Guitar Effects Basics - Part 2


Hi. In this Part 2 of Guitar Effects Basics, we take a look at the following effect types and what they do: wah-wah, auto-wah, octaver, pitch shifter and harmonizer.



In part 1 i've already described popular guitar effects like overdrive, distortion, fuzz, delay, reverb, compressor and equalizer, so let's move on to see another very popular effect: the Wah-wah.


The wah-wah pedal is also referred to as just wah. What does wah-wah do exactly? A normal wah type foot pedal has a base that you can rock back- and forwards with your foot. The foot base controls a potentiometer or potmeter that itself controls which frequencies of your guitar signal are boosted and which frequencies are cut.

In toe-up position the pedal boosts your bass frequencies and cuts your higher frequencies (treble), giving you a dark bassy tone.

In middle position, the mid frequencies are boosted, giving a throaty sound (much like the 'Money for Nothing' guitar intro of the Dire Straits).

In toe-down position, the bass is cut and the highs are boosted, giving a very sharp and edgy sound. The total range from toe-up to toe-down position and the corresponding sounds, is called the 'sweep'. As you can imagine, by rocking your foot backwards and forwards your guitar's tone is constantly changing, giving that famous 'wah-wah' sound that gives the effects its name.


Famous examples of guitar songs using the wah effect are:

Jimi Hendrix - 'Voodoo Chile (Slight Return)'. The intro is famous for the distinct wah sound. It has an almost human quality. The pedal used in the recording was probably custom-built for him by Roger Mayer.

effects octave pedals Boss OC-2 EH Pog
Octave pedals: Boss OC-2 and Electro-Harmonix Pog2


Santana - 'Europa (Earth's Cry, Heaven's Smile)'. In the long guitar solo that starts halfway into the song, Carlos Santana uses the wah-wah almost like a tone control, subtly controlling the guitar tone with his foot. Together with the overdriven sound, reverb and use of amp feedback, 'Europa' has one of the most memorable guitar sounds in history.


Auto-wah/Envelope Filter

An autowah does not employ a foot-controlled pedal. Instead, there are two types of auto-wah. The first type is also referred to as Envelope Filter in which the frequency cut and boost are controlled by how hard the guitar player picks, so by the input volume. The other type oscillates the frequency 'filter' at a constant speed which is controlled by a 'speed' button.


The envelope filter type is highly responsive to the playing dynamics and can achieve some very specific sounds that you can't do with a normal Wah-Wah pedal. It was used a lot during the 70's in disco and funk music. A famous auto-wah/envelope filter pedal is the DOD FX25. Funk bass player Bootsy Collins used one.



An octaver doubles your guitar signal and transposes the doubled signal one or two octaves down or up. The added octave signal(s) can each be adjusted for their volume. Octaving can give your sound a synthesizer-like quality and make it sound deeper. Famous octave pedals are the Boss OC-2 and the Electro-Harmonix POG. The octave effect is supposedly invented by Roger Mayer in the late 60's, he combined the octave effect with a fuzz in one pedal ('Octavia').


Pitch Shifter

A pitch shifter also duplicates the guitar signal and transposes it, but in addition to octave transposition it can also transpose over other intervals like the fourth and fifth. Some pitch shifters can deliver 3 or more transposed signals at once.



A harmonizer does the same as a pitch shifter, but allows the player to set a key so that the interval transpositions correspond to the key the song is in. This results in a more musical and harmonical sound than can be had from a pitch shifter. A famous harmonizer is the Eventide Harmonizer, used by, among others, Brian May (Queen).


That's it for Part 2, in Part 3 we'll look at modulation effects, stay tuned!


effects jimi hendrix wah pedal