Image of guitar pedals

It has been a staple of guitar FX boards since the ‘60s – but exactly what is a wah pedal?

Guitar effects have been around almost as long as electric guitars have. The ’60s were perhaps defined by a spirit of experimentation and discovery. This touched nearly all areas on the western world, but in the rapidly developing field of electronics, and of course, in music, developments were moving at some pace.

Where they overlapped, great music technology was created, and guitar effects were are a part of this.

The wah was one of the first of these early effects, and one that has stood the test of time with ease.

Most are familiar with how this effect can sound, but what exactly is a wah pedal?

A brief history

The wah pedal is characterised by a weeping, crying tone, akin to human voice. The guitar wasn’t the first instrument to benefit from this type of effect. As early as the 1920’s, trumpet players used hats and other baffles to cover and uncover the bell of their instruments to create a ’wah’ effect.

The guitar effect was developed almost by accident. The engineers at Vox were working on a solid-state, Beatles endorsed amp, when a junior accidentally created circuit with odd, audible effects. The team housed it in an organ volume pedal chassis, and began experimenting with brass instruments (brass players in big-bands frequently used these effects, after all).

The patent was filed for a ‘foot-controlled continuously variable preference circuit for musical instruments’, but thankfully, the name ‘wah pedal’ stuck a bit more…

So, what is it?

Image of a wah pedal

Put simply, a wah pedal is a type of filter. There are various standard types of audio filter. Low pass filters let low frequencies passed a set frequency cut-off point, filtering out frequencies above. Hi-pass filters are the opposite, letting high frequencies past the cut-off frequency and filtering out low frequencies.

The wah pedal features what is essentially a band pass filter. This is a combination of the two above types, letting the audio from a set frequency band past, whilst filtering out frequencies above and below. With me so far? Good.

The wah features a resonant peak at the upper cut-off frequency, and a rocker pedal mechanism connected to a potentiometer sweeps the audible band of audio, giving the effect the ability to change from closed ‘www’ sounds through to open ‘aaahhh’ sounds.

Nowadays, there are countless varieties of wah pedal available, but Vox and the Jim Dunlop Crybaby (also an early model) are still among the world’s most popular.

The beauty of the wah pedal is that it allows the guitarist an extra facet of expression. Unlike many effects, which are switched on, and forgotten about, the wah can be ‘played’ like an extension of the instrument. Just listen to Hendrix to hear how much this can add to a performance…

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