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Cheap, Easy Wall-Mounted Monitors

May 27th, 2017

For my home recording rig, I use a 7×3′ desk (made out of an old door) to hold my audio interface and any instruments or effects I’m using - keyboards, pedals, mics, preamps, etc. I don’t like that real estate to be cluttered up with stuff that could live somewhere else. The computer, the speakers, lighting and monitors should ideally be sitting somewhere other than the desk.

At my last place, I solved the problem by attaching picture hanger D-rings to the backs of my monitors and hanging them from drywall screws. That meant having a big ugly piece of wood spanning at least two studs, and lots of room for error when it came to making things level and straight.

So here’s my new method. It cost about $10, looks a lot nicer and is a lot easier to get things hung straight.

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It’s all based on this stuff I found at Menard’s. It’s a rail used for hanging garage shelving. It’s steel and it already has holes every 8″ which should line up with the studs in most walls. I bought one 7′ piece for hanging on the wall and a smaller 40″ piece to cut up and attach to the monitors.

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To cut the stuff, I used a jigsaw with a fine-tooth metal cutting blade.

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I also used a drill press and a step bit to drill the holes for the bolts that go into the back of the monitors.

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An orbital sander with a 60 or 80 grit disk is handy for removing the burrs so the screws fit tighter.

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I cut the smaller rail into 8″ chunks, and drilled two holes 10cm apart, which will line up with the mounting holes on the backs of my monitors.

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To hang the long rail — a drill, a level, some long drywall screws and some washers.

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I used three screws, figuring the material is strong enough. The idea behind using such a long piece is that I can slide the monitors anywhere along the rail. The center screw is going into a known stud. The other two I didn’t check because it’s a plaster and lath wall and the wood lath should hold it well enough. Going into drywall you may either want to be sure there’s a stud or use some heavy-duty anchors.

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Detail of the wall rail. The brackets on the monitors are the same material but upside down. You can see how they will interlock that way.

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The back of the monitor without the bracket. I’m using just the top two holes.

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Back of monitor with bracket installed.

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Detail of the bracket. The top of the bracket will click into the bottom of the rail.

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The monitors installed.

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And here’s everything hooked up and powered on. Now, if I want to set up synths or mics on my big table and need to move the monitors down, I can. I can also make pegboard panels that hang the same way to store cables and stuff. And no more wasting space on the table with monitor stands.


INA217 Microphone Preamp

July 17th, 2016

This project incorporated a lot of firsts: my first working circuit powered by mains electricity, my first preamp and the first time I actually took some design initiative — I designed the (very simple) power supply and incorporated a clip detector into the circuit.  I opted for a “wall wart” input to supply phantom power for a couple reasons.  First, it kept the power supply design simple.  Second, it allowed me to eventually use the same supply to get power to multiple preamps, so long as I add the same input jack to all of them.

The preamp design is straight off the INA217 op amp’s datasheet.  The clipping indicator design was sourced from the Elliot Sound Products website. I source a lot of my parts from ebay, looking for multiples of the same item so I’m always building an inventory for future projects.  As a result, I have no idea how much the total supply cost is.  The expensive parts were the transformer ($24) and the case ($12).

Some other design considerations were to use a 1/4″ TRS jack instead of the standard XLR connector.  They’re cheaper, and I was intending from the get-go to incorporate the preamp into a patchbay setup.  Using a TRS connector doesn’t change its ability to take a balanced line.  What it does do, however, is allow the careless user to damage a mic by using a TS cable with phantom power.  For the single-engineer home studio this isn’t a problem.  It actually gives me a really good excuse to keep my roommate from using my gear.

The op amp’s datasheet does not specify a design for balanced output, and while that may be a minus on a commercial unit, it’s of little consequence to me since the pre will always be in my control rack with about a 3 foot cable run to the audio interface.

I opted for stripboard construction over more compact methods because I just wanted a working, reliable preamp.  For me, that requires plenty of soldering room.  I actually like the industrial look and size of it.  Perfboard irks me to no end and at the time I hadn’t yet worked up to etching.

For the phantom power supply, I found a 48v 375mA wall wart on ebay and rehoused it with a standard output power jack in the front and a standard mains IEC connector in the back.  To get the power to the pre, you can use a run-of-the-mill pedal daisy-chain cable.  With microphones typically consuming 10mA of power tops, there’s plenty of capacity in this supply.

Circuit design sources:

Schematic:

Stripboard Layout:

The schematic for project 146 specified a pot between pins 2 and 5 of the TL072, and in the notes, it is recommended that the pot be replaced with a 10k resistor for fixed-gain applications so I ended up going for the 10k resistor.

I had a hard time finding the right pot, but in the end — contrary to what’s recorded in the schematic — I went with a 2.5k reverse-log taper.

Build Photos:

Designing the circuit board.


Building the circuit board.


Putting the box together.


Rehousing the phantom power adapter.


Label of the phantom power adapter specs copied from the original housing.


The transformer.


Power supply detail.


Installed circuit detail.


Power section all put together.


Open box with front panel.


Open box with rear panel.


Top View

Finished Preamp:


Front panel: Pilot light, +48v input, phantom power switch, phantom power indicator, clip indicator, gain pot.


Rear panel: Input (TRS), Output (TS), power on/off switch, mains power jack.


Hooked up and powered on.


In the rack.

This pre definitely holds its own alongside the stock preamps in my interface, which was exactly what I wanted: simply more channels of clean gain. Considering the ART TubeMP retails at about $50, this maybe wasn’t the cheapest option. On the other hand, the DIY build is more elegant, not to mention repairable — should something go wrong.


