http://www.instructables.com/id/800watt-12-long-16quot-diameter-Bass-Cannon/

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800watt, 12' long 16" diameter Bass Cannon.by NastySpill on July 26, 2009

Table of Contents

intro:   800watt, 12' long 16" diameter Bass Cannon. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

step 1:   Ingredients . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

step 2:   Cut the Sonotube into two pieces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

step 3:   Cut the sub woofer mounting flanges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

step 4:   Install the sub woofer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

step 5:   Wire up and test. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

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Comments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

http://www.instructables.com/id/800watt-12-long-16quot-diameter-Bass-Cannon/

intro:  800watt, 12' long 16" diameter Bass Cannon.I built this Bass cannon, based on the Bose WaveCanon. Its a resonating tube driven by an internal sub woofer.Basically a Giant Sub Woofer.

I built this as part of an audio visual project for Burning Man 2007. Using a tube with the driver mounted inside it resonates much like a church pipe organ within a specificfrequency range. Hopefully the bass frequency range.

Called "Rare Angles" it comprises 12' of cardboard Sonotube as used by concreters to form columns. Its cheap, easy to work with and rigid enough to use for thisapplication. You can get it at a concrete supplier.

As soon as I laid eyes on what Holly and team over at positron.org did, I knew it was just a matter of time, and any flimsy excuse to build my own.

This Bass Cannon is designed very basically. I was able to buy a 12' length of 16" sonotube. The driver has to be placed exactly 1/4 the distance down the full length ofthe tube or 3 feet.

From what I can gather from research, the longer the tube length will raise your resonant frequency. I figured my resonant frequency was about 30Hz. I am probablywrong. I did the calc a while ago so can't be sure how I arrived there.. It wasn't too loud on the "test fire" audio sweep, but a neighbour from 2 doors down, certainly heardit and came running down the street.. "Are you making that noise?!"Maybe me sitting on my deck with a giant carboard tube and earmuffs on gave me away.

step 1: IngredientsMaterials;1 x sub woofer 12 or 15" depending on the sise of tube you want 15" in this case1 x length of sonotube slightly larger than your sub woofer diameter 16" in this case1 x sheet of 3/4" plywood screwsglue / sealant (sikaflex works well)

Tools;RouterCircle cutting jig for router3/4" spade bitDrillcircular saw or jig saw.

http://www.instructables.com/id/800watt-12-long-16quot-diameter-Bass-Cannon/

step 2: Cut the Sonotube into two piecesWork begins by cutting the sonotube. The sub woofer mounting flanges need to meet 1/4 of the way down the length of the tube. For me and my 12' long piece thats 3'along.Do do this accurately I measured with a large sqaure 3' from one of the ends at about 6 points around the circumference of the tube. I then wrapped a piece of maskingtape around, making sure one edge of the tape passed through the points I'd just marked. I used this as a guide for the jigsaw. I drilled a starter hole to get the jig sawblade in then went at it! Afterwards I removed the tape. The cut will be kinda fury but that ok, this will be concealed inside the flanges.I didnt take a photo of this step so I drew it. See the diagram with the light grey lines being my 3'long marks then the dark band being the tape which i used as a guide to cut the tube squarely.

step 3: Cut the sub woofer mounting flangesThe flanges are used to mount the driver and also to couple the two tube sections. The following description is kinda general as if you make one of these, yourdimensions will be different to match your tube and your driver.

I used a circle cutting jig, consisting of a strip of ply with the router mounted on one end. This was nailed to the centre of a board of 1/2" ply which would become the firstflange. I began to cut out a the diskusing a 1/4" bit at 10" radius to give a 20" flange disk.Starting from the outside of the flange in, I cut out the perimeter.Then cut a 1/4" wide groove 1/4" deep at 8" radius for the top half of the sonotube to sit in. This is where the cut is concealed, and also provides a little extra surface forthe adhesive to bond and create an airtight seal.Then I flipped the disk over and cut a 10mm deep groove at 7.5" (I love changing between metric and imperial) then another 2 at the same depth inside that, whichmakes a shoulder for the driver to sit in.The next cut is just inside the last to go all the way through to remove the centre section.

