL into the pop-up box and the software will add the "img" tags for you.

P.P.S. BTW, Welcome to the HTF! Have fun here!

 

[Chuck Bogie]

Just remember - there is no replacement for displacement...

FWIW, just modeled 4 Peavey 18" Lowrider pro speaks in a sealed 44 cubic foot box, and with under 300 watts total, they looked darn interesting.

 

[Bud Huey]

OK - this is my first try at this, but here are the links to the photos of the enclosure. I included a 4' long level in the picture for a size reference.

http://i97.photobucket.com/albums/l2...y/03fac417.jpg
http://i97.photobucket.com/albums/l2...y/b7fa5347.jpg

Thanks,
Bud

 

[Bud Huey]

Chuck - thanks for the suggestion, but 15" is a large as I can get with my enclosure height. I think my set up should work out pretty well thanks to everyones suggestions. Now I just need to decide if I am going to port it and how long to make the two 8" port tubes - depending on which frequency I model the box for.

Thanks,
Bud

 

[SteveCallas]

Looks pretty well braced, but you will still want to add a layer of MDF to the walls, and probably two to the front walls the drivers will be mounted to.

Here are some in room FR measurements of single-driver large and low tuned ported subs without any EQ or with minimal EQ.











With a tuning around 13hz, as long as your room isn't extremely difficult, results like the first and last graphs shouldn't be too hard, and with 4 drivers, you'll have tons of headroom and extremely low distortion.

 

[Bud Huey]

I know it has been awhile, but my oldest daughter started playing travel softball so my free time to work on the HT went to zero. I am picking it back up now and am about to finish installation of the subwoofer. My question is regarding insulation of the subwoofer cabinet. Do I need to put some type of insulation inside the cabinet? What type would you recommend if it is needed? I ended up going with two 8" diameter, 36" long tubes in case that helps! Thank you for all of the great advise!

Thanks,
Bud

 

[Robert_J]

No stuffing needed. Just line the enclosure with acoustic foam. Or the cheaper method open cell foam from Wal-Mart. It's the egg crate foam mattress tops in the home section.

The porting recommendations are above. For an Fb of 15hz, the 8" ports need to be around 22". 36" ports are tuned lower. Have you modeled this?

-Robert

 

[Bud Huey]

I was working off of the recommendations in this thread - I do not have any modeling software, and this is a one time project for me, so I am hoping to get by without having to buy anything. It was recommended that I use a 35-36" tube to tune it @ 13Hz. Any other suggestions before I seal the enclosure would be appreciated!

Thanks,
Bud

 

[Robert_J]

Assuming that after you add more bracing, the net enclosure size is 42cf after additional bracing and ports, then a pair of 8" ports, 32" long would give you an Fb of 13hz. Most use longer ports and trim them down as required.

-Robert

 

[Bud Huey]

Ok, so you think I should trim the ports to 32". Any other suggestions before I close it up?

Thanks,
Bud

 

[Robert_J]

Just the additional MDF that Steve suggested.

And the port length of 32" is based on an internal port diameter of 8". If it is not exactly 8", then we need to make adjustments. If you bought an 8" Quicrete tube, they all are not the same size.

-Robert

 

[Bud Huey]

The Quikcrete tube is acutally 8.25" on the ID.

Thanks,
Bud

 

[Robert_J]

Then using the full 36" ports will tune your box to 12.65hz. That small difference is not enough to worry about actually trimming down the ports.

-Robert

 

[Bud Huey]

Thanks for all of your time and effort to help me!!!!