This is a DIY (Do-It-Yourself) project. I hope to give you insight in the overall construction process of the SunoSub III that I built all by myself over the course of a few months from September 13, 2000 to December 1, 2000. The reason for the length of time was just waiting for the brand new 15" Tempest driver. Actual construction time shouldn't take over a couple of weeks if you know what you are doing. There are some places where I screwed up in doing this project, and it's all documented, but all I can ask from you is to learn from my mistakes!

After using up almost 9 feet of sonotube on Sunosub I and Sunosub II, all from a 12 foot section of sonotube, I still had a section that was 27" long left over, so what the heck, let's build one more sub!

This is a totally experimental subwoofer design with many trade-offs due to the volume constraint placed on using the leftover sonotube material on hand.

Design

• 1 Tempest 15" driver
• 1 4" ports 23" long (with a flared port kit) - tuned enclosure to about 16Hz
• 6 ft^3 of internal volume
• 24" wide sonotube roughly 25.25" tall before endcap thickness.
• 3/4" thickness of MDF endcap on the inside of the sonotube.
• 3/4" thickness of MDF endcap on the outside of the sonotube
• 1/4" of plywood laminated to the inside bottom endcap for the t-nuts.
• Stuffed with polyfill material to increase the "perceived" volume by the subwoofer driver - I gain 10-20% more internal volume this way.

Tools

• Power drill - Black-n-Decker 4.5A corded model ($35)
• Power sander with sanding plates/attachments - Ryobi 5" Orbital model ($35)
• Plunge router - Skil Plunge Router ($65)
• Router bit ($21) - 1/4" upcut spiral twist is what I used upon recommendation from many members of the DIY HT community.
• Router guide/circle jig (for cutting in circles) ($20) - I had to go to Sears to find this part.
• Screw drivers (slotted and/or philips head)
• Drill bits ($13) - assorted sizes to make pilot holes and final width holes.
• Clamps ($4/each) - 4 of them as a minimum, but 8 of them as a maximum for clamping down the glued endcaps
• Saw horses or work tables ($13/each)
• Scissors
• Terminator crimper tool ($12)

Materials

• 1 sheet of 49"x97" 3/4" thick MDF (Medium Density Fiberboard) from Home Depot for the endcaps ($20/sheet)
• OSB or plywood 1/4" to 3/8" thick ($2.5) as the inside of the bottom endcap (so the T-nuts have something to sink their teeth into)
• 1 Tempest driver from Adire Audio ($140/driver)
• Sonotube (24" diameter) 27" tall ($50/6 feet)
• 1 Precision Port 4" diameter pipe with flared openings, also courtesy of Adire Audio (Roughly $30)
• Terminal cup ($5) for the speaker connection from the amp, I recommend getting the dual terminal cup.
• Plenty of sand paper (80, 120, 220 grit) ($6-$10)
• Plenty of wet sandpaper (400, 600, 1500 grit) ($6-$10)
• Speaker wire preferably 12-14 gauge ($0.30/foot), and spade connectors ($1.5/6 connectors).
• Wood glue ($3)/Siliconized Acrylic caulk ($4)
• Machine screws (10-24, 2" $0.78/4 screws) and the appropriate T-nuts 10-24 5/16" depth ($0.78/4)for mounting the driver(s), at least 8 per driver.
• Machine screws (10-24, 2.5" 0.78/3 screws) for table leg mounts, flared port and terminal cup.
• Thin tacking nails ($1.5/box) one inch long.
• Some form of legs ($2/leg) for the sonosub, at least 3 legs. I bought some 6" legs from Home Depot with table leg attachment plates ($.80 each) that I bolted with the 10-24 2.5" machine screws (12 screws) with nuts.
• Weatherstripping foam tape ($3) - I used 3/8" wide tape.
• Bags of polyfill ($2.50/24 ounce bag) - I got these bags at Wal-Mart.
• Black lacquer spray paint ($4/can) - around 6 cans (if done right)
• Clear lacquer spraycoat ($4/can) - around 3 cans (if done right)
• Primer spray paint ($2/can) - around 2 cans (if done right)

