Distorting a guitar signal generates more harmonics. With more harmonics, your amplifier’s inherent tone becomes more dominant. Unlike a tree falling in the woods, a pedal won’t make a


Distorting a guitar signal generates more harmonics. With more harmonics, your amplifier’s inherent tone becomes more dominant.

Unlike a tree falling in the woods, a pedal won’t make a sound unless an amplifier is there to amplify it. (If no one is there to hear the amplifier, that’s a different philosophical discussion entirely.) This may seem a bit obvious, but when we talk of a pedal’s tone we need to discuss it in the context of a particular rig. This is particularly relevant when discussing overdrive, distortion, and fuzz pedals.

In a typical rig, the signal goes from guitar to pedals to amplifier. As the last item in the chain, the amplifier has a great deal of say in the matter of tone. Your amp acts as a “mastering suite” to your pedals, complete with EQ and dynamics, and the results can vary greatly— not only from amp to amp, but within a single amp, depending on the control settings.

When you run your guitar through a dirt pedal, harmonics are generated as the signal gets distorted. Higher gain or more distortion results in more harmonics. With more harmonics, the tone of your amplifier becomes more dominant. To make some sense of this, let’s look at playing an A power chord with no dirt. After the initial strum, the strings’ natural vibration quickly decays to a few harmonics that are much quieter than the fundamental frequencies, which would be 110 Hz and 165 Hz. There would be no appreciable harmonic content above 1 kHz in your “clean” power chord, so your amplifier’s response at 2 kHz doesn’t matter. That same power chord, after running through a fuzz box, will contain a host of appreciable harmonics that extend well beyond 2 kHz, making your amplifier’s response at 2 kHz very important.

Overdrive pedals have lower gain than fuzz pedals—hence fewer harmonics—but many still have distinctive EQ properties. The low frequencies are reduced before clipping for a “tighter” low end, and the high frequencies are reduced after the clipping to create a smoother overdrive. This creates a characteristic “mid hump,” which is really a high and low trough. Not coincidentally, many Fender blackface amps have a “scooped” clean tone, lacking in strong mids, but full of strong lows and sparkling highs. This clean response makes for great chords and rhythm tones, but can be on the thin side for soulful blues soloing. When an overdrive with the mid hump is added for soloing, it’s a match made in blues heaven. This same overdrive in front of a mid-heavy amp may be less satisfying.

Similarly, fuzz pedals that have an extended high- and low-frequency response were originally paired up with Marshall amps that had a famously strong midrange. Place this same fuzz pedal in front of the bright channel of a Fender blackface amp and it might sound thin or buzzy. So when you talk about the tone of your pedal, you’re also talking about your amplifier’s tonestack frequency response, output transformer, speaker, feedback topology, and more. Early dirt pedal designs were made to purposely complement the tonal characteristics of a particular amp. While many newer dirt pedals allow for a higher degree of tone sculpting, they are still subject to variation based on the amplifier they are running into.

So how do you decide what dirt pedal is right for your amp? Generally, the right pedal will have a strong frequency response in areas that your amp is lacking, and vice versa. Ultimately, this is best determined by trial and error. Borrow a friend’s pedal to see how it sounds in your rig, or get suggestions from people who have the same amp as you. If you try out a pedal in a store, try to play through the same amp that you have. As always, you’re the final judge on tone. Have fun playing in the dirt!

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Let’s take a look at the basics and break down some of the mystery of the flanger.


Block diagram of a flanger pedal.

LFO curves: With a low width setting, the manual knob determines the filter/pitch nature of the flange effect. With a high width setting, the width sweeps through filter and pitch effects, and the manual setting has only a small influence.

As sonic chameleons, flangers can create lush chorus sounds, airy harmonic textures, moody frequency swirls, sweeping jet-airplane swooshes, seasick pitch warbles, or sci-fi ray-gun blasts. However, if you don’t have an understanding of what the pedal is actually doing, this tweakability can lead to frustration when you try to dial in a particular sound. Let’s take a look at the basics and break down some of the mystery.

