15" Sonosub Build Pictorial

[bikedave]

Alright, well, I have finished my sub all except for the finish. So now I have time to post some pics and description. I would appreciate any feedback as I will no doubt get a case of what someone else has aptly called "upgraditis." I would like to thank ThomasW, ---k---, and Kevin Haskins for their tidbits of truth. I will be posting pictures and thoughts over the course of the next few days hopefully.

The first picture below is the tube all ready to go, if it looks like it has a seam its because it does. I had two 20" Diameter pieces roughly 40" long, but i needed one longer one to achieve the 300liter I wanted. So I cut one to length i needed to add on and stuck it on top. Then, as you can see in picture #2, I cut maybe an 8" long piece of tube, then cut out a section of it so I could squeeze it down inside the big tubes. I slid it into place at the seam, glued it and then drove a wedge in the gap which I had sawn in order to get it in. Then I screwed it from the outside, so it is secure.
Then, in picture #3, you can see my sophisticated circle jig. I wanted to keep cost down obviously so I just took my time taking measurements and cut really carefully with my jigsaw.

[bikedave]

Next

Ok, in the first picture you can see my tube, one of the layers of MDF for the top plate and both bottom plate pieces cut and ready to assemble. I used two layers of 3/4" MDF for both the top and bottom plates. Took a while to make the cuts but I was meticulous and they are all good tight fits, even though i used a jig saw without a guide.

Next there is the bottom plates glued and screwed together. Then i had to devise feet for this thing which would be strong. I have seen pictures of others' feet which have broken off when moving because of the tremendous weight. I got the 4" legs at Lowes, they had a quarter inch mounting bolt pressed into them so I just found a long connecting nut, which you can see in picture is screwed tight down onto the leg. Then I got a short piece of quarter inch threaded rod and screwed it into the other end of the connecting nut. I then drilled a quarter inch hole at one third intervals around my bottom plates, and drilled counter sink holes to accomodate the larger connector nut on the bottom. Then all there was to do was press them into the holes while squishing in some silicone, put on a washer and locknut and tighten her down. Man is that sturdy! I feel quite comfortable with them.

[bikedave]

Continueing

Alright, here i've got the driver mounted in the baffle using t-nuts, man are those things a pain, I heard that they don't mount into OSB well so I pressed them into some thin strips of wood attached to the baffle, then I ran a pool of glue around the t-nut to give some additional holding power should i ever want to remove the driver and remount. I sure don't want to pop one of those loose. I used an auto/marine foam gasket from Lowes to seal the driver on the bottom side then tightened down the nuts. I wanted to cut a groove into the mounting ring area of the baffle so the driver would be recessed about a 1/4" but I didn't have the tools to accomplish that so I just surface mounted.

[bikedave]

Now on to the top plates, both 3/4" MDF as well. I got the holes cut and the plates glued and screwed together. Then I cut my port tube to size. I was originally going to go with a 6" thin wall PVC sewer pipe then use a heat gun and mold to form flares on both ends, but I was having trouble finding it locally so I was just wandering around Lowes looking for inspiration when I look into the quickcrete tubes. They have an 8" nominal tube which has a 7.5" ID which I figured would work so I got it then went home and reran my numbers in Unibox for that vent. It works out to 29.5" long, which tunes my tube to 18hz. Just before cutting the port I got paranoid and decided to recheck all my volumes and realized that I hadn't adjusted the volume of the enclosure in Unibox to reflect the size of the port. So, I put in the new numbers for an enclosure with an actual volume of 275 liters, which takes into account the driver volume and port volume.

Then i just glued the port tube into place, I really like using the cardboard port tube because it is lightweight, easy to attach, and I was even able to round over the opening with a router. (I also rounded over the revealed top and bottom plate)

And finally, the top plates, complete with port, pressed into tube. The picture makes it look a little skewed but I assure you its not!

[Hdale85]

Me like the 8" port. I have a TC3000 15" and been thinking about doing a sonosub with the 10" port.

[bikedave]

Me like the 8" port. I have a TC3000 15" and been thinking about doing a sonosub with the 10" port.

Ya, I used the Exodus XJ-15 in this one and am really happy with it so far and have heard no chuffing yet.

[Kevin Haskins]

Looking good.... I like the base.

A pair of 4" flared ports by Precision Sound can also do the trick. My general rule of thumb is that the flared ports (inside + outside flare) are equal to a port 1" larger in diameter in terms of compression/turbulence. Its just a rule of thumb but its a fairly good one and using them keeps your port lengths more manageable.

[bikedave]

More

Here we have the insulated tube and top cap. I used an acoustic polyfill in batt form which i cut to length, removed the backing and stapled into place. It filled the tube more than I thought, but sure sounded better! Then I secured the top plate into the tube and mounted the tube onto the bottom plate with screws and silicone. The last picture is one that I took by reaching into the port tube, it shows the wiring. I ended up just using bolts for binding posts because they are just stronger and easier to install and seal. The real reason I took the last picture though was because I forgot to label the polarity of the second set of binding posts! Oops, glad I used the 8" port! Thanks Kevin for the port tube rule of thumb that will be quite useful in the future. I wired the thing to my xover'd proamp and played some test tones and found the resonance of windows, doors, walls and the room it was in! So, so far I consider it a success! But I need to play some movies and see how it does. Does anyone have any movie recommendations? I know I've heard War of the Worlds, Serenity, and Master and Commander. Also, right now I've got a couple of 3-way mains with 12" woofers in them, any recommendations as to what to cross the sub at? I'll get some finished pictures up when I can.

[WillyD]

Also, right now I've got a couple of 3-way mains with 12" woofers in them, any recommendations as to what to cross the sub at?

