Patman's Sunosub Construction Resource Page

The Sunosub I Construction page.

Sunosub I Sunosub II Sunosub III

I hope to give you some insight in the overall construction process of my Sunosub that I built all by myself over the course of a couple of weeks from June 25, 2000 to July 7, 2000.

Design

I have decided to go with a dual 12" Shiva water heater sonosub 24" wide, 8" port - tuned to 19-20Hz, with 12 ft^3 of internal volume, one driver on top, one on the bottom. Sonotube is just one brand of cylinders made up of fiberboard for pouring concrete for the formation of round concrete poles and structures. It's very strong stuff. Here's a link for the Sonotube FAQ if you want to know why to use sonotube over conventional wood-making.

Tools

Since I don't have any decent power tools at my disposal, and after a dose of Home Improvement's Tool Time, I went to Home Depot and came home with a Skil Plunge Router (Model 1823), Ryobi 5" orbital power sander, Black-n-Decker Power Drill (4.5A, corded - didn't want to run out of power, ya know), and Black-n-Decker Jigsaw (with easy blade attachment contraption). That was about $175 of tools, but it'll be worth it since it'll also allow me to build some flexy racks down the road too, and maybe full-range speakers again.

Materials

I need large enough 3/4" MDF (Medium Density Fiberboard) material, 2 subwoofer drivers, the sonotube (24" diameter), some 8" diameter pipe, a dual speaker binding post plate, and some misc. bits and pieces, different types of coarseness for the sand paper, some glue, liquid nails. Then the fun begins!

June 25, 2000

Last night, after checking out one Home Depot and finding no 3/4" MDF at all, I went to another one 5 miles away. I lucked up and was able to I picked up 2 sheets of 3/4" MDF (24"x49") for the endcaps, the bonus being they were pre-cut and fit in my lil' Honda Civic with the rear seatback folded down. I also picked up 2 sheets of 1/4" plywood (24"x24") to be used so that the t-nuts have something to hold on to for the inner endcap.

I also bought 48" of Quikrete tube (it's like sonotube but a lil' thinner). I will cut it down to around 24" for use in the sonosub. I found one which had the closest inner diameter of 8" that I was looking for to use as the port. The 24" length comes from modelling for the port length by using a handy little program called WinISD (ISD = Interactive Speaker Design). You can download the program at Linear Team.

Just a reminder for those planning on using 2 drivers in their sonosubs, remember to double the Vas parameter (for example, the Shiva's Vas is 144, so with 2 of them, you'd set up the driver parameters in WinISD so that you put in 288 for the Shiva's Vas parameter.

Lucky me, I now have an extra 24" piece of 8" diameter port for future use.

Hint: For faster navigation, when you click on your first picture link, don't close that 2nd window, but resize this window and position it so you can see both windows concurrently. I've designed it so that you can leave that 2nd (photo) window open, and you can click to your heart's content in this first window, and the images will only show up in that 2nd other window. This should also speed up your visit here. If you want separate windows, then right click of the photo links and select the "open in new window" option.

June 26/27, 2000


I round up lots of stuff, mostly at Home Depot. Here's a couple of raw material shots: As a bare minimum you'll need the following in raw materials:
As a bare minimum you'll need the following in hardware/tools:
As a bare minimum you'll need the following in personal protection - wear them while using power tools:

Like I said, I needed to start buying some power tools, so this is a good opportunity to "prove" them into my daily budget of life.

If I can borrow a truck tomorrow, I will bring home two 6 foot sections of 24" sonotube tomorrow morning. This is because most construction materials places will only sell you a 12-foot section of sonotube. That will be the final piece of the puzzle, all that's left is the elbow grease.

I will buy the cloth material covering up the sides of the sonosub later, but I'm thinking of doing it up in a lighter hunter green color.

Making the endcaps: I made my endcaps by cutting the 24"x49" MDF into 2 equal pieces (nearly 24"x24.5") and glueing them together as well as the 24"x24" piece of OSB/Plywood. Then clamp them together for at least an hour or two.

Check out these photos:

June 28, 2000


I got my buddy, Jim J., to bring home the two 6 foot long sonotubes for me in his truck. Yay!

Well, after some experimenting with the router, I figured out how to cut circles with the router guide. The main thing is to draw out the circles in pencil, and find the center of the circles, and drill a 1/8" hole all the way through the endcaps for the router guide to pivot around. Use the plunge router, make several circular cuts - starting with 1/2" depth, then 1" depth, and 1.5" depth. Then flip it around and put the router guide in place where the center hole was drilled through, and finish off the circle by routing to 1/2" depth, which should be enough to make the final cut through the endcap. Do the largest circle first, and start on the smaller circles inward on the endcap.

So today I finally got the endcaps done and the circular cutouts too:

July 3, 2000

Now 5 days later (after 4 days of Dragon Con attendance), I'm ready to start back on the sonosub.

