Acting a Little Crazy in Public

I think one of my favorite things that I recently did while on BART was this:

I was minding my own business when fifteen or twenty college kids got on the train, obviously they were really new to BART and really new to the bay area, and one of them sat down next to me and introduced himself to me right off the bat. I was just commuting or going someplace normal, and he seemed like he was just excited to be on a train, so I mumbled something and went back to my book. The kid’s name was Jimmy, and Jimmy didn’t know yet that it’s not standard operating procedure to introduce yourself to ever seat-mate on public transit.

Anyway, four or five stops went by, and it was time for Jimmy and his friends to get off at downtown Berkeley. He walked out, fifteen or twenty excited kids got off, and I a bell went off in my head. Something compelled me to stand up and walk to the door of the now empty train, and I shout right at him through the crowd, “HEY JIMMY!!”

He had a shocked look on his face as he looked at me, and all of his friends looked at me, and then looked at him, and back at me, and back at him, trying to discern why I knew his name and was yelling for his attention. So, with no further explanation I maintained my grinning eye contact with Jimmy and gave him a huge thumbs-up and a knowing wink as the train doors closed. I assume that his friends badgered him for the rest of the night, asking him what that was all about and who I was.

Bike Speakers

This spring I went to my first East Bay Bike Party, and it was really neat. There were a thousand people riding bikes together at night, with lights and awesome stereos on their bikes, and people were wearing costumes. We were mostly law abiding, polite, quiet in residential areas- it was much better than Critical Mass! When I say it was better, I mean that it’s the kind of scene that a person could have some pride in talking about in most places

I saw the kinds of things that people were bringing to make music- they were using boom boxes, a few custom things, and portable DJ speakers on trailers. Some of these were powered by heavy batteries that were driving inverters that regular PA amps were plugged into. By the end of the night I heard stories about people having to be pushed up the hills to get their speakers to the next party spot.

I’ve long had a love for designing and building speakers, and I always keep my eyes out for new technology and ways to make things happen, so I got the idea that I could make a totally cool bike stereo that would be light and loud. Light, loud, and good sound! I hope that I can make it look good too, but my priority is on good sound, as it always is when I approach audio, and on weight. I don’t want it to be any heavier than if I’m riding home from Berkeley Bowl with a good pile of produce (and beer).

My brain started chewing on the design problem in the background as life went on, and from time to time I collected another puzzle piece. The first thing I found was that there are a lot of high efficiency, light weight, high quality “class D” amplifiers. These are the new generation of amplifiers that take advantage of the better (and cheaper) electronic chips that are available today, and make sound by switching on and off very quickly to create a pulse stream rather than modulating an analog voltage, and so their efficiency can be in the +90% range. This lets them sip power from a battery, so I don’t have to carry around such a heavy battery. They also have versions available that take DC battery input instead of AC input from a plug into the wall, so there will be no need to use an inverter.

That was the first step to make it possible; it cut the battery requirement at least in half. The next step that made it possible was the Aura NS6, a lightweight paper coned woofer with neodymium magnet, on sale at Parts Express. Even compared to professional audio drivers, I couldn’t find anything that would allow me to get more bass per pound- not unless I wanted to spend BIG money. These cost less than $8 each when I bought eight in one order, and I am certain that for $64 there’s nothing that will be able to play louder.

I’m loading them up into a pile of enclosures like this:

I used cardboard tube that’s normally sold as a form for concrete columns. It’s fairly strong and stiff, and it’s very light compared to most speaker enclosures. They may not seem very substantial, but the round shape is great at resisting pressure. The end caps are laser cut acrylic (gotta love Tech Shop!), which will be transparent once I remove the protective liners. The laser made it fast and easy, since instead of cutting round holes and doing precise drilling, I was able to place the sheet of plastic into the laser cutter and hit “go”. The other cool thing about the acrylic is that it will let me put glowing LEDs inside the tubes. This will make my bike more visible, and it will be fun!

If you know much about the physics of sound, you probably know that making a lot of bass from something small and light isn’t easy, and it’s not efficient. To get efficiency out of this arrangement, I am doing a few things. The final build will include eight bass modules, four on each side of the rear wheel, and it will be electronically limited not to play much below 50hz. I’ll be the first to admit that this isn’t very low, but I did an experiment back in college to see where most of the bass ‘lives’ for the kind of music you hear at clubs and in concerts. It turns out that the ‘pounding’ bass that you can feel in your body is largely between 80 and 160 hz. There’s a solid component of many bass drums where the initial impact is even higher! Yes, a bass guitar’s low string goes down to around 40 hz, and many styles of electronic music contain much much lower notes- but sacrifices had to be made.

These are light, not especially expensive, and although they’re not small, they’re not too big to fit on my rear cargo rack.

That covers the amplifier and the bass, two of the hard parts, but what about the tweeters and crossovers? Tweeters were easy- I got a pro midrange tweeter with a big horn that plays nice and low, and a smaller tweeter that plays as high as you can hear. No big deal, light cheap and sure to work. The really cool thing is the crossover- this is the component that made me look at the project and go from saying “This is too much work!” to “Yeah, I could totally do that!”