I suppose its best for you to experiment with that, but I'd think 60Hz would be a good starting point.

[---k---]

I would shoot for 50-60hz. But, if your mains are in a spot that causes a null in 60-70hz, having a higher may work better.

[mikieson]

I have a question...As a few of you here know, I have been asking a few questions about sonotubes. I have decided to hold off untill the first of the year. But...This is something I have to know.

Manufactures and pro box builders have certain ways of designing boxes. They have rules they go by. They have cubic feet and ports figured down the exact size.

How in the heck can a person get as good of performance out of something they dont know anything about?

So you just go buy a tube, put a speaker in it, put some insulation, cap it off, buy an amp and POOF!...You have this perfectly tuned, perfectly measured TUBE that has had no serious thoughts into the size, or design???

I just dont understand how it works. Please fill me in on this as I think this is one thing that helped to sway my decision to wait..Thanks.

[---k---]

We do the same thing the manufactures do. We model the sub in a computer simulation program, like Unibox. If you read most of the threads here, you'll see the Unibox plots.

[mikieson]

We do the same thing the manufactures do. We model the sub in a computer simulation program, like Unibox. If you read most of the threads here, you'll see the Unibox plots.

But dont everything change from sub to sub? How do you know if this or that sub is gonna work with this size tube or that size box? Im just curious...Thanks

[Dennis H]

Good driver manufacturers provide complete specs (Thiel Small parameters) for the driver and you plug those into the simulation program. Of course that doesn't work if you're using some mystery driver you know nothing about.

http://www.soundsplinter.com/rlp15_subwoofer_information.html

Scroll down to tech specs.

[mikieson]

Good driver manufacturers provide complete specs (Thiel Small parameters) for the driver and you plug those into the simulation program. Of course that doesn't work if you're using some mystery driver you know nothing about.

http://www.soundsplinter.com/rlp15_subwoofer_information.html

Scroll down to tech specs.

So then when im ready,all I have to do is give you all the driver and you can help me with the tube size and port size right???....If so, that is cool. Thanks

[---k---]

No, when you're ready to build a sub, you need to download Unibox (its free) and put the parameters for your chosen driver in it. We'll be here to help you use Unibox and interpret your graphs, and any questions you might have about construction.

[mikieson]

No, when you're ready to build a sub, you need to download Unibox (its free) and put the parameters for your chosen driver in it. We'll be here to help you use Unibox and interpret your graphs, and any questions you might have about construction.

NO....You will give me the box size, and port size "uses Jedi mind trick" :rofl:

[1Michael]

Why not copy one of the designs here that have already been tried and tested?

[bikedave]

Mikieson,
Its really not that hard at all if you are willing to take some time and look at it. With the free software available its quite simple, does all the calculations for you. Like buggers said, there are designs for various size sonotubes on this site which explain the process in a very detailed manner. And like ---k--- said, find a driver with published t/s parameters and there are plenty of people who would be willing to give you advice. I don't know about the others on this thread, but personally, the design and building process is as much fun as actually getting to listen to the fruits of my labor.

[bikedave]

Thanks also to WillyD and ---k--- for your crossover recommendations. Man is this stuff addicting, i haven't fully finished my first project and I'm already researching more designs for some surrounds and mains. This could become obsessive!

[Gir]

Thanks also to WillyD and ---k--- for your crossover recommendations. Man is this stuff addicting, i haven't fully finished my first project and I'm already researching more designs for some surrounds and mains. This could become obsessive!

Tell us about it... 8O

[---k---]

No need to thank me. I'm just repeating what others have told me.

[bikedave]

Low output???????

Ok, having some issues here. First off I will describe my setup. Right now I am running a line from the headphone plug of my computer into a Samson S-xover 2-way crossover. From there I go into my 2-channel Carver pro amp which is rated at 450watts a channel at 4ohm or 900 bridged at 8ohm. I've got my voice coils wired in parallel to accept the 450watts. If I play a test tone only, say a 20-30hz sweep, I've got plenty of power and could easily over drive the sub if turned up. However, when I play any music my output drops to a whisper. Both of the above scenarios occur with the xover on not changing any settings. I could understand the output drop if it was a passive crossover but it is powered still dropped significantly. Any ideas? Also, does anyone know how to bridge the carver amp? It says on the back that you connect to both (+) terminals to be bridged but I can't tell any difference? Thanks guys.

[JoeyG]

For the amp, there is a recessed "bridge" button on the back, next to your posts. Use a pen to push the button in and it will light up red. The upper middle red posts are the posts used for bridging. You will see a + and - there for the bridge.

[JonP]

Ok, having some issues here. First off I will describe my setup. Right now I am running a line from the headphone plug of my computer into a Samson S-xover 2-way crossover. From there I go into my 2-channel Carver pro amp which is rated at 450watts a channel at 4ohm or 900 bridged at 8ohm. I've got my voice coils wired in parallel to accept the 450watts. If I play a test tone only, say a 20-30hz sweep, I've got plenty of power and could easily over drive the sub if turned up. However, when I play any music my output drops to a whisper.

Do you have the active crossover set too low? First thing that popped into my head, maybe it's crossing at 30-40Hz. So your lower sweep rocks the house, but most music doesn't have much below 40, and the sub isn't making much output. Check out and play with your lowpass setting.

I just looked at the spec sheet for the Samson. It will tune down to 35Hz, which is way too low... so move that to 60 or higher for starters. You might even try directly running to your Carver, to see the difference without it.

You also probably want that mono switch on, sounds like that would sum both channels, which you would want. Having only one channel driving the sub will give low output as well.

Hope that helps...