Control Pedals

These are a series of continuous control pedals, that are controlled by the foot pressing on the upper portion of the pedal. Pedals can be divided into three basic types:
- Volume pedal
- Expression pedal
- Wah Wah pedal

Volume pedal

This isn't exactly an effect because it doesn't modify the sound: the only purpose of the volume pedal is to control the volume of the signal. The volume pedal is composed of a metal base (economical versions are in plastics but, as we will see, are not recommended) with an upper pedal, which checks a control that regulates the volume of the signal: a raised pedal closes off the sound and a lowered pedal (flat) allows the entire signal to pass. This is therefore a simple procedure, that demonstrates a strange paradox: a high quality volume pedal can cost more than double the price of a pedal effect (such as overdrive). This remains an essential component on the pedalboard of the guitarist, because it gives you a considerable amount of control in real time during a performance, especially live.
There are two main categories of volume pedals:

• Mono volume pedal. It has one input and one output. If placed immediately after the guitar, it does nothing more than replace the volume control of the guitar. It is a frequently used and comfortable system that gives the right hand more freedom.
• Stereo volume pedal. It has two inputs and two outputs (input and output 1, input and output 2). If you use only one input, it works like the mono version. Connecting two inputs, the lowered pedal opens the 1 and closes 2 while a raised pedal closes 1 and opens 2. This system is useful when connecting two amplifiers or two effects and you want to mix or select the sounds. It's also possible to find pedals with one input with two outputs, in this case the sound passes through either one output or the other (with the pedal half open through both). This is a good system to manage two amplifiers.

When purchasing a volume pedal (mono or stereo) you should also verify the resistance, because this influences the management of the line signal.
It's best to place a low resistance volume pedal at the end of the pedalboard, or to use it on a guitar with active pick-up's. On the other hand, a high resistance volume pedal is put at the beginning of the pedalboard, directly after the guitar.
Many pedals also have a minimum volume control on the exterior of the pedal, that checks the initial volume of the pedal. If set high, even with a raised pedal, the signal still passes at the level that the control was set. This system is useful if you want to maintain the same sound, and only slightly varying the volume (for instance: raised pedal for rhythmics, lowered for a solo).
Besides the volume control, many pedals can have an output for the tuner. Signal always passes from this output, therefore with a raised pedal the instrument can be tuned without disturbing the others on stage. In any case, it is very convienient to use this output because it also allows tuning during a musical performance (therefore no wasting time looking for the tuner, attach and detach cables, etc.).
Various manufacturers produce high quality volume pedals (Boss, Morley, Jim Dunlop, etc.). Attention: an inexpensive volume pedal can negatively influence the signal. The most common defect is a slight loss of volume even at low levels, and a loss of high frequencies (treble).
Remember that it is possible to find volume pedals combined to other effects, or included on control pedalboards.

Expression pedal

This type of pedal, aesthetically similar to the volume pedal, doesn't directly work on the signal but is connected to equipment that have input's. By programming the equipment it's possible to check the parameters of that same piece of equipment (volume levels, effects, etc.). We will look at this more in depth when we analyze midi devices.

Wah Wah pedal

The Wha-Wha pedal is probably the pedal whose sound is most easily recognizable (makes a sound similar to its name), besides being one of the first pedals invented. The structure is also aesthetically similar to the volume pedal. It's operation is fairly simple. The pedal checks a tone control that is designed to vary the tone of the sound produced by the guitar. This control is very different from a normal tone control because it can change both the highs and the lows at the same time. The effect is inserted at the end of the pedal board and is controlled by a switch, even if in some recent models the insertion of the circuit is done by a photoelectric sensor sensitive to foot pressure on the pedal.
The use of this pedal is very interesting both from a rhythmic (i.e. funk, dance) and a purely melodic point of view (especially with crunch and distorted sounds).
Using a small parametric equalizer, which maintains the played note at a constant intensity and only increases a certain set frequency, the Wha-Wha pedal must be connected before the other pedals, the preamp and the effects, second only to the high resistance volume pedal.
Modern technology also offers some automatic Wha-Wha effects. Correctly adjusting the various controls for sensitivity, frequency and bandwidth can produce more complex sounds than with a normal Wha-Wha. There may also be an input to connect an expression pedal (exp in), which can check the frequency parameter in real time, coming close to a true Wha-Wha effect.