Fun With Fixed Filters

Fixed, cocked and locked, parked, cracked - regardless of what you call it, a stationary wah can be a  terrific tonal tool

By Phil O'Keefe

This is an article about wah wah pedals, but we're not going to go too far into discussing the traditional uses - you're going to have to figure out how to get funky with a wah on your own. Instead, let's take a look at a less frequently discussed use for wah pedals, but one that has nevertheless been used by many musicians: the parked wah.

First of  all, let's review what a wah is and how it works….

A wah pedal is basically a sweepable resonant filter that boosts the signal in a narrow frequency range. The center frequency can be adjusted or "swept" by moving the pedal's treadle. Essentially this resonant filter is a type of tone control, with a rather large boost applied to a fairly narrow range of the frequency spectrum.  The player can change the frequencies that are boosted by adjusting the pedal on the wah. (Fig. 1) The degree to which frequencies to either "side" of the center frequency are affected - in other words, the bandwidth of the affected frequencies, is known as the Q. While some wah pedals offer adjustable bandwidth or Q controls, this is pre-set in many models.

In short, what a wah does is to boost a narrow range of frequencies, kind of like a super-strong, narrow bandwidth tone control… heel down will emphasize low frequencies, and toe-down will emphasize the treble range.

Figure 1: By adjusting the position of the wah's pedal, such as the one on this Dunlop Crybaby, a player can sweep the wah's boosted resonant frequency

IN USE

Using a wah as a fixed filter is simplicity itself.

• Engage the wah
• Slowly move the treadle to adjust the boosted frequency until you hear a tone you like
• Stop moving the treadle, remove your foot and leave the pedal "fixed" in that location
• Play normally

Fixed wah is at least as useful as swept, funky "wacka-wah" techniques that rely on nearly unceasing movements of the pedal, and has been used on a surprising number of recordings. Instead of the sweeping "movement" associated with traditional wah pedal use, the pedal functions as more of a static tone modifier and narrow-band, variable frequency boost.

GEAR OPTIONS

A few companies have marketed "fixed wah" pedals, including Rocktron's Sweet Spot Fixed Wah, Dunlop's discontinued Q Zone, Wilson Effect's Parked Wah, and the Keeley Nova Wah. These pedals have at least one advantage in that instead of a treadle, a regular knob is used to set the center resonant / boost frequency, so it's easier to mark down and return to your favorite settings with them, but any standard wah pedal will work fine to achieve the basic effect we're after. In fact, the foot treadle of a standard wah pedal has the advantage of allowing you to sweep and adjust the frequency while actually playing and listening to the results in real time, which makes it much easier to zero in on the sound you're after.

Where a treadle based wah is at a disadvantage over a fixed filter pedal like the Q Zone is in bypass and repeatability. Suppose you want to be able to turn the wah off in mid-song for an un-effected tone, and then return to the same tone you used earlier. With most wah pedals, this requires depressing the treadle fully in order to hit the bypass switch, which of course causes you to lose the carefully selected frequency that you dialed up during soundcheck. To get around this, you can insert your wah pedal into a true bypass looper and switcher, such as the one made by Keeley, or the Radial Big Shot EFX Effects Loop. (Fig. 2) This will allow you to leave the wah pedal's treadle alone while still bypassing and removing the wah from the signal path at will.

Figure 2: A true bypass loop pedal such as this Radial Bigshot can be a useful accessory when using a fixed wah as a tonal modifier

TONAL TIPS

On most wah pedals, engaging the wah and moving the treadle to a toe-down position will give you a bright tone with snarling treble emphasis, while the heel-down setting will be much darker sounding. In between are countless variations, depending on where you park the pedal and what the boosted resonant frequency is. Sweeping the pedal from one extreme to the other relatively slowly will allow you to hear the changes to the tone as you sweep the resonant filer across the frequency spectrum from low to high and back again. When you find something you like the sound of - stop! Leave the pedal there. I like to listen for and select frequencies that complement the other things that are going on in the song, but that do so without interfering with them. The fixed filter guitar tone will pretty much "own" whatever frequency it is set to, and dominate that frequency range in a mix, so you should try to avoid using frequencies that step on the snare drum or lead vocalist. A parked wah does have some vocal-like qualities when set towards the middle of the wah's sweep range, so while a wah used like this can help give you a focused sound that will help cut through a dense mix, you want to keep it musical and avoid stepping on the other musical parts.

EXAMPLES

Parked wah has been used on many famous recordings. Whole Lotta Love by Led Zeppelin, Money For Nothing by Dire Straits, Down by 311, and Killer Queen by Queen are just a few examples. Mick Ronson also used it extensively on David Bowie's The Rise and Fall of Ziggy Stardust and The Spiders From Mars album. Michael Schenker was also well known for his use of a parked wah. It can be clearly heard on songs such as UFO's Rock Bottom. Billy Duffy of The Cult and Josh Homme of Queens Of The Stone Age are also fond of the technique.

In fact, parked wah pedals are often used as a tone shaping tool or layer in multitracked guitar arrangements by a wide range of players in the studio. You might be surprised by just how many records it has been used on.  It can also be a useful tonal tool for live use as well. The next time you need a different tone in the studio, or you're trying to be heard through a wall of drums and bass on stage, try hitting the wah, sweeping the pedal until you find a hole - the boost will help you blast through it.   

Phil O'Keefe is a multi-instrumentalist, recording engineer / producer and the Associate Editor of Harmony Central. He has engineered, produced and performed on countless recording sessions in a diverse range of styles, with artists such as Alien Ant Farm, Jules Day, Voodoo Glow Skulls, John McGill, Michael Knott and Alexa's Wish. He is a former featured monthly columnist for EQ magazine, and his articles and product reviews have also appeared in Keyboard, Electronic Musician and Guitar Player magazines.