|12" Woofer Sonotube Subwoofer
After buying the Martin Logan
Aerius I loudspeakers I felt the bass was a little weak. I liked what
bass they had but they just didn't go low enough. So I started looking
at the subwoofers that were available in the stores and couldn't afford
any of the ones I liked (spent all my money on the Martin Logan's). So I
decided to build one. Here's how I did it.
After much research I decided to
build a Sonotube sub. There is a ton of information on the net
describing people's projects. I didn't want to spend hours building a
cabinet only to find that it didn't sound very good. I figured the
sonotube was the easiest way to get my feet wet in DIY speaker building
without devoting a boatload of time and money. I would recommend this
approach to anyone who is building their first subwoofer. Checkout the
links to see some other peoples projects that I thought were pretty
good. I won't spend a lot of time describing construction
technique or the merits of various designs. Its already covered in great
detail on the net.
had to decide on the speaker I would use. After looking at the Shiva
and the ACI
SV-12 , I decided to go with the SV-12. The main reason was that it
would dip down to the lowest frequency according to the cabinet design
program I was using. Another benefit is that they offered a trial
version of Winspeakerz to aid in the design. Since my
amplifier only has a Dolby Digital 5.1 output I also needed an
amplifier. ACI had a package deal so I got a PSA-1
amplifier with the speaker.
modeling the cabinet using Winspeakerz and WinISD
I ended with the following cabinet.WinISD
is nice because it will provide the flattest frequency response
automatically but it doesn't model driver excursion.Winspeakerz models
driver excursion but doesn't provide the flattest response. Both
programs gave pretty much identical results
. The end result was was a compromise between a ported design and a
sealed one. I can't remember now why I picked the volume I did. I think
it was the smallest cabinet that gave a three db down frequency of 20 hz
using ports. I figured I would listen to the sealed cabinet and decided
at that point if I wanted to add ports. As it turned out I really liked
the sound of the sealed design for music but it didn't go low
enough for home theater and ended up adding ports. This gave the rumble
that makes movies exciting but it definitely wasn't as accurate as
originally thought that I could set the cabinet sideways on the floor
hence the square ends on the tube. After trying it, I didn't like how it
sounded and added legs to the bottom to make it upfiring. The tube is
covered with a brown cloth sock and the ends are painted with Rustoleum
Stone Creations paint. It could use a couple more coats of paint.
I'm fairly happy with this design.
It's much cleaner than any commercial subwoofer in this price range
(about $400). Its so clean that its deceiving how loud it is. I might,
however, have a tuning problem as it seems to bottom out a little easier
than I would like. I definately wouldn't use two 2" ports again. I don't
think they flow the air that is required.There aren't any funny noises
coming out of them but it just doesn't seem that enough air is moving
when the woofer is really jumping.
like I said, its not bad for my first effort. The PSA-1 works well. It
has plenty of power (I can't turn it up past 25% of the minimum without
bottoming the woofer) and I can adjust the crossover frequency as well
as the phase. I guess I'll need to do some testing to see exactly what
needs to be tweaked to give optimum output.
that I've finished my center and rear speakers the subwoofer cabinet
looks a bit crude. I'm going to build an MDF cabinet so that I can
finish it with oak veneer like the other speakers. I'll probably try a passive radiator since it would
make it much easier to tune. I'm also going to make the cabinet bigger
(8.2 cubic feet) so it will go all the way to 20hz before rolling off.
I'll post an update after its built.
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