The second flange was identical.

Again I have drawn a cross section of the flange piece.

I then clamped the two flanges together and drilled 4 x 3/4" holes with a spade bit for the bolts to hold the two flanges together. When drilling through ply (or any timer)with a spade bit, keep an eye on the underside and when the point of the bit starts to emerge flip the piece over and finish the hole from the other side. This will preventtear outs and give a nice clean hole..

http://www.instructables.com/id/800watt-12-long-16quot-diameter-Bass-Cannon/

step 4: Install the sub woofer.As seen in the photo, the sub woofer faces downward. It can go either way around without too much issue..I screwed the sub woofer securley onto the lower flange, added the second flange ontop then added the second length of sonotube.

I worried that the wind would possibly snap the tube out of the 1/4" grooves so re enforced the tubes with ply triangles made from scraps.

I used marine Sikaflex to glue the tube into the grooves, then screwed the ply rib triangles from inside the sonotube. I used more sikaflex to bead between all the supportribs. It ended extremely strong.

I did have to drill a hole through the lower flange to let the sub woofer cable pass through. This was an oversight. In future I'd run the cable to the sonotube wall and passthrough to lugs on the outside.

http://www.instructables.com/id/800watt-12-long-16quot-diameter-Bass-Cannon/

step 5: Wire up and test.Thats the majority of the work done!

I made a stand for the whole thing to stand on, but this was an error. The resistance of the bass cannon standing close to the ground created back pressures thatintroduced some unwanted characteristics.. nasty resonances that caused humming and nasty distortions.

This should always be mounted with plenty of room beyond either end of the tube.

Finally is a pic of the bass cannon in situ on the playa with the remainder of the paraphenalia attached..

See a full description here;http://fle33.com/public/content/view/5/2/

http://www.instructables.com/id/800watt-12-long-16quot-diameter-Bass-Cannon/

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http://www.instructables.com/id/800watt-12-long-16quot-diameter-Bass-Cannon/

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Comments44 comments Add Comment

 hot-fresh-rider says:  Jul 30, 2009. 5:19 PM  REPLYthe bottom part is a rocket :D great ible

 thelandlord says:  Jul 27, 2009. 4:12 PM  REPLYThere's an easy way to make people very ill without needing tubes big enough to resonate right down there... make two tubes, one tuned for about 20HZ,another for about 27HZ. Feed your stereo amplifier with the matching tones on each channel.

Aim them toe-in to make the 'beams' cross a safe distance away, and turn up the steam... where the two soundfronts meet, they'll beat against each otherand that'll make two tones other than the ones you've put in... 20+27=47Hz, and 27-20=7Hz.

47Hz you will hear as a very loud hum, slightly flat of a mains hum.7Hz, you will not hear at all (unless you're an elephant) however anybody unfortunate enough to encounter the 'sweet spot' will soon feel very poorly indeedas their internals begin to resonate - think extremely seasick, only so much worse - they'll pray for death to come quickly. :-)

If you have a bad neighbour, this could completely ruin their night. ;-)

 pikaj00 says:  Jul 30, 2009. 3:58 PM  REPLYmyth busters tested that its a myth.

 strangebike says:  Jul 30, 2009. 4:31 AM  REPLYdidn't mythbusters do that one or was that for the other end ? can't remember now

 diskincluded says:  Jul 30, 2009. 3:28 AM  REPLYOh reeeeeeeeally? Any chance of an 'ible appearing? :3

 grungehead says:  Jul 27, 2009. 9:56 PM  REPLYWhere do you learn to do this? "Sounds" interesting.</bad jokes>

 thelandlord says:  Jul 28, 2009. 12:22 AM  REPLYOriginally, by spending too much time with 'musical theatre' types - there was a musical called 'Time' written by Dave Clark that was quite popular inthe UK a while ago, and it used something similar as a special effect.They needed the audience to feel 'space-sick' during a rocket-launch, and clearly couldn't physically pick the auditorium up and shake it... sosomebody had the idea of beating a 20Hz tone against a 17Hz one through the PA system... not loud enough to risk an 'accidental brown' ifsomebody was a little weak in that department (google 'Ben Folds' and 'Improv Everywhere' for one of the best pranks ever...) but enough to shakethe room a bit and make everybody feel 'nervous' without quite understanding why.Of course, then you have to 'experiment', don't you? ;-)

