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.

Published by Elias Puurunen

Elias Puurunen is a versatile entrepreneur and President of Northern HCI Solutions Inc., an IT consulting firm which has worked with Fortune 500 companies, governments, and startups. He has spoken at conferences in Canada and the United States and has been published around the world. Part of his work led to an agreement between the Canadian Government and Siemens Canada, creating jobs and investment into green infrastructure. His company's event management app, the Tractus Event Passport connects people at conferences, seminars and symposiums across Canada. Today he is a consultant and advisor to technology firms and government organizations. He lectures at the University of Waterloo on Coding for Policy Analysis for the School of Public Policy. He is the author of Beyond Passwords: Secure Your Business, a cyber-security book for small business owners.

Leave a comment

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: