This January I thought it might be fun to change up my look, so I did. It’s been a lot of fun!
I was recently out to brunch, and as I sat with my friend and coffee waiting for food I noticed that a nearby table had paid and left, but did not even touch a plate of delicious berries. I knew that the berries would most likely be dumped unceremoniously in the trash, and so I had to act quickly.
Looking around to see if anybody would notice, I got up and grabbed that plate, and brought it back to our table. My date was mortified at first, in less than five minutes she polished off half the plate.
This happens all the time. People are starving all over the world, and we’re throwing delicious healthy food into the trash. If it doesn’t look sketchy, you totally should help yourself! Just make sure that they’re really done with it.
I thought to myself, “You know what would be fun? Tutoring some kids on track to be engineers, but only if their parents are cool enough to wink at the whole thing and have some fun with it.”
The cool thing about Craigslist is that you can throw something at the wall to see if it sticks, cast a line to see if anybody bites. Sometimes it works out beyond your expectations- other times there are no responses whatsoever, or it gets flagged for removal.
Here’s my latest:
One thing that I’ve been seeing in the news entirely too much lately is how police in the East Bay have been dealing with protesters. They are wearing a lot of riot gear, and are quickly resorting to spraying chemicals and gasses, beating with weapons, and otherwise doing things that send people to the hospital. This isn’t right- no matter where you stand on the issues at the center of the Occupy movement, this is fascism. I wouldn’t want to see this kind of treatment against anyone.
The first example that comes to mind is this:
I don’t know what anybody’s yelling, but they’re just yelling. That’s no excuse for a baton to the guts, is it? I heard she lost her spleen to those blows.
Another recent event was the May 1st General Strike with protests and demonstrations. The police showed up in full riot gear with each officer that I saw hanging a carabiner full of zip-tie handcuffs. Here’s a gallery from that:
SF Gate Coverage of May 1st Protests
Some people (not necessarily protesters) showed up in black hooded sweatshirts with their faces covered, and tried to smash things. I’d like to think that we can get our points across without smashing things, and affect change without violence, just on the power of our words and the presence of our numbers. Wouldn’t that be great? Amazingly, technology has allowed us to do things that sound incredibly utopian, things that don’t really sound plausible. For example, when everybody and their mother shows up at the same place and same time, to collectively show their disapproval. Thanks to SMS messaging it happened in the Philippines in 2001, and with Twitter in many countries in 2010 in the Arab Spring.
An incident that hit a little closer to home happened this past fall. I saw a man loudly harassing an elderly woman on Lakeside in Oakland. By the time I got within 100 feet there were already two men defending her, and at least three other people who didn’t look like they’d be worth much in a fight who had their cell phones out and recording videos. I’m ambivalent about this. On the one hand, their cell phone videos could have been useful for prosecuting the guy later if he got violent without provocation. On the other hand, I didn’t see anybody using their phones to call the police. I have to cynically wonder if they were thinking about helping the old woman, or getting a hundred thousand hits on their youtube accounts. Fortunately the man left. I don’t know if the threat of being recorded caused him to re-think his actions, or if the mere presence of so many vocal bystanders telling him to cool it made him stop. He didn’t seem like a reasonable guy.
Assuming that more people are thinking in their right mind than not, my idea is this- why not have a wearable camera with remote storage, and sends a live feed for a record of what’s going in? The technology exists to make it time stamped, GPS aware, and able to survive having the cellular network shut down or jammed. The non-centralized storage would make it pointless for thugs to steal or break the camera (and if police do this, they become thugs)- the evidence would already be safely stored and unable to be deleted. Adding two or three different cameras that all show the same thing from different angles with identical timing would fill in the gaps in information, and make forgery and tampering very difficult to pull off. Police have cameras on their cruisers, why don’t we have them on our protesters?
Could something like that cause a major change in how we exercise our rights to peaceable protest and assembly, discouraging cops from beating us and from rogue elements from turning a protest into a riot? I hope so.
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.
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!
This is a website that I’ve been reading almost since it was launched. It’s a nearly constant stream of people who have had these moments where they have an idea, make it happen, and then share it with the internet.
Enjoy!