The process of modding one’s pedals can seem like an arduous task: many players will seek to get his or her pedals modified by the local solderjock, and the vagueness of the term often leads to murky conversation at best. Most discussion of mods in the real world begins and ends with “this person did something to it, and now it sounds good.” For most players, this explanation is as good as any, and playing resumes forthwith—many players think of pedal modification as a black art whose implementation is the stuff of mystery. In fact, some mods are so mysterious that they bear the name of their creators from now until eternity. Fear not, readers! I shall attempt to remove the black veil of enigma from the world of modding, and explain what does what in classic circuits. Feel free to take this information as a reference, or as fodder for full-on mad scientist experimentation.
Disclaimer: Neither I, nor Tone Report Weekly bears any responsibility for any kind of personal or property damage that may occur as a result of the instructions provided herein. Legal mumbo-jumbo aside, we ask that readers be familiar with a soldering iron and its accompanying safety procedures before trying anything listed here. Furthermore, if a pedal worked before trying any mods and it doesn’t anymore, it’s through no fault of these instructions, as I’ve personally performed every mod listed, some several times over.
That said, hello! Before continuing with specific pedal talk, I’d like to introduce a couple prevalent mods that can be found on a ton of different boxes. The first one: “modding for bass.”
Stop me if you’ve heard this one: “Oh yeah, this has been modded for [more] bass.” If I had a dollar for every time I’ve heard this statement, or its equivalent question, “can you mod this for more bass,” I could probably retire inside of five years. That said, this is an overwhelming request, and for the most part, it’s one of the easiest mods there is.
The simplest way to go about doing this is swapping out one or both coupling capacitors in your pedal. These capacitors are generally the first and last capacitor in the signal path. Of course, some pedals have more. However, a good rule of thumb is to stick with the first and last—it’s easiest both in resources and implementation. Coupling capacitors are generally on the edges of circuit boards rather than clumped in the middle, so accessing them is easy, and by swapping out just the two… well, you only need two replacements. If you’d like more bass in your circuit, use a higher value capacitor than what’s in there; generally speaking, the value is written on the capacitor, in code form. Google “capacitor code calculator” to find out how to decipher it, then substitute larger values for the existing ones.
“But wait! How do I know which ones are coupling capacitors? They all look the same,” you might say. Well, my friend, you’re going to learn to read a schematic, right here and now. Don’t worry, it’s not hard. Think of the schematic as a map for your signal, and just like a map, you may need to take a good, long look at it before it makes sense. Find where the input jack wire leads, usually to the footswitch, and find where the associated switch wire leads. If the first component on the board matches the schematic, you have the gist of it. Take, for example, the schematic of the lowly Fuzz Face:
Note capacitors C1 and C3 are the “first” and “last” components that your signal sees. These are the capacitors that make a huge difference when altered. In the stock D-A Fuzz Face, C1 is a 2.2μf capacitor, while C3 is a 0.01μF capacitor. In the grand scheme of pedal coupling capacitors, 2.2μF is rather large, and 0.01μF is rather small. With that said, would-be modders may experience diminishing returns when enlarging the value of C1, whereas the tiny value of C3 lends itself to experimentation quite well. Many modern Fuzz Face clones leave C1 alone and change C3 to 0.1μF, ten times the stock value. This, as expected, tilts the pedal’s output more in favor of lower frequencies. As previously stated, this works the opposite way too; consider the case of the Vox Tone Bender. This pedal bears a striking resemblance to the Fuzz Face schematic with one extra resistor. Some aficionados might acknowledge it as the first modded pedal. This Italian Bender has a tiny output capacitor of 0.004μF. As expected, this makes the sound of the Vox thinner and raspier than an original D-A Fuzz Face. Bass players might want to consider increasing the value of both C1 and C3. As bass players utilize an extended frequency range, they might thinking about really juicing both capacitors; better yet, why not install sockets instead of the components themselves? Modders can then swap out components in seconds without having to mess with a desoldering pump.
(voltage Starve/Fuzz Face)
Ever plugged in a really old dirt pedal with a battery and noticed it got super farty and weird? This is the sound of a dying battery, known more colloquially as “voltage starve.” Fuzz aficionados have likely seen this control labeled as “bias” in most applications, or “sag,” “texture” and “character” in more esoteric applications. Luckily for us, this is one of the simplest controls to implement, and it can be fine-tuned to a near-infinite degree.
Consider the diagram below. Figure 1 shows how easy it is to install a starve control. First, decide how much you want this pedal to suffer: a 5k potentiometer is a variable resistor, so at its maximum, it’s like placing a 5k resistor in series with the power. This will be a subtle effect, and more drastic effects are heard when the value is increased. Personally, I like to use 100k, because it alters the sound a lot when fully clockwise, and it’s not such a big value where more subtle starvation is harder to dial in. Keep in mind that when using Figure 1’s setup, the entire circuit will be starved this amount, rather than just one component.
Figure 2 demonstrates a typical “bias” knob in a Fuzz Face, and for the sake of illustration, it’s inserted into the standard Fuzz Face topology. Note that in this case, the starve control takes the place of a resistor, R3. Because a potentiometer is just a resistor whose amount can be varied, you can now bias the transistor (Q2) as you see fit. This is the “dying battery” effect as heard in songs like “Without MSG I am Nothing” by mclusky.
Figure 3 is the setup for the guitarist that desires ultimate control in a starve setup. Trust me when I say this: resistors, when placed in series, i.e., one after the other, get their values added together. For example, a 100k and 22k resistor placed in series creates, in effect, a 122k resistor. For this application, a 5–100k variable resistor is placed in series with a 1–2k variable resistor. The resulting setup is a fine and coarse voltage control. Once the first potentiometer is set, players can fine-tune the level of starvation to meet his or her needs.
A word on starvation: the world of starvation lives according to a non-rule I've coined as “the uncertainty axiom,” which is to say, with a rudimentary grasp of circuit theory, the effects of starving pedals is near impossible to predict unless you know for sure how the circuit reacts in general. For example, if you install a voltage starve into a Tube Screamer, you can guess as to how an EarthQuaker Palisades will react to the same condition. Some pedals may do nothing, and some will also react unfavorably. For example, starving the voltage on an MXR Phase 90 simply thins out the signal, and not in a particularly exciting way.
Starving the voltage of a digital pedal will accomplish nothing except turning the pedal off, as the pedal is designed to see a certain number of volts. When these conditions are not met, the unit simply won't function, and someone’s time has been wasted—either yours or the person you're presumably paying to do this. If you're unsure of whether or not, refer to the Internet. If that gives no answers, open it up. If you see a chip marked PT2399 or SPIN FV-1, it's digital and can't be starved.
Some pedals take voltage starvation better than others, and generally, these are fuzz pedals. One of my absolute favorite pedals to starve is the Jordan Boss Tone and its compatriots. The Electro-Harmonix Satisfaction Fuzz is a Jordan Boss Tone variant and plays extremely well with a starve knob added. While you're at it, put a capacitor in the provided empty slot on the Satisfaction—the pedal sounds raspy because it has no output capacitor. Add your own for maximum fuzz!
In part two, we’ll discuss individual pedals and what parts in each circuit have the most effect on the overall sound. Until then, go forth and mod some pedals for more bass—guitarists everywhere will thank you.