 ItsTheHobbs says:  Jul 28, 2009. 5:54 AM  REPLYImprov Everywhere is awesome. I especially liked the mirror subway.

 frollard says:  Jul 27, 2009. 7:17 PM  REPLYI was always curious about the brown note...they said it was busted on mythbusters, but I dont 100% trust those guys. It's crazy neat either way.

 thelandlord says:  Jul 28, 2009. 12:23 AM  REPLYTrust them or not, they've still got the best job in the world...

 frollard says:  Jul 28, 2009. 12:37 AM  REPLYYeah, pretty much!

http://www.instructables.com/id/800watt-12-long-16quot-diameter-Bass-Cannon/

 clark says:  Jul 27, 2009. 9:24 PM  REPLYexcept thelandlord isn't talking about a brown note.

 frollard says:  Jul 28, 2009. 12:37 AM  REPLYhehe...seemed like it fit the bill...

 thelandlord says:  Jul 28, 2009. 12:22 AM  REPLYCorrect. :-)

 barshterd says:  Jul 30, 2009. 2:30 PM  REPLYBack in the day, we used to design and build speaker enclosures that similarly boosted the low frequency volume of a woofer. The design started out asbasically a large tube, approximately the same diameter as the woofer we were using.

As most know, a speaker produces sound by pushing air out when the cone moves forward and pulling the air back in when it moves backward. What manypeople don't realize is that the rear side of the speaker cone does exactly the same thing - except that the wave from the back side is exactly 180 degreesout of phase with the wave from the front. If you can delay the back wave just long enough, you can bring it into phase with the front wave thereby almostdoubling the volume of the speaker.

For a given, single frequency, this is pretty easy to do and pretty easy to calculate.

Using 100 Hz as an example, we know that sound travels at ~1,100 ft/sec. So for 100 Hz, the sound wave completes one cycle (in/out, up/down, etc.) forevery 11 feet that it travels. (the wavelength) Since we want to bring the back wave into step with the front wave, we want to delay the back wave by 1/2 ofthe wavelength or 5.5 feet. To do this, all we need is a tube that is 5.5 ft long and, better yet, ends up pointing the same direction as the front of the woofer.(think of the letter "U".)

All speakers have a frequency at which they resonate naturally. (producing the loudest sound level for the amount of power that is driving them) Speakermanufacturers usually provide this number in the speaker's specifications. If all you want is a "LOUD," boomy speaker, design your tube length for thisfrequency.

On the other hand, if you want a speaker with a louder, but smoother, low end performance, design your tube around 1/2 of the speaker's resonatingfrequency. This will help dampen the speaker's natural boominess at its resonating frequency while reinforcing (amplifying) the sound below and above theresonating frequency. Hence louder but smoother bass response overall.

Because low frequency sound goes around bends and turns easily, you can feel free to bend the tube into all sorts of interesting shapes provided that thecross-sectional area of the tube remains the same and the end of the tube eventually aligns with the front of the woofer.

Bending or folding the tube also gets rid of a lot of the higher frequency sound waves which we're not interested in and would be out of phase anyway. Youcan fill the tube with loosely packed fiberglass wool or cotton fiber to further reduce the high frequency noise, if you like.

Incidentally, the tube doesn't have to be round or made from a length of sonotube - although sonotubes are really hard to beat. You can use any shapedtube made from wood or plastic for instance , but any flat and/or parallel surfaces will probably resonate at their own frequency thereby adding unwanteddistortion to the sound produced. (I even recall people making their tubes out of concrete pipes or chimney tiles to avoid unwanted resonance.) Cheap andeffective, but very heavy.