The MiniDSP is the most expensive part of the build, but it does the job of something that would have cost three times as much just five years ago, and barely existed ten years ago. In real time it takes the audio and digitizes it at high quality, and mathematically manipulates it to emulate the circuitry normally used to separate sounds into high, medium, and low pitches to send to each of the speakers. This is the kind of thing that could be done on a circuit board with op amps, and people have been doing that for a long time- but to get good sound you need to use a lot of expensive op amps, you have to do a lot of soldering, and you have to change the values of components based on measured and calculated values specific to your speakers. It’s hard to tweak, easy to break, still not cheap, and there are things you might want to do that are very difficult to achieve in an analog circuit. You can also buy one off the shelf, like the Marchand XM9, but that’s really expensive, and still not as flexible as the MiniDSP.

I used WinISD to simulate the woofers boxes, and with eight of them together I should get an efficiency of nearly 98 decibels per watt, and with the 4×100 watt amplifier I should be able to just produce just over 120 decibels. That’s probably louder than your stereo, and it’s more than loud enough to cause hearing damage and get the police involved.

More pictures coming as I build this thing!



One of the things that I love about taking pictures is the excitement of it. I’m not saying that I like taking pictures because I think it’s exciting- I mean that taking a picture gives me a chance to capture that moment in time when I’m feeling excitement at what I see in front of me, or the possibility of an image.

Some of my favorite photos that I’ve taken have been born of an instant of realizing, “I should totally take a picture of that!” For me, photography at its best is when I can have a moment of “I totally should take a picture of that!”, and capture it in an instant. It doesn’t turn out every time, but when it does turn out I think it’s really exciting. I’d like to share a few examples here.

I was walking through the gym during a day of power soccer games, and I saw my friend Scot Goodman letting a young player have a look through his camera. My DSLR was in my backpack across the gym, and it had a telephoto lens on it at the time, so there was no way I was going to get a shot if I was sprinting around and changing lenses, so I whipped out my blackberry and snapped one.  It may not have the highest technical quality, but I still consider it one of my favorites. Her parents loved it too!

Here’s another one- it was back in early December 2011, and I read that there was going to be a complete lunar eclipse starting at 4 AM. I set my alarm, and it was tough to drag myself out of bed to see the thing. I told myself I’d just head outside in my PJs to see if it was cloudy, and I’d go back to bed if it was. It was a clear sky, and as I saw the first bite of the moon disappearing I had that moment of excitement, and ran inside to pack a thermos of coffee and my gear.

This shot took a little work, and all of my technical fiddling, but the important part was having the moment of excitement where I dragged myself out of bed and went out looking for the right angle for a good shot.

A much more impromptu shot was this one-

I was out walking with a friend, and I grabbed my camera at the last minute because it seemed like something was going on in the neighborhood. She said, “You should take a picture of that!”, and so I did! I ended up liking this shot, the one she thought was exciting, much more than any of the others that I came up with on my own that night.

Another picture I took that was just a “What the hell!” moment, but took a little preparation was this:

For reasons that you may or may not be familiar with, I’ve had some evenings where I’ve been home alone and bored lately. I thought, “Hey, people take pictures of themselves in bathroom mirrors all the time, I should put a twist on that!”, and so I put on a vintage bath robe, set up a flash on a stand (camera left), used a big lens, and I went for it. Pretty goofy, but it’s more or less what I was going for!

Lately I’ve discovered a new toy that allows me capture and share these moments more quickly and easily than ever before. It’s Instagram!

In case this sounds like it’s turning into a commercial, I’ll go ahead and admit that a part of me is cynical about an iphone application that lets you post a small square image with a short list of arguably cheesy effects applied after the shot. However, I do think that Instagram also brings a few positive things to the table. The constraint to a given format forces you to be creative, and the limited number of things you can do after the shot keeps you from screwing around on your phone for an hour trying to create something after the fact. It’s really about the moment and the idea, and what you did to put your phone in the right place at the right time. Sometimes the effects look really cliched and overdone, but other times they seem to add something to the image.

You can follow my Instagram gallery on Flickr to see what I do with it. I hope you like it!

Should I make a website? Yeah, totally!

Have you ever thought of something, maybe a gadget or invention that you wish you could go buy in a store, and then you realized that it didn’t exist? Or maybe you wanted to make a meaningful contribution to a cause, but could not find any existing organization set up to address  that issue? Have you ever had a song stuck in your head, and you struggle to figure out who sang it, and eventually realized that nobody sang it yet?

These situations can be frustrating. Depending on your personal abilities, level of motivation, and free time, you might feel shocked, angry, hopeless, resigned, or… excited at the chance to have found the edge of what’s been done, and to have the motivation to push our world farther. This thing does not exist, but it should. It totally should!

This website is devoted to that moment. It will aim to find and share the experience of finding that edge of what’s possible, and what we do when we get there.