Personal Protection

• Safety glasses ($6)
• Ear plugs ($2)
• Mask to cover nose and mouth ($3 - cutting MDF results in lots of sawdust)

Day 1: September 13, 2000

I took a leisurely pace on this project. Again, it'll feature some different construction challenges from the previous 2 Sunosubs. I think I'll go with a piano black table top cover, and perhaps use a black ribbon sock to cover the sonotube. The top cover will overhang the sonotube by 1"-1.5" all around.

I go shopping and come home with most of the raw materials from Home Depot:

• Photo 1 : Here are the cut pieces of MDF. I went to Home Depot, and bought a 49'x97' section of MDF and had Home Depot cut it into 2 pieces of 28"x28" (I plan on having a 27" wide table top on the sub, and a 24.5" width for the bottom endcap), and 2 pieces of 25"x24" for the internal endcap on both ends. I wound up with some excess MDF as you can see.
• Photo 2 : Here's a close-up of the 2 pieces of 28"x28" MDF, 2 pieces of 25"x24.5" MDF, and 1 piece of 24"x24" of plywood (for screwing/glueing in the T-nuts for the driver holes).
• Photo 3 : Since I have stuff left over from the previous Sunosub efforts, here's what I picked up - Wood glue, Silicone caulk, beefy 6" table legs, leg mounts, enough 2" 10-24 machine screws (for leg mounts, driver screws) and 8 10-24 T-nuts, enough 2.5" 10-24 machine screws (for the terminal cup).
• Photo 4 : Here's a look at the sonotube-like material that was left over from the last two Sunosub projects: 27" of sonotube.

The tune might be asking a little too much for a 6 ft^3 enclosure for the 15" Tempest driver, and I might pick up more port noise than optimal, but I'll get to see how adversely port noise will affect the overall sound quality of this subwoofer in normal operating conditions. The reason I choose 16Hz as the tuning frequency is to provide as much driver protection with such a low tune. This is because the driver is "unprotected" at frequencies underneath the tuned frequency of the box/enclosure, so by going with 16Hz, it's protected for most low end frequencies while sacrificing a bit of output near the 20-25Hz range. But for a subwoofer this small, I can live with a few less dBs of SPL (Sound Pressure Level) down in that low end region.

Day 2: September 16, 2000

Since this design is a little different from the previous designs, I will only have a 3/4" layer of MDF on the inside of the top and and a 1" (3/4" MDF plus 1/4" plywood) bottom endcaps because I'm trying to conserve as much internal volume as I can.

This means I'll be cutting each layer's endcap individually because they will have different widths to them. The outer top endcap will be around 27" wide, the outer bottom endcap will be 24.5" wide (just flush enough to provide a ledge for the sonotube material) and both inner endcap will be roughly 23.75" wide.

Well, after some experimenting with the router on my previous Sunosubs, 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, and then 1" depth since we are just cutting through 3/4" of MDF thickness. Do the largest circle first, and start on the smaller circles inward on the endcap. Make sure you route in the recommended direction for your router. I have to go in a counter-clockwise direction for my particular router, otherwise, you'll risk injury and bad router cuts.

