Patman's SBS Construction Resource Page
The SBS (Sun Box Subwoofer) Construction page.
This is a DIY (Do-It-Yourself) project. I hope to give you insight in the
overall construction process of the SBS (Sun Box Subwoofer) that I built all by myself
over the course of weeks from April 14, 2002 to April 28, 2002.
I'm using the original 12" driver from SVS
that was used in the PC and CS line of subwoofer. SVS offered a driver upgrade to their customers,
and many of the customers decided to sell off their old drivers for the credit price of $40 plus
shipping so they would save on the shipping cost if they were to send the drivers back to SVS.
The drivers aren't being supplied by SVS, so don't expect them to offer much in selling their old
drivers, but if you head over to the Hardware For Sale area at the
Home Theator Forum, you just may be
able to score one of these drivers, one of the better used bargains around nowadays.
Just to recap the design specs
for this effort:
- 1 Original SVS 12" driver
- 1 4" flared 19" long from end to end (18" usable) - tuned enclosure to about 18Hz
- 4.7 ft^3 of internal volume
- Plate amp (180W@8 ohms/250W@4 ohms)
- Outer box dimension of 18"x18"x40.5 (WxDxH)
The usable 18" length for the flared 4" wide port comes from modelling for the port length for a targetted
tuning frequency of 18Hz for the enclosure by using a handy little program called WinISD (ISD =
Interactive Speaker Design). You can download the program at
The reason I chose 18Hz as the tuning frequency is to provide as much driver protection
with such a low tune in conjuction with setting up a rumble filter in the plate amp.
I played around with different rumble filter corner frequencies, and finally settled on
a configuration that provided a small 1dB boost around 31-35Hz while providing a rumble
filter corner frequency of 21Hz. This is done because the driver is "unprotected" at
frequencies underneath the tuned frequency of the box/enclosure, so by going with 18Hz,
it's protected for most low end frequencies under 20Hz in combination with the rumble filter
to provide as much driver protection while sacrificing very little output in the 20-25Hz range.
I was able to use the power tools from my previous Sunosub efforts, as well
as non-power 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.
- Power Jigsaw - Black-n-Decker model ($30)
- Screw drivers (slotted and/or philips head)
- Drill bits ($13) - assorted sizes to make pilot holes and final width holes.
- C-Clamps ($4/each) - 4 of them as a minimum, but 8 of them as a maximum for
clamping down the glued endcaps if you don't have heavy bags of sand.
- 24" Clamps (free due to borrowing from friend) - 8 of them.
- Saw horses or work tables ($13/each)
- Terminator crimper tool ($12)
Tool costs: roughly $245 - but I had all of these tools from my previous
construction efforts, so dividing among 3 sunosubs, center channel speaker, 2 sets of speakers, my tool costs were about
$35/subwoofer project (including tax).
As a bare minimum you'll need the following in raw materials:
- 2 sheets of 49"x97" 3/4" thick MDF (Medium Density Fiberboard) from Home
Depot for the side of the enclosure and internal shelf braces ($20/sheet)
- 2 sheets of 25"x49" 3/4" thick MDF ($5/sheet) for top and bottom layers and double thick base plate.
- Scrap plywood 1/4" to 3/8" thick ($2) as the inside of the bottom
endcap (so the T-nuts have something to sink their teeth into)
- 3-4 2x2's 8 feet long for the internal bracing pieces inside the enclosure ($2/8' section)
- 1 12" driver from SVS ($50/driver)
- 1 4" flared port - I got it from Parts Express
under the "Precision Port" brand. ($14 plus shipping)
- Plate amp (Parts Express had a nice sale on the 300-794 amp for $99 plus shipping, usually $125-$135.)
- Sand paper (80, 100, 120, various grit) ($6-$10)
- Speaker wire (used 16 gauge, but 12 or 14 gauge is fine ($0.30/foot), and male spade connectors
- Wood glue ($3)/Siliconized Acrylic caulk ($4)
- Machine screws (8-32, 3" $0.83/4 screws) for the driver, need 8 screws.
- Machine screws (8-32, 2" 0.83/4 screws) for flared port and plate amp, need 12 screws.
- T-nuts (8-32, 1/4" depth, $0.83/4 t-nuts), need 20 t-nuts.
