Bedroom update 2

This morning I had to take care of something for work, and Kaitlyn headed over to the house before me and got the baseboards coated in Citristrip. By the time I got there they were ready to go, and we spent a while scraping the paint.

This part is gross, but… I got really pruney inside my rubber gloves. Not fun!

It also became clear that we need to think more seriously about popping these off and really finishing them well outside. It just isn’t that easy to get the edge that’s close to the floor. I read an internet tutorial, and it worked out pretty well. Fist you insert a couple of flat blades in between the wall and the molding:

You have to use really thin blades to get in there, and I already found out how easy it is to bend a corner. I might have to grind that off…

Anyway, the next step is to stick a pry bar in there and carefully work your way around all of the finishing nails to pull the trim off.

To our surprise, this baseboard is actually two pieces. There’s a small decorative piece at the top that came off with just a little patience, but the bottom board is plain and attached much more firmly. I think I’m going to get them off, but I had to call it quits for today. 

Another surprise from the house is the number plate.

What’s up with that? 

Apparently this used to be illuminated! I’m not sure if it’s on a switch, or what. It wouldn’t work very well with the numbers that are on the glass right now. I’ll need to do some work to get some back-lightable numbers, in case I ever get the illumination back.

12-16 volts… that means there’s a transformer in the wall somewhere! Next time we go back I will bring a multimeter to see if it still works. 

Bedroom Update 1

One of the first places we got to work was the bedroom, the one we want to be our room. It’s the one without water damage, and it is the farthest from neighbor’s houses.  Over the last few weeks we have stripped off all of the wallpaper and have prepped the walls for plaster repair.

Rookie mistake, we forgot to put down plastic first. We plan to redo the floors before we move in, but…. it just wasn’t good.

Better… for it all cleaned up, plastic down, as now we start on the molding. We spent about 10 minutes trying to sand it, and it was a stupid gummy mess that wasn’t going anywhere. Now we’re using Citristrip.

It goes on like spreading jelly, and it doesn’t smell too bad. I don’t bother with anything but safety glasses while applying it, but I use rubber gloves and a respirator while scraping it off.

This is what it looks like after two rounds of citristrip, and some rubbing with a scrub pad soaked in mineral spirits. We think it might be worth doing it all, and staining it. 

That’s going to take a while though! My P100 respirator wasn’t doing anything for the fumes, so we took Penny out to Orchard Supply and picked up some cartridges rated for organic vapor. After getting some box fans for enhanced ventilation I might get to keep some brain cells. 

Bonus picture of Penny in her OSH gear!

Room equalization

This is a topic that I’m still fairly shaky on, so anybody out there reading this as a possible reference should probably take this all with a grain of salt. After building the LX521 speakers I could tell that they weren’t delivering precisely the sound that I know that they’re capable of when they’re set up correctly. As you’ve probably seen in photos, Siegfried Linkwitz’s home does not have any visible acoustic treatment, just some normal ‘stuff’ around the room. Furniture, a nice rug on the ground, nothing like walls full of acoustic foam or avant garde looking diffusers. It’s just a regular room, and most people who build his designs agree that you don’t to do anything special to get the good sound.

Before we go too much farther, I should say that there are two different things that I’ve noticed about the sound in my system that differ from what I heard when I auditioned the original. First, I hear a bit more of the room in the bass response than expected. Things boom/echo just a bit, and its’ the difference between a natural sounding reproduction of a sound that can truly fool you, and the sound of a speaker in a room. We’re not *quite* there yet, though it’s miles better than what I had before. The second part is that there’s a bit of imprecision in the imaging. In the demo I could very plainly localize sounds in space, like I could hear a xylophone player moving up and down the keys and tell the left/right position of each key. That might sound like a wild claim, but that’s what I heard and what convinced me that this thing was worth building. Having my TV between the speakers may be hurting the sound a bit, but I think there’s more that needs to change than just that.

I’m setting out to learn how to improve the sound of the speakers in my room, and I want to be able to do this well enough that when we eventually move I’ll be able to repeat the process with a reasonable certainty that I’ll be able to make the stereo sound good there too. I’m using a program called Room EQ Wizard (REW) to perform measurements. I use a Behringer ECM8000 room measurement microphone that I’ve had for years, a small powered mixer, and my computer sound card to capture the sound. Based on the reputation of the microphone and a loop-back measurement that I did with the rest of the signal chain, I think I have a fairly accurate measurement system…. if I can figure out how to use it right.