• Photo 5 : The Power Tools - Skil Router 1823, Black & Decker Power Drill, B&D Jigsaw, Ryobi Orbital Sander - all bought on previous Sunosub I construction in July.
• Photo 6 : I start on the inner top endcap (with the help of The Hollow Man again) and find the center of the MDF board and mark off the radius for use with the plunge router.
• Photo 7 : I do the same for the inner bottom endcap (denoted by its plywood layer on the inside).
• Photo 8 : The routing for the inner bottom endcap begins.
• Photo 9 : Once I finish the inner bottom endcap, I test for fit by using a 4" piece of sonotube from my previous Sunosub construction. I find that I'm off by about 1/4" in width, but have no fear, I'll fix that later with wood filler.
• Photo 10 : Now I start on the inner top endcap.
• Photo 11 : Once I finish the inner top endcap, I test it for fit, and it fits better than the inner bottom endcap, so no wood filling will be required.
• Photo 12 : I start on the outer bottom endcap. Instead of doing more measuring to find the center of the board, I simply drill the pivot hole from the other endcap (with the test piece of sonotube since that give me the width of the MDF and sonotube) all the way through. Then it's a simple matter to make a mark for the radius to set up the circle jig for routing an endcap that's about 1/4" wider than the sonotube/MDF which will provide a slight ledge for the bottom side.
• Photo 13 : As with my last project, I used a paint stirring stick to make a circle jig extender to make endcap over 24" in width (this endcap will wind up 24.5" in width). This is a close up of how I did the extension. I had to drill 2 small holes through the steel piece of the circle jig pivot arm to hold 2 small nails (this keeps the paint stirring stick aligned with the rest of the jig. Then I drill a 1/8" hole for a larger nail to be used as the pivot, and insert a 1/8" thick nail as the pivot. I also had to drill a hole in the paint stirring stick for the circle jig original pivot piece.
• Photo 14 : This gives you an idea of how the circle jig extender looks in operation (I was able to flatten out the angle a little more when I'm routing so the sides are cut pretty straight and not at an angle).
• Photo 15 : I used 2 passes to route through the MDF boards, and this shows me starting through the 2nd routing pass, as I get done with the outer bottom endcap.
• Photo 16 : Using the same technique for finding the center hole for the outer top endcap as described above, I place the endcap/sonotube test piece, and then I align it so I have enough material to make a 1.5" overhang for the outer top endcap (you can see the marks I made for my router radius reference length).
• Photo 17 : I start routing the outer top endcap, employing the 2-pass routing method (makes for less stress on the router/bit).
• Photo 18 : The outer top endcap is finally routed completely.
• Photo 19 : Yes, another shot of me in my sawdust gear, always remember to wear safety glasses, ear plugs, and a nose/mouth mask because breathing MDF sawdust is no fun.
• Photo 20 : Using my bottom piece from Sunosub II, here is a quasi-isometric view of what Sunosub III will look like when it's finished (pre-paint/fabric covering).
• Photo 21 : This is a side view of what Sunosub III will look like.
• Photo 22 : Here's a shot of all 4 endcaps, stacked in a way to show the differences in width.
• Photo 23 : And another shot of all 4 endcaps side by side one another.

• Photo 24 : Again, using the same idea to find the center for holes/endcaps, I work on the driver hole once I measure out a 14" wide hole. I drill all the way through both endcaps.
• Photo 25 : I route the driver hole on the inner bottom endcap first, and I'm using some excess MDF board underneath to keep the hole from just dropping out, along with the router itself (I only route about 1/2" deep on the first pass, and then flip it over and route the final pass).
• Photo 26 : As you can see, I flip the inner bottom endcap over and successfully routed out the hole for the driver.
• Photo 27 : Next, I keep the same circle jig radius and start cutting out the driver hole on the outer bottom endcap.
• Photo 28 : I flip the endcap over and complete the routing of the driver hole on the outer bottom endcap.
• Photo 29 : Ta-da! Another driver hole is born!
• Photo 30 : I make sure the 2 bottom endcaps align themselves with the new driver hole. I try and make sure the ledge is consistent all around the perimeter for the outer bottom endcap.
• Photo 31 : Just to see how all the bottom endcap accessories will fit, I lay out the terminal cup, the leg mounts, and a 4" port as a place holder for the flared port (just to make sure I have enough real estate on the endcap in the layout).
• Photo 32 : The terminal cup's depth is exactly 3/4" (not including the actual terminal spade connectors) so I all I need to route is the outer bottom endcap, so I sketch in the hole that needs to be routed.
• Photo 33 : I start routing in the terminal cup hole. I set the plunge depth to 3/4" so I don't cut too much of the MDF board underneath, which is used for support, and I clamp down both pieces so the board don't move around.
• Photo 34 : I finish routing a rectangular hole for the terminal cup hole.
• Photo 35 : Here's the piece that I routed out, but I had to do some hole expansion to get the terminal cup to fit snugly, so I did some touch-up routing too.
• Photo 36 : On the inner bottom endcap, I needed to cut in the holes for the terminal spade connectors, so I draw the 2 sets of holes that need to be cut through.
• Photo 37 : I finish cutting in both holes for the 2 sets of terminal connector holes. I do this to maximize the bottom endcap material and reduce air leak possibilities.
• Photo 38 : Here's both pieces of bottom endcaps after the holes for the driver and terminal cup has been cut into them.
• Photo 39 : I laid the bottom endcaps together to see how they fit, and I make lines inside the driver hole so I can line it up consistently later on when I'm glueing the pieces together.
• Photo 40 : Believe it or not, but this is all the sawdust I managed to sweep up afterwards. Whew!

