Home Theater with Insane Subwoofer

After the mediocre commercial successes of some of my previous audio products, I decided to pursue a project that has absolutely no commercial potential.  Although my Automated Gmail Assistant had a 0.1% view to purchase rate, they definitely delighted their new owners!   On the other hand, my novel audio surround sound processor, audio-visual processor and audiophile headphones did not produce any revenue, despite being manufactured in an exclusive edition of one each.  Not to be discouraged, the goal of this project was to expand on the core idea behind the aforementioned audiophile headphones, but to overcome the main two drawbacks of using headphones:  1) Many people find that headphones are too uncomfortable and impractical for long term listening. And 2) most headphones lack the concert-like visceral bass impact, which is that feeling of the kick drum shaking your chest that only rock and roll shows could provide.

BIG_HMMMMMM2

Simply put, the Humorously Maniacal Milwaukee Makerspace Multimedia Machine (HMMMMMM) is a personal sized movie theater, with 5.16 surround sound.  That’s right, this theater is like a conventional 5.1 home theater, but with 15 extra subwoofers to delight the senses. While the bass in a live concert can be felt in your chest, the bass in the HMMMMMM can be felt in your soul(!).  In addition altering listener’s consciousness, the HMMMMMM will soon be used to screen our yet-to-be-filmed Milwaukee Makerspace orientation video as an integral part of our onboarding process for all new members. The HMMMMMM measures about 7 feet long and about 4 feet wide.  An eager movie-goer can simply climb up the integral stairs (shown on the left) and jump in through the 27” diameter escape hatch in the top of the HMMMMMM. Despite its crazy appearance, the HMMMMMM offers a surprisingly comfortable reclining position, much like that of a lazy-boy.  Check out this photo of the HMMMMMM under construction for a better idea of the ergonomic internal layout: There is a pillow for one’s head, and ones feet extend to the right.  The 27” display is mounted to the angled portion on the top surface, about 24” from the viewer.  Eventually, two 24″ monitors will expand the visual experience into the periphery.

The_Incomplete_HMMMMMM4

The audio portion of the HMMMMMM is a 5.16 system.  The high frequencies are played by 5 uninteresting Swan/HiVi speakers that are arranged in a properly boring 5 channel surround configuration.  The more exciting portion of the audio system is the subwoofer – well, the 16 (Sixteen) 10″ high efficiency subwoofers that provide that TrueBass™ sensation the masses crave.  Its clear from the use of 16 subwoofers that one object of the HMMMMMM was to create an audio system that plays low bass.  Playback of really low bass typically requires an extremely large speaker box, and still notes as low as 20 Hz are rarely audible.  However, inside any speaker box the bass response is naturally flat to much lower (subsonic) pitches.  For more on the sound pressure level inside and outside speaker boxes, check out this link.  The graph below is a measurement of the SPL or sound pressure level (how loud it is) versus frequency (pitch) at the listener’s ears in the HMMMMMM.

SPL_in_HMMMMMM

The graph shows that with a sine wave input, the SPL inside the HMMMMMM is 148.6dB at 40 Hz.  That means the acoustic pressure on the 27” diameter escape hatch is 45 pounds.  Excellent.  Note that earplugs in addition to earmuff style hearing protectors are mandatory to safely experience the TrueBass™.   To understand this strict hearing protection requirement, lets compare the sound pressure level inside the HMMMMMM to other audio systems that may be more familiar.  Note that the loudness of these other audio systems are not visible in the graph above, because essentially all other audio systems (including yours) are inferior.  Adjusting the margins of the graph a bit produces the following graph:

SPL_of_many_systemsThe plot shows how loud typical audio systems are, and how low they play.  For example, cellphone speakers play only a bit below 1khz, and are ~90 dB if they’re 40cm from you.  When a Jambox-type bluetooth speaker is about 60cm from you, it plays ~10 dB louder, and another 1.5 octaves lower, to 200 Hz.  Typical bookshelf speakers can get another 5 dB louder if you’re 1.5 meters from them, but only play down another octave to 100 Hz.  OEM installed car stereos are a big improvement, but they’re still not in the same league as the HMMMMMM.  Yes, the IASCA record holding car is louder than this, but it plays only from 50 Hz to 60 Hz, which isn’t even really bass.

Note that the difference in loudness between a cellphone and a car is 20 dB, while the HMMMMMM is 30 dB louder than a high-performing car stereo.  Also note that the frequency range of a piano, with its 88 keys, is about the same as a bookshelf speaker – a bit over 7 octaves.  Surprisingly, the subwoofer portion of the HMMMMMM has a 6 octave bandwidth, but it plays the 6 octaves you’ve never heard before!  The HMMMMMM plays 6 octaves below what your bookshelf speaker or Jambox calls bass. The HMMMMMM has a +/- 6 dB passband extending down to 2 Hz, with the output at 1 Hz being nearly still above the 120 dB “threshold of pain.”

