Home Theater Forum and Systems banner

1 - 20 of 34 Posts

·
Registered
Joined
·
63 Posts
Discussion Starter · #1 ·
I'm a longtime lurker on this forum who is finally going to take the plunge into a DIY sub. I have to say that the advice and guidance this community provides is unreal and has been hugely helpful (I've taken a lot of advice here and elsewhere on other aspects of my home theatre too). So thanks in advance.

I have a somewhat large "L" shaped basement that I'm looking to fill with more bass (somehow I suspect you've all heard noobs asking for "more bass" before...). The dimensions are at the bottom of this post. I currently have a single Velodyne 12" DLS4000R sub positioned in the back right corner. I thought it was great until i started demoing some of the recommended scenes like "Irene" in Blackhawk Down and How to Train your Dragon and realized that I must be missing a lot of lower frequency content as neither were very impressive. There are definitely scenes where you can feel the bass (for example, the scene where the Treadstone agent shoots up the pill factory in the Philippines in the Bourne Legacy) but nothing like what some people are describing on the forums.

We use the theatre for movies and games exclusively, no music. We typically watch movies at around -15db so I'm after definition and extension as opposed to just being loud.

I don't need (and can't really afford) to build multiple subs right now but I'm not going to rule out a second unit down the road.

After a lot of research I am leaning towards building a ported sonotube with an 18" driver. Probably the Dayton HO-18 (unless there's a better option in a similar price range?). I've found an iNuke3000 at a good price on Ebay so I will probably pick that up (there is also a locally available Crown XLS1000 for $250). I can get either 20" or 24" sonotube locally with "above grade" walls.

So now that I've subjected you to my novel-length preamble, here are the questions I was hoping people might be able to answer for me:

Questions:

I am planning on using 24" sonotube cut to 48.25" tall. I thought about making a 20" sonotube, but thought it would be tight with the 18" driver and figured it would have to be too tall. I read on here that a 6" by 27" port would provide tuning to 14.5hz, does that sound right?

What kind of driver would work best with the iNuke 3000 in this application? I was looking at the Dayton HO-18 but am open to better suggestions.

Could the iNuke power a second 18" down the road if I decide to build it?

Can I use 3/4" Birch veneer Plywood instead of or along with 3/4MDF? I already have a sheet of the plywood i would like to use up if possible. Would the veneer prevent me from gluing two layers together for the baffle?

What kind of router bit should I use to cut the baffles?

Here are my room dimensions and current gear:

Room Dimensions: screen wall is 11' wide. Right side wall is 21' long. Viewing distance to the front chairs is about 14'. The left side wall is 4', then opens up into the rest of the basement (the screen is in an alcove bordered by the media closet on the left). The rear wall is about 35' long. The basement opens up at the far end into another 28 x 9' area at the far end, where the stairs are. The ceiling height is 7'7" in half the room, but there is a huge soffit that drops that height to 7' in the other half.

Gear: Denon AVR-891, Goldenear Triton 7 LR and Goldenear SCXL center. 4 Paradigm ADP surrounds. Epson 6030 projector and a PS3 for Blurays.
 

·
Registered
Joined
·
66 Posts
Hi RHSS,
I'm not an expert but I do have some opinions on a few of your questions. The genesis of a sound wave is vibration. In a speaker, the only thing you want vibrating is the driver. A simple test of a speaker's quality is to touch the cabinet while it is playing. The less it vibrates, the better the speaker. I would not recommend solid lumber for a speaker. The wood grain pattern would make it more prone to having harmonic frequencies that would distort your sound. A homogeneous substance like MDF or my favorite HDF, would treat the frequency range a little more fairly. Plywood is a substance that lies between homogeneous and grained. I would expect its performance to lie between the two but closer to homogeneous. I do like sandwiches. On my Fried satellites I have zebrawood veneer attached to 1/4" Masonite with contact cement. This was wood glued to 3/4" HDF. On the inside I stuck on a product, made for the purpose of dampening sound. My cabinets do not vibrate. The idea is that gluing together materials with different harmonic frequencies will result in a sandwich that is resistant to vibration. I recommend that you use the material that you have on hand. I conjecture that the difference between it, MDF, and HDF is inaudible. I'd be curious to hear what others have to say on the subject. Good luck!
 