Day 3: September 24, 2000

• Photo 41 : Using some primer, I start on painting the legs.
• Photo 42 : Since this will be a black sub, the legs are painted black. A clear coat will be applied tomorrow if I have time.

• Photo 43 : It's now time to start on the top endcap cover. Here's a shot of the straight edges that will be smoothed off.
• Photo 44 : Here's a shot of the rounded edge on one side.
• Photo 45 : Here's a shot of both edges rounded over.
• Photo 46 : Now I start to apply a coat of primer.
• Photo 47 : I completely primer the outer cover, plus I also prime the undersides (where it was needed - mainly 2" of the outer circumference) and edges.

• Photo 48 : Now I start on the sonotube preparations by sanding off the little bits of black paint with 80 grit sandpaper.
• Photo 49 : I check for rough edges on the top portion of the sonotube and smooth out what I can.
• Photo 50 : Glue is applied where the endcap edge meets the sonotube sides.
• Photo 51 : I smear the glue on the top 3/4" of the sonotube.
• Photo 52 : I apply glue on the edges of the endcap too.
• Photo 53 : The endcap is put in place (I do the best I can to get it level with no leveller).
• Photo 54 : I start tacking in small nails, and I do this every 2"-3" around the sonotube. This will also keep the endcap in place.
• Photo 55 : This shows all the nails tacked in, and I had to nail them within 0.5" of the end of the sonotube.
• Photo 56 : Next up is the caulking of the inside using silicone caulk that doesn't require a caulk gun (costs more, but worth it to me).
• Photo 57 : I've finished caulking and smearing the caulk into the edge gaps. I also caulk up the pivot hole in the center from the circle jig.
• Photo 58 : Now I will be using wood filler on the internal endcap to fill in the gaps between the edges of the endcap and sonotube.
• Photo 59 : Here I start to sand away the wood filler and the excess sonotube edges.
• Photo 60 : I noticed that I have some slight unevenness to the top internal endcap, so I apply a little more wood filler.
• Photo 61 : And finally, I sand it down to its final flatness/smoothness. This part is now done.

Day 4-6: November 1, 2000

Well, it's finally November, and I'm still waiting for the Tempest drivers. But I hear that they are finally being shipped out from Adire, so I'm keeping my fingers crossed that I'll be able to work on the sub this weekend or next weekend.

Here's some photos of the final sanding for the bottom endcap from September 25, 2000:

• Photo 62 : Here's a shot of the bottom endcap's surface and edges being sanded smooth.
• Photo 63 : This is a close-up shot of sanding down the edges of the endcap.

Don't do what I show in the next section of photos. My fundamental mistake was using normal ENAMEL spray paint underneath LACQUER paint. You'll see what happens and what I tried to do to fix it...