First, a little history. The flanging effect originated from a studio trick involving two synchronized tape reels playing identical source material. The second reel was forced out of sync by applying pressure to the tape-guide “flange,” creating a varying delay relative to the unmolested first reel. When the two signals were combined, it produced a dramatic and chaotic sweeping effect. The introduction of bucket-brigade-delay (BBD) chips in the ’70s opened the door to capture this same effect in a stompbox, with the BBD chip taking the place of the “flanged” tape machine.

A low-frequency oscillator (LFO) replicates the varying delay time of the flanged deck. A typical flanger pedal has four knobs, and three of them—speed (or rate), width (range or depth), and manual—are related to the LFO (see the flanger pedal block diagram at right).

So what’s up with the fourth knob? The regen (intensity or enhance) knob feeds some of the delay output back into the input. This control may have originally been added to compensate for the fact that the studio tape flanger trick could produce some extreme sounds by speeding up the flanged deck ahead of the original signal (creating what’s sometimes called a “negative delay”), and then slowing it down to pass through zero delay time, whereas the pedal can only delay the signal by positive amounts. The regen knob doesn’t produce this particular sound, but it intensifies the flanging effect and adds a bunch of sonic possibilities. Later pedals obtained the “through-zero” effect of actual tape reels by adding a short delay in line with the input signal, but we’ll save that for another discussion.

The typical delay range of a flanger is about 0.5–10 ms. These delay times are heard as filter effects at the shorter end of the range (because frequency rises as delay times get shorter), and pitch effects (chorusing) at the longer times when combined with the input signal. This is the nature of comb filtering, which is what happens when a delayed version of a signal is added to itself. The three LFO controls determine how fast (speed), how much (width), and in what delay region (manual) the modulation occurs.

From a technical standpoint, the width knob sets the LFO amplitude, and the manual knob sets the LFO offset. Note that, as the width is increased, the manual control becomes less effective. When the width is at maximum, then the entire region of delay times is being used, so the manual control doesn’t do anything. At the other extreme— with width at zero—there is no oscillation, just a fixed delay time that is adjusted by the manual control, which allows a physical sweep of the entire delay range.

With this information in mind, we can formulate some general ideas about how to craft particular sounds. Below are some starting points to help you explore the diverse sounds that a flanger is capable of. To add more variables into the mix, the LFO sweep shapes can be linear or logarithmic, depending on the flanger—and some flangers allow polarity changes on the feedback. Luckily, the same basic principles still apply.

Chorus-like sounds: A chorus doesn’t have any regeneration, so set the regen to minimum. Set manual to its lowest setting for long delay times. Keep the width low, but not at minimum. (Remember, if the width is at minimum, the LFO is not oscillating—hence, there will be no modulation sounds.) If the effect is too pitchy, try reducing the width or the speed.

Jet flyby: Set a moderate speed. Turn the manual to halfway and crank up regen. Set width to the desired sweep range, then adjust manual to dial in the sweep region to taste.

Auto-wah: Set a reasonably fast speed and keep width low to stay in a limited region of delay times. Add some regen to enhance the filter resonance. Then, experiment with the manual control to tune the auto-wah frequencies.

Classic flanger sweep: A moderate speed with maximum width allows the delay line to sweep from the lowest to highest delay times, thus showcasing the underlying character of the flanger. Add some regen to taste.

Resonant filter: Set width to zero to “freeze” the LFO. Add a generous amount of regen to increase the resonance, and turn the manual knob to dial in the filter frequency.

Freq out: Set all controls to maximum. (As we mentioned earlier, with width at maximum, the position of the manual control is irrelevant.)

With this knowledge and a little practice, you should now be able to use your flanger to dial in a lot of different sounds with authority. And don’t forget the value of experimenting—turn knobs, play guitar, and have fun!

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