In part 1 of this blog series, I covered the basic design of PurpleBlu2, my first from-scratch Raspberry Pi-powered Wi-Fi speaker. To recap: I designed a speaker system from scratch using some small 2″ full-range drivers (for good quality audio), a Raspberry Pi 3 B+, a small 5 watt amplifier, and a wood box I designed myself.

Now it was time to do the first dry fit. How would it all come together? Had I done my measurements correctly? The second I got home with the cut pieces I did a dry fit. The first thing that struck me was how small it ended up being. I know I’d measured it to be a foot wide, but I didn’t realize how small a foot… was.

I was also struck at how cramped the build was going to be. Everything just fit.


I did a quick test with the amplifier hooked up to my smartphone and to my USB power source. I was stunned at how the system sounded. At this point I was excited to get to the cottage with my girlfriend. My vacation project was ready!


After we arrived and everyone was settled in, I laid out all the parts. It was go-time. I had a few hours of uninterrupted time to do some cuts.

This was going to be my first time cutting wood. It was the part I was most nervous about, as the only tool I have is a Dremel. Regardless, I forged ahead, dry-fitting components and sketching out where I wanted to put everything. “Measure twice, cut once” was my mantra!


My first step was to label all the panels. It might seem trivial, but I didn’t want to make the mistake of making two front panels. I had two side panels that were exactly the right length, and two that were 1/8″ off. Marking those was important too. With everything marked out, it was Dremel time.


I drilled the holes for the standoffs, the speakers, the Pi back panel, and a mount for the USB power connector. As I used my Dremel, I realized I could use it as a makeshift router by varying the depth of the cutting bit. I used this to make space to mount the power connector.


Mistake #3: I didn’t measure the power connector size properly. As a result, the power connector didn’t mount to the panel. I had to drill another hole later. The Pi hole was nearly right, with a little work with the sanding wheel bringing the panel opening to the perfect size.


Next I mounted the Pi and amplifier onto the standoffs. This is when I discovered I’d bought the wrong size of screws. It was also time for…

Mistake #4: I forgot to account for the height of the standoffs when I marked out the volume control knob. I had to go back and bore out a larger hole for the volume control. Whoops.


I took this opportunity to go back and make a new hole for the USB power connector too.


With the holes drilled, I was ready to start my assembly. First I wired everything up and dry-fit everything. My plan was to solder everything, so I wanted to get it right before making the connections permanent.


The last dry fit before I went outside to solder. Notice I’d drawn lines on the base and back panel to mark out where everything would line up. This was more of a sanity check for me.


With the soldering done, I wired up the speakers. I had to take the front panel out a couple more times to cut away more material to make the speakers mount nicely to the front.

Mistake/Lesson #5: I didn’t route out a nice space to mount the speakers. In fact, I pretty much screwed up everything I possibly could with the speakers.

At first I didn’t quite know what didn’t look right. After some staring, I realized what it was. Most professional speakers have a nice “sunken” look to them. They also probably use tools like compasses to draw proper circles. I didn’t have that.


The right speaker wasn’t bad, but the left was a mess. Plus the screws I used were way too thick for the material. I think I used #10 wood screws. I could have gotten away with much thinner, which is what I eventually did. Despite the gaudy looks, I decided to start assembling the box a bit more.


Even though I wasn’t happy with the looks of it, at this point I was actually quite pleased with what I’d done! It was my first real woodworking project. At this point I realized there were some design changes I wanted to make.

  1. I wanted to sink the speakers into the front a little more. I would route out a nice mounting space the next day to do this.
  2. I was going to replace those awful #10 screws. They were way too big, plus they actually bent the speakers when screwed in.
  3. I wasn’t going to need nearly as many screws as I’d thought.

At this point PurpleBlu2 was quite functional! I connected to it over Wi-Fi, hooked up my external hard drive, and we all got to enjoy some lovely music.

Unfortunately I ran headfirst into my next mistake, which I think is the critical flaw (at the moment) of this project.

Mistake #6: I didn’t use a dedicated DAC.

Why was this a problem? I’ll save that post for next time.

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