Disclaimers: For safety, the big 2000 Watt amplifier that drives the HMMMMMM to its full potential is not available when the author is not present.  Ironically, the author has taught 75-100 people, the eager early HMMMMMM listeners, how to properly insert earplugs, meaning that the HMMMMMM is actually a learning tool for hearing safety! Finally, the author has some hesitancy in having the HMMMMMM reproduce recordings with 5 Hz content at 140 dB, because typical hearing protection has little effect at these unnaturally low frequencies.

PS:  Please don’t hesitate to contact me if you’d like to help with the video scripting, filming or editing.

Robbie is safely enclosed!

Finished room!

Whew.  This project was a D-O-O-O-ZY!  We needed to enclose our giant industrial arm so he can’t run away and join the robot circus…

Well…maybe not for THAT reason, but when we start cutting stuff with this robot, we need to keep spectators out of his reach and make sure that if a cutting bit does break, it doesn’t go flying out into the shop and maim someone.

This entire project was the work of several people and really shows why the Milwaukee Makerspace is a great place to build stuff/hang out with friends/play with power tools, etc…

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Step 1: Design it!  I used Solidworks and modeled each and every piece of wood that went into this project.

SW screen capture

Step 2: get the wood!  We made multiple trips to Home Depot, which thankfully is only 5 minutes away and we had great weather during the whole building process.  I love having a truck!  Fortune also shined upon me, as we had a new member join up right before I started this project, Jake R., and his help in building the wall was immeasurable.

Get the wood!

Step 3: Bolt the wood to the floor so we know where to put the wall, and then build some framing!

  4 - put in windows

Step 4: Put in the windows, drywall paneling and metal wainscoting.  We were very lucky to get seven pieces of slightly-smoked Lexan from one of our members, Jason H.  We also cut small holes in the ceiling tiles and ran 4 braces up to the metal ceiling trusses above.  This enclosure is ROCK-solid stable!  Thanks to Tony W. and Jim R. for helping with that!

When I went to Home Depot, I thought my truck could handle a 48″x 120″ sheet of drywall.  Not so much… one of their employees helped me split 10 sheets of drywall in half, in the parking lot…so I would later find out that I did not have drywall tall enough for the wall corner.  Hence the need for more “framing” so I could use smaller pieces.

10 - outer framing

The large cabinet that powers the robot arm is right next to the enclosure; I placed it outside to keep it away from foam & wood shavings.  However, we will need to have the programming pendant next to the machine every now and then….hence the need for 2 small pass-thru doors next to the cabinet.

6 - hole for mini-door

11 - outer door installed

 

 

 

 

 

 

 

 

 

 

I used doweling to help hold the door frame components together…..probably not needed, but it ensures a STRONG door!

16 - drilling door frames  15 - door framing 1

Again, hooooray for the Makerspace and all its tools! We have several LONG pipe clamps that came in VERY handy for gluing the door frame pieces together.

17 - frame glued up - 1

Here’s the outside of the enclosure.  The big metal control cabinet will go right here, hence the framed “mouse hole” in the lower right corner so we can pass the cables through from the cabinet to the robot arm.

13 - outer door and mouse hole

The same area viewed from inside the enclosure.

14 - inner door and mouse hole

Here’s the ginormous sliding door.  It’s mounted on a barn-door track-rail and supported on the bottom by two custom-made wheel brackets.

23 - finished door on track

Here’s how I made the wheel brackets.  I got two lawnmower-style wheels and bearings from Tom G., then Tom K. enlarged the center holes on the wheels on his Bridgeport mill so I could use bearings for smoother action.

18 - wheels in slot - 1

I figured on four carriage bolts for a super-strong connection to the door frame.

19 - wheel assembly done

This is the track and wheel bogies that hold the sliding door to the wall.

22 - wheels and track

Bolting the brackets onto the door was “fun”…I forgot that the very bottom of the door framing is two horizontal pieces, so the very bottom bolt had to go.  ’DOH!

21 - inside door frame 1

Here’s the final, assembled view.  You can see the robot’s control cabinet in the lower right corner.

Now that the fabrication is complete, we’re working on decorative ideas for all that blank-looking drywall.

24 - finished room!

Whenever I look at this finished project it feels like to took several months to get it up, even though construction only lasted about 2-1/2 weeks.

Thanks to Jake R., Tom G., Tom K., Tony W., Jim R., and Bill W. for their assistance with this project!

More Banned Nerdy Derby Cars!

I made the car “Sling Shot” to enter in the recent 2012 Milwaukee “Nerdy Derby.”  During a few initial test runs, my car proved to be more than 10 times faster than the super-clever winning car made by HaveBlue.  Unfortunately, my  car was banned from competition because it was considered a threat to the spectators’ safety!  The consensus was that it had “too much momentum, or energy,” and would hurt someone if it went off the track and hit them.  What does too much energy mean, you ask?  Well, kinetic energy is ½ X Mass X Velocity^2.  Really then, the car was banned because the velocity is too high: It is just too fast!  I’ve already minimized the mass by making the car out of pine, although I could have made it from Balsa Wood, or even entertaining alternate materials such as these.