For my first measurement I put the microphone on a tripod positioned at the spot where my head would usually be, and ran a test sweep from 20hz to 400hz. I did a few more, but for the purposes of room equalization I thought that I was interested in things below 200hz.

raw measurement

The first thing that you’ll notice is that this response looks totally ragged and nasty. It’s hard to say exactly where the average is if it was ‘flat’, and there are clearly peaks and dips of 10db. That’s partly because this is a real in-room measurement, the room isn’t treated with much of anything, and it’s like a big echoing box. Concrete floor, flat ceiling, thin rug that doesn’t cover much, and not much stuff on the walls yet. Regardless, there are some good things about it. The response doesn’t drop like a rock below 30hz, and I can tell you that the woofers really made some impressive sounds in the mid 20hz range. The system can do bass, but the room still needs help. Lets see what we can do.

After collecting this data I opened the REW equalizer window, and I selected “miniDSP” as my equalizer so that the program would know what it’s allowed to do in terms of suggesting correction. I assume that some of the other selections have more or less EQ bands available. Next I had to come up with the ‘target settings’. This is what tells the program what you want the ideal system to do. I have some trouble with this one, knowing what to set. I think maybe this is where a sweep to more like 20khz would have given me more information about where the average is supposed to be. Regardless, lets give this a shot.


I picked 72db as a target level, set the target as flat with a 24 db/octave rolloff at 20hz. For a full range equalization I hear that you are supposed to set a gradual rolloff above 1 to 3 khz, but I’m mostly interested in taming room modes here, and those are all well below 1khz.

In Room EQ wizard I clicked on the “filter tasks” tab and then “match response to target”. It twiddles things around for a second, and then gives five parametric EQ settings that shifts the response to something closer to the target.

target response

Here you can see a brighter red line that is closer to the blue target, and a brownish line that’s the original response. The bright red line is the predicted response if I load the EQ settings. I’m able to save those to a text file and then use my MiniDSP software to read those, or I could enter them manually. Clicking “eq filters” let me see what those are; they looked like this:

filter suggested

Overall it’s a few sharp cuts at specific frequencies, and a broad boost at 40hz, giving the flatter response. I loaded these into the second configuration slot on my MiniDSP, and now I can flip back and forth between the unmodified and equalized versions. That has been very interesting.

Subjectively it sounds as though most of the room ‘boom’ is gone. However, I still somewhat prefer the unaltered version. The equalized version seems to take too much of the bass away. That may have to do with my target curve, or it may have to do with the settings when I clicked “match response to target”. The MiniDSP 4x10HD allows four configurations to be stored, so I could even try a few different versions and audition them each without leaving the couch.

I’m going to hopefully meet with some local audiophiles to discuss this more, and when I get a chance I’ll repeat the measurements with a few changes. Other than dialing in the available EQ, I think that my next step might be to hang up something cloth on one or more walls to absorb some of the sound that’s bouncing around. It’s a lot to research, but I’ll keep reporting back as I figure it out.


LX521 Speaker build- the Hypex multi-channel amplifier

It’s about time I had an update! This is basically skipping to the end from the last post, building cables, but I’ve been pressed for time in getting them built so I didn’t keep blogging as I went. I have a few pictures of putting the cabinets together, but it’s boring. I didn’t design that part, and I’m not a master craftsman with fancy insight into how you’re supposed to do woodwork. Hopefully the amplifier is a little more interesting.

The LX521 is a four-way speaker with an active crossover, which means that a pair of them need a total of eight amplifier channels. In order to provide uniform sound, all eight channels need to be identical. The amplifier that the designer uses is the ATI 6012, a 73 pound monster that costs about $2800. It’s an excellent piece of gear, but I was trying to keep the budget a bit more reasonable. A pair of Outlaw Audio Model 5000 could have also worked for about $1200 total, but then I’d need to put two 50 pound amps someplace. For just a little more than that I was able to put together a 25 pound amp that keeps everything in one box, and theoretically measures a little bit better. Also, I think that the more you build for yourself the more fun it is!