In case someone asks, the correct name for a speaker enclosure of this design is "Acoustic Labyrinth." If you fold it as suggested here, then it is called a"Folded Acoustic Labyrinth" speaker enclosure. It's an old (1930's, I think) design but, if you think about it, there is one, very high-end, audio systemmanufacturer that still uses it today. Enjoy.

 Car6on14 says:  Jul 30, 2009. 2:07 PM  REPLYcool project. Landlord, would they have to be 180 out of phase to add or subtract? have any good links on how that works?

 bears0 says:  Jul 30, 2009. 1:30 PM  REPLYuse audacity to increase the bass also then it would probably be ear piercing

 gsidhe says:  Jul 30, 2009. 11:21 AM  REPLYSo...Where do the fish shoot out? Does it only work on bass or could you use trout as well?

 Kulawend says:  Jul 30, 2009. 1:18 PM  REPLYThat gave me a chuckle.

 teZca says:  Jul 30, 2009. 11:58 AM  REPLYthe last pic was amazing...

http://www.instructables.com/id/800watt-12-long-16quot-diameter-Bass-Cannon/

 pyroal says:  Jul 30, 2009. 11:53 AM  REPLYthat is awesome!!! where did you get the idea to buid it

 Ian01 says:  Jul 28, 2009. 8:13 PM  REPLYIf your tube is 12 feet long...

Givenl, length (m) = 12 ft = 3.6576 m?, wavelength (m). This is derived from the length.v, speed of sound (m/s) = 340.29 m/s (at sea level and ~0°C, from Google)

Requiredf, frequency (Hz or cycles/second)

Analysisv = ?f (wave formula)f = v/?

Also, ? is 4 times the length in this case, because there is a standing wave in a tube that is open at one end and closed at the other. There is a displacementantinode at the closed end (because it can’t move—I am ignoring the driver in favor of resonance) and a displacement node at the open end. The distancebetween a node and adjacent antinode is ?/4, or one quarter wavelength. Therefore, the length of the tube is ¼ wavelength, or the wavelength is 4 times thetube length.

Solutionf = (340.29 m/s)/?f = (340.29 m/s)/4lf = (340.29 m/s)/4(3.6576 m)f = 311.161176 m2/s

f = 311.161176 Hzf ? 310 Hz

ParaphraseA tube 12 feet or 3.7 m long will have a fundamental frequency of approximately 310 Hz, assuming the speed of sound is 340.29 m/s at sea level.

This, or course, will give a more accurate result if you put in a more accurate length. 310 Hz is the fundamental frequency of the tube. There are morefrequencies (harmonic frequencies) that the tube can also resonate at. Their wavelengths will be 3?/2, 5?/2, 7?/2, and so on. These frequencies result fromthe fact that there must be a displacement node (pressure antinode) at the closed end, and a displacement antinode (pressure node) at the open end.

(I just did this in Physics 20 class today.)

 NastySpill says:  Jul 28, 2009. 10:24 PM  REPLYThats magnificent!, But the tube is open at both ends, its freely vented. So how does this change the calculation? In my scribbings it changes the freq to408Hz, which seems way off.I recall when I built this arriving at a figure like 27.8Hz.. can't for the life of me recall how.

 NastySpill says:  Jul 28, 2009. 10:34 PM  REPLYWait, now math has NEVER been a strong point for me, but your solution is borne from this equation...f=340.29 m/s / (4 / L)if I calc out your equation as written I get;f= 340.29 m/s / (4* L)f= 21.2 Hz

which is sub audible!

 lutin says:  Jul 30, 2009. 10:49 AM  REPLYYou're completely right.What he did was:((340.29 m/s)/4)*3.6576 m = 311.161176When it should have been:(340.29 m/s)/(4*3.6576 m) = 23.2591043Which is what you did

 nusnel says:  Jul 30, 2009. 2:48 AM  REPLYYes, but since you also get the harmonics, you also have 40, 80, etc.

