9/20/2020

Get started making and modding guitar pedals for cheap


One of my hobbies is to build and mod distortion pedals. I really enjoy exploring how iconic guitar sounds are shaped just by varying a few electronic components. It's also surprisingly cheap once you know how to find cheap parts. Here are some of my tricks to get started modding and building.


1. Start by modding

It's easier to modify a pedal than to build one. I suggest starting with reversible mods like these wah and diode clipping mods.


Behringer Hellbabe Wah mod

The Behringer Hellbabe (60$) is a cheap clone of the Dunlop Cry Baby from Hell (160$). One thing I didn't like about it is the course. When you press down on it, the first part of the course does almost nothing to the sound and the whole "wah" sound just happens on the very end of the movement. It appears that this wah is optical and easy to hack with a simple utility knife, which would not be possible with mechanical wah.

Picture from TDPRI

A wah is mostly a hi-Q bandpass filter. This one works with an optocoupler: the amount of light a photoresistor sees determines the frequency of the filter. So if it sees less light, you get the "W" part of the "Wah", and more light gives the "ah" sound.

The pedal moves a little panel with a triangular opening in it. This panel hides or shows more light to the photoresistor. So if you change the shape of that triangular window, you change the way the pedal movement will affect the change in filtering. Here's a video about how to do it.



Boss OS-2 clipping diodes

My experience is that changing the clipping diode is what has the most impact on the distortion/overdrive character. I bought a used Boss OS-2 for 20$. This pedal has in fact 2 separate circuits (hard and soft clipping) with a blend knob. It sounded like garbage though. When I opened it, I noticed that all the clipping diodes have been crippled. That's a typical amateur move to just remove them and let the opamp clip. I simply replaced them with a combination of LEDs and silicon. The variations I can get from that pedal is crazy.


Avoid surface-mount electronics as it is harder to mod. The very compact pedals and the cheap Behringer clones (even though they are excellent pedals) are often surface mount. Also, be aware that the very latest Boss pedals are in fact digital. If you want to be safe, try to find the schematics online and advice on forums. Otherwise, in every used pedal I opened the clipping diodes were easy to identify and change. They are even often conveniently labeled. Just look for a pair of diodes so you don't confuse them with an eventual protection diode.

2. Expand pedals


Boss DS-1 and Tube Screamer mods

I wrote a separate article about modding the Boss DS-1. Here instead of just changing the clipping diodes, I added some toggle switches to make any combination of LEDs, germanium, silicon diodes or opamp clipping. I also changed the tone filter shape, the preamp boost and some capacitors to filter the sound. 


I see it as the next stage of pedal modding: not just replacing some components but actually adding more functionalities. Also, it's not just about swapping internal components but modding the enclosure to expose more settings. Let's now move on to more involved pedal building.


3. Build a kit

You can find plenty of kits to build your own pedal. I really like the Stoning distortion kit. it doesn't come with an enclosure but I like to build my own anyway, which I will write about in another article.


4. Design your own sound module


Using a Joyo pedal as a base

What I advise to do is to use a cheap pedal as the base so you don't have to rebuild the boring stuff like 1/4 jack connector, bypass switch, 9v connection, LED and filtering, etc. These Joyo pedals sound very good, especially this Delux Crunch. I was pleased to discover that this line of pedal all use the same base so different pedals only have different sound modules attached to it with a 4 pins connector. So I desoldered the sound module and attached a strip ribbon to it. Every pedal I build simply connect to that Joyo base.



Simple circuits: Elektra

One of the fun parts of building pedals is hunting for schematics. Some circuits are so simple that it's hard to believe that they can sound so good. For example, here's one called Elektra.

From this page

If you are not comfortable reading schematics, you can find many perfboard illustrations that you just have to replicate. Otherwise, there are some nice kits here and here.

For my version, I used Easy EDA to model the circuit and see if I could improve it. 



My final version has a single gain knob going from clean to really saturated in just around 8 components.



Other simple circuits

Here are other simple but impressive circuits that I have in various phases on breadboards: Multistage jfet if you like amp-like distortions, Matsumin Valve Caster if you want a cheap way to get into tube circuits, Earthquaker Device Bellows for another amp-like distortion that is simple but very powerful.