- 1.25" thick dowel rod cut down to size for the legs ($3.50 for 48" long dowel)
Material costs - roughly $275 (these prices listed are estimates from
my sieve-like memory)
Panels (quantity and dimensions):
3/4" MDF panels:
- two 18"x39" (front and back panels)
- two 16.5x39" (right and left side panels)
- two 12"x16.5" (vertical internal brace panels)
- two 16.5"x16.5" (horizontal internal brace panels)
- two 16.5"x16.5" (internal top and bottom panels)
- two 18"x18" (external top and bottom panels)
- two 18"x18" (base plate double thick)
- twelve 12" long section (vertical edge bracing)
- eight 13.5" long section (horizontal edge bracing)
- eight 10.5" long sections (vertical middle panel bracing) - I used scrap MDF for these sections.
As a bare minimum you'll need the following in personal protection -
wear them while using power tools:
- Safety glasses ($6)
- Ear plugs ($2)
- Mask to cover nose and mouth ($3 - cutting MDF results in lots of sawdust)
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
Day 1: April 14, 2002
I bought all the MDF from Home Depot, and took it over to the workshop of
my friend, Jeff, who helps me cut the MDF into the correct panel dimensions
that I drew up on a piece of paper.
- Photo 1 : Here are the cut pieces of MDF and 2x2's.
- Photo 2 : I do a test fit of all the of panels and port to get an idea of how things will fit together.
Day 2: April 15, 2002
I create little plywood squares and strips for the t-nuts (to be used with the driver and plate amp).
- Photo 3 : I use some scrap 1/4" thick plywood on hand, and drill the appropriate sized holes for the t-nuts.
- Photo 4 : Then I use my powered jigsaw to cut up the plywood.
- Photo 5 : The other plywood strips and pieces are used to line up t-nut holes with the plate amp's screw holes.
- Photo 6 : Using a power drill, the holes are created for the plate amp plywood strip/pieces.
Day 3: April 17, 2002
Internal bracing panel creation:
- Photo 7 : This is the vertical brace that's vented, so that's why there is a lot of MDF marked for cutting within the panel.
- Photo 8 : Using my router, I free hand the rectangular holes to cut out of this panel.
- Photo 9 : This is the top horizontal brace, I mark off a hole to accomodate the flared port, and the 3" wide ledge that will become the plate amp's separate enclosure inside the box.
- Photo 10 : I free hand more holes out of this brace panel.
- Photo 11 : This is the bottom horizontal brace. I mark off the ledge for the plate amp enclosure, and then put in holes for air flow.
- Photo 12 : I free hand these holes as well. Towards the end of construction, I remove the plus-shaped piece in the middle of the brace and re-do the panel to allow more air flow for the driver.
Plate amp hole creation:
- Photo 13 : I mark off a 9.25"x9" for the plate amp. I had to situate the hole so that it would line up in the middle section of the enclosure.
- Photo 14 : More free hand routing to create the hole for the plate amp.
- Photo 15 : This is a test fit of the hole I just made for the plate amp.
Day 4: April 18, 2002
Driver and port holes creation:
- Photo 16 : Working on the internal bottom panel for the driver hole. To find the center, I draw diagonal lines, and the intersection is the center of the panel. That's my pivot hole being drilled for the router circle jig.
- Photo 17 : The router in action, on top of the router guide to cut the hole for the driver.
- Photo 18 : The hole (11" in diameter) is routed.
- Photo 19 : I do a test fit of the driver in the newly created hole. .
- Photo 20 : To line up the hole for the outer bottom panel, I find the center, and situate the internal panel do maximize the fit of the driver hole for both panel layers.
- Photo 21 : The router does its job and a new hole is born.
- Photo 22 : The driver is used to test the fit of the holes.
- Photo 23 : Moving to the internal top panel for the port hole. I find the center pivot hole location the same way as previously described.
- Photo 24 : Test for fit of the hole created for the port.
- Photo 25 : I line up the outer top panel, find the center, and draw in the hole required for this panel.
- Photo 26 : The router yields another hole in the panel.
- Photo 27 : The port is test fitted in the port hole for the outer top panel.
Day 5: April 19, 2002
Drilling in holes for the screws.