The amplifier I put together is based on a Hypex UCD180HG class-D module. I couldn’t really figure out precisely what their fancy voltage regulator upgrade would do for the sound, so I skipped it. If you have a dedicated listening room with soundproofing and are *really* into this stuff, then maybe you can give them a try (or go hog wild building with the Ncore modules). Now that I’ve built it I realize that this is dumb, but I used two of the 1200 watt switching power supplies, the SMPS1200A180. There is no way in hell I need that much power. Maybe I could throw a rave some day, but for now it just means that I have a bottomless pit of reserve power that I’ll never touch. By my best estimate, as loud as I’ve turned it up I don’t think I’ve used more than a few dozen watts yet. Hey dad, that means you could run these off of a solar panel pretty easily!

Anyway, on to the case and construction! I used the Modushop Mini Dissipante as the basis for the enclosure. I did some calculations of waste heat and fin area and all of that, and I must have messed up a decimal place or something, because I definitely didn’t need all of that cooling area. Oh well, I guess the parts will just last longer since they run cool.

The finished amp looks like this in my living room:


It’s just a plain aluminum panel with an on/off switch. Minimalist, right? The next step will be to make the guts look so nice.

The amp modules have a blue aluminum T-shaped piece with two M3 holes tapped in it. I decided to put all of the holes into an interface plate, and then bolt the plate to the heat sinks. First I drilled and tapped some holes in the aluminum heat sinks, as shown here: note that I used an old T-shirt to protect the kitchen table, and the glass of beer with a lime in it was in fact a mexican style beer by the local brewery, 21st Amendment.


Next I laid out the interface plate using some calipers and an automatic center punch to give even spacing. You can see that tool in the upper left corner of this picture. This is really useful for achieving a medium level of accuracy in an apartment with hand tools. It’s not like when I had a techshop membership and would do this stuff on a mill, but it at least keeps the hole positions accurate enough that I can generally get them to line up.


There are two 1/4-20 pan heads at each end of the interface plate, and if this were going to have a really significant heat load then I would have used more of them (and a different head) to ensure solid contact along the full length of the heat sink base. It was reasonably convenient though, and I’m not producing that much waste heat, so i thought it was a corner worth cutting.

The power supply module comes with six M3 screws already installed, holding a compression piece against an L-shaped plate. You have to take these out in order to have access to tapped holes to get this face against the heat sink interface plate. You could mount another way, and the manufacturer even says you can just let this thing hang out in free air, but I know that if I keep things cool they’ll last longer (like to pass down to my kids some day).


The amp module is surprisingly small for something that can do 180 watts and drive a one ohm load. I slathered on the heat sink grease before attaching them to the interface plate.


Once they’re all mounted it’s ready to mate up with the heat sinks assembly. You might be able to see that I did some really rough and rowdy countersinks to get those M3  screws to sit flush below the surface of the interface plate. I have some slight concern that some day one of them could be pressed against a capacitor and wear through from vibration and short something out, but probably not. I’m just documenting that concern in case anybody cares, and as something to think about for next time.


I know you wanted to see this all greased up. Look at those nasty countersinks! Eww!


IMG_6465 IMG_6466

There it is! Four 180 watt modules with a 1200 watt supply, all ready for assembly.

And…. Oops. I built them the same, and that’s not going to work for wiring. I had to redo one of these.


This is a really useful tool that I wanted to take a minute to talk about. This is a ratchet offset screwdriver, and it lets you reach into tight spaces that a regular screwdriver can’t reach. A well designed product won’t require this, but sometimes the designer just can’t be bothered to think about tool access… so that’s when you break this out. The best one I know of is what they used to work on medical linear accelerators at Siemens, and it’s the Chapman. You’ll notice that compared to mine, the ratchet area is much smaller, and the divisions between ratchets are signficantly smaller. That lets you reach into smaller spaces and tighten screws when you don’t have space for much rotation.

This is how I connected the mains power to the front panel toggle switch. It’s a DPDT switch rated for 20 amps, and I made sure that it was large because I wasn’t sure what kind of inrush current the power supplies would draw. As it turns out, they seem to have a nice polite soft-start, or else their inrush is much smaller than the spec sheet indicated because they’re just getting US voltage instead of the 230V that europeans are working with.


This ended up being a little easier than I expected. The power supply sends a few leads over to the terminal blocks, and each amp takes a positive, negative, and ground input for power. The worst part was all of the crimping. I think I ended up doing about a hundred crimps. There’s a reason they make machines to do that.