Bike Upgrades for Touring

January 26th, 2013

Trek 850 Touring Bike

I went on my first bike tour in august with a minimal amount of upgrades to my 1983 Trek 850. It was awkward, but I did pretty well with what I had. Now, I’m taking the winter as an opportunity to get ready, piece by piece, for the next trip. I chose the fun part first: new handlebars.

Trek 850 Touring Bike

I got a set of trekking handlebars from Nashbar.com for $15 and wrapped them myself. I was able to reuse the gear shifters and brake levels without changing the cables or anything, so it was a really easy upgrade. And they feel much better than the flat bars. I don’t know why trekking bars aren’t more popular in the U.S.

The rest of my setup includes a new Axiom Journey rear rack, a new Banjo Brothers quick release handlebar bag (with built-in map holder), a frame-mounted Blackburn pump, and a handmedown kickstand I found lying around.

I’m also using Wald fold-out baskets attached to the rear rack. They’re supposed to be permanently installed, but I’m experimenting with using them as removable panniers. I taped and zip-tied pegboard hooks to the top and attached a bungee along the bottom to secure it to the rack but still allow it to be easily removed. For touring, I’ll be getting regular panniers. You may also notice the knobby tires. Those are my studded winter tires. For now, I’m using this bike as my winter commuter. Next year I’ll have a utility bike and I’ll be able to save the Trek from all this disrespect.

Technically, this is a mountain bike, but only technically (in my opinion.) It was the first mountain bike Trek built. In those days, that pretty much meant a tough road bike with low gears and wide tires. Since then, mountain bikes have gotten smaller frames, suspension forks and other features which make them poor touring-conversion candidates. This bike has way more in common with modern touring bikes than it does with modern mountain bikes. It has a long wheelbase, steel frame, rack braze-ons, room for any tire width, triple chain rings, 26″ wheels (more of a world standard than 700c) and mounts for two bottle cages.

Trek 850 Touring Bike

The other planned upgrades for the winter:

  • Front rack
  • Fenders
  • 26×1.75 touring tires
  • Front and rear panniers
  • Bike computer
  • Compass
  • Rearview mirror

And where am I going? I’m hoping to volunteer for the State Parks working on prairie restoration for a short trip in the spring, and then in the late summer, pick a route according to one of Adventure Cycling’s maps.


A cheap solution for a shitty couch

August 16th, 2011

When I moved into my friend’s house in April there were three couches, a console TV and a dining room table in my new room. I decided to keep one of the couches in there, and we moved the rest of that stuff downstairs.

My initial plan was just to sleep on the couch, but the springs were removed and replaced with a couple of motors from a massage chair to make the couch vibrate, as well as to scare any squirrels living in the roof or wake up anyone who may be sleeping anywhere in the house. When you sat down, you just sunk into the back of it, almost as if you were a quarter about to get lost in the cushions. So I built a loft bed with a foam mattress to sleep on. I’ll publish the design some day.

As I was reading and sinking into the cushions and getting irritated, I looked up at the slatted support structure I used for my bed, and I got an idea. I went into the basement where I knew there were some scrap 1×3 furring strips and I experimented with fitting them on top of the couch frame.

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After sticking some temporary supports under a few cushions and feeling it out for about a week or so, I eyeballed what seemed to be a good placement interval for the 28″ slats.

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To make it secure, I ran two 5′ 4″ furring strips underneath the slats and used 1 1/4″ gold screws. The corners each got two screws diagonal from one another to keep the boards at right angles.

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It’s a much more stable couch now. It feels a lot firmer obviously, but it’s comfortable. And the supports slide out all in one piece with a little work. Still a junky looking couch, but who am I trying to impress?

I could’ve gone to a thrift store and bought a different couch with everything in tact. The estimated cost would be at least $40, plus the hassle of borrowing a truck and moving it, plus the hassle of throwing away the old one. (Also, I designed my bed so that the couch fits perfectly underneath it, with a long shelf running along the back.  I’d be losing design points.)

I also could’ve tried to figure out how to respring it. Uh-uh, no way.

Instead, I spent about $8 to rig up wooden supports — $4 on wood and $4 on screws. Nothing was wasted. When I get a spring mattress someday, I’m going to cut up the one I’m using now and use the foam to re-stuff the couch cushions.


Guitar Design

June 12th, 2008

I get into these phases which, if you’re on the periphery of my life, look like ruts, but they’re not. I get an idea and I want to run with it, and that gets in the way of what I’m “supposed” to do.

I’ve completed my guitar design, and now I have a general drawing of the whole thing, left and right sideview drawings (to show the contours), a wiring diagram and pickguard layout, and a rough routing diagram.

On top of that, I got another idea for a guitar design, and it threw off my sleeping schedule. I was laying in bed a few nights ago, trying to fall asleep, and it hit me. I stayed up sketching it out until about 4 a.m. I’m not saying what it is yet. I want to get the plans done first. It’s a unique idea that there may be a niche market for. It would also be a good one to start out with as a practice build–but that’s all I’ll say! I already bought a neck off of Ebay.

I’ve been harassing Geek Squad the best I can. I sent a customer complaint online and by phone, demanding my computer be done by Saturday, and I’ve been calling them constantly. I had to explain to one of them on the phone that it doesn’t need to take a week for something to get shipped from Minneapolis to Kentucky. Every time I buy something expensive it gets shipped two-day Fed Ex. Geek Squad, on the other hand knows they’re losing money when a repair job is under warranty and instead goes with the pony express. Figures.