- Photo 28 : Yes, that's a litter box being used to provide some support/clearence while I drill in the screw holes into the panels.
- Photo 29 : Using the port, I make marks for the screw holes and commence to drill in the holes.
- Photo 30 : The screws are test for fit with the port screw holes.
- Photo 31 : The plate amp screw holes are marked on the side panel which will have the amp installed.
- Photo 32 : The screw holes have been drilled.
- Photo 33 : I test for fit of the screw holes with the amp and screws installed.
- Photo 34 : I start on installing the t-nuts into the plywood strips for the amp.
- Photo 35 : With glue in between the t-nut and the plywood, the t-nut is hammered into the plywood.
- Photo 36 : This is a test fit for the screws being screwed into the t-nuts.
- Photo 37 : I mark where the plywood strips need to be placed for things to fit just right.
- Photo 38 : Glue is applied to all the plywood strips.
- Photo 39 : To maintain the fit, screws are screwed into the t-nuts while the glue dries for the plywood strips.
- Photo 40 : Next up is preparing the t-nuts and the plywood squares. Glue is being applied to the t-nut area when bonded to the plywood squares.
- Photo 41 : The hammer is used to pounded the t-nuts
- Photo 42 : Screws holes for the port is being drilled here.
- Photo 43 : The screws are tested for fit through 2 layers.
- Photo 44 : T-nut squares are being glued to their respective positions on the internal bottom panel.
- Photo 45 : Final look at the t-nut plywood squares put in place, and tested for fit with screws. .
- Photo 46 : Screw holes for the driver are marked by me.
- Photo 47 : A little help from the power drill and the screws holes for the drivers are done.
- Photo 48 : Here is a test fit for the driver's screw holes.
Day 6: April 20, 2000
- Photo 49 : Clamping the bottom layers together so I can drill in the driver screw holes for a consistent fit.
- Photo 50 : Holes are drilled through both bottom panels for the driver.
- Photo 51 : More testing for fit of the screw holes through both panel layers.
- Photo 52 : The driver screw holes are filled with screws with the driver in place.
- Photo 53 : This is where the t-nut squares come in handy with you need to align them with the new screws.
- Photo 54 : A shot of all 8 t-nut squares glued and screwed with the driver in place.
- Photo 55 : With the new internal brace pieces in to see if they fit.
- Photo 56 : I mark the holes for the dowels.
Day 7: April 21, 2002
Routing out holes for the legs/dowels:
- Photo 57 : I free-hand the dowel holes with the router.
- Photo 58 : To ensure that the holes for the base plate and the bottom panel layers line up, I line up each layer to the other one.
- Photo 59 : I draw in the holes that line up with the existing holes from the other panel.
- Photo 60 : Soon the holes for the legs are routed.
Day 8: April 22, 2002
Glueing up the internal brace structure, and enclosure panels:
- Photo 61 : In order to apply the glue for bracing panels in right place, I draw in the lines for the panel edges.
- Photo 62 : I apply the glue to appropriate brace panels.
- Photo 63 : Using the rest of the enclosure panels to provide the proper alignment for the internal brace, the glued panels are clamped together.
- Photo 64 : Here's a shot of the glued up internal brace structure.
- Photo 65 : Now it's time to glue the enclosure panels to the internal brace structure. I draw in the areas where glue is needed on the outer panels.
- Photo 66 : One side of the outer panels is clamped as the glue dries.
Day 9: April 23, 2002
Glueing up the rest of the panels to the internal brace structure, plus caulking and edge bracing installation:
- Photo 67 : The other panel is glued up and ready for clamping to the rest of the enclosure.
- Photo 68 : Again, more clamping pressure is applied while the other panel is glued to the rest of the enclosure.
- Photo 69 : The enclosure is finally taking shape.
- Photo 70 : Next up is glueing the back panel to the enclosure.
- Photo 71 : Using the enclosure's weight, I apply clamping and gravitation pressure as the glue dries.
- Photo 72 : Once the back panel has been glued in, I caulk the edge seams.
- Photo 73 : Then 2x2's are glued into the edge seams of the interior of the enclosure for additional bracing.
- Photo 74 : Here's a shot of all of the possibible bracing installed at this point in time.
- Photo 75 : After the 2x2s are glued into place, I flip the enclosure over and glue in more makeshift bracing to fortify the side panels.