• Photo 64 : I spray primer on the underside of the endcap.
• Photo 65 : I then spray on the black ENAMEL paint (don't do this!)
• Photo 66 : After I primed the top side, I painted it with black ENAMEL spray paint. Here's the wetsandpaper I used (both 400 and 600 grit) and a cup of water - I use a big bucket of water later on).
• Photo 67 : I start to wetsand the surface with the wetsandpaper.
• Photo 68 : More wetsanding of the top surface.
• Photo 69 : This is what happened when I applied a coat of clear LACQUER! Yuck! It's downhill from now on...
• Photo 70 : I sand my butt off and then fill in the gaps with wood filler. It's just plain sad.
• Photo 71 : Well, I painted it with black LACQUER paint, so it look okay...but...
• Photo 72 : Here's a photo of the clear and black LACQUER spray paint that I start to use from now on (I bought lots of cans at $4/can at Home Depot).
• Photo 73 : The surface was still pretty yucky, so another round of surface repair attempt with more sanding and wood filling.
• Photo 74 : I re-paint the top and then wetsand it yet again. I still have lots of problems with the surface. It's becoming futile...
• Photo 75 : At this point, I see that it's just not going to work...

• Photo 76 : I prime the other side in an effort to start anew.

Day 6-8: November 11-21, 2000

I applied about 6 coats of alternating clear LACQUER, wetsand with 400 grit and then 600 grit, black LACQUER, wetsand with 400 grit and 600 grit. Then I decided to try something that another HTFer, Julian Data, did to get a really nice finish. I renewed my efforts on the table top.

• Photo 77 : Here are the new ingredients: 1500 grit wetsandpaper, Meguire's Show Car Glaze, Rubbing Compound, and tack cloth.
• Photo 78 : I use the 1500 grit wetsandpaper to try to flatten the surface as much as possible.
• Photo 79 : I then load up some rubbing compound on some wet down cloth.
• Photo 80 : I apply the rubbing compound. I wasn't able to truly buff the rubbing compound as well as I should, so I found myself with lots of scratchy streaks. This part was a failing on my part, if I could have truly power buffed out the rubbing compound, I'm sure I would have gotten good results.
• Photo 81 : I press on and apply some of the Meguire's Show Car Glaze on a cloth.
• Photo 82 : I apply the glaze on the table top. but once I was done, I saw a nice shiny finish, but underneath there are still the scratchy streaks.

• Photo 83 : No camera flash, here is the reflection of my garage door opener on the ceiling.
• Photo 84 : No camera flash, here is the reflection of a table lamp I was using while working at night.

So here's what I learned: Never, ever, use ENAMEL paint underneath any LACQUER paint. It's a road paved with bad intentions. You must absolutely have good air flow when you spray LACQUER paint, that stuff will give you a headache if you inhale too much of it. Also, I'll be letting the table top's painted surface "harden" for 3 months before I wax it to get the final shine of the surface.

Also, I must confess: I've played the game of golf, but I've never cussed as much as I did when I saw what ENAMEL paint does when it interacts with LACQUER paint. I was cussing under my breath for quite a few days as I work to try and salvage the top. But I felt better once I moved to use the other side. It did go better once I figured out what I was doing.

Hopefully my Tempest drivers will show up soon so I can finish my Sunosubs!

Day 9: November 26, 2000

These are miscellaneous bits and pieces that needed to be done.

• Photo 85 : I drill the hole for the roller caster for the each of the 3 legs.
• Photo 86 : Here's all 3 legs with their roller caster inserted in the newly drilled hole.
• Photo 87 : I spray paint the leg mounts in black to keep the whole bottom endcap the same color.
• Photo 88 : I received a flared port kit from Adire Audio, but it's too long with the added section, totalling 30" of length.
• Photo 89 : To get 24" of port length (23" of true port length), I needed to cut off 6" off one of the sections. I measure off the length and wrapped a piece of paper as a guide for me to cut the tube.
• Photo 90 : Here's the sawed off section.
• Photo 91 : Here's what it'll look like inside the sonotube later on.

