Guitar pedals work by taking the electrical output signal of between 140mV and 1.4V from the instrument the signal is passed through ether a multi-processor for digital effects or a series of transistors and capacitors for analogue effects they are connected to an amp to increase the signals volume.
we may earn commission from affiliate links displayed on this page
The electrical signal that comes from the guitar is a very low output at between 140mv and 1.4v this should make it safe to handle when touching the metal components but do check the manufactures guidelines before you attempt it.
|1. Firstly what do guitar pickups do?|
|2. What happens to a guitar signal in an effects pedal?|
|3. How does a distortion pedal work?|
1. Firstly what do guitar pickups do?
Guitar pickups do an amazing job of converting energy waves of between 80 Hz and 1200 Hz from the guitar strings using a magnet surrounded with coils of wire, this creates an electric induction field that is influenced by the metal strings vibrating and converting it to an electrical signal.
This can then be used by an amplifier and speaker to produce sounds in the frequencies that are audible to humans of between 20 Hz and 20,000 Hz.
Guitar pickup outputs signals are really just very small variable electrical voltages of between 140mV and 1.4V that are sent out via the input jack on the guitar, the guitars pickups have magnetic fields that are affected by the strings vibrating.
If we dive deeper into why the guitar string changes the magnetic field of the guitar pickup it is the magnet in the pickup that is magnetizing the string, the magnetized string when it vibrates will manipulate the electrical field producing a viable voltage signal.
This can be simple shown in the experiment usually done in a high school science lesson on magnetic induction which is very similar to a guitar pick up but shows what is happening much more clearly, when a magnet passes through a loop of copper wire that is connected to a multi meter it will generate an electrical signal, if you wobble the magnet in the coil of wire it will make the AC voltages go up and down on the multi meter.
If this was connected to an amp it would probably make quite a loud sound as the movements would be way bigger than the very, very tiny movements the guitar strings make when they are played.
The guitars signal will going up and down a lot each time the string vibrates near the pickup, it will slowly die down until the string has no vibration energy left to cause the signal to change.
2. What happens to a guitar signal in an effects pedal?
The guitars signal when it goes into the pedal will do different things depending on whether it’s analogue or digital, in analogue pedals the signal will pass through a series of diodes and capacitors converting the signal. Changing the rating of capacitors and diodes will change the signal.
If the pedal is a digital one the signal will go into a micro-processor CPU on the pedals mother board and will be converted into a digital signal just like to picture below.
Depending on what the microprocessors programing is will dictate what signal changes there will be, the most common signal processing for guitar signals for both analogue and digital are created using different types of clipping, soft clipping for overdriven or hard clipping for distortion.
The digital effects are achieved by the type of microchips on the motherboard, the analogue ones use more capacitors, diodes and resistors but others things will also be used before it goes to an output speaker.
The analogue signals of between 140mV and 1.4V that are received into the effects pedal from the guitar will go through one or more gain boosts too, this is achieved by adding a power source to the input signal to increase the level of amplitude.
When used in conjunction with the on-board resistors and diodes (these are also inside ICU microprocessors with set designs much like little circuit boards themselves) will clip the top off the signal as it can’t go any higher because the resistor is resisting the extra signal power.
The barrier the guitars boosted signal is hitting is called the rails, they look like the signal is being cut off top and bottom like it is trapped in between two train track rails hence the name.
Digital pedals use much the same circuitry as analogue ones but they are using other components called transistors. They use analogue to digital sampling circuitry to convert the analogue guitar signal to a digital computer signal before it is processed with the desired effects circuitry and finally converted from digital to an analogue signal for the speakers to use.
These are known as solid state circuits, as they contain no moving components unlike analogue distortion valves or spring reverbs these solid state circuits are in nearly all amplifiers mass-produced today as they are cheaper to make and use less electricity.
When the input signals are soft clipped they cause changes to the natural harmonic overtones from the guitar or instruments signal.
This brings the sound frequency limit down very slightly to create an even harmonic signal, these are either known as warm tones (overdriven) if they are positive or distortion if they are negative as they are harsher.
The 2 Most common distortion pedals
• Boss ds1
3. How does a distortion pedal work?
Distortion pedals work by taking the guitars signal and boosting it above its maximum level causing it to break down and distort, when the signal reaches the max level resistors in the circuitry pervert it going higher clipping the signal creating natural harmonic overtones (the distortion effect).
Distortion was seen as a problem in early electronic systems as they were trying to boost sounds like human voices so that information could be transmitted to large areas which needed to be clearly heard.
But is used by guitar players around the world to gain that perfect sound.
An example of these distortion problems would be early public announcement systems, these needed to be clear and loud enough to be heard over large distances.
Tannoy were early pioneers in solving this and quickly became a house name making speakers and systems right until they were bought in 2002 by TC group.
A signal from the microphone when it is boosted needs to have a lack of resistance, this is so the signal is not clipped off too soon when the volume is increased.
The way that guitar input signals get amplified is by adding power directly to the input signals wire from a power source, this could be from a 9V battery or 9V mains lead supply.
The rating of the resistors and diodes dictates the threshold that the signal can be boosted to without it being clipped.
As more power is added it boosts the signal to a higher level than it was before, causing it to distort slightly as it gets bigger, clipping is then used to increase the distortion effect.
When the signal is clipped by the resistors, the resistors are resisting the extra power that is trying to flow through them causing natural signal overtones (overdrive).
The more power/gain that is added the more the signal will be clipped and the more overtones will be created, creating a harsher harder clipped signal called distortion.
The 2 Most common distortion pedals
The Boss ds1 has got to be the most popular effects pedal, It is used by so many pro guitarist like
- Robert Smith (The Cure)
- Kurt Cobain (Nirvana)
- Joe Satriani.
And many, many up and coming ones too and you can see why in this video.
The Behringer HD300 heavy distortion pedal is a really good affordable pedal that is so near to the expense modals and sounds great too, check out this video.
As you can see guitar pedals do amazing things really, the time and research that goes into making each one as good as it can be is unmeasurable, because even now guitar pedal manufacturers and hobbyists around the world are constantly designing and testing new ideas and projects.
Along with the ever changing landscape of guitar designs and hardware that is always improving to meet new tastes and fashions within the music industry.
- Should you hang a guitar for a long time?
- How Long Does It Take To Learn Guitar?
- 8 Easy tips to spot lawsuit guitars, are lawsuit guitars any good?
image sources amazon