Patman's SBS Construction Resource Page

The SBS (Sun Box Subwoofer) Construction page.

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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.

Design


1. 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:


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 Linear Team.

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.

Tools

I was able to use the power tools from my previous Sunosub efforts, as well as non-power tools:

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).

Materials

As a bare minimum you'll need the following in raw materials:
Material costs - roughly $275 (these prices listed are estimates from my sieve-like memory)

Panels (quantity and dimensions):
3/4" MDF panels:


2x2 bracing:

Personal Protection

As a bare minimum you'll need the following in personal protection - wear them while using power tools:

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.

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.

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).

Day 3: April 17, 2002

Internal bracing panel creation:

Plate amp hole creation:

Day 4: April 18, 2002

Driver and port holes creation:

Day 5: April 19, 2002

Drilling in holes for the screws.

Day 6: April 20, 2000

Day 7: April 21, 2002


Routing out holes for the legs/dowels:

Day 8: April 22, 2002


Glueing up the internal brace structure, and enclosure panels:

Day 9: April 23, 2002


Glueing up the rest of the panels to the internal brace structure, plus caulking and edge bracing installation:

Day 10: April 24, 2002


Front panel is glued into place:

Day 11: April 25, 2002


Sanding and top panel installation:

Day 12: April 26, 2002


Cosmetic touch-up and installation of the legs:

Day 13: April 27, 2002


The home stretch: Sanding, port preparation, driver and plate amp installation:

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):

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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