• Photo 92 : On the inner bottom endcap, I make some circles in the best spot for the port to give me an idea where everything is laid out.
• Photo 93 : On the outer bottom endcap, I put the outer flared port in position and use that to find the center that I'll need for route out the port hole.
• Photo 94 : I carefully line up both layers and drill the pilot hole all the way through so I have the center hole for the inner endcap too.
• Photo 95 : Here's the port hole for the outer endcap layer, I made it around 5" wide and will be sanding out some flare in the MDF for the port to fit in the hole snugly.
• Photo 96 : Here's the port hole for the inner endcap layer, I made it just over 4" wide so the port will fit snugly and preserve MDF surface area.
• Photo 97 : After some sanding and elbow grease, I flare out the outer layer's port hole.
• Photo 98 : Testing for fit of the flared port kit opening.
• Photo 99 : I placed the leg mounts in position, and marked where the screws needed to be, and then I drilled holes for all the leg mounts as a marker for the holes later on.
• Photo 100 : Using the flare to make the holes for it.
• Photo 101 : Finish with drilling holes for the flare.
• Photo 102 : Now it's time to glue the layers together.
• Photo 103 : Now both layers are one.
• Photo 104 : I make sure the layers are glued tightly by placing lots of weight on the bottom endcap.
• Photo 105 : It's time to paint. Here's the start of the priming the inner side of the endcap.
• Photo 106 : I prime the outer side of the endcap.
• Photo 107 : I start painting the inner side with black lacquer spray paint. I apply 2 coats with drying time between coats.
• Photo 108 : I then flip the endcap over and paint the outer side with the same black lacquer spray paint. This is the first of many layers.
• Photo 109 : I wetsand with 400 and 600 grit for the first 2 layers of paint, and then I used 1500 grit for the next couple of layers of paint.
• Photo 110 : I then apply a coat of clear lacquer (shown), and then wetsand with 1500 grit again, and finally just lathered on 2 thick coats of black lacquer paint for the final coat.
• Photo 111 : No camera flash, here's a shot of the shine. Not awesome, but for the bottom endcap that will rarely be seen, it's good enough.
• Photo 112 : With camera flash, here's another shot of the paint job.
• Photo 113 : No camera flash, one last parting shot of the paint, not great, not terrible.

Day 10: November 30, 2000

• Photo 114 : Here's a shot of the Tempest, with my cat Fred used as point of reference (he weighs around 14 pounds).
• Photo 115 : A side shot of the Tempest. I'm guessing it weighs about 15 pounds or more.
• Photo 116 : Time to get back to work - On the bottom endcap, I start drilling in the driver mounting holes. Just a word of caution, I would route out a 13.75" wide hole for the driver, not 14" wide, if I were to do this again.
• Photo 117 : I drill out holes for the flared port.
• Photo 118 : I drill out holes for the terminal cup.
• Photo 119 : Here's a final look at all the holes that needed to be drilled for bottom endcap.
• Photo 120 : The legs are screwed into the leg mounts of the bottom endcap.
• Photo 121 : The t-nuts I'll be using require their holes to be slight larger for a depth not more than 1/2". That explains the masking tape on the drill bit.
• Photo 122 : Heres's a shot of t-nuts, and the application of glue around the holes to keep it snug and tight.
• Photo 123 : I then hammer in the t-nuts for all 8 holes.
• Photo 124 : Once all the t-nuts are hammered, I apply glue all around the edges fo the t-nuts and the wood to seal it in.