·
Premium Member
Joined
·
19,397 Posts
Probably the Dayton HO-18 (unless there's a better option in a similar price range?).
Stereo Integrity HT 18D2, better performance at a cheaper price.

I read on here that a 6" by 27" port would provide tuning to 14.5hz, does that sound right?
What is the net volume?

Could the iNuke power a second 18" down the road if I decide to build it?
Yes as long as you don't push the amp into clipping.
Can I use 3/4" Birch veneer Plywood instead of or along with 3/4MDF?
Instead of if it's void free, along with if it isn't.
What kind of router bit should I use to cut the baffles?
A two flute up spiral works the best, it ejects the cuttings so the bit doesn't over heat.
 

·
Registered
Joined
·
63 Posts
Discussion Starter · #4 ·
Thanks to both of you. This is really appreciated.

What is the net volume? - I believe it will be about 320 litres.
 

·
Registered
Joined
·
63 Posts
Discussion Starter · #6 ·
Truthfully no - I copped the design and stats from an old build thread and I thought the drivers would all take up close to the same volume. I only have a mac and haven't been able to use winisd.
 

·
Registered
Joined
·
44 Posts
If you are using birch ply or any kind of veneer product an up spiral bit can cause breakout to occur. Cleanest cut is to use an undersized up spiral followed by a down spiral bit to not damage the top layer.
 

·
Premium Member
Joined
·
19,397 Posts
If you are using birch ply or any kind of veneer product an up spiral bit can cause breakout to occur. Cleanest cut is to use an undersized up spiral followed by a down spiral bit to not damage the top layer.
You are correct. I should have stated an up spiral if using MDF.
 

·
Registered
Joined
·
63 Posts
Discussion Starter · #10 ·
Mike P. "Did you model the driver in that volume?" "...the SI would use less of its available XMAX"

Mike P., thanks again for taking the time to comment. I did not understand the implications of your second comment with respect to the dimensions of the port or the total volume of the enclosure. I have been doing a lot of reading on the forums but I'm afraid I only have a beginner's understanding of the effect that a driver's specs have on the size of the enclosure and even less regarding how to design a port. Do I need to make an adjustment?

I'm now shopping for an up-spiral and a down spiral (though part of me is thinking about just flipping over the board!)
 

·
Registered
Joined
·
683 Posts
FWIW you can also get a compression spiral router bit that may save you money by buying one bit vs buying an up-spiral and a down-spiral bit together and is designed for dual-sided veneered stock. Something like this.
 

·
Registered
Joined
·
76 Posts
I just went through phase 1 of where you are. I was going to do 2 10+cf ported si-18s. From what I read they would have been great. I would really like to hear a few large ported sub's in my space to compare with my current set-up. Make sure to do research on the port type and length you use.

I am loving my single sealed ftw-21 though. I am hearing low stuff and definition in music I have never heard before. Even older CDs are providing details I have never heard before from old favorites and they can't have much ulf?

Bought a inuke 3000dsp for $240 before x-mas off of make an offer on eBay. Bad time to buy as others have got it for $230 to $235.

I am still playing around, but having fun. I need measuring equipment and I think I need more power, but in 2100 cubic feet, it is doing great. Most of the family complains of the shakes if I turn it up. The ultra low rumbles are very addictive and the impact diminishes after awhile. Friends come over and are shocked by the raw power at first, but grow into it during a good ulf show...

Take your time, have fun and do your research. I think for your room size you will eventually want more than one ported si 18 (esp. For movies) if you have the room, time and can afford it....
 

·
Registered
Joined
·
63 Posts
Discussion Starter · #13 ·
Cellarnoise, what led you to go with the sealed 21 instead of the 18 ported?