I went out and bought two 2 square yards of this hunter green cloth with a wood grain pattern from Wal-Mart and some velcro strips, which I plan on using to attach the cloth to the sonosub's exterior.

Today I cut my sonotube to the final height (including the endcap depths). Cutting a cylindrical object with a 2 foot diameter very square/straight and perpendicular to inner axis isn't as easy as it looks. Based on an idea from ThomasW (when he and J6P [AKA Joey Millison] did a sonosub in a day), here's what I did:

If you use a jigsaw, you'll notice that there is a lot of ragged paperfiber edges on the cut. I used a pair of scissors to trim away the ragged edges. Later on, I'll use a sander to smooth out the edges so it'll be flush with the endcaps.

I have a 48 inch section of quikrete tube that I'm using for my port (8 inch diameter), and needed only 24 inches of the tube, so I used the same principles above and cut the port down to size:

Then I preceded to start painting the sonotube with black spray paint: Next I wanted to drill the holes for the screws for the Shiva driver. You need to prop up the endcap so that you can put in the driver and mark where the screw holes should be drilled through the endcap. Since I'm using 10-24 machine screws and t-nuts, I have to drill progressively larger holes until I get the right size so the screw fit into the hole nice and snug. This take longer than you think it would. But you persevere and you get them drilled.

Next, you have to make sure the t-nuts will fit when you hammer them into the insides of the endcap screw holes, so you have to drill a slightly larger hole on the inner side of the endcap. Be careful not to drill more than 0.5 to 1 inch in depth when making this slightly larger hole for the t-nuts.

At this point, the endcaps can be painted.

July 4, 2000

Here's what happened today:

Whew! That was quite a day, another 7-8 hours flew by.

I go back to work tomorrow, so I won't have as much time as I'd like to work on it.

July 5, 2000


You'll probably think I'm really really slow. I made progress, but I'm not quite finished. Here's what happened today: So that's it for tonight (I squeezed in mowing the grass too). I'm fairly confident I'll have the sub up and running by tomorrow night!

July 6, 2000


I now have a functional Sonosub! I finished up around 10 p.m. tonight. I'm so tired. But here I am to update the rest of the story:

I get home and notice some more bumps on the top endcap, so I sand them down, apply some more spray paint, and then a clear coat. Finally I ran out of spray paint, so it was a good time to stop with the top endcap finishing for now. Then I was ready to put in the bottom Shiva driver.

Well, there you have it, how to build a 2-driver sonosub in 107 photos. Take a bow if you been here with me the entire way! Thanks for words of wisdom and encouragement along the way from the following folks from both the Home Theater Forum and Home Theater Talk:

Since I finished it late this evening (had to edge/trim the yard while the paint/finish was drying), I haven't been able to crank it up, but what I've heard, I like it veddy, veddy much. :D

I can't wait to give it a workout tomorrow night! Stay tuned for the qualitative evaluation, and some SPL numbers if I get a chance soon.

July 9, 2000

You want numbers? Here's what I did for the measurements:

Note 1: I decided my present HK PA5800 5-channel amp wasn't beefy enough to provide the necessary current for good 4 ohm operation, so I have re-wired each driver to only one voice coil for 8 ohm operation for the time being (instead of 2 voice coiles in parallel. It's more stable this way given the amp I'm using now. Once I pay off the bills for the Sunosub, I'll be shopping for a more powerful amp.

Note 2: With the system volume calibrated for 75dB SPL for each speaker, at 0dB for the subwoofer preout level, I was getting 85dB SPL for the subwoofer, which I felt was too boomy, so I went to -5dB for the subwoofer preout level for a level of 80dB for the subwoofer, and it blends in better. But now I have plenty of headroom if I ever did want to raise the bass levels. So if I want to increase the bass, I can adjust the subwoofer output for a bit more boom if I want it.

For the 1m on-axis measurement, I ran up the master volume level to read 75dB and kept the volume setting there. Then I ran through my StrykeZone Bass CD for the following frequencies and recorded the SPL reading off a digital Radio Shack SPL meter. The meter requires some adjustments to the raw number reported, so there's a column for the adjusted SPL value. Here's the results:

1m from the bottom of the subwoofer with SPL meter on the floor:

Freq SPL SPL(adj)
15 76 85.5
17 74 82.5
20 80 87.5
22 77 83.5
25 76 81.5
28 78 82.5
32 80 83.5
36 81 83.5
40 84 86
45 86 87.75
50 86 87.5
56 90 91
63 90 90
71 89 89
80 82 82
89 88 88
100 77 77
112 86 86

As you can see I have a nasty room induced hump around 56-63Hz (which I've alway had, so I expected it). I also have a small hump at 20Hz (the sunosub is tuned to around 19-20Hz). There's a sliver of port noise, but nothing too annoying during normal playback of music and DVDs. One day I'll get the Behringer EQ device to get rid of most of that bump I get from 56-63Hz.