In the lower right of this image you can see the twisted pairs of wires going to the speaker output jack, and the black cables soldered directly to the XLR jacks. I need to go back and get everything twisted and trimmed more appropriately before I’ll say I’m done, but for now it works.


The last thing I did was put channel numbers on each of the amps so that I can keep things straight, and I checked a test signal on each to make sure it wasn’t putting out a measurable DC voltage and a full range music signal sounded right with one of my old speakers. During this step it was really promising to hear music coming out of my old speaker that (I think!) sounded better than the eight year old cheapie receiver that had been driving them.

One thing you’ll notice here is that I used blue paper painter’s tape as a temporary measure to keep anything from shorting out. The maximum voltage in here is 48 volts relative to ground, and 96 volts from the positive to negative terminals. Everything is firmly connected to screw terminals inside of insulated blocks, but a little bit of metal peeks out at the edges, and so I didn’t want to take any chances on something shorting out. The end goal is to have the terminal blocks bolted to the bottom panel of the enclosure in a neat row so that the wires can be routed in a clean and proper way.

The 120V mains line goes to the switch on the front panel using a tightly twisted pair of 14 gauge wires in some ring terminals. I used fork terminals for the rest, but for 120VAC I used insulated ring terminals so the screw would have to fall completely out before the crimped part could fall and contact something else. The rear panel has a three-prong jack, and there’s an earth ground that’s similarly connected to the chassis (you can make that out in the photo above).


The back of the amp looks fairly neat thanks to Front Panel Express making the panel for me. The large cutouts in thin aluminum and added threads saved me a *ton* of work, and I know they made it look nicer than I could have. I’ll add more labels when I’m done, but for now I know how they’re laid out well enough that a prompt of “1” and “2” is enough that I won’t plug something in wrong. If I did do that, it would blow up my tweeters.


Ok, so that’s all I’ve got for now. I’ll leave you with a cell phone picture of the speakers and amp in the living room. They sound pretty good. I hope you’ve enjoyed reading!


Dog pictures

Tonight I was looking through some of my pictures from Instagram and Flickr, and I thought, “I should totally round up all the pictures I’ve ever taken of dogs”.

This might not be *all* of the dog pictures, but here’s a quick stab at it:

Black-out poems!

My friend, Alexandra Naughton, recently created an E-book of poetry created by taking a black marker to Billy Corgan’s book of poetry. It’s a technique that’s sometimes called black-out or deletion poetry, and I thought it was a really cool idea.

I was inspired to give it a try, and so I went looking for material. I figured out that there are some emails and messages that we send and receive that have another message to show, and so I started collecting those emails .

If you’ve ever received one of those emails that make you say, “wow, this is crazy. I need to show somebody.”, then send it to me at ! If you’ve been broken up with over email, had a crazy ex-landlord, a school project partner with insane excuses, send them my way!

Have a happy new year!

Picking one day to make resolutions for the new year is not a good idea. We can do this any day of the year, and indeed we should resolve to make change whenever we recognize that it’s a good idea. What’s special about today is that we can take it as a reminder to look back, to look forward, and see our lives in a different scale of time than what we do on the day-to-day. What have you been up to for the last 365 days? Has it been a good year, are you making the most of your limited time?

I’m thinking about how it’s gone as I look toward the future. This year I’ve found a job and an apartment of my own. I’ve met many wonderful people (including Kaitlyn!) and reconnected with old friends. I’ve traveled, practiced old hobbies, and tried new things. I want to thank all of you for being a part of this, and I hope you all have a wonderful new year. Go out and make 2014 the best year yet!

And don’t forget to take pictures!

Lasers, sensors, cameras! A 3D scanning backpack for UC Berkeley (part 1)

About a year ago I was contacted by a professor at UC Berkeley who had found my resume online. Her team had produced a backpack device that was capable of collecting data to generate 3D models of internal spaces, and she needed a new backpack designed that would be smaller and lighter. I took this on as a part time project while I was looking for full time work, and it was a fun challenge. I’ve talked about this project in the past, but they finally went live with the backpack so I thought it was time for a post.