Anyway, its no fun to think of how to slow Sling Shot down so that its slow enough to safely race, but still fast enough to win.  Instead, I made some new car prototypes that amp up the speed and danger.  If I’m going to be banned in the future, I may as well get banned with style!

Below is a photo of Sling Shot, which traveled the 40′ track length is 0.1 or 0.2 seconds, for an approximate average speed of 300 feet per second, or 200 mph!  Note that the block is anchored to the finish line, thereby stretching the surgical tubing which acts as a spring to propel the car.

I realized that the dominant energy loss mechanism is air resistance – largely because Sling Shot’s wheels don’t even touch the track.  You see, the car doesn’t follow the contour of the track, it just heads directly to the finish line, through mid-air.  I spent some time engineering a more aerodynamic shape to further boost Sling Shot’s speed, searching for a shape that would really slice through the air.  I even consulted a team of highly trained German aeronautical engineer friends, who all approved of my slingshot propelled Henckel Car.  With the improved aerodynamic design, it should easily be faster than the 200mph Sling Shot car shown above.

The other car I built this weekend is also based on Sling Shot, but incorporates some classy chandelier bulbs.  The numerous ‘safety’ lights alert the time keeper of the imminent arrival of the derby car – for safety.

Nerdy Derby Car From The Future

I made the car “Sling Shot” to enter in the 2012 Milwaukee “Nerdy Derby” at Barcamp7 this weekend.  A lot of people were talking about adding motors and fancy electronics, but my car is powered by a spring – a 10 foot length of surgical tubing that is stretched to another block of wood that must be clamped down.  I added wheels, but they aren’t necessary – they don’t actually even touch the track.

Check out what may end up being the only two runs the car has.  Fortunately, JRock captured some video of them.  I’d estimate that the car took 0.1 or 0.2 seconds to travel the 40 foot length of the race track, giving an average speed of 300 feet per second (200 mph!).  The great part about this “sling shot” design is that the car is accelerated by the surgical tubing spring throughout the first 30 feet of the track – until the surgical tubing is completely unstretched.  “Beautiful!”

 

Ridiculously Large Jacks

On June 18th, Milwaukee Makerspace participated in The Great Milwaukee Race as a challenge sponsor.

Great Milwaukee Race 2011 - Ridiculously Large Jacks

The Great Milwaukee Race is a scavenger hunt/series of challenges across downtown Milwaukee that was started in 2010 by Fit Milwaukee and friends.  This year’s event was put on by Fit Milwaukee, AJ Bombers and Performance Running Outfitters.  In 2010, 50 teams of 2-4 racers competed in the inaugural race. This year 75 teams raced throughout downtown Milwaukee and along the lakefront to find all 10 of the challenge locations and get their passports stamped.

The post i made a couple weeks ago (I’m welding! I’m a welder now!) about my Ridiculously Large Jacks was a preview of the challenge that we would run at the race.  After the initial batch of jacks was finished, Sean, Kevin, Adam and David helped me fine tune the game a bit in our hangar before the event itself.

Shane helped me run the event on race day and it worked like this:

  • Team would decode the clue to our location and decide on when they should come to our station.
  • When they showed up, they had to nominate two players.
  • One player was the bouncer and was in charge of bouncing and catching a kickball.
  • The other player (the grabber) donned a pair of gardening gloves and had to pick up the jacks.
  • On the first bounce, the grabber would have to pick up and hold onto one jack before the bouncer caught the ball.
  • On the second bounce, the grabber would have to pick up 2 more jacks while holding onto the previous jacks.
  • Repeat for 3 and 4 jacks.

The game only took a couple of minutes when done correctly, but some teams were faster than others. We also saw a variety of techniques.  Some grabbers would try to stash the nearly 12″ diameter jacks under their arms.  Some folks spread the jacks out between their hands and used them like claws to scoop up the remaining jacks.  One women even stashed the jacks in her running shorts, but they were a bit heavier than she bargained for.

We were stationed at the underpass at water and pearson, across from Trocadero.  After watching what was happening for a while, the Trocadero bartenders popped out to see what was happening up close.  We invited them to play a game and they did pretty well!  Another couple came by to watch and started laughing at the silliness they saw so we invited them to play as well.  They had a few close calls with some wild bounces, but took care of the round with only a couple of do-overs.  They looked pretty happy by the end of the game.

Great Milwaukee Race 2011 - Ridiculously Large Jacks

We heard really good feedback from racers and the organizers of the event.  The game was odd enough to give people pause before they jumped in, but easy enough that it could be completed in a couple of minutes.  The fun we had with this has led us to discuss making some more oversized games to bring to parks in the area. Stay tuned for more info on this front.

Thanks again to Fit Milwaukee and the other Great Milwaukee Race organizers for letting us be a part of this event and thanks to the racers for being such good sports!