ascii art logo: drofmij

Hello my name is Jim and I'm a software developer. You can find me on twitter as @originaldrofmij.

Blueberry Bass Overdrive

I play bass guitar, and in my quest to improve my bass sound, I started researching various bass guitar effects pedals and came to the conclusion that they are, for the most part, expensive. Sadly, I do not have room in the budget for all the effects I would like to try. I remembered hearing or reading somewhere that a lot of original guitar effects were DIY type things. I did some googling and discovered the Guitar FX Layouts blog and thus began my introduction to building guitar effects pedals. Thanks to Ivlark, Mirosol and all the other cool folks at Guitar FX Layouts blog, without these guys I would never have been able to start this hobby.

Finished pedal (with electrical tape patches to cover badly placed in / out holes) 2 The first guitar effect pedal I built is a clone of the Mad Professor Blueberry Bass Overdrive (here is the layout). This should not have been my first build, I should have started with something simpler, probably a kit. I ordered all of the parts from Tayda Electronics or so I thought. Once I had received the parts and started getting things together to start soldering I noticed I had missed a few things and ordered some more parts. I had ordered the wrong type of 3pdt footswitch (momentary, not latching), I missed a couple of capacitors, and did not order any knobs for the potentiometers.

I discovered that there are 5 distinct learning curves when building an effects pedal: 1) components, sourcing, and ordering; 2) reading layouts; 3) soldering components to the board; 4) prepping the enclosure and drilling holes for jacks, knobs, and switches; 5) painting / etching / decorating / labelling the enclosure.


A great place to learn about components is once again at the Guitar FX Layouts community. Mirosol has a great 2 part guide to components which taught me the basics and got me started. There is also a build guide, offboard wiring guide, and fault finding guide for when things go wrong.


I spent a lot of time watching youtube videos about soldering, reading how-to guides etc. There are plenty of resources for starting out. One thing that I learned was to use regular steel wool pad for cleaning the tip of my soldering iron. There is a lot of back and forth about the proper way to clean your iron, I find that using steel wool works for me and is a lot cheaper than some alternatives.

Build Pictures

Now that I've spent time babbling about stuff I learnt, here are some pictures of the first Pedal I built.

project board 1
This is the front of the board with the jumpers soldered in place.
Back of cut vero board with first few solder joints
This is the back of the board after I made all of the cuts and solder the jumpers in place.

project board 2
Here you can see I am making progress soldering components to the board.

project board 11
All of the onboard components are in place, on the board :D
If you want to see all of the pictures take a look at my flicker album

enclosure closeup of pot holes
In parallel I spent some time preparing the enclosure.
enclosure after sanding
Here is the 1590B enclosure box after drilling (almost) all of the holes and sanding. I did some experimenting with paint and did everything wrong, so I ended up with a brushed metal look eventually (more on that later).

enclosure with (almost all holes drilled) (front)
Here is the enclosure with the switches, jacks, led bezel, and potentiometers in place. I found out later that I did not measure correctly for the placement of input and output jacks and had to move them.

enclosure with (almost all holes drilled) (inside)
This is the inside before drilling second set of in / out jack holes. You can see the leftmost potentiometer in this picture has one solder lug actually touching the box. I had to bend the lugs on that one in painful ways in order for it not to short.

offboard wiring begins (note enclosure with second set of in / out jack holes now in the correct place)
When I started offboard wiring, I checked where everything would fit into the box and that was when I discovered that I needed to move the in and out jacks. Here you can see the new in jack hole between original in jack and the DC power jack hole.

checking enclosure + board
Checking for board fit with new IN and OUT jack location.

offboard wiring is a bit messy at this point
This picture is more than halfway through offboard wiring. As you can see I did a pretty messy job.

IT LIVES!!1! All offboard wiring done and did the first test with the case off. Realized at this point that the water clear blue LED is freaking bright!
Finished Pedal with knobs on
After some fault checking, redoing a couple of sold joints, adding some non-conductive plastic sheets (from hard drive shipping envelope), and some electrical tape to cover the extra holes, here is the finished pedal (with some slightly too short knobs).


Originally I had grand plans to paint the enclosure black and to stencil a very cool, distinctively nerdy pixel design on the front. This did not work out as well as I had envisioned.

My original blueberry pixel design (knobs, footswitch, and led bezel have pixel placeholders)
Acrylic paint for enclosure box painting attempt 1
I first sanded the box, then painted it with a few coats of acrylic black paint (hey it was free, I already had it) and it did not look very good.
Results of acrylic, even after 3 thick coats, the grain of the
aluminum is visible and the color does not look right.

Then I remembered that I had some black spray paint in the garage from a different project. I Purchased this spray paint specifically because it was the cheapest stuff walmart sold.

El-Cheapo spray paint
Resanded the box and tried a couple of coats of spray paint
I sanded the box again and sprayed on a couple of coats and it looked pretty good.

After spray painting the box, I was back to fiddling with stencils. I built the stencils using graph paper and an exacto knife. The main logo was to be built with 3mm "pixels," but my name logo for the side of the pedal would have been too big, so I targetted 1.5mm - way too small to cut out with exacto knife.

Test of 1.5mm per pixel stencil idea - way to small for my equiptment
My logo at 1.5mm per pixel.

I tested the logo with 3mm pixels and discovered that my stenciling technique needed some work.

Test of 3mm stencil before I got stencil brush and (kinda, sorta) learned stenciling techniques
Stencil test using regular brush and bad technique.

I did some googling and discovered that people use special "stencil brushes" for this sort of thing and using less paint on the brush also helps. I picked some up at our local craft store for cheap and tried again.

Test run of main design stencil - not too shabby on cardboard
Main logo stencil test with 3 colors, better equiptment, and better technique.

After this, more successful, test run I felt confident enough to try stencils on the enclosure box.

Here I am partway through stenciling the light blue onto the enclosure box
This picture shows me two-thirds of the way through the stenciling process, painting the light blue.

It was at this point that I started to see the black spraypaint peel off of the box.

Partial success - partial failure. This is the point at which I gave up stenciling for this project.

After a long dissapointing saga painting and stenciling, I ended up back where I started. I peeled the paint off with an x-acto knife and sanded the box once more and left it at that.

Finished pedal (with electrical tape patches to cover badly placed in / out holes) 2
Finished pedal - sans paint

There are a variety of painting angles I could pursue for future projects, acid / etch primer for aluminum is at the top of my list to try. As for stenciling, I will likely not be using it for future pedals. I am hoping to explore printable transparent labels for logos and labels.

Lessons Learned

  1. Measure carefully the board does have to fit in the pedal :D
  2. Be neater when wiring off board components it makes it easier to get everything in the case, and easier to fault test later
  3. Drilling metal can be tricky, starting with small bit helps center the larger bit, clamp the enclosure to a bench or table before drilling, use a drill press if available
  4. Painting aluminum requires some extra steps, more research would have prevented some headaches there

You can find the full project album on flicker.

Here is a quick, badly recorded clip of the pedal in action :D