Day 11: December 1, 2000

• Photo 125 : I screw in the terminal cup.
• Photo 126 : To help seal the port, I put 3/8" wide compressible weather stripping on the port's underside.
• Photo 127 : The port is now screwed into the endcap.
• Photo 128 : The underside of the endcap shows all the screws and nuts for the terminal cup, port, and leg mounts.
• Photo 129 : I use some muscle to get the sonotube onto the bottom endcap, and notice I use a blanket to minimize scratches later on.
• Photo 130 : I bought some black ribbon material from Joann's Fabric Store, it was 61" in circumference, a little stretchy, and fit my 24" wide sonotube with ease.
• Photo 131 : To make sure the sonotube is mated to the endcap, I nail in lots and lots of nails around the perimeter, my guess about 50 nails.
• Photo 132 : Then it's time to caulk the inside edge. This is not fun at all. I call it "Blind Man Caulking" since I had to apply some caulk on my finger and stick my hand through the driver hole and feel my way around the edges to apply the caulk.
• Photo 133 : Here's a shot of my internal caulk work. Plenty messy, it is.
• Photo 134 : And one more fabulous shot of my caulking. Notice the port hasn't been assembled yet (it would have been near impossible if it were in place before I caulked).
• Photo 135 : Time to make the cables to connect the driver to the terminal cup. I need 2 sets of cables for each voice coil of the Tempest. I will be able to jumper them externally from the dual-input terminal cup.
• Photo 136 : I use a terminal crimper, and I crimp a notch on the top side of the terminal connector after threading 3/8" of bare wire into the connector. I also use black electrical tape to denote one wire being the negative wire. I am using 12 gauge wire, and got the 12 guage terminal connectors from Home Depot (they come 6 in a package).
• Photo 137 : Here are both sets of cables all terminated and labelled.
• Photo 138 : This is a close-up of the terminated cables. Notice the notch in the yellow connector is on the top side. This will provide a snug and tight connection.
• Photo 139 : Here's a shot of the cable connected to the underside of the terminal cup.
• Photo 140 : Now it's time to put the flared port together. I use epoxy to glue the ports and the rings together.
• Photo 141 : Epoxy is a bit yucky to mess with, but here's the result, one flared port sectioned together. If you look closely, the last section is taped together with black electrical tape in case I want to be able to take apart the port and cut it down in length.
• Photo 142 : I put the port inside the enclosure, and I do epoxy the section near the flare outer port opening to the rest of the port. I don't have much clearance at the top, but the flare helps. My vent mach will probably be off the charts, but if I need to, I can cut down the port.
• Photo 143 : Here are all the bags of polyfill I got from Wal-Mart. I wind up using only 3 of the 4 bgs for 72 ounces of polyfill inside the enclosure.
• Photo 144 : This is how I felt after Thanksgiving meals. I was able to use 3 of the bags.
• Photo 145 : I then line the driver hole with 3/8" compressible weather stripping. This is to minimize air leaks.
• Photo 146 : Now it's time to screw in the driver to the bottom endcap. To make it easier, I move the enclosure and the driver separately into my living room (I had been working in my garage up until this point). I do this due to weight considerations.
• Photo 147 : Ta-Da! The driver has now been screwed into each of the t-nuts. That's Pooh, my kitty in the background sniffing the weather stripping backing.
• Photo 148 : After adding the wheels for each leg, I turn the sub right side up and position it in my usual sub space. It stands 36" tall without the table top.
• Photo 149 : I fold in the ribbon material at the bottom edge to get a cleaner edge. I haven't decided how to permanently attach the ribbon material to the outside of the sonotube. The table top has been place on the top, but it isn't fastened to the top yet. I may just use velcro strips because using dowels would affect the top endcap's integrity. Like the shine of that table top?
• Photo 150 : To get a shot of the shine, I didn't use the camera flash for this shot of the sub.
• Photo 151 : One shot showing the side view and the height of the sub.

Day 12-14: December 2-5, 2000

My reaction: Holy Smokes! I'm really amazed at what this little beast can do! On my Sunosub I (2 Shiva's, tuned to 19Hz with 24" long 8" wide port, 12 ft^3 of internal volume), I would get some minor pops when I played the DVDs/LDs with really strong low frequency content, like TPM AC-3 LD, and dts Haunting DVD. Basically this means some form of bottoming out by the Shiva driver. It only happens on really stressfull LFE (Low Frequency Effects), so for most applications, my Sunosub I is still a nice sounding subwoofer.

