Tag: guitar

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Build Report: Swollen Pickle (Modified Big Muff Pi)

Some years ago I developed interest in guitar pedal effects and stompboxes in general. Built a Woolly Mammoth that I learned a lot on the subject, then soon after a bunch of TubeScreamer Clones. I did it for personal use and to give to friends. Just as I started the TS projects, a long time fella presented me the Swollen Pickle MkII, a modified version of the famous Big Muff Pi.

The MkII version didn’t had any schematics or PCB layout on the internet. I only found a veroboard version of it, I really don’t like the veroboard layouts because they are clumsy and big. For the first time I used EagleCAD Software and tried to reverse engineer the layout back to the schematics. While still looking for more information I found a discussion with a non tested schematic and suggestions over that one. No working pcb layout though, so I continued to draw the schematic.

After I finished the schematics I started the board layout, like the schematic, I never did it before. It was a completely new experience for me, a mix of trial and error until everything fits on the board. With the finished board layout I had one more step: the enclosure.

After some measurements I chose a Hammond 1590XX for the enclosure and the aluminium etching method. I used the same tone transfer method as used for the PCB, but I ended up using caustic soda instead of ferric chloride. I had some bleeding on the edges because I used tape to mask and some bleeding where the toner didn’t transferred properly, maybe next time I will seal everything with nail polish and use ferric chloride instead. 

With the corrosion done, I sanded everything, painted the bas-relief with black spray, sanded again and applied varnish. I drilled it with my power drill, using one spade bit to start all holes(just the tip) and then used a step cone drill bit to the right size.

Nothing new with the PCB and Pedal assembly. I chose a super bright green LED as status indicator. It gives nice touch to the pedal, but ruined the video.

To the video I just downloaded some bass DI tracks over the internet and reamped them using the pedal.

Conclusion:

It was a long and complex project for me. If I had the opportunity to redo anything today I would test the aluminium etching on a small scale first. The Eagle CAD part was tiring, but insightful. As for the video the LED ruined it, but I was so tired and wanted to publish something, so I didn’t record another take.

You can download the used Eagle files, ready to transfer pcb layout and partlist on my GitHub repository.

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Modifying my cheap guitar – Part II – The Appearance

Continuing to the first part, I will now tell about how I modified the look of my guitar. I considered doing swirl painting or buying a customized pickguard online, but none of those options got me excited.

The Pickguard

After some time thinking and incubating ideas I started the composition by picking trippy and psychedelic elements, being Alice in Wonderland a huge influence as well as the line “The rabbit is just a monkey in disguise” of the song Organ Grinder by Marilyn Manson.

Unfortunately, visual arts are not part of my skill set. I contacted a friend artist (Daniel de Carvalho) with the ideas and soon he started to present me some sketches. Some months and some drawings later he started to work on the pickguard.

He developed the art using acrylic paint and India ink. Check out more photos of the process and other works on his page, Daniel is a very experienced, talented and passionate professional.

Pickup Selector

While assembling the guitar pickguard with Daniel, we come up with the idea of a mushroom pickup selector. I really liked the concept and resolve to try it out.

I used a recipe of cold porcelain. To my surprise it’s a very cheap and easy to use material, I have some leftover and consider using it on other projects. I regret choosing nail polish for painting, it’s too thin and inconvenient to use.

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Modifying my cheap guitar – Part I – The Wiring

A friend lend me his electric guitar for quite a while when I determined to learn a string instrument. After a lot of months I finally got my act together and bought a cheap an inexpensive electric guitar bundle(with a 15-Watt amplifier, gig bag and strap).

After a period of time it occurred to me to experiment, modify and change some aspects of the guitar wiring. All the applied modifications were found over the internet and, as you can imagine, there is nothing innovative.

Modifications:

  1. Switch between the original tone capacitor and a new one.
  2. Hard clipping using two diodes connected in antiparallel.
  3. Neck ON Switch (David Gilmour wiring).
  4. Treble bleed mod.

Motivation

It was a cheap guitar, however its value reflects its quality. I was a bit unsatisfied with its tone, with a little research I found out some ways to improve the tone.

Schematics and part list

guitar-wiring

C1 - 0.002uF / 2nF / 2000pF
C2 - 0.047uF / 47nF / 47000pF (original film capacitor)
C3 - 0.1uF / 100nF / 100000pF (ceramic capacitor)
D1,D2 - 1N5819
R1 - 100k Ohms resistor
SW - DPDT

Switch between the original tone capacitor and a new one

Simple selector between two capacitors. The second one helps to get a darker sound and not so strident like Stratocasters usually are.

Hard clipping using two diodes connected in antiparallel

Sometimes called as “passive distortion” or even wrongly as “passive overdrive”, it’s a fun modification. Gives a harsh sound, but loses volume since it clips the sound without any boost.

Neck ON Switch (David Gilmour wiring)

This wiring, when enabled, connect the neck pickup with whatever selection in the 5-way switch. David Gilmour may be the most famous musician to use this mod. Now with up to 8 possible combinations, the guitar has so much possibilities. In my opinion, the sound is colorful now.

Treble bleed mod

When you turn the volume down on a guitar you can feel that the sound loses a bit of treble. It happens because the pickup, the volume potentiometer and the capacitance in the cable act as a low pass filter. To compensate this loss we “bleed” more treble into the signal as the volume is turned down.

Further modifications

After all that, I ordered and installed a hotrail pickup in the bridge position. Unfortunately I don’t have any pictures, but If I did it again today I would use the Gilmour/neck mod with the bridge pickup instead of neck. I customized the pickguard with an artist, that being the subject of the Part II of this post.

Conclusion

guitar-guts-and-componentsI learned a lot in the process. From something stupid like how a 5-way switch works to something unexpected like fixing to a stripped screw hole.