My 1st Sonotube sub - 40-19 Stealth Sub

[rbartyczak]

Hi All,

Happy Valentine's Day.

I just completed my first sonotube sub. I had upgraded the driver in my SVS CS-Plus 46-16 subwoofer so I had the original SVS DB12 driver sitting around for about a year. After reading many of the DIY subwoofer threads, I decided to try to build one myself. My son-in-law has a 73" JVC DLP rear projection TV, a Pioneer VSX-1015TX receiver but only has Bose Acoustimass speaker system. I figured he needed a real subwoofer.

Using Sonosub.exe, I modeled a sonotube sub which would get to at least 20Hz. What I ended up with is a 20" sonotube, 36" tall, with three 3" diameter ports 24" in length. Other than the sonotube, MDF, paint and glue, I got most of my parts from Parts Express (they are super quick for shipping).

As my daughter was a little more than a bit concerned about the size of the subwoofer, I decided to make it "blend in" with their room. That is, I tried to build a 40" tall, 19Hz Stealth Sonotube subwoofer. I got them to pick out some nylon pile carpeting at Lowe's that matched the carpeting in their rec room. I then matched the carpet with some paint from Home Depot to paint the end caps and the base plate.

I think the sub came out pretty well as far as appearance is concerned. My daughter still has not seen it but I think she will not have a major objection.

As I have a spare receiver, a Kenwood KR-V990D, I plan on powering the sub with the receiver. I had communicated with Ron Stimpson (of SVS) and he thought that the Kenwood would have sufficient power to drive the sub. It has 120 watts into 8 ohms with both channels driven. I believe it has about 290 watts into 4 ohms. I was thinking about bridging the amp into mono output but before I did I hooked it up and listened/watch Star Wars I and II and Titan A.E. (Ice Fields to the end) and it sounded **** good. Not quite the SPLs were as high as my upgraded (DB 12.3 SVS) but I have absolutely no doubt that it is going to be a serious improvement over the Bose Powered Acoustimass ("Bass") module.

I am going to try to attach a few pictures showing the various stages of the build.

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[Geoff St. Germain]

Looks great. I have no doubt that that subwoofer absolutely destroys the acoustimass module.

[Warmon]

Nice job..one of the best looking sono's I've seen. What did you use for the port covers on top?

[Robert_J]

rbartyczak wrote:

As I have a spare receiver, a Kenwood KR-V990D, I plan on powering the sub with the receiver. I had communicated with Ron Stimpson (of SVS) and he thought that the Kenwood would have sufficient power to drive the sub. It has 120 watts into 8 ohms with both channels driven. I believe it has about 290 watts into 4 ohms. I was thinking about bridging the amp into mono output but before I did I hooked it up and listened/watch Star Wars I and II and Titan A.E. (Ice Fields to the end) and it sounded **** good. Not quite the SPLs were as high as my upgraded (DB 12.3 SVS) but I have absolutely no doubt that it is going to be a serious improvement over the Bose Powered Acoustimass ("Bass") module.

120 w @ 8 ohms is more like 190 w @ 4 ohms. Not even high current car amps can more than double their output by cutting the resistance in half. And it was a good thing you didn't try to bridge it. Unless your receiver says it is bridgable (99.9% aren't) then you could have fried it and the sub by doing it.

Warmon wrote:

What did you use for the port covers on top?

I bet it was this or something very similar. And some paint.

-Robert

[rbartyczak]

Geoff and Warmon,

Thanks for the compliment. For my first attempt, I was pleased with how well it turned out.

Warmon,

I used the 6 1/2 inch speaker grills from Parts Express. The inside diameter of the inner ring was just slightly smaller than the diameter of the outside port flare. Since the ring sets up about 1/4", it worked perfectly. I spray painted the grills with Rust-oleum American Accents SandStone fine textured finish (from Home Depot). It was the spray paint that most closely matched the color I used on the end caps.

[Robert_J]

Geoff St. Germain wrote:

Looks great. I have no doubt that that subwoofer absolutely destroys the acoustimass module.

The Bose bass module should still be used. It covers the gap between the low end of the satellites (about 200hz) and it's low end which is about 50hz. Without it, there is a huge gap in the frequency response.

-Robert

[Warmon]

rbartyczak wrote:

I used the 6 1/2 inch speaker grills from Parts Express..

Ya know, I haven't seen anybody else do something like that. It's a really great idea!...especially for homes with kids who might find those vent holes very tempting, if you know what I mean. Hope your daughter appreciates it, I know I would. Seriously - great job...

[rbartyczak]

Mike P.

In response to PM -- Information for the DIY Subwoofer Database:
Driver: SVS DB12 - 12"
Enclosure type: Sonotube - 20" diameter/36" height
Enclosure volume: 5.75 cu. ft/163 liters
Tuning frequency: 19 Hz
Number of ports: 3
Port length: 24"

[Mike P.]

Thanks for the specs. You've been added!

[rbartyczak]

Robert_J wrote:

120 w @ 8 ohms is more like 190 w @ 4 ohms. Not even high current car amps can more than double their output by cutting the resistance in half. And it was a good thing you didn't try to bridge it. Unless your receiver says it is bridgable (99.9% aren't) then you could have fried it and the sub by doing it.

Robert,

Before I purchased the Kenwood KR-V990D, I did quite a bit of research on it. It was Kenwood's first AC-3 (i.e., Dolby Digital) receiver and their top of the line receiver at the time (1996). There were only two other Dolby Digital amp/receiver that I could find at the time; a Yamaha (DSP-A3090) and a Denon (AVR-5600). Both of those units were selling in the $2,000+ range. The Kenwood listed for $1,200 and selling for about $1,000. Based on the articles that I read, its amplifier section was very robust. The product information sheet from Kenwood Electronics Deutschland showed the following information: Sinusleistung 2 x 120 Watt (DIN, 1kHz, 8 Ohm), Dynaikleistung 2 x 290 Watt (4 Ohm), Surroundbetrieb 3 x 100 Watt + 2 x 50 Watt.

I can't find the information any longer, but I believe it may have been from review (in Stereo Review or some other respected audio magazine) that indicated that the amp could be bridged to obtain an output of something like 420 Watt at (2 Ohm).

I found these output numbers very impressive, to say the least. However, I was actually somewhat disappointed in the surround sound (Dolby Digital) output when I was using this receiver. Switching to the stereo mode or "line straight" mode seemed to kick the amplifier up several notches -- cleaner and more robust sound. The receiver's amplifier seems to drive the subwoofer to sufficiently satisfying SPLs just fine which, in the end, is what I was hoping for.

[SteveCallas]

Warmon wrote:

Ya know, I haven't seen anybody else do something like that

It's quite common actually