I tested The Phantom Menace (TPM), and everywhere that I got pops/bottoming out (the Jedi ship getting blasted, Pod Race toward the end of the race, and some other spots) with Sunosub I, I got no such pops or bottoming out with Sunosub III with the single Tempest driver. That made me very happy.

I couldn't totally crank it up since it was around midnight when I was listening to stuff, but I will do so the next day just to see how hard I can push it. But at relatively low (normal DVD/LD listening levels) I was getting up to 106dB during the Pod race at my normal seating area about 11 feet from the speaker/sub. My dual Shiva would pop at this volume level in the past.

The next day, I tested the space dogfight fight at the beginning of the Lost In Space DVD, and it played through it without a hiccup.

It also survived the dts version of The Haunting DVD (for my purposes) with peaks hitting 109dB from my seating position (and even then I needed to be listening at insane volumes, probably measuring a reference level of 80dB at the same position) from 10-11 feet away, I normally wouldn't even listen to DVDs at this level, but I was curious to push the sub a little harder than normal.

Here's a graph I made from some measurements today of Sunosub III:

Click here.

The nearfield measurement shows a F3 around 22-23Hz (using 103-104dB as the average SPL level), you can see where the Fb (tuned enclosure frequency) of 16Hz show up in the dip near 17.5Hz on the 1m measurements. Remember, this particular enclosure isn't optimal, so I expected the low end F3 not to reach 20Hz, and I was right. If I tuned higher, I might have gotten it, but I would sacrifice driver protection, and I just would rather have driver protection (from bottoming out the driver) over a few dB's down really low.

I made the near field measurement by playing a 22Hz tone, placing the SPL meter right near the dustcap of the driver, and turning up the volume until it was near 93dB (totally arbitrary dB number, you can use any useful SPL, like 75dB if you wanted to, but I wanted some separation between the near field and the 1m measurement for the graph.

I got the 1m measurement by playing some pink noise and raising the volume to get 75dB on my SPL meter, and then left the volume setting alone, proceeded to play bass tones from my BassZone CD and recorded the values with the SPL meter 1 meter away from the sub.

My room absolutely pumps up the high end bass in the 56-89Hz range (hopefully a Behringer Feedback Destroyer will show up soon so I can do some peak taming).

As I stated at the beginning of this webpage, this design is a compromise brought upon by its limitation of enclosure space. I had this last piece of sonotube lying around, and I knew using the Tempest with this piece of sonotube would be a compromise. I would say that it would make a welcome addition for a HT setup but I wouldn't use it for a serious music setup (the rhythmic thumping might call attention to port noise and chuffing much sooner than any DVD would over the long haul). I have listened to music at loud volumes with this sub, and it actually surprises me as to the tight thumping bass it can put out. I didn't find much to complain about regarding the port noise (if any) because I didn't hear much of it.

Things I may change/add: I may add some bracing inside the enclosure, perhaps two 2"x2' poles glued snugly between the top and bottom internal endcap because I did feel some vibrations coming through the top endcap while it was being worked very hard by my tests.

Hope this helps people get off their duffs and build their own sonosub, with the right tools, they are easy to make and you'll be surprised at the quality of bass you can get with a lot less money. Also, the pride of building stuff you use in your HT is another plus.

Well, there you have it, how to build a Tempest sonosub in 151 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 at: Home Theater Forum, Home Theater Talk, and Home Theater Guide:

• Dan Wiggins and Brian Bishop of Adire Audio
• Tom Vodhanel and Ron Stimpson of SVS Subwoofers
• ThomasW
• Mike Knapp
• Andrew Pratt
• TerryC
• Lex Mann
• Pat from Iowa
• Julian Data
• Brian Steeves
• and so many others whose names escape me at the moment!

I hope you've enjoyed looking at how I created my 3rd SunoSub! It was a time-consuming process, but I learn something from each one of these subs I build. And as always, I make mental notes on how I'd do something different/better the next time I do one of these subwoofer in the future.