This thing rocks!!

 axiesdad says:  Jul 30, 2009. 10:42 AM  REPLYDumb question time. What does it do? I understand that it creates low frequency sound, but what's the point? Is it just loud? Does it shatter masonry walls?Cause convulsions or hallucinations? This is a very well done Instructable; I'm sure I could build one of these if I just knew why I would want to. Please helpcure my ignorance.

http://www.instructables.com/id/800watt-12-long-16quot-diameter-Bass-Cannon/

 downeasta says:  Jul 30, 2009. 10:21 AM  REPLYWow! When I first saw it I thought how bad it would be to be your neighbor.. but after you added the spinning light organ even old cranky me had to admitthat it is a very cool rig! I'd love to hear/see it. I'd try Saint-Saëns, Organ Symphony #3. (attached) The "16 foot stop" low notes would be just mind blowing ifnot metal bending! Please let me know if you try it. http://www.youtube.com/watch?v=0d0itDEs9uo

 tartanphotographic says:  Jul 30, 2009. 9:07 AM  REPLYA simple method I have used to mark exactly around the circumference of a cylinder is with a piece of paper longer than the circumference and at least 2"wide. Wrap around column and match up the nice straight, factory edge. Tape the strip together and either draw line against paper edge or spray paint theedge.

 casey321b says:  Jul 30, 2009. 7:25 AM  REPLYIf you used bungie cords to suspend for even better sound would the pressure push it to the ground or would there be enough resistance from the cords tokeep everything up?

 ruffboy says:  Jul 30, 2009. 5:04 AM  REPLYWhat made the rings of light?We make Sonotubes in Texas. If you will start marketing these canons it may help our business.

 Martinmayhem says:  Jul 30, 2009. 4:40 AM  REPLYAwesome! I'd love to here that thing at full tilt!What music do you like to play through it?

 covey12 says:  Jul 29, 2009. 6:47 PM  REPLYis it illegal to put one on a car roof?

 Thermionic says:  Jul 28, 2009. 7:43 PM  REPLYCould something like this be aimed? I have a neighbor who loves to wake my three year old up at 1 in the morning with his hot rod. I would like to rattle hishouse with one of these!

 NastySpill says:  Jul 28, 2009. 10:14 PM  REPLYYou could, but it'd be incriminating..It'd be quicker, cheaper, and have longer lasting effect to just report him to your relevant tax agency for tax evasion.No body expects nor enjoys a tax audit.

 bcnr33skyline187 says:  Jul 27, 2009. 9:09 PM  REPLYi kinda discovered this type of thing by accident when i put my sub into some old tires stacked it increased the power amazingly, especially when you putyour head inside of the tires

 theRIAA says:  Jul 27, 2009. 9:57 AM  REPLYthat is just freakin awesome!

although I have to admit, at first I thought you could point this at people, evoking a solid wave of bass to cripple them to the ground...

 NastySpill says:  Jul 27, 2009. 6:19 PM  REPLYYeah it was going to run that way, but it can do some damage without you really knowing it..

 jeff-o says:  Jul 27, 2009. 10:27 AM  REPLYSure, but you'd need to lower the frequency to about 7Hz.

 frollard says:  Jul 27, 2009. 7:15 PM  REPLYStill a couple hundred watts of directed energy can do damage even if it's not harmonic...

 deemerch says:  Jul 27, 2009. 5:27 PM  REPLYcan you make a video and post it to youtube?

http://www.instructables.com/id/800watt-12-long-16quot-diameter-Bass-Cannon/

 NastySpill says:  Jul 27, 2009. 6:18 PM  REPLYA video of this thing running? as with many things at Burning Man it was consumed by fire.

 robotkid249 says:  Jul 27, 2009. 5:15 PM  REPLYHaha, add a rocket to the bottom, and we're off to mars!

 bowmaster says:  Jul 27, 2009. 11:09 AM  REPLYThe bottom part looks like a rocket.