The next one I'm building from PedalPCB is the Fuzz Foundry. The typical fuzz schematic is very simple but can be difficult to do right, especially when it requires germanium transistors which are hard to find and often unreliable. I also have the Omni Drive by John Hollis. This circuit has many toggles to try to mimic a great variety of sounds from a minimal number of components. Impressive piece of circuit design.


Typical opamp distortion: MXR Dist+

This circuit is a good starting point to learn about distortion (hard clipping) and how to wire opamps. It's very easy to mod and is a template used by most distortion pedals I know. Once you make a distortion, an overdrive and a fuzz, and you understand the similarities and differences, you see how most pedals are a variant of these 3 schemas, even the 1000$ pedals. This article is an excellent explanation of that circuit and how to modify it. 

I like to model my schematics using EasyEDA, but I use Blackboard as a simpler tool to layout my perfboard.
 

One good alternative if you don't want to design your perfboard or print your own PCB is to buy one. PedalPCB as tons of very well made PCB for any type of pedal. You need to provide your own electronic components though, they are not complete kits, just the board. For this one I stayed very close to the original schematic, just changed a few values and the clipping diodes.

I like how much resources you can get to build your own clone. For example, I really like the Catalinbread sound. Here's an article about the Catalinbread SFT and a PCB for it.


5. Have your components ready

If you are building your pedal from scratch, you need to have some basic components at hand. It can be very frustrating to just order the exact list of components for your project and then wanting to modify it and not have the right components. I had the basic equipment 20 years ago when I started toying with analog electronics but I had no components.

After much research, here's the cheapest bill of material I can list (all costs in CAD).


Base electronics components

Breadboard x3: 12.99$
Perfboard x10: 6.99$
Potentiometers kit x30: 19.99$
Resistor kit x400: 10.19$ 
Capacitor kit x150: 17.99$ 
Gemanium diodes x10: 3.91$
Quad opamps TL074 x10: 1.24$
Opamps LM741 x10: 1.50$
Dual opamps TL072 x10: 0.99$ (9.99$ when not bought directly from China)
Jfet transistors J201 x10: 1.31$

Total: 77.10$

Of course you need to add the basic tools required for electronics (pliers, soldering iron and wire, multimeter). You can probably build more than 40 pedals with this kit (if you get more perfboards). That's less than 2$ a pedal. Then you need to add the enclosure and fixtures.


Enclosure

For 1 pedal
2 jack 1/4 sockets: 3$
dc socket: 1.40$
footswitch: 3.60$
enclosure: 5.96$
water slide decal: 1.35$

Total: 15.31$

Enclosure 1590B = standard: (11.1 x 6 x 3.1) = 5.96$
Enclosure 1590BB = double: (12 x 9.3 x 3.5) = 7.15$

As you can see, the enclosure costs way more than the actual audio circuit. You can even find these parts in kit for just 1$ more. But it's worth it. Here I printed a drawing from my daughter's on a waterslide decal to add on an aluminiumm enclosure that has been primed.




Conclusion

Modding and building pedals are fun. My goal here was to show that it doesn't have to be expensive. But if saving money is your goal, I found excellent pedals for cheaper than that, like this impressive Suhr Riot clone for 11$. And they really do sound great. So why pay for expensive pedals that most often are just glorified Tube Screamer clones? My opinion is that when you buy a pedal you like, regardless of if you can build or buy a clone, you also pay for the real thing, for these awesome creators that are not just able to design impressive circuits but to manage a company, to drive a whole industry, to make you dream and to inspire you. When I listen to the folks at JHS, Strymon, Wampler, EHX, Death by Audio, I always feel like my pedal modding hobby is like I'm painting by number and these people are like Bob Ross. Look inside their pedals, hear how they sound, look at the design, it's the same circuit, why is it so much better? That's their magic.

Buying pedals also encourages local creators. I'm from Montreal and we have Johnny Rock Gear, Montreal Assembly, Fairfield Circuitry, Ground Control and SolidGoldFx to name just a few.

But before destroying a 300$ Wampler Triple Wreck I will practice on that 50$ clone. And building my own circuits makes me appreciate what these creators are doing even more, like playing music helps appreciate what musicians are creating. I also like that my errors are something that you can't get on a professional pedal or in digital emulations, that moment when the feedback loop makes it oscillate, when a fuzz is starved and starts to sputter, when a JFET explodes in smoke at the right moment. At the end of the day, it's fun to watch clipping sine waves on an oscilloscope, but it's even more fun to see how it brings your playing into unexplored territories.