26 June 2012

Pedal Effects: What they do? - Part 1


Usually, any guitarist will have at least one pedal effect between his guitar and the amp but, why?.
Which kind of pedal effects do we have?. What are they useful for?.
When stacking several pedal effects, which is the right order on the chain?.

Pedal effects are like colors in a painter's palette. They allow as to color our sound to get some nuances that we cannot achieve with the guitar and amp alone and, as in the case of that painter's palette, we cannot abuse so much of a single color.

Let review the pedal cathegories that we have.

Categories of Pedal Effects

We can group the several families of effect pedals in some bigger groups. Later in this articles, these categories will make full sense.

Signal Followers

Signal followers are all those pedals that need a clean signal from the guitar to deliver their best.
One of the example is just the tuner, in order to tune our guitar, we need to feed a clean signal to the tuner, for maximum accuracy.
Pedals like Q-Filters, Pitchers, Arpeggiators, harmonizers, octavers, etc., all they need a clean signal because the effect is based on how that clean signal changes during the time.

Signal Recovery

Some pedals are just designed to restore part of the signal level that was eventually lost because of guitar's cable. Line Drivers are increasing the gain of the signal. Buffers are readjusting the output impedance to a level that's good for the amp or rest of pedals in the chain. Treble boosters are restoring or enhancing part of the high frequencies rolled off by the cable, etc.
More than trying to give a new color to the sound, those pedals are trying to restore what is missing in the original guitar' sound.

Gain Pedals

Similarly to Signal Recovery pedals, gain pedals are raising the signal level but, differently, gain pedals add some kind of color to the signal. These pedals can raise more or less the signal level on the whole or part of the frequential spectrum and, some of them are highly reequalizing the signal.
Example of those pedals are compressors, equalizers, overdrives, distortions and fuzzes.

Modulation Pedals

Modulation pedals are affecting in a cyclical way the signal, varying its phase, frequency or volume.
Even that most of gain effects can be achieved just with the right amp, modulation pedals are really special pedal effects that clearly modify the sound.
Phasers, Vibes, Flangers, Chorus, Vibratos, Tremolos are all them modulation pedals.

Time Pedals

Time pedals are those that create repetitions of the original signal during certain duration and, they were designed to restore the sense of space when playing in dry environments. They help to place the instrument whitin the mix, in the wanted spatial location.
Reverb and Delays are time pedals.

Link Types of Pedal Effects

How a pedal affects the the link with other pedals, while is on or while is off is what I mean a Link Type. We can have following types.

Hardwired / True Bypass

A Hardwired or True Bypass pedal remains off of the chain when switched off. The conductors of the input jack are directly linked to the conductors of the output jack.
Benefits are that those pedals will not disturb the chain if they run out of batery. Since the signal is hardwired from jack to jack, there is no need of a batery to power the signal.
Other characteristic is that the input impedance (delivered by previous pedal) is the same on the output, since there is no electronics component that can alter it.
In fact, when a True Bypass pedal is off, the effect is quite similar to just extend the length of the cable just a bit (the length of wires that link input to output jacks).

Main drawback is that, since is just some virtual extension of our cables, we have to sum up the length of cable that goes from guitar to pedal, the jumper inside the pedal and the cable that goes form pedal to amp. Most of times, once we reach a "virtual length" of about 10m (30ft), loss of signal level and roll off of frequencies is noticiable.
So, it is very often to see at least one Buffer or buffered pedal within the pedal chain to raise a bit the signal and restore that impedance that the amp is expecting on its inputs.

Pure True Bypass pedals, doesn't have a buffer neither when switched on.


A buffered pedal routes the input into an input-buffer and the output into an output-buffer.
A buffer is some electronic design that addapts impedance levels.
The input buffer is getting the impedance expected on its input and, modifying it to give the impedance that pedal's components need (by example, transistors).
The output buffer is getting the impedance that exits the pedal effect and, alters it to deliver the best impedance level at its output.

Theoretically, a perfect pedal would have an infinite input impedance and a zero output impedance.
That not possible in real world but, a good relation is to have inputs impedances of 1 MOhm (same that the amp expects) and output impedances of about 600 Ohm (similar to micro levels). At least, a relation 10:1 is a good thing.

Buffered pedals are affecting the signal. Even than the effect itself can be off, the input and output impedances are being transformed by pedal's buffers.

Main drawbacks are that buffered pedals need battery to work so, if battery goes off, the whole chain of pedals goes off so, we have a blackout.
Other drawback is that, depending on the position of the buffered pedal, the operation of the following pedal effect can be seriously affected, delivering a bad sound, by example, if the output impedance of the buffered pedal doesn't match the needs of the following pedal.

Buffered Bypass

Buffered Bypass is a mix of the other two.
While the pedal is off, the link is Bypass so, nothing happens if we run out of battery and, we have the good and the bad of such a link.
As soon as the effect is switched off, the signal is being buffered, in the same way that we were discussing above, with the good and the bad.

This kind of pedals can be a surprise because their behavior change when switched off or switched on. If they are in a position not affecting previous or following pedals, everything is OK.
So, you need to check this pedal in both conditions, before being sure that it's not affecting the rest of chain.

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