I have the room for some fairly large enclosures in a few parts of the room so I've been going back and forth quite a bit between a cube and the sono. I like the idea of the sub being taller rather than wider in the spot where I'd like to place it and I think it will have a higher waf too. Since I've never actually heard any Ulf subs, I can't really compare performance between any of the options.
 

·
Registered
Joined
·
76 Posts
I went with the ftw-21 as I have limited space and the sealed box fit between the outer tower and center channel, and under my screen. A larger ported box would have required the mains to sit on top of the subs.

In my space 21s provide an upgrade path that also provides some under 20 hz that I want to try and play with. Watching the 7 hz note from "bass I love you" on the sub is a good time and rumbles the house...

Big ported sonos will work good from what I have read and the inuke 3000 seems a perfect fit for two 18's. With your large space you could always add more if the bug bites you really low ;)
 

·
Registered
Joined
·
63 Posts
Discussion Starter · #15 ·
Bought a inuke 3000dsp for $240 before x-mas off of make an offer on eBay. Bad time to buy as others have got it for $230 to $235.
I must be shopping at an even worse time, I can't find a DSP model for under $399. Still I'm glad you posted as I know what to look for. How far below the advertised price did you offer?
 

·
Registered
Joined
·
76 Posts
I would either keep an eye out on eBay or contact uniquesquared.com

The had a buy it now of $270 before. Hopefully they are just out of stock on the 3000dsp.

Now I am glad I bought when I did!
 

·
Registered
Joined
·
63 Posts
Discussion Starter · #17 ·
Yeah, you definitely grabbed yours at the right time. I talked to unique squared and they are sold out for a while.

UPDATE: today I ordered my SI 18"D2. They originally wanted $230 to ship it to me (I'm in Canada) but I figured out a way to ship to the border and pick it up for $5. My mother even offered to take a day trip to upstate New York when it arrives to pick up home theater toys for her adult son. Thanks ma!

I am heading out shortly to pick up a Behringer EP2500 that I found locally for $300CAD (about $250US)

I just need to finish working out a design and picking up the building supplies locally. I sold my Velodyne to finance the EP2500 so am looking forward to getting this subwoofer built.
 

·
Registered
Joined
·
76 Posts
You will love it. Go easy on the gain and volume at first.

The best ulf movie overall I have so far is tron legacy.
Show suchs batman, u-571, and iron man have some great ulf scenes, but tron pummels you every 5 minutes or so. It has a few very dynamic scenes so watch the volume.

Good deal on your amp. I could not find even a used one for that price. You can power two big ported si-18s with that amp.

This stuff is addicting! My room has a concrete floor which takes out some of the imact from the ulf and shakes.
 

·
Registered
Joined
·
63 Posts
Discussion Starter · #19 ·
I can't wait. I haven't seen Tron so that's now on my must see list.

I found an appropriate router bit today and just ordered the following parts from Parts-Express. Hope I'm not missing anything. I plan to pickup the sonotube and mdf locally once these parts come in next week.

- Speakon terminal
- Speakon connectors (I have speaker wire already)
- Driver screws 1/4-20 with T-Nuts
- Jasper 200 Circle Jig
- Driver gasket tape
- XLR to RCA adaptor
- Digi-key fan to mod the helicopter rotor sounding fan on the EP2500

I am considering picking up a second SI HT18"DR now that they are on clearance but haven't quite decided yet if I want to bite off two builds for my first try.
 

·
Registered
Joined
·
76 Posts
If you are going sealed you want to make sure that the speakon connector on the sub is the sealed kind. They make a non-sealed also.

I think you will want to make sure you have the 4 post Speakon connector on the amp output if you go bridged. It was that way on the Inuke 3000. You may get away with a 2 post Speakon if you are not going bridged, but I don't know for sure.

Are you going to use some kind of "feet" for your box? My local hardware stores did not carry as nice of feet as Parts Express.

How are you going to attach the sub to the box? You can use wood screws. I used hurricane nuts and metric allen head bolts. I think they look better than wood screws. Though I can't really see them on the black speaker on black box.

Looking forward to watching this come together.

Have you decided on your build yet?
 
1 - 20 of 34 Posts
Top