Day 10: April 24, 2002
Front panel is glued into place:
- Photo 76 : Glue is applied to the edges for the front panel to mate with the rest of the enclosure.
- Photo 77 : Using whatever I can find to apply pressure on the front panel while the glue dries.
- Photo 78 : I install/glue the rest of the 2x2 edge bracing into the enclosure now that the front panel is glued into place.
- Photo 79 : Here's a shot of the internal bracing through the driver hole on the bottom.
- Photo 80 : And here's a shot of the internal bracing through the port hole on top.
Day 11: April 25, 2002
Sanding and top panel installation:
- Photo 81 : To smooth out the edges on the bottom side for the driver, I use my orbital sander and 80-100 grit sandpaper.
- Photo 82 : I mark the leg holes on the inner bottom panel using the outer bottom panel as a guide.
- Photo 83 : I then sand the edges of side panels for a smooth finish.
- Photo 84 : I start on sanding the inner top panel nice and smooth before glueing the outer top to it.
- Photo 85 : Glue is applied to the inner top panel.
- Photo 86 : More pressure is applied with the usual suspects.
- Photo 87 : The bottom base plate's screw holes for the legs is marked using the top panel's hole cutouts.
- Photo 88 : I bought a drill guide to make more straight perpendicular screw holes.
- Photo 89 : Glue is applied to the bottom layer of the base plate.
- Photo 90 : Using C-clamps, I glue the 2 layers together.
Day 12: April 26, 2002
Cosmetic touch-up and installation of the legs:
- Photo 91 : To fill in any gaps between the layers of the panels, I use wood putty. Here's a close-up of the sanding to get a roundover edge.
- Photo 92 : More wood putty for the base plate.
- Photo 93 : Now onto cutting the 1 1/8" dowel rod down to size. I use the banner approach once again with a sheet of paper to come up with the cut line.
- Photo 94 : I use a small saw to cut the dowel.
- Photo 95 : 4 legs are cut to the same length (or close enough).
- Photo 96 : Here's a test fit of the legs to the base plate and the bottom base plate.
- Photo 97 : Using the drill and drill guide, I start pilot holes for the wood screws for the legs.
- Photo 98 : This is the bottom of the base plate, I drill in pilot holes for the wood screws.
- Photo 99 : Now I screw in the #6 2" wood screws.
- Photo 100 : Using the drill press, I pop in more pilot holes for the wood screws for the leg connection on the bottom driver panel.
- Photo 101 : Here's a shot of me screwing the wood screws from the inside of the enclosure - tight spot.
- Photo 102 : Here's of shot the wood screws screwed through the bottom panel.
- Photo 103 : I screw in the 4 legs, with the outer bottom panel not glued in yet. I will test for fit and leg slack with the base plate.
- Photo 104 : Once I'm satisfied with the fit, I apply glue for the outer bottom panel to be glued to the rest of the enclosure.
- Photo 105 : I make sure the driver hole screws will fit, so I screw them in while clamping the outer bottom panel to the enclosure.
- Photo 106 : After the glue is dry, I apply wood filler to seal up any visible gaps between the panels.
Day 13: April 27, 2002
The home stretch: Sanding, port preparation, driver and plate amp installation:
- Photo 107 : Then I sand away the excess wood filler for a smooth finish.
- Photo 108 : The bottom panel is nice and smooth from the sanding process.
- Photo 109 : I needed one extra inch of port length, so I use an extra piece of black plastic pipe, and use the banner idea again to mark the cut perimeter.
- Photo 110 : Using my PVC pipe saw, I proceed to cut the pipe as required.
- Photo 111 : Carefully sawing the pipe, I have my 1" port extension.
- Photo 112 : I use plain black electrical tape to tape the inside of the 1" port extension to the rest of the flared port kit.
- Photo 113 : Extra port is now taped to the flared section.
- Photo 114 : More electrical tape is used to tape the rest of the flared port together.
- Photo 115 : This is what the final flared port assembly looks like.
- Photo 116 : Next I drill a small hole for the speaker wire to go from the plate amp to the driver through the plate amp enclosure.
- Photo 117 : I feed the speaker wire through the hole, and later apply some caulk in the hole to seal it up.