You can read all about Professor Zakhor’s original backpack on the EECS website. This is what they had before I arrived. It weighs over 70 pounds, is built to hold an changing array of sensors and cameras, and I understand that it went through many iterations and changes as they developed the software techniques that could turn the data into usable 3D representations of internal spaces. My job was to provide a compact, lightweight platform that provided stable and well defined positions for a suite of sensors. Many of the sensors needed to be adjusted to different angles to accommodate users of different heights, or movement through different environments.

The sensors on the version of the backpack that I designed include:

That’s it for now, but it’s possible to attach other pieces as needed. I sourced an embedded PC that seems to have the processing power to shove all the data from those sensors into some SSDs, and the entire collection of parts is powered by several lithium ion batteries. The batteries are an off the shelf solution, and have a good amount of intelligence and safety built in. We run the batteries in series to create a voltage from about 18 to 60 volts, and a DC-DC converter regulates this to a main system voltage of 24 volts.

Here’s a creepy render of the system on a mannequin.


Check back soon, and I should have an explanation of what each of the sensors is doing, and how I designed this thing!


Bike tour 2013, the rest of it!

One of the big differences between doing a solo bike tour and riding with friends is that when you’re not riding it seems like a lot more fun to socialize with everybody than it is to isolate yourself with a cell phone writing blog posts. Especially with a truck to move us along and coordinated meals, there was a lot less time to just sit around blogging.

Of course that doesn’t stop me from taking pictures along the way, so here are some of those!

This is one of the bridges that we crossed, and if I remember right we were able to zoom over it quite quickly.

As always, the California coast is gorgeous.


We had to stay lotioned to avoid burns.

I thought this irrigation pond was cool.

We had to cut through a field full of vegetables, and some rubber bands had spilled out onto the ground.

This is what it looked like for a while. I was glad to have far tires.

This is how I imagine touring across the Midwest looks.

Hey, free rubber bands.

Comically large taco salad.

We need all this food for energy.

This was out only link to the outside world in Big Sur. Oh, and the wifi once we got the password.


Some people have no respect!

The aftermath of not enough lotion. 90% of that was one morning before lunch.

That’s all for now! We camped three nights and did around 150ish miles, and I think I learned a lot about touring with friends. It’s fun in a different way, but still a blast!

Snap away!

I see that I haven’t posted any new projects since February, but I’ve definitely been keeping busy!

Just before my last photo post I flew up to Washington and did some photography for my friend Molly, shooting her bikini project.  Check it out!

Just before that I shot Oakland Nights… Live! on a BART train, and then right after that I flew to Wisconsin for Thanksgiving with my family. In February I scouted out a “post apocalyptic folk drone-core doom” band by the name of Feral Booty, in March I shot a power soccer match in Berkeley, and also Oakland Night… Live! in their new location!

All of these photo sessions felt like a pretty steady progression from what I’ve been up to (though flying to Washington for a project was special and out of the norm!), but things have recently started to intensify even more. In late March I got a text about a super secret event in an undisclosed location, and boy was it something! Check it out- and if you have a Flickr account and your settings adjusted for it, you’ll even see some ‘adult’ content. Some folks had taken over an old disused movie theater, and the show on stage was very “anything goes”. Very exciting!

I had one more ONL show since then, but then this week something kind of special happened. I was walking home from work, taking a different route than usual when I saw a car across from the post office that had been absolutely covered in bird poop. A family of herons had made its home up there, and somebody parked under them for a few weeks. I took an Instagram picture and got a good reaction from my friends and family:

shitty car

It was cool, but I felt like I could do better if I had the right light and a better camera. I looked up this website to see what direction light would be coming from at different times of the day (, and saw that walking there before work would make the light come in from the front of the car, the side by the sidewalk, so that was maybe as good as it was going to get- specifically really darned early so that light would have some good directionality and color. I decided that since the car could get towed any time there was no time like the present. I said, “I totally should!!” and set my alarm. It was really hard to get out of bed at dawn, but then I reminded myself, I TOTALLY SHOULD TAKE THAT PICTURE!!!

It didn’t really make me less tired, but it was enough to get me out the door.

I was borrowing a super wide angle lens from UC Berkeley, and so I brought that along and took this picture, which I posted on When I went to bed a couple of dozen people had upvoted it, and there was no count on how many had seen it. When I woke up it had made the front page, and over 200,000 people had seen it. Now, in less than a day nearly three quarters of a million people have seen my picture!! This is the most exposure, by far, that any of my images has ever had, and I’m totally psyched.

many views