I'm roughly flat 85dB +/-3 dB from 20-80Hz with a bit of hump as mentioned above.

For the nearfield measurement, I kept the same master volume level, and placed the SPL meter real close to the cone of the bottom driver and recorded the SPLs for each frequency listed below:

Freq SPL SPL(adj)
15 89 98.5
17 93 101.5
20 96 103.5
22 97 103.5
25 99 104.5
28 101 105.5
32 104 107.5
36 106 108.5
40 106 108
45 106 107.75
50 105 106.5
56 106 107
63 104 104
71 102 102
80 102 102
89 101 101
100 99 99
112 101 101

From 20-80Hz, I'm pretty flat at 105db +/- 3dB for the near field response.

It's too late for another go at a reference level SPL readings.

Anyhow, I was pleased with the low end performance, it does go low, and I do fear for structural damage to my house at some point in time if I play it loudly.

July 10, 2000

I tested for my tuned frequency for the sub, and it's right around 18-19Hz, so I didn't do too badly with the port length at all. I had tuned it for around 19-20Hz. And I also tested both drivers with the same results. If I had a CD with frequencies in 1Hz increments, I could nail down the tuned frequency (I had to guess between 17.5Hz and 20Hz from my BassZone CD).

I did a lot of listening to demo quality scenes tonight. I took a listen to Air Force One, Dances With Wolves, Fight Club, The Phantom Menace LD, The Matrix, and both dts Demo DVDs #3 and #4. My volume level was set to about 3.25 on my Sony DB930 (only a Sony owner have an idea where that is on the volume scale), and then I took out my Radio Shack digital SPL meter, and for the peak LFE scenes, I was getting 100-105dB and all I was feeling was the bass. Believe me, it's plenty loud enough at that level.

Both the Relic and The Haunting clips had incredibly active bass, and the Sunosub was getting broken in quite nicely. The jet fighters and the explosion of the refueling tankers and the dogfights in Air Force One made the sub come alive. The rumbling in the Buffalo Hunt scene from Dances With Wolves places you right in the middle of the action. When Neo gets "awakened" from his pod in The Matrix, the bass in that scenes is heavy and intense (as well as the helicoptor scene near the end of the movie. Saving Private Ryan also was amazing in that you really feel like you're on the battlefield with the soldiers, ducking from all the artillery fire and the bombs while being pushed back by all the tanks marching on. It's bass like this that makes the entire sub building exercise worth every second and every penny you spent on the sub.

Here's gag photo #1: a shot of a gag cover for this SUNoSub:

July 31, 2000

I finally decided to finish the outer covering for the Sunosub. I needed two 6 feet pieces of cloth (roughly 44" wide, 60" long) to cover the beast because the pattern was running length-wise, and I needed about 76" of circumference to cover the Sunosub. So I had to put two pieces of cloth together. Here's the photos:

Then I needed to use something to attach the cloth to the Sunosub, I decided to use velcro with a sticky backing to attach to the cloth and the outer cover of the Sunosub:

I put four 3" sections equally spaced on both the top and bottom of the sub (8 pieces). I also put one half-way down the side of the initial starting point of the cloth wrap for added adhesive power.

I put all the velcro cloth sides on the inside of cloth pieces and carefully attach the cloth to the Sunosub's velcro hooks. At the outer flap of cloth where the cover ends, I used the velcro hooks/cloth at the junction. This allowed me to secure the cloth onto the sub in a tight form-fitting fashion. I wrapped the cloth in such a manner that the flap is facing the back wall.

So how did it turn out? You can be the judge:

And just one more look including the top side driver:

But here's a couple of final looks of the SunoSub:

  • Photo 119: A close-up of the Sunosub in the home theater setup.

    And how it looks integrated in the overall home theater:

    I hope you've enjoyed looking at how I created my first SUNoSub! It was a time-consuming process since I was playing it by ear as I was going along, but I did make mental notes on how I'd do something different on the next time I did one of these subwoofer in the future.

    Update: 9-15-00: New roller casters on the legs!

    Based on the favorable feedback on roller casters on sonosubs, I decided to put them on my present Sunosub I.

    I like having these roller casters on my Sunosub I, it really makes moving it around a lot easier without worrying about breaking off one of the legs if I'm not careful moving it. I will be doing the same for my other 2 Sunosubs. It's a little work, but worth it.

    I got the beefy legs ($1.61 each) and the roller casters ($2.97 each) at Home Depot.

    9-20-00: Last update

    I finally got around to picking up some hunter green glossy spray paint and painted my new legs with the roller casters.

    That's it, I'm finished with Sunosub I.

    So how many have visited this subsonic webpage since 7-9-2000?

    Back to the Patcave

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