- Photo 118 : These are the 3 items that will be installed into the enclosure: flared port kit, SVS driver, and plate amp.
- Photo 119 : Just another view of these 3 items.
- Photo 120 : I wasn't happy with the T-pattern near the driver's end horizontal brace, so I cut the T out, which opened up of area, and then fortified the opening with 2 strips of MDF as shown.
- Photo 121 : The nice thing about the SVS driver is that it comes with compression fittings for its driver connection to the amp, so I didn't need to buy banana plugs for the speaker wire connection to the driver.
- Photo 122 : I start screwing the driver into its hole.
- Photo 123 : I finish screwing in all 8 of the 3" 8-32 machine screws into the enclosure. I relied on the SVS driver's rubber surround to provide an air-tight seal, so no weather-stripping was needed on this project.
- Photo 124 : I finally get to screw in the base plate to the rest of the enclosure with the driver screwed in place.
- Photo 125 : The base plate is now screwed into the enclosure.
- Photo 126 : The plate amp was modified to remove the 6dB boost in the 30-35Hz range. I went with 1dB of boost around 30-35Hz and a rumble filter corner frequency of 21Hz by making R26=39K ohms and R27=150K ohms on the amp's pre-amp circuit board. I placed the resistors on the bottom side of the circuit in case I wanted to experiment with resistor values. After 3 other different resistor combinations, this is what I settled on for a final modification of the plate amp.
- Photo 127 : I make the connections from the driver to the plate amp here.
- Photo 128 : The plate amp is now screwed into the enclosure.
- Photo 129 : This is the flared port kit before it's installed into the enclosure.
- Photo 130 : Now the flared port kit has been screwed into the enclosure's top side.
- Photo 131 : Here's a shot of the SBS with some of my other DIY projects.
- Photo 132 : Here's an isometric shot of the SBS from a tall basketball player's point of view.
- Photo 133 : Here's a shot of the SBS looking at it from the plate amp's level.
- Photo 134 : Here's a shot of the SBS in the backseat of the Honda Accord of my friend, Leo. It really did fit!
Day 14: April 28, 2002
Here's a graph of the near field response of the SBS:
Graph 1 :
This is a hodgepodge of measurements. You can see 1m SPL measurement where my room modes accentuate the frequencies above 50Hz, and the tuning frequency was right about 18Hz. Also, you'll see nearfield measurements of the driver output and the port output, and also the combined driver+port output which is pretty flat (the dark blue line). I won't swear on a stack a bibles that these measurements are the true representation of the sub's performance, it's just what I can provide with a Radio Shack SPL meter and 1/3 octave sine wave bass tones.
Day 14-15: April 28-29, 2002
Here's some of my comments in regards to how the SBS performs in my
Home Theater setup:
The sub does well with music, not super punchy, but not sluggish either. For its tuning frequency,
the sub was tight enough in its transient response for me.
At my normal listening levels, with peaks up around 96dB from my seated position:
I tested The Phantom Menace (TPM), and it survived the Pod Race scene pretty easily.
U-571's depth charges did little to change my opinion of the sub.
The opening scene from Toy Story 2 play through fine.
The dts Jurassic Park LD had me believing dinosaurs were in my living room. I tested it with other DVDs, but none really pushed it until
popped in the dts Haunting DVD, which was the one DVD that gave this sub problems with driver pops/unloads during an intense bass scene. But this DVD has one of the toughest bass-laden audio tracks around.
Later, when we installed the sub in Leo's dedicated HT in a corner-loaded position, the bass was reinforced, and even 20 feet from the sub in the back row of seats, the bass was pretty amazing and made an impact in whatever DVD that was being played if it was loaded with bassy scenes.
This is what the SBS looks like in Leo's dedicated HT (I've left it up to Leo as to the cosmetics of the SBS):
- Photo 135 : Close-up with a PSB 4T for comparison in size.
- Photo 136 : A front view of the SBS and the right/left front PSB 4T speakers and his Mitsubishi 65" RPTV.
I hope you've enjoyed looking at how I created my 1st box subwoofer! I did it because it
was a relatively inexpensive project, around $275 since I had most of the tools I needed.
The drill guide was the only new piece of hardware I bought for this project.
So how many have visited this subsonic